Federal Motor Vehicle Safety Standards; FMVSS No. 305a Electric-Powered Vehicles: Electric Powertrain Integrity Global Technical Regulation No. 20, Incorporation by Reference, 26704-26754 [2024-07646]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety
Administration
49 CFR Part 571
[Docket No. NHTSA–2024–0012]
RIN 2127–AM43
Federal Motor Vehicle Safety
Standards; FMVSS No. 305a ElectricPowered Vehicles: Electric Powertrain
Integrity Global Technical Regulation
No. 20, Incorporation by Reference
National Highway Traffic
Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Notice of proposed rulemaking
(NPRM).
AGENCY:
Consistent with a Global
Technical Regulation on electric vehicle
safety, NHTSA proposes to establish
Federal Motor Vehicle Safety Standard
(FMVSS) No. 305a to replace FMVSS
No. 305, ‘‘Electric-powered vehicles:
Electrolyte spillage and electrical shock
protection.’’ Among other
improvements, FMVSS No. 305a would
apply to light and heavy vehicles and
would have performance and risk
mitigation requirements for the
propulsion battery. Relating to a
National Transportation Safety Board
recommendation, FMVSS No. 305a
would also require manufacturers to
submit standardized emergency
response information for inclusion on
NHTSA’s website that would assist first
and second responders handling electric
vehicles.
DATES: Comments should be submitted
no later than June 14, 2024.
Proposed compliance date: We
propose that the compliance date for the
proposed requirements be two years
after the date of publication of the final
rule in the Federal Register. Smallvolume manufacturers, final-stage
manufacturers, and alterers would be
provided an additional year to comply
with the rule beyond the date identified
above. We propose to permit optional
early compliance with the rule. After
FMVSS No. 305a is finalized, NHTSA
intends to sunset FMVSS No. 305.
ADDRESSES: You may submit comments
identified by the docket number in the
heading of this document or by any of
the following methods:
• Federal eRulemaking Portal: Go to
https://www.regulations.gov. Follow the
instructions for submitting comments
on the electronic docket site by clicking
on ‘‘Help’’ or ‘‘FAQ.’’
• Mail: Docket Management Facility.
M–30, U.S. Department of
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SUMMARY:
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Transportation, 1200 New Jersey
Avenue SE, West Building, Ground
Floor, Room W12–140, Washington, DC
20590.
• Hand Delivery: U.S. Department of
Transportation, 1200 New Jersey
Avenue SE, West Building, Ground
Floor, Room W12–140, Washington, DC
20590 between 9 a.m. and 5 p.m.
Eastern Time, Monday through Friday,
except Federal Holidays.
• Fax: 202–493–2251.
Instructions: All submissions must
include the agency name and docket
number. Note that all comments
received will be posted without change
to https://www.regulations.gov, including
any personal information provided.
Please see the Privacy Act discussion
below. We will consider all comments
received before the close of business on
the comment closing date indicated
above. To the extent possible, we will
also consider comments filed after the
closing date.
Docket: For access to the docket to
read background documents or
comments received, go to
www.regulations.gov at any time or to
1200 New Jersey Avenue SE, West
Building Ground Floor, Room W12–140,
Washington, DC 20590, between 9 a.m.
and 5 p.m., Monday through Friday,
except Federal Holidays. Telephone:
202–366–9826.
Confidential Business Information: If
you claim that any of the information in
your comment (including any additional
documents or attachments) constitutes
confidential business information
within the meaning of 5 U.S.C. 552(b)(4)
or is protected from disclosure pursuant
to 18 U.S.C. 1905, please see the
detailed instructions given under the
Public Participation heading of the
SUPPLEMENTARY INFORMATION section of
this document.
Privacy Act: In accordance with 5
U.S.C. 553(c), DOT solicits comments
from the public to better inform its
decision-making process. DOT posts
these comments, without edit, including
any personal information the
commenter provides, to
www.regulations.gov, as described in
the system of records notice (DOT/ALL–
14 FDMS), which can be reviewed at
www.transportation.gov/privacy. In
order to facilitate comment tracking and
response, we encourage commenters to
provide their name, or the name of their
organization; however, submission of
names is completely optional. Whether
or not commenters identify themselves,
all timely comments will be fully
considered.
For
technical issues, you may contact Ms.
FOR FURTHER INFORMATION CONTACT:
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Lina Valivullah, Office of
Crashworthiness Standards; Telephone:
202–366–8786; Email: Lina.Valivullah@
dot.gov; Facsimile: (202) 493–2739. For
legal issues, you may contact Ms. K.
Helena Sung, Office of Chief Counsel;
Telephone: 202–366–2992; Email:
Helena.Sung@dot.gov; Facsimile: (202)
366–3820. The mailing address of these
officials is: National Highway Traffic
Safety Administration, 1200 New Jersey
Avenue SE, Washington, DC 20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
II. Background
a. Overview of FMVSS No. 305
b. Overview of GTR No. 20
1. The GTR Process
2. GTR No. 20
III. Proposals Based on GTR No. 20
a. Expanding Applicability of FMVSS No.
305a to Heavy Vehicles
1. Heavy School Buses
2. Heavy Vehicles Other Than School
Buses
i. Request for Comment; Mechanical
Integrity Test
ii. Request for Comment; Mechanical
Shock Test
b. General Specifications Relating To Crash
Testing
1. Low Energy Option for Capacitors
2. Assessing Fire or Explosion in Vehicle
Post-Crash Test
3. Assessing Post-Crash Voltage
Measurements
4. Electrolyte Spillage Versus Leakage
c. REESS Requirements Applicable to All
Vehicles
1. Vehicle Controls for Safe REESS
Operation
i. Overcharge Protection
ii. Over-Discharge Protection
iii. Overcurrent Protection
iv. Over-Temperature Protection
v. External Short-Circuit Protection
vi. Low-Temperature Protection
2. Mitigating Risk of Thermal Propagation
Due to Internal Short Within a Single
Cell in the REESS
i. Safety Need
ii. GTR No. 20 Phase 1 Requirements
iii. NHTSA Proposal
3. Warning Requirements for REESS
Operations
i. Thermal Event Warning
ii. Warning in the Event of Operational
Failure of REESS Vehicle Controls
4. Protection Against Water Exposure
i. NHTSA Proposal
A. Vehicle Washing Test
B. Driving Through Standing Water Test
ii. NHTSA’s Consideration of Submersions
5. Miscellaneous GTR No. 20 Provisions
Not Proposed
i. REESS Vibration Requirements
ii. REESS Thermal Shock and Cycling
iii. REESS Fire Resistance
iv. Low State-of-Charge (SOC) Telltale
IV. Request for Comment on Applying
FMVSS No. 305a to Low-Speed Vehicles
V. Emergency Response Information To
Assist First and Second Responders
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VI. Request for Comment on Placing the
Emergency Response Information and
Documentation Requirements in a
Regulation Rather Than in FMVSS No.
305a
VII. Proposed Compliance Dates
VIII. Rulemaking Analyses and Notices
IX. Public Participation
X. Appendices to the Preamble
Appendix A. Table Comparing GTR No. 20,
FMVSS No. 305, and FMVSS No. 305a
Appendix B. Request for Comment on Phase
2 GTR No. 20 Approaches Under
Consideration by the IWG
I. Executive Summary
NHTSA is issuing this NPRM to
achieve two goals. First, NHTSA
proposes to establish FMVSS No. 305a,
‘‘Electric-powered Vehicles: Electric
Powertrain Integrity,’’ to upgrade and
replace existing FMVSS No. 305.
Proposed FMVSS No. 305a would have
all the requirements of FMVSS No. 305,
but the proposed standard would
expand its applicability to vehicles with
a gross vehicle weight rating (GVWR)
greater than 4,536 kilograms (kg) (10,000
pounds (lb)) and add requirements and
test procedures covering new aspects of
electric vehicle safety, such as the
performance and risk mitigation
requirements for the propulsion battery,
referred to as the Rechargeable Electrical
Energy Storage System (REESS). NHTSA
is also proposing requirements to ensure
first and second responders have access
to vehicle-specific information about
extinguishing REESS fires and
mitigating safety risks associated with
stranded energy 1 when responding to
emergencies. The restructured and
upgraded FMVSS No. 305a will
facilitate future updates to the standard
as battery technologies and charging
systems continue to evolve. After
FMVSS No. 305a is finalized, NHTSA
intends to sunset FMVSS No. 305.
The second goal is to further
NHTSA’s effort to harmonize the
Federal Motor Vehicle Safety Standards
under the Economic Commission for
Europe 1998 Global Agreement (‘‘1998
Agreement’’). The efforts of the U.S. and
other contracting parties to the 1998
Agreement culminated in the
establishment of Global Technical
Regulation (GTR) No. 20, ‘‘Electric
Vehicle Safety.’’ 2 FMVSS No. 305
already incorporates a substantial
portion of GTR No. 20’s requirements
due to a previous NHTSA rulemaking.
In 2017, NHTSA amended FMVSS No.
305 to include electrical safety
requirements from GTR No. 13,
1 Stranded energy is the energy remaining inside
the REESS after a crash or other incident.
2 GTR No. 20, https://unece.org/fileadmin/DAM/
trans/main/wp29/wp29wgs/wp29gen/wp29registry/
ECE-TRANS-180a20e.pdf.
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‘‘Hydrogen and fuel cell vehicles,’’
pertaining to electric vehicle
performance during normal vehicle
operation and post-crash.3 Because GTR
No. 13’s provisions for electric vehicles
were later incorporated into what would
become GTR No. 20, the 2017 final rule
that adopted GTR No. 13’s provisions
adopted what later became many of the
requirements of GTR No. 20. That 2017
rulemaking, however, did not expand
the applicability of FMVSS No. 305 to
include heavy vehicles nor did it
include requirements for the REESS.
This NPRM proposes these and other
GTR No. 20 requirements.
High Level Summary of the Proposal
FMVSS No. 305 currently only
applies to passenger cars and to
multipurpose passenger vehicles,
trucks, and buses with a GVWR of 4,536
kg (10,000 lb) or less (‘‘light vehicles’’).
Consistent with GTR No. 20, proposed
FMVSS No. 305a expands the current
applicability of FMVSS No. 305 to
vehicles with a GVWR greater than
4,536 kg (10,000 lb) (‘‘heavy vehicles’’).
Under proposed FMVSS No. 305a:
• Light vehicles would be subject to
requirements carried over from FMVSS
No. 305 that ensure the safety of the
electrical system during normal vehicle
operations and after a crash (postcrash).4 They would also be subject to
new requirements for the REESS.
• Heavy vehicles would be subject to
the requirements for electrical system
safety during normal vehicle operations
and to requirements for the REESS.
However, except for heavy school buses,
they would not be subject to post-crash
requirements. This proposed exclusion
of heavy vehicles, other than school
buses, from crash tests, aligns with
similar exclusions in FMVSS No. 301,
‘‘Fuel system integrity,’’ for
conventional fuel vehicles and FMVSS
No. 303, ‘‘Fuel system integrity of
compressed natural gas vehicles,’’ for
compressed natural gas vehicles.
• Heavy school buses (GVWRs greater
than 4,536 kg (10,000 lb)) 5 would be
subject to the requirements for electrical
system safety during normal vehicle
3 GTR No. 13 only applied to light vehicles.
Normal vehicle operations include operating modes
and conditions that can reasonably be encountered
during typical operation of the vehicle, such as
driving, parking, standing in traffic with vehicle in
drive mode, and charging. Final rule, 82 FR 44950,
September 27, 2017.
4 Current FMVSS No. 305 light vehicle post-crash
test requirements (front, side, and rear crashes) are
aligned with FMVSS No. 301’s light vehicle postcrash test requirements.
5 In the school bus safety area, stakeholders,
including NHTSA, commonly refer to buses with a
GVWR over 4,536 kg (10,000 lb) as ‘‘large’’ school
buses.
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operations and to the requirements for
the REESS, and would have to meet
post-crash test requirements to ensure
the vehicles protect against
unreasonable risk of electric shock and
risk of fire after a crash. The post-crash
tests are the same tests described in
FMVSS No. 301 for heavy school buses
(impacted at any point and at any angle
by a moving contoured barrier).
The post-crash requirements of
proposed FMVSS No. 305a for light
vehicles and heavy school buses include
electric shock protection (there are four
compliance options—low voltage,
electrical isolation, protective barrier,
and low energy for capacitors 6); REESS
retention; electrolyte leakage; and fire
safety. The requirements for REESS
retention and electrolyte leakage are
already in FMVSS No. 305, but this
NPRM proposes to enhance some
provisions consistent with GTR No. 20.
For example, current FMVSS No. 305
does not specify that there must be no
fire or explosion after a crash test.
Electric vehicles may catch fire long
after a collision or other occurrence
resulting in a fault condition. To
account for the potential delayed
response, NHTSA is proposing to
prohibit fire or explosion for a one-hour
post-test period.
A substantial portion of this NPRM
focuses on safety provisions for the
propulsion battery, the REESS. For what
would be the first time in an FMVSS,
proposed FMVSS No. 305a includes
comprehensive performance
requirements and risk mitigation
strategies for the REESS. These REESS
requirements would apply to all
vehicles, regardless of GVWR. A REESS
provides electric energy for propulsion
and may include necessary ancillary
systems for physical support, thermal
management, electronic controls, and
casings. The proposed requirements set
a level of protection of the REESS
against external fault inputs, ensure the
REESS operations are within the
manufacturer-specified functional
range, and increase the likelihood of
safe operation of the REESS and other
electrical systems of the vehicle during
6 FMVSS No. 305 already includes the first three
compliance options for electrical shock protection
but not the low energy option that is available for
capacitors in GTR No. 20. This NPRM would
complete the alignment by proposing the low
energy option for capacitors in FMVSS No. 305a.
NHTSA had considered this option years ago and
had decided against it. As explained in detail in
sections below, NHTSA has changed its view on the
matter after further considering data and analysis
from the GTR.
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and after water exposure during normal
vehicle operations.7
Proposed FMVSS No. 305a addresses
some aspects of REESS safety through
documentation measures, consistent
with GTR No. 20. ‘‘Documentation
measures’’ means a list of information
provided by manufacturers, at NHTSA’s
request, that demonstrate that they
considered, assessed, and mitigated
identified risks for safe operation of the
vehicle. These proposed documentation
requirements would address: (a) safety
risk mitigation associated with charging
and discharging during low
temperature; (b) the safety risks from
thermal propagation in the event of
single-cell thermal runaway 8 (SCTR)
due to an internal short-circuit of a
single cell; and (c) providing a warning
if there is a malfunction of vehicle
controls that manage REESS safe
operation. The GTR takes a
documentation approach on these
aspects of safety because of the rapidly
evolving electric vehicle technologies
and the variety of available REESS and
electric vehicle designs. The Informal
Working Group experts that drafted the
GTR determined there currently are no
objective test procedures to evaluate
safety risk mitigation designs or the
operations of warnings of a malfunction
of vehicle controls in a manner that is
not design restrictive.
NHTSA tentatively agrees with this
approach given the current state of
knowledge. Thus, until test procedures
and performance criteria can be
developed for all vehicle powertrain
architectures, proposed FMVSS No.
305a would require manufacturers to
submit documentation to NHTSA, at
NHTSA’s request, that identify all
known safety hazards, describe their
risk mitigation strategies for the safety
hazards, and, if applicable, describe
how they provide a warning to address
a safety hazard.9 The purpose of the
documentation approach is two-fold.
Given the variation of battery design
and design specific risk mitigation
systems, the documentation
requirement would be a means of
assuring that each manufacturer has
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7 ‘‘Normal
vehicle operation’’ means situations
such as driving through a pool of standing water or
exposing the vehicle to an automated car wash.
This NPRM does not propose requirements to
address vehicle fires due to vehicle submersions in
floods and storm surges, as GTR No. 20 does not
have specific requirements to address this area.
NHTSA is researching this latter area.
8 Thermal runaway means an uncontrolled
increase of cell temperature caused by exothermic
reactions inside the cell.
9 Section 30166 of the Vehicle Safety Act
authorizes the Secretary of Transportation (NHTSA
by delegation) the ability to request and inspect
manufacturer records that are necessary to enforce
the prescribed regulations.
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identified safety risks and safety risk
mitigation strategies. The requirement
provides a means for NHTSA to learn of
the risks associated with the REESS,
understand how the manufacturer is
addressing the risks, and oversee those
safety hazards. This approach is battery
technology neutral, not design
restrictive, and is intended to evolve
over time as battery technologies
continue to rapidly evolve. It is an
interim measure intended to assure that
manufacturers will identify and address
the safety risks of the REESS until such
time objective performance standards
can be developed that can be applied to
all applicable REESS designs. NHTSA
would also acquire information from the
submissions to learn about the safety of
the REESS and potentially develop the
future performance standards for
FMVSS No. 305a. The proposed
documentation requirements are based
on the approach of GTR No. 20, but
NHTSA proposes to focus the GTR’s
documentation requirements to enable
the agency to obtain more targeted
information from manufacturers.10
As part of NHTSA’s battery
initiative 11 and in response to a 2020
NTSB recommendation,12 this NPRM
proposes to include in FMVSS No. 305a
a requirement that vehicle
manufacturers submit to NHTSA
emergency response guides (ERGs) and
rescue sheets for each vehicle make,
model, and model year. The purpose of
the requirement is to provide
information to first 13 and second 14
responders regarding the safe handling
of the vehicle in emergencies and for
towing and storing operations. The
uploaded ERGs and rescue sheets would
be publicly available on NHTSA’s
website for easy searchable access. ERGs
and rescue sheets communicate vehiclespecific information related to fire,
10 Given the proposed documentation
specifications are more akin to disclosure
requirements that could be issued under general
NHTSA regulation rather than pursuant to an
FMVSS with specified test procedures, the agency
also requests comment on whether the proposed
documentation requirements would be better
placed in a general agency regulation than in the
proposed FMVSS No. 305a.
11 https://www.nhtsa.gov/battery-safety-initiative.
12 ‘‘Safety risks to emergency responders from
lithium-ion battery fires in electric vehicles,’’ Safety
Report NTSB/SR–20/01, PB2020–101011, National
Transportation Safety Board, https://www.ntsb.gov/
safety/safety-studies/Documents/SR2001.pdf.
13 ‘‘First responder’’ means a person with
specialized training such as a law enforcement
officer, paramedic, emergency medical technician,
and/or firefighter, who is typically one of the first
to arrive and provide assistance at the scene of an
emergency.
14 ‘‘Second responder’’ means a worker who
supports first responders by cleaning up a site,
towing vehicles, and/or returning services after an
event requiring first responders.
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submersion, and towing, as well as the
location of components in the vehicle
that may expose the vehicle occupants
or rescue personnel to risks, the nature
of a specific function or danger, and
devices or measures which inhibit a
dangerous state.
NHTSA would require standardized
formatting of the information. The ERG
and rescue sheet requirements would
meet the layout and format specified in
ISO–17840, ‘‘Road vehicles—
Information for first and second
responders,’’ which standardize colorcoded sections in a specific order to
help first and second responders
quickly identify pertinent vehiclespecific rescue information. The
standardized information would be
available and understandable to first
and second responders so they can
easily refer to vehicle-specific rescue
information en route to or at the scene
of a crash or fire event and respond to
the emergency quickly and safely.
NHTSA believes there are no notable
costs associated with this NPRM. This
proposal closely mirrors the electrical
safety provisions of GTR No. 20, which
have been voluntarily implemented by
manufacturers in this country. The
agency believes that the proposed safety
standards are widely implemented by
manufacturers of light and heavy
electric vehicles and heavy electric
school buses. Manufacturers are also
already providing emergency response
information to the National Fire
Protection Association (NFPA); under
proposed FMVSS No. 305a they would
just have to standardize the format and
submit the information to NHTSA.15
Lastly, current FMVSS No. 305 does
not apply to vehicles that travel under
40 km/h (25 mph), such as low-speed
vehicles.16 Given there are low-speed
vehicles that are also electric-powered
vehicles, NHTSA requests comments on
the possibility of applying aspects of
FMVSS No. 305a to low-speed vehicles
to ensure a level of protection against
shock and fire, particularly during
normal vehicle operation, and to assure
the safe operation of the REESS.
II. Background
a. Overview of FMVSS No. 305
The purpose of FMVSS No. 305,
‘‘Electric-powered vehicles: electrolyte
15 Similar to the issue discussed above regarding
having the proposed documentation requirements
in a general regulation rather than in FMVSS No.
305a, the agency also requests comment on whether
the proposed ERG and rescue sheet requirements
would be better placed in a general agency
regulation than in proposed FMVSS No. 305a.
16 ‘‘Low-speed vehicle’’ is defined in 49 CFR
571.3. See also FMVSS No. 500, ‘‘Low speed
vehicles,’’ 49 CFR 500.
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spillage and electrical shock
protection,’’ is to reduce deaths and
injuries from electrical shock. The
standard applies only to light vehicles
(vehicles with a GVWR less than or
equal to 4,536 (kg) (10,000 (lb)). The
standard’s requirements reduce the risk
of harmful electric shock: (a) during
normal vehicle operation; 17 and (b) in
post-crash situations (to protect vehicle
occupants, and rescue workers and
others who may come in contact with
the vehicle after a crash). The standard’s
requirements for the former protect
against direct and indirect contact of
high voltage sources during everyday
operation of the vehicles. The focus of
this ‘‘in-use’’ testing (unlike ‘‘postcrash’’ testing, discussed below) deals
with performance criteria that would be
assessed without first exposing the
vehicle to a crash test.
Normal Vehicle Operations. FMVSS
No. 305 requires vehicles to provide the
following measures to protect against
electric shock during normal vehicle
operations. Vehicles must prevent direct
contact of high voltage sources (those
operating with voltage greater than 30
VAC or 60 VDC) 18; prevent indirect
contact of high voltage sources;
electrically isolate high voltage sources
from the electric chassis (500 ohms/volt
or higher for alternating current (AC)
and 100 ohms/volt or higher for direct
current (DC) sources); mitigate risk of
driver error (indicate to the driver when
the vehicle is in possible active driving
mode at startup and when the driver is
leaving the vehicle, and prevent vehicle
movement by its own propulsion system
when the vehicle charging system is
connected to the external electric power
supply).
Post-Crash Protections. For post-crash
protections, FMVSS No. 305 requires
vehicles to meet the following
provisions during and after the crash
tests specified in the standard. FMVSS
No. 305 limits electrolyte spillage from
propulsion batteries and requires the
REESS to remain attached to the vehicle
and not enter the passenger
compartment. The standard requires
that during and after a crash test, high
voltage sources in a vehicle must be
either electrically isolated from the
17 Normal vehicle operation includes operating
modes and conditions that can reasonably be
encountered during typical operation of the vehicle,
such as driving, parking, and standing in traffic, as
well as charging using chargers that are compatible
with the specific charging ports installed on the
vehicle. It does not include conditions where the
vehicle is damaged, either by a crash or road debris,
subjected to fire or water submersion, or in a state
where service and/or maintenance is needed or
being performed.
18 VAC—volts of alternating current; VDC—volts
of direct current.
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vehicle’s chassis; of a voltage below
specified levels considered safe from
electric shock hazards; or prevented
from direct or indirect contact by
occupants or emergency services
personnel by use of physical barriers.
The standard specifies that the postcrash requirements must be met after
crash tests involving: a frontal impact
up to and including 48 kilometer per
hour (km/h) (30 mile per hour (mph))
into a fixed collision barrier; an impact
of a moving barrier at 80 km/h (50 mph)
into the rear of the vehicle; an impact
of a moving barrier at 53 km/h (33 mph)
into the side of the vehicle; and under
static rollover conditions after each such
impact.
FMVSS No. 305 already has many of
GTR No. 20’s requirements for light
vehicles, including requirements for
electrical safety during normal vehicle
operation; post-crash electrolyte
spillage; post-crash REESS retention;
and most of the GTR’s post-crash
electrical safety options for high voltage
sources.
b. Overview of GTR No. 20
1. The GTR Process
The United States is a contracting
party to the ‘‘1998 Agreement’’ (the
Agreement concerning the Establishing
of Global Technical Regulations for
Wheeled Vehicles, Equipment and Parts
which can be fitted and/or be used on
Wheeled Vehicles). This agreement
entered into force in 2000 and is
administered by the UN Economic
Commission for Europe’s (UN ECE’s)
World Forum for the Harmonization of
Vehicle Regulations (WP.29). The
purpose of this agreement is to establish
Global Technical Regulations (GTRs).
In March 2012, UNECE WP.29
formally adopted the proposal to
establish GTR No. 20 at its onehundred-and-fifty-eighth session.
NHTSA chaired the development of
GTR No. 20 and voted in favor of
establishing GTR No. 20.
As a Contracting Party Member to the
1998 Global Agreement who voted in
favor of GTR No. 20, NHTSA is
obligated to initiate the process used in
the U.S. to adopt the GTR as an agency
regulation. By issuing this NPRM,
NHTSA is initiating the process to
consider adoption of GTR No. 20. As
noted above, under the terms of the
1998 Agreement, NHTSA is not
obligated to adopt the GTR after
initiating this process. In deciding
whether to adopt a GTR as an FMVSS,
NHTSA follows the requirements for
NHTSA rulemaking, including the
Administrative Procedure Act, the
National Traffic and Motor Vehicle
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Safety Act (Vehicle Safety Act),
Presidential Executive Orders, and DOT
and NHTSA policies, procedures, and
regulations. Among other things,
FMVSSs issued under the Vehicle
Safety Act ‘‘shall be practicable, meet
the need for motor vehicle safety, and be
stated in objective terms.’’ 19
2. GTR No. 20
GTR No. 20 establishes performanceorientated requirements that reduce
potential safety risks of electric vehicles
(EVs) while in use and after a crash
event. The GTR includes provisions that
address electrical shock associated with
high voltage circuits of EVs and
potential hazards associated with
lithium-ion batteries and/or other
REESS. One of the principles for
developing GTR No. 20 was to address
unique safety risks posed by electric
vehicles and their components to ensure
a safety level equivalent to conventional
vehicles with internal combustion
engines.
The requirements in GTR No. 20 were
developed in Phase 1 of the GTR. GTR
No. 20 was developed in phases due to
the differing stages at which
technologies have been developed and
evaluated. The informal working group
(IWG) that developed the GTR
determined that Phase 1 would address
issues relating to the safe operation of
the rechargeable electrical energy
storage system (REESS), and for
mitigating risks of fire and other safety
risks associated with the REESS. In
Phase 2, which is on-going, the IWG is
addressing issues involving long-term
research and verification.20 This NPRM
pertains to the adoption of the GTR as
developed in Phase 1.
GTR No. 20 applies to all electricpowered vehicles regardless of GVWR,
in contrast to FMVSS No. 305, which
only applies to light vehicles. FMVSS
No. 305 currently includes the majority
of GTR No. 20’s requirements and
applies these to light vehicles. GTR No.
20 also has safety requirements for the
REESS beyond those in FMVSS No. 305.
These additional requirements in GTR
No. 20 for the REESS include:
• Safe operation of REESS under the
following exposures during normal
vehicle operations:
Æ REESS protection under external
fault conditions and extreme operating
temperatures:
—External short circuit
—Overcharge
—Over-discharge
19 49
U.S.C. 30111.
Appendix B to this preamble, NHTSA
requests comments on some issues under
development in Phase 2.
20 In
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—Overcurrent
—High operating temperature
—Low operating temperature
Æ Management of REESS emitted gases
Æ Water exposure during vehicle
washing and driving through 10centimeter (cm) deep water on
roadway.
Æ Thermal shock and cycling (¥40 °C to
60 °C) * 21
Æ Resistance to short duration external
gasoline pool fire *
Æ Vibration environment during normal
vehicle operations *
• Warning systems for REESS safe
operation in case of:
Æ Low energy content in REESS * 22
Æ REESS control operational failure
Æ Thermal runaway propagation due to
single cell short circuit in REESS
Æ Thermal event in REESS
• Installation (location) of REESS on the
vehicle 23
This NPRM proposes to complete the
alignment of FMVSS No. 305 with GTR
No. 20 by extending the standard’s
electrical safety requirements to heavy
vehicles. This NPRM also proposes to
adopt the above requirements for the
REESS to light and heavy vehicles,
except as noted by an asterisk, because
requirements for thermal shock and
cycling, resistance to short duration
external pool fire, and vibration
environment are already included under
United States Hazardous Materials
Regulations (HMR), 49 CFR parts 171 to
180, in accordance with the
international lithium battery
transportation requirements of UN 38.3,
‘‘Transport of dangerous goods: Manual
of tests and criteria.’’ To avoid
redundancy, NHTSA is not proposing
adding these requirements into FMVSS
No. 305a. NHTSA explains the bases for
the proposals and, for provisions not
proposed, the reasons the agency has
not proposed them in this NPRM.
GTR No. 20 includes post-crash
requirements but does not specify the
crash tests for post-crash evaluation.
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21 The
asterisk notes that this NPRM is not
proposing to adopt the GTR No. 20 requirement.
22 This NPRM does not propose to require a
warning for low energy in REESS. There is no such
warning requirement for conventional fuel vehicles
in the event of low-fuel, yet all conventional fuel
vehicles have a low fuel indicator because it is a
consumer convenience feature. The agency expects
that, similarly, a low energy in REESS indicator will
be voluntarily provided in all electric-powered
vehicles.
23 This requirement is intended for countries with
type approval systems where a generic REESS can
be approved separate from the vehicle. A vehicle
with a pre-approved REESS that complies with the
REESS installation requirement would not have to
undergo post-crash safety assessment for approval.
This installation requirement would not apply in
the U.S. with a self-certification system.
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Instead, the GTR allows contracting
parties to apply the crash tests in their
regulations. Further, the GTR allows
contracting parties to permit regulated
entities to comply with post-crash
requirements without conducting
vehicle crash tests. In place of crash
tests, a contracting party may specify
tests for ‘‘mechanical integrity’’ and
‘‘mechanical shock’’ of the REESS. The
mechanical integrity test uses a quasistatic load of 100 kN on the REESS to
evaluate the safety performance of the
REESS under contact loads that may
occur during vehicle crash. The
mechanical shock test accelerates the
REESS on a sled system to evaluate the
safety performance of the REESS and
the integrity of the REESS mounting
structures to the vehicle under inertial
loads that may occur. NHTSA discusses
its assessment of the component level
mechanical integrity and mechanical
shock test procedures and requests
comment on these issues later in this
NPRM.
III. Proposals Based on GTR No. 20
a. Expanding Applicability of FMVSS
No. 305a to Heavy Vehicles
NHTSA proposes to harmonize the
application of FMVSS No. 305a with
GTR No. 20. Currently, FMVSS No. 305
applies to electric-powered vehicles
with a GVWR less than or equal to 4,536
kg (10,000 lb); it does not apply to
electric vehicles with a GVWR greater
than 4,536 kg (10,000 lb). GTR No. 20
applies to both light and heavy electric
vehicles. NHTSA proposes to apply
FMVSS No. 305a to both light and
heavy electric vehicles. The
fundamentals for protecting against an
electrical shock for light vehicles are the
same as for heavy vehicles. A failure of
a high voltage system may cause
injurious electric shock to the human
body.
Specifically, NHTSA proposes to
apply FMVSS No. 305a to all passenger
cars, multipurpose passenger vehicles,
trucks, and buses, regardless of their
GVWR, that use electrical propulsion
components with working voltages
greater than or equal to 60 VDC or 30
VAC, and whose speed attainable over
a distance of 1.6 kilometers (km) (1
mile) on a paved level surface is more
than 40 km/h (25 miles per hour
(mph)).24 The NPRM proposes to carry
over the current requirements for light
vehicles in FMVSS No. 305 to FMVSS
No. 305a, except some provisions as
enhanced by this NPRM if adopted by
a final rule. To sum, light vehicles
24 Current FMVSS No. 305 does not apply to these
vehicles that travel under 40 km/h (25 mph).
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would have to meet the requirements for
normal vehicle operations and the
requirements proposed in this NPRM for
the REESS. Further, they would have to
meet requirements for post-crash
protections following a crash test. Under
proposed FMVSS No. 305a, heavy
school buses would have to meet the
requirements for normal vehicle
operations and for the REESS, and,
following a specific crash test,
requirements for post-crash protections.
The agency is not adopting the
provision in GTR No. 20 that conducts
mechanical integrity and mechanical
shock tests (component-level) for light
vehicles and for heavy school buses.
NHTSA believes that post-crash safety is
better evaluated at a system level in a
crash test than in component-level tests.
Currently there are crash tests for light
vehicles and school buses, thus, NHTSA
proposes to conduct post-crash safety
after the specified crash tests.
Heavy vehicles other than heavy
school buses would be subject to the
requirements for normal vehicle
operations described above and the
requirements for the REESS. They
would not be subject to crash testing
requirements because the agency does
not know of a crash test that would be
appropriate for the vehicles at this time.
However, while NHTSA does not have
a sufficient basis to proceed currently
with dynamic or quasi-static
requirements for heavy vehicles other
than school buses, this NPRM requests
comment on this issue. NHTSA is
interested in the merits of componentlevel tests that are representative of
impact loads in heavy vehicle crashes
and the appropriateness of applying the
tests to different weight classes of heavy
vehicles. Even in the absence of postcrash testing requirements, NHTSA
tentatively concludes that meeting
requirements for normal vehicle
operations and for the REESS, as a
starting point, will enhance the safety of
these heavy electric vehicles.
1. Heavy School Buses
NHTSA proposes to distinguish heavy
school buses from other types of heavy
vehicles and subject them to crash
testing because the school vehicles will
be carrying children. This NPRM
proposes to assess the post-crash safety
of heavy school buses (school buses
with a GVWR greater than 4,536 kg
(10,000 lb)) in a dynamic moving
contoured barrier test. This proposal
would be consistent with current school
bus safety standards. FMVSS No. 301,
‘‘Fuel system integrity,’’ and FMVSS
No. 303, ‘‘Fuel system integrity of
compressed natural gas vehicles,’’
require heavy school buses using
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conventional fuel or compressed natural
gas for propulsion, respectively, to
maintain fuel system integrity in a crash
test where a moving contoured barrier
traveling at any speed up to 48 km/h (30
mph) impacts the school bus at any
point and angle. These standards set
this high level of safety for heavy school
buses even though FMVSS Nos. 301 and
303 do not apply to other types of heavy
vehicles.
NHTSA recognizes that FMVSS No.
305 currently does not apply to nor has
a crash test requirement for heavy
school buses. When FMVSS No. 305
was first promulgated in September
2000, NHTSA decided not to apply
proposed FMVSS No. 305 to heavy
school buses. NHTSA made this
decision after agreeing with commenters
that applying the standard to the
vehicles at that time could have
substantial effect, in terms of cost and
weight, on heavy school buses and
potentially restrict further
development.25 The prevailing
technology at that time was a series of
conventional lead-acid batteries as the
energy source for propulsion. Since the
1990s and early 2000s, battery
technology and electric powertrains
have evolved to include nickel metal
hydride and lithium-ion batteries for
electric vehicles. The weight and cost
concerns raised for electric school buses
in 2000 are no longer obstacles with
current lithium-ion battery technologies
because of their high energy density and
their widespread use. Several school
bus manufacturers are currently
manufacturing and offering for sale
heavy school buses with high voltage
electric propulsion systems. Given the
development of the technology and
practicability of designing and
producing heavy electric school buses,
NHTSA tentatively concludes it is
appropriate to adopt requirements to
ensure post-crash safety of heavy
electric school buses and maintain the
current high level of safety of heavy
school buses.
NHTSA is proposing to include in
FMVSS No. 305a a requirement that
heavy school buses with high voltage
electric propulsion systems meet the
requirements for normal vehicle
operations (assessed prior to a crash
test) and the proposed post-crash
electrical safety requirements when
impacted by the moving contoured
barrier specified in FMVSS No. 301. The
crash test requirement would align
FMVSS No. 305a’s requirements for
heavy school buses with those of
FMVSS Nos. 301 and 303. Due to the
number of electric school bus
25 Final
rule, 65 FR 57980, September 27, 2000.
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manufacturers and sales since 2000,
NHTSA tentatively concludes that
meeting the proposed standard would
have no substantial effect on cost and
weight due to widespread use of
lithium-ion battery and conformance to
the proposed post-crash safety
requirements.26
2. Heavy Vehicles Other Than School
Buses
There are currently no heavy vehicle
crash tests in FMVSS. Heavy vehicles
are typically made to order with
different configurations 27 based on the
operational needs of the purchaser and
are produced in low volume.
Conducting crash tests of various design
configurations from a small volume of
representative vehicles would be cost
prohibitive. There could also be
practicability constraints for conducting
crash tests on higher weight classes of
heavy vehicles.
In this NPRM, NHTSA has proposed
requirements to ensure post-crash safety
using full vehicle crash tests for light
vehicles and heavy school buses. Such
full vehicle crash tests evaluate postcrash safety at a system level, so NHTSA
is not considering component-level tests
of the REESS for those vehicles.
However, since there are no full vehicle
crash tests currently in FMVSSs for
heavy vehicles (other than heavy school
buses), NHTSA seeks comment on
considerations for component-level tests
(other than the mechanical integrity and
mechanical shock tests in GTR No. 20)
that are representative of impact loads
in heavy vehicle crashes and that can be
applied to different weight classes of
heavy vehicles.
i. Request for Comment; Mechanical
Integrity Test
There are currently no crash tests
specified in the FMVSSs 28 for
evaluating the integrity of the fuel
system or propulsion system of heavy
vehicles other than heavy school buses.
GTR No. 20 provides an option for
26 Currently, all major school bus manufacturers
(Blue Bird, IC Bus, Thomas Built) are offering large
and small electric school buses (see AFDC-electric
school bus) and many school districts have
introduced electric powered school buses in their
fleets. As of June 2023, there are 2,277 electric
school buses that are either on order, delivered or
operating in the U.S. In total, there are now 5,982
committed electric school buses in the U.S. https://
www.wri.org/insights/where-electric-school-busesus#:∼:text=As%20of%20June%202023
%2C%20there,more%20buses%20since
%20June%202022.
27 These differences include the number of fuel
containers and battery packs and the location and
attachment of fuel lines and fuel containers.
28 FMVSS No. 301, ‘‘Fuel system integrity,’’ and
FMVSS No. 303, ‘‘Fuel system integrity of
compressed natural gas vehicles,’’ only applies to
light vehicles and to heavy school buses.
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26709
evaluating post-crash safety of light
vehicles by way of a mechanical
integrity test (crush test) of the REESS
as an item of vehicle equipment, instead
of a full vehicle crash test as in FMVSS
No. 305. The loads in the mechanical
integrity requirements in the GTR No.
20 were derived from REESS contact
loads measured in light passenger
vehicle crash tests per UN Regulations
ECE R. No. 12, ‘‘Uniform provisions
concerning the approval of vehicles
with regard to the protection of the
driver against the steering mechanism in
the event of impact,’’ ECE R.94,
‘‘Uniform provisions concerning the
approval of vehicles with regard to the
protection of the occupants in the event
of a frontal collision,’’ and ECE R.95,
‘‘Uniform provisions concerning the
approval of vehicles with regard to the
protection of occupants in the event of
a lateral collision,’’ using electric and
hybrid-electric vehicles available on the
market.
In the mechanical integrity test, a
quasi-static load is applied to the
charged REESS 29 along with any
subsystem components (including crush
protection systems specified by the
manufacturer) along the longitudinal
axis of the vehicle (along the direction
of vehicle travel) or the lateral axis
(perpendicular to the longitudinal axis).
A peak load of 100 kN is applied within
3 minutes and maintained for at least
100 milliseconds. During the integrity
test, the REESS is required to have no
evidence of electrolyte leakage, fire, or
explosion. The REESS is required to
have electric isolation of at least 100
ohms/volt or provide protection level
IPXXB against direct contact of high
voltage sources.30
Because there are no full vehicle crash
tests currently in FMVSSs for heavy
vehicles (other than heavy school
buses), NHTSA seeks comment on a
mechanical integrity test for REESS on
heavy vehicles to evaluate post-crash
safety at a component-level. As noted
above, the current quasi-static loads of
the integrity test specified in GTR No.
20 are specific to light vehicles. NHTSA
seeks comment on the parameters for a
29 The REESS is charged to 95 percent state-ofcharge for REESS designed to be externally charged
and charged to no less than 90 percent of state-ofcharge for REESS designed to be charged only by
an energy source on the vehicle.
30 IPXXB and IPXXD ‘‘protection levels’’ refer to
the ability of the physical barriers to prevent
entrance of a probe into the enclosure, to ensure no
direct contact with high voltage sources. ‘‘IPXXB’’
is a probe representing a small human finger.
‘‘IPXXD’’ is a slender wire probe. Protection degrees
IPXXD and IPXXB are International
Electrotechnical Commission specifications for
protection from direct contact of high voltage
sources.
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possible quasi-static crush test for the
REESS on heavy vehicles.31 The agency
requests feedback on the merits of the
integrity test in assessing post-crash
safety for heavy vehicle REESS. NHTSA
seeks comment on the practicability of
such a test and on the specifics of
subsystem components that should be
included with the REESS while
conducting the crush test. NHTSA
requests that commenters provide data
to substantiate their assertions.
ii. Request for Comment; Mechanical
Shock Test
NHTSA seeks comment to inform our
research on a mechanical shock test for
REESS on heavy vehicles to evaluate
post-crash safety at a component level.
The aim of the mechanical shock
requirement in GTR No. 20 is to verify
the safety performance of the REESS
under inertial loads which may occur
during an impact. The requirement
evaluates specifically the performance
of the REESS mountings and fixtures to
the vehicle.
The mechanical shock test is
conducted with the REESS along with
any subsystem components installed on
a sled system using the mounting
structures that are used for installing the
REESS to the vehicle. The REESS is
decelerated or accelerated with an
acceleration profile within the
acceleration corridor in Figure 1 and in
accordance with acceleration
magnitudes in Table 1 through Table 3
for different vehicle GVWRs. The test
concludes with an observation period of
one hour at the ambient temperature
conditions of the test environment.
Figure 1—Generic Description of Test
Pulses—Mechanical Shock Test
TABLE 1—MECHANICAL SHOCK TEST—ACCELERATION VALUES FOR VEHICLES WITH A GVWR LESS THAN OR EQUAL TO
3,500 kg (7,716 lbs)
Acceleration (g)
Time
(ms)
Point
A ...................................................................................................................................................
B ...................................................................................................................................................
C ..................................................................................................................................................
D ..................................................................................................................................................
E ...................................................................................................................................................
F ...................................................................................................................................................
G ..................................................................................................................................................
H ..................................................................................................................................................
Longitudinal
20
50
65
100
0
50
80
120
Transverse
0
20
20
0
10
28
28
0
0
8
8
0
4.5
15
15
0
A
B
C
D
...................................................................................................................................................
...................................................................................................................................................
..................................................................................................................................................
..................................................................................................................................................
31 NHTSA’s research evaluated the crush
resistance of REESS using a displacement-based
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Acceleration (g)
Time
(ms)
Point
loading method. See Ford Safety Performance of
Rechargeable Energy Storage Systems, Appendix A,
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Longitudinal
20
50
65
100
0
10
10
0
DOT HS 812 756, July 2019. https://
rosap.ntl.bts.gov/view/dot/41840.
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Transverse
0
5
5
0
EP15AP24.044</GPH>
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TABLE 2—MECHANICAL SHOCK TEST—ACCELERATION VALUES FOR VEHICLES WITH A GVWR GREATER THAN 3,500 kg
(7,716 lbs) AND LESS THAN OR EQUAL TO 12,000 kg (26,455 lbs)
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TABLE 2—MECHANICAL SHOCK TEST—ACCELERATION VALUES FOR VEHICLES WITH A GVWR GREATER THAN 3,500 kg
(7,716 lbs) AND LESS THAN OR EQUAL TO 12,000 kg (26,455 lbs)—Continued
Acceleration (g)
Time
(ms)
Point
E ...................................................................................................................................................
F ...................................................................................................................................................
G ..................................................................................................................................................
H ..................................................................................................................................................
Longitudinal
0
50
80
120
Transverse
5
17
17
0
2.5
10
10
0
TABLE 3—MECHANICAL SHOCK TEST—ACCELERATION VALUES FOR VEHICLES WITH A GVWR GREATER THAN 12,000 kg
(26,455 lbs)
A ...................................................................................................................................................
B ...................................................................................................................................................
C ..................................................................................................................................................
D ..................................................................................................................................................
E ...................................................................................................................................................
F ...................................................................................................................................................
G ..................................................................................................................................................
H ..................................................................................................................................................
ddrumheller on DSK120RN23PROD with PROPOSALS3
During the mechanical shock test, the
REESS is required to have no evidence
of electrolyte leakage, fire, or explosion.
The REESS is required to have electric
isolation of at least 100 ohms/volt or
have protection degree IPXXB.
Since there are no full vehicle crash
tests currently in FMVSSs for heavy
vehicles (other than heavy school buses)
to evaluate post-crash safety at a system
level, NHTSA seeks comment to inform
possible future research on a
mechanical shock test for REESS on
heavy vehicles to evaluate post-crash
safety at a component level. Among
other matters, NHTSA requests
comment on the following apparent
limitations of the GTR test. The
mechanical shock test in GTR No. 20
aims primarily at evaluating the safety
performance of the REESS mounting
fixture, which does not appear to
address a safety need presently observed
in the field.32 Furthermore, the
accelerations captured in the GTR No.
20 for the mechanical shock
requirement may be too low, according
to a technical study performed by the
Transportation Research Laboratory.33
The aim of the technical study was to
review the appropriateness of the crash
32 Under the Vehicle Safety Act, the FMVSSs
must, among other things, be practicable, meet the
need for motor vehicle safety, and be stated in
objective terms. (49 U.S.C. 30111(a).)
33 European Commission, Directorate-General for
Internal Market, Industry, Entrepreneurship and
SMEs, Edwards, M., Hylands, N., Grubor, D., et al.,
Technical study to review the appropriateness of
crash pulses used in current EU legislation: final
report, Section 4.4, Publications Office, 2021,
https://data.europa.eu/doi/10.2873/58935.
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Acceleration (g)
Time
(ms)
Point
pulses used in current European
regulations. This study determined that
the crash pulse requirements in a
number of the EU regulations (including
R67, R100, and R110) are not
representative of current vehicles.
(These are among the reasons NHTSA is
not proposing the mechanical shock test
in GTR No. 20 for heavy vehicles in this
NPRM.)
NHTSA seeks comment on the
relevance of the mechanical shock test
for heavy vehicles. NHTSA seeks
comment on how the mechanical shock
test would be performed on heavy
vehicle REESSs, the appropriate
accelerations levels that would be
representative of acceleration levels
observed in the field or in crash tests,
and appropriate requirements which the
REESS would need to meet in a
mechanical shock test.
NHTSA seeks comment on the best
approach or test method for evaluating
post-crash safety for electric vehicles
with a GVWR greater than 4,536 kg
(10,000 lb). Specifically, NHTSA seeks
comment and recommendations on
other applicable safety tests and
corresponding objective performance
criteria to evaluate the propulsion
system crash safety performance of
vehicles with a GVWR greater than
4,536 kg (10,000 lb). NHTSA seeks
comment on whether the moving
contoured barrier crash test proposed
for heavy school buses in the above
section in this preamble can or should
be applied to all heavy vehicles.
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Longitudinal
20
50
65
100
0
50
80
120
Transverse
0
6.6
6.6
0
4
12
12
0
0
5
5
0
2.5
10
10
0
b. General Specifications Relating To
Crash Testing
This NPRM proposes several general
provisions from GTR No. 20 that would
apply to various testing and
performance requirements. NHTSA
highlights the following proposals
below. These provisions pertain to light
vehicles and heavy school buses subject
to the crash testing requirements of
proposed FMVSS No. 305a.
1. Low Energy Option for Capacitors
Currently, FMVSS No. 305 S5.3
requires that vehicles meet one of the
following three criteria post-crash:
electrical isolation; absence of high
voltage; or physical barrier protection.
This NPRM proposes a low energy
option for capacitors in the electric
powertrain in FMVSS No. 305a.
Capacitors store electrical energy and
may be connected directly to the chassis
in some electric power trains. In fuel
cell electric vehicles (FCEVs), the highvoltage systems may contain capacitors
that are connected to high voltage buses
and are not electrically isolated. Such
capacitors may be high voltage sources
post-crash (because a charged capacitor
may not discharge quickly) and may not
be able to comply with post-crash
electrical safety requirements using the
direct and indirect contact protection
option or the electrical isolation.
However, capacitors may not pose a
safety hazard when contacted, even
though they may be high voltage sources
post-crash, because they are low energy
high voltage sources.
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NHTSA has previously considered
this issue. In a 2007 NPRM responding
to petitions for rulemaking from what
were then the Alliance of Automobile
Manufacturers (Alliance) and the
Association of International Automobile
Manufacturers (AIAM),34 NHTSA
sought comments regarding a request of
the petitioners to include 0.2 Joule (J) as
an appropriate low energy threshold for
electrical safety compliance post-crash
for high voltage sources.35 The
petitioners believed that the low energy
option was non-harmful, and argued in
their subsequent comments to the
NPRM 36 that the option is necessary
due to the presence of x- and ycapacitors in the powertrain of fuel cell
vehicles. After evaluating the
comments, NHTSA ultimately disagreed
with the petitioners and decided against
a low energy option for post-crash
electrical safety because the agency was
not convinced that a low energy option
was needed and had concerns about the
possible disparity between the level of
safety provided by 0.2 J of energy and
the electrical isolation requirement.37 At
that time a safety need for a low energy
option was not yet clear and the agency
expressed concerns regarding the
practicality of measuring the residual
energy in a crash test environment.
NHTSA is reconsidering this issue in
this NPRM. GTR No. 20 contains a
detailed analysis of the 0.2 Joules energy
limit for the low energy post-crash
electrical safety compliance option.
While the 2007 NPRM considered a low
energy post-crash electrical safety
compliance option for any high voltage
source in the powertrain, GTR No. 20
only provides this option to capacitors
in the powertrain.
NHTSA conducted an analysis using
human body resistance charts, long and
short duration capacitance discharge
pulse profiles, and the graphs of
physiological effects of AC and DC body
current by duration of exposure from
two International Electrotechnical
Commission (IEC) technical
publications,38 to determine safe energy
levels for the human body. NHTSA has
submitted a technical memorandum to
the docket for this NPRM that provides
details and results of the agency’s
analysis.
Based on the analysis results, NHTSA
tentatively concludes that a post-crash
electrical safety compliance option for
capacitors based on an electrical energy
of 0.2 Joules or less provides adequate
safety from electrical shock and longterm harmful effects on the human
body. Providing this post-crash
compliance option would allow for
practicable powertrain designs for
battery electric and fuel cell vehicles
without any reduction in safety.
Automotive high-voltage systems
typically utilize a number of capacitors
connected to high voltage buses, and it
is not always practical to discharge
every capacitor post-crash. NHTSA
tentatively believes that by providing
this compliance option for a safe energy
limit, vehicle manufacturers would have
the flexibility to design products that
assure safety. NHTSA seeks comments
on the parameters (human body
resistance, discharge profiles) used in
the analysis and the analysis method.
34 In January 2020, the two industry associations
merged to form the Alliance for Automotive
Innovation (generally referred to as the Auto
Innovators).
35 72 FR 57260, October 9, 2007.
36 NHTSA–2007–28517–0004.
37 Final rule, 75 FR 33515, 33519; June 14, 2010.
38 IEC 60479–1 and 60479–2 Effects of Current on
Human Beings and Livestock—Part 1: General
Aspects, Part 2: Special Aspects, 2005–07,
Reference Nos. CEI/IEC/TS 60479–1:2018 and CEI/
IEC/TS 60479–2:2019. https://webstore.iec.ch/
publication/62980; https://webstore.iec.ch/
publication/63392 (last accessed September 26,
2023).
3. Assessing Post-Crash Voltage
Measurements
This NPRM proposes to clear up a
source of ambiguity in FMVSS No. 305.
FMVSS No. 305 requires that the postcrash voltage measurements be made at
least 5 seconds after the vehicle comes
to rest. However, at times it is not
entirely clear when the vehicle comes to
rest because there is always some
vibration and slight vehicle motion
post-crash. For consistency with the
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2. Assessing Fire or Explosion in
Vehicle Post-Crash Test
After a real-world crash, passengers
within the vehicle need time to safely
egress from the vehicle or be rescued by
first responders. During this time,
passengers should not be exposed to
hazards such as fire or explosion of the
REESS, which may hinder their egress
or rescue.
GTR No. 20 requires that for a period
of one hour after a crash test, there shall
be no evidence of fire or explosion of
the REESS. However, such a
requirement is not currently in FMVSS
No. 305. In accordance with GTR No.
20, NHTSA proposes to include in
FMVSS No. 305a a requirement that
there be no evidence of fire or explosion
for the duration of one hour after the
crash test for heavy school buses, and
for the duration of one hour after each
crash test and subsequent quasi-static
rollover test for light vehicles. The
assessment of fire or explosion would be
verified by inspection without removal
of the REESS or any parts of the vehicle.
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GTR No. 20 test procedure, NHTSA
proposes that the voltage measurements
in FMVSS No. 305a would be made
between 10 seconds and 60 seconds
after the impact. The agency tentatively
believes that 10 seconds after impact is
sufficient time for voltage measurement
and 60 seconds after impact is early
enough that any high voltage arcing
would be detected. NHTSA seeks
comment on this approach.
4. Electrolyte Spillage Versus Leakage
Currently, FMVSS No. 305 S5.1
addresses ‘‘electrolyte spillage from
propulsion batteries.’’ The standard
specifies that following a crash test, not
more than 5.0 liters of electrolyte from
propulsion batteries shall spill outside
the passenger compartment, and that no
visible trace of electrolyte shall spill
into the passenger compartment.
NHTSA proposes to use terms related to
‘‘leakage’’ instead of spillage. When the
electrolyte spillage 39 requirement was
originally adopted in 2000, EV
propulsion batteries were envisioned to
be a series of lead-acid batteries. Leadacid batteries at the time had large
quantities of liquid electrolyte that
could spill out of the battery if the
battery structure were compromised in
a crash. At that time, it was appropriate
to eliminate the term ‘‘leakage’’ due to
its synonymity to ‘‘spillage,’’ to avoid
questions of whether different meanings
were intended by the different words.
Current EV propulsion batteries,
however, are lithium-ion batteries. The
cells of lithium-ion batteries have small
quantity of electrolyte that could leak
out of the battery casing rather than
spill. Thus, NHTSA proposes to use the
term ‘‘electrolyte leakage,’’ which is
more relevant than ‘‘electrolyte
spillage’’ for these batteries.
NHTSA seeks comment on the
inclusion of a post-crash electrolyte
leakage requirement in FMVSS No. 305a
and the necessity and relevance of such
a requirement for current EVs.
Specifically, NHTSA seeks comment on
whether this requirement is still
relevant given today’s propulsion
battery technologies and if it is still
necessary based on the safety incidents
observed in the field or in crash tests.
NHTSA seeks comment on whether a 5liter maximum amount of electrolyte
permitted to be leaked is still relevant
and requests commenters to provide
data based on safety incidents observed
in the field or in crash tests to
39 Per Section B, ‘‘S5.1 Electrolyte Spillage from
Propulsion Batteries,’’ NHTSA stated in 65 FR
57980 that ‘‘leakage’’ is synonymous for ‘‘spillage.’’
Both words indicate the escape of electrolyte from
the battery.
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Introduction
Currently, FMVSS No. 305 does not
have any requirements for the safe
operation of the REESS and for
mitigating risks of fire and other safety
risks associated with it. This NPRM’s
proposed requirements would protect
the REESS against external fault inputs,
ensure the REESS operations are within
the manufacturer-specified functional
range, provide protection from thermal
propagation in the event of single-cell
thermal runaway (SCTR) due to an
internal short-circuit, provide a warning
if there is a thermal event within the
REESS or a malfunction of vehicle
controls that manage REESS safe
operation, and ensure safe REESS
operation during and after water
exposure.
While REESS is a general term to
represent any rechargeable electrical
energy storage system, currently all
electric powered vehicles use REESS
with lithium-ion chemistry. Therefore,
the current safety hazards associated
with REESS identified in literature and
in the field are those specific to lithiumion chemistry REESS. However, the
proposed requirements in this NPRM
will apply regardless of REESS
chemistry.
REESSs are designed and
manufactured to operate safely within a
range of operating parameters, including
temperature ranges, charge levels, and
current levels. If the REESS is subjected
to fault conditions outside these
The performance criteria specified in
GTR No. 20 for each of the vehicle
control performance tests specify no
evidence of electrolyte leakage, rupture
(applicable to high voltage REESSs
only), venting (applicable to REESSs
other than open-type traction
batteries 41), fire, or explosion. For high
voltage REESSs, the electrical isolation
is required to be greater than or equal
to 100 ohms per volt, for a DC high
voltage source. This NPRM proposes the
same performance criteria to protect the
REESS against external faults, such as a
fault in an external charger that could
result in the charger supplying greater
current than requested by the vehicle
and/or charging the REESS beyond full
state of charge.42
Under proposed FMVSS No. 305a, the
evidence of electrolyte leakage,
venting,43 or rupture is verified by
visual inspection without disassembly
of any part of the vehicle. Visible smoke
during and after the test, and/or the
presence of soot and/or electrolyte
residue in post-test visual inspection are
indicators of venting and electrolyte
leakage. The overcharge, over-discharge,
overcurrent, over-temperature, and
external short-circuit test procedures
specify that the agency would perform
a standard cycle after completing
exposure to each of the external faults,
provided that the vehicle permits
charging and discharging at that time. A
standard cycle, as specified in GTR No.
20 and proposed FMVSS No. 305a,
consists of a standard discharge and
followed by a standard charge. If the
vehicle is operable after exposure to the
external fault, running the standard
cycle after exposure to the external fault
condition—while observing the vehicle
for one hour for evidence of electrolyte
leakage, rupture, venting, fire, or
explosion, followed by voltage
measurements for determining electrical
isolation—would ensure that continuing
operating the vehicle would not result
in safety hazards.
The vehicle might not permit charging
and discharging after detecting a
dangerous condition; NHTSA considers
this a safety feature and that such a test
outcome would not amount to an
apparent noncompliance. The inability
to perform a standard cycle after
exposure to the external fault does not
terminate the test. If the vehicle does
not permit charging and discharging
after exposure to an external fault, then
the standard cycle is simply not
performed and the test proceeds.
Specifically, the test ends with the
vehicle observed for one hour for
evidence of electrolyte leakage, rupture,
venting, fire, or explosion, followed by
voltage measurements for determining
electrical isolation.
The standard cycle would be
conducted with the breakout harness
connected to the manufacturer-specified
location(s) on the traction side of the
REESS 44 on the vehicle’s electric power
train. The REESS is charged and
discharged using a high voltage battery
tester/cycler (with appropriate power
and voltage ranges) which is connected
to the vehicle through the breakout
harness, as shown in Figure 2 below (for
illustration purposes only).
40 GTR No. 20 requires that the electrolyte leaking
from the REESS during and after the crash test is
no more than 7 percent by volume of the REESS
electrolyte. However, there is no practical way of
measuring the quantity by volume of the electrolyte
in the REESS.
41 Open-type traction batteries are a type of
battery which are filled with liquid and generate
hydrogen gas that is released into the atmosphere.
42 The control pilot pin of the charger
communicates with the vehicle during charging.
Based on the state of charge (SOC), the vehicle
requests a certain level of current and the vehicle
charger provides that level. Other external faults
could arise when attempting to drive the vehicle
beyond the lowest safe operating SOC of the REESS
(over-discharge of the REESS), driving fast up a
steep hill for a long period of time that could cause
the REESS to heat beyond its highest safe operating
temperature, and charging a REESS at very cold
temperatures that could cause lithium plating.
43 NHTSA elaborates on the proposed venting
requirement at the end of this section.
44 The manufacturer is required by proposed
FMVSS No. 305a to specify the location for
connecting the breakout harness and may also
provide appropriate breakout harnesses for testing
the vehicle. If the manufacturer does not provide a
breakout harness, NHTSA would use a generic
breakout harness to connect to the traction side of
the REESS.
substantiate their assertions.40 NHTSA
seeks comment on and
recommendations regarding electrolyte
leakage detection methods and how
these detection methods can discern
between the presence of electrolyte and
the presence of other liquids such as
coolant.
c. REESS Requirements Applicable to
All Vehicles
This section of the NPRM addresses
REESS safety performance requirements
during normal vehicle operation. The
REESS requirements would apply to all
vehicles subject to FMVSS No. 305a.
ddrumheller on DSK120RN23PROD with PROPOSALS3
operating ranges such as overcharge,
over-discharge, overcurrent, overtemperature, external short-circuit, or
low temperature, these conditions can
result in damage to the cells. Cell
damage increases the risk of hazardous
conditions such as electrolyte leakage,
reduced electrical isolation, and fire in
the REESS (thermal runaway).
Manufacturers include controls in
electric vehicles to manage REESS
operation to ensure they stay within the
specified safe operating range, thereby
mitigating damage to the REESS. The
system that monitors and controls the
REESS is referred to as the battery
management system (BMS). NHTSA
proposes requirements to assure that the
BMS has controls that protect the
REESS against these faults by, e.g.,
stopping the vehicle from charging to
prevent overcharge.
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Performance Criteria For Normal
Vehicle Operations—General
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Electrical Chassis
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Figure 2—Connection of the Breakout
Harness & Laboratory Test Equipment
to the Vehicle
NHTSA proposes that the discharge
and charge rates for the standard cycle
would be provided by the vehicle
manufacturer. NHTSA proposes that, if
the discharge rate is not specified by the
manufacturer, NHTSA would use a
discharge rate (C-Rate) of 1C current. A
‘‘nC Rate’’ is the magnitude of constant
current that would charge or discharge
the REESS in 1/n hour between 0
percent state of charge (SOC) and 100
percent SOC. Discharge would continue
until automatically terminated by
vehicle controls at the manufacturerspecified minimum operating SOC of
the REESS. After discharge, the standard
cycle would include a 15-minute rest
period before the charging procedure
commences. If a charge procedure is not
specified, then a charge rate (i.e., C-Rate)
of 1⁄3C current would be used. Charging
is continued until automatically
terminated by vehicle controls at the
manufacturer-specified maximum
operating SOC of the REESS.
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Laboratory Test
Equipment
__
REESS Venting
Venting is the release of excessive
internal pressure from a cell or REESS
in a manner intended by design to
preclude rupture or explosion. Venting
during normal vehicle use may be
associated with (a) combustion and/or
decomposition of electrolyte, or (b)
vaporization of the electrolyte. In case of
condition (a), the emissions from the
cells may increase the risk to vehicle
occupants if they are exposed to such
substances. In case of condition (b), the
amount of the gases released is
considered less likely to pose a safety
risk to the occupants. Venting in the
case of condition (a) may result in the
release of gases and particulates from
the REESS, thereby potentially exposing
vehicle occupants to the emissions
(gases and particulate matter).45 Hazards
associated with toxicity, corrosiveness,
and flammability of the gases emitted
45 Gases generated in and vented from lithium-ion
(Li-ion) batteries typically include carbon dioxide
(CO2), carbon monoxide (CO), hydrogen (H2),
oxygen (O2), light C1-C5 hydrocarbons, e.g., methane
and ethane, and fluorine-containing compounds
such as hydrogen fluoride (HF) and fluoro-organics,
e.g., ethyl-fluoride.
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Breakout Harness
from the REESS and associated human
health exposure limits vary
considerably. As noted above, NHTSA
proposes to include a provision in
FMVSS No. 305a to limit the safety risks
to vehicle occupants due to venting
during normal vehicle operations. The
provision is based on GTR No. 20
requirements described below.
GTR No. 20 specifies that under
normal vehicle operation, the vehicle
occupants are not exposed to any
hazardous environment caused by
venting from the REESS. To avoid
human harm that may occur due to
potential toxic or corrosive emissions,
GTR No. 20 specifies that there be no
venting from the REESS for the
following normal vehicle operations
tests: vibration, thermal shock and
cycling, external short circuit
protection, overcharge protection, overdischarge protection, over-temperature
protection and overcurrent protection.
GTR No. 20 includes a no-fire
requirement in these tests which
addresses the issue of vented gas
flammability. During the development
of GTR No. 20, a robust and repeatable
method to verify the occurrence of
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venting and the potential exposure of
vehicle occupants to various gases from
the venting was sought, but no suitable
method was found. Visual inspection
was found to be the best approach at
this time for verifying the occurrence of
venting for assessing the influence of
vented gases on vehicle occupants.
Therefore, GTR No. 20 specifies that
evidence of venting in these tests is
verified by visual inspection (evidence
of soot, electrolyte residues) without
disassembling any part of the REESS.
NHTSA proposes to use a similar
approach in FMVSS No. 305a to
evaluate the safety risks to vehicle
occupants resulting from venting from
the REESS. The agency acknowledges
that research is needed to develop a
repeatable, reproducible, and practical
method to verify the occurrence of
various vented gases and the potential
exposure and harm to vehicle
occupants. However, NHTSA tentatively
concludes that in the absence of such a
method, the requirement that there must
be no fire, electrolyte leakage or venting
during the tests evaluating vehicle
controls for safe REESS operation
(external short-circuit protection,
overcharge protection, over-discharge
protection, over-temperature, and
overcurrent protection) would reduce
some safety risks to vehicle occupants
due to venting from the REESS. The
evidence of venting in these tests would
be verified by visual inspection
(evidence of soot, electrolyte residues)
without disassembling any part of the
REESS.
NHTSA also requests comment in an
Appendix to this preamble on the IWG’s
continuing work on venting in Phase 2
of the GTR.
ddrumheller on DSK120RN23PROD with PROPOSALS3
1. Vehicle Controls for Safe REESS
Operation
This NPRM proposes the following
performance requirements and
associated test procedures for vehicles
to ensure they have controls managing
safe REESS operations. There are some
minor differences between the GTR No.
20 test procedures and those proposed
in this NPRM that are based on the
lessons learned from NHTSA’s test
program. Those differences pertain to
the ease of conducting the test.46
NHTSA funded research to validate a
collection of test procedures that assess
safety hazards to electric vehicles while
being charged or when the REESS
exceeds its recommended operational
46 For example, the state of charge of the REESS
at the beginning of the test differed in some
instances from that in GTR No. 20 to enable
completing the test more readily.
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limits.47 48 The research independently
evaluated, refined, and validated
vehicle-level test procedures that could
be robustly applied to a wide range of
vehicle technologies and battery
configurations. Based on the results of
NHTSA’s research, the agency proposes
to conduct full vehicle-level tests using
a breakout harness connected to a
battery tester/cycler 49 to evaluate
vehicle controls for safe REESS
operation, rather than conducting the
tests on the REESS as a separate
component. NHTSA is proposing
vehicle-level testing because evaluating
REESS safe operation at the vehicle
level would evaluate the entire vehicle
system and the associated vehicle
controls, whereas conducting the tests at
the equipment level would not evaluate
all the relevant vehicle controls or any
interaction or interference between
vehicle controls.
NHTSA evaluated the GTR No. 20 test
procedures for feasibility, practicability,
and objectivity by conducting the test
procedures on a 2019 Chevy Bolt, 2020
Tesla Model 3, and 2020 Nissan Leaf S
Plus.50 51 52 NHTSA’s test program
demonstrated the ease of conducting
tests at a vehicle level using breakout
harnesses connected to a battery cycler/
tester for the external inputs to the
REESS without having to remove the
REESS from the vehicle to conduct
component level tests. The proposed
test procedures for overcharge, overdischarge, overcurrent, overtemperature, and external short-circuit
tests are non-destructive tests intended
to evaluate vehicle controls to protect
the REESS and can be conducted in
serial order on the same vehicle.
47 DC Charging Safety Evaluation Procedure
Development, Validation, And Assessment, and
Preliminary AC Charging Evaluation Procedure—
DOT HS 812 754 and DOT HS 812 778—July 2019.
https://rosap.ntl.bts.gov/view/dot/41933.
48 System-Level RESS Safety and Protection Test
Procedure Development, Validation, and
Assessment—Final Report—DOT HS 812 782
October 2019 https://rosap.ntl.bts.gov/view/dot/
42551.
49 A battery tester/cycler is equipment that can be
used for charging and discharging REESS and for
conducting specialized tests on the REESS. An
example of a battery tester with hybrid and battery
electric vehicles is the NHR 9300 battery test system
(NHR 9300).
50 NHTSA Test Report on the 2020 Tesla Model
3 Standard Range 4-Door Sedan can be accessed
here: https://downloads.regulations.gov/NHTSA2021-0029-0003/attachment_2.pdf.
51 NHTSA Test Report on the 2020 Nissan Leaf S
Plus (62kWh Battery) 5-Door Hatchback can be
accessed here: https://downloads.regulations.gov/
NHTSA-2021-0029-0002/attachment_2.pdf.
52 NHTSA Test Report on the 2019 Chevy Bolt
can be accessed here: https://
downloads.regulations.gov/NHTSA-2021-00290001/attachment_2.pdf.
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26715
i. Overcharge Protection
A battery pack experiences an
overcharge when a charger forces its
state of charge (SOC) level to rise above
100 percent. Overcharge of a REESS can
occur because of a failure of the
charging system, such as a fault in an
external charger, a fault in the vehicle’s
regenerative braking system, a sensor
failure, or a voltage reference drift.53
Overcharge can lead to swelling of an
electrochemical cell, lithium plating,
stability degradation, or over-heating,
and ultimately can lead to thermal
runaway.54 Severe events such as fire or
explosion may occur. Therefore, vehicle
controls to ensure the REESS does not
get overcharged are important for longterm safe operation of the REESS.
Vehicle level controls or the BMS
typically prevent charging when the
manufacturer-specified maximum
operating SOC of the REESS is achieved.
GTR No. 20 includes a test to evaluate
the performance of vehicle controls to
prevent overcharge of the REESS.
NHTSA tentatively concludes that GTR
No. 20’s overcharge test is practical and
feasible based on the agency’s own
testing.55 NHTSA proposes to include
the overcharge protection requirement
and test procedure in FMVSS No. 305a.
The proposed overcharge test would
be performed on a complete vehicle as
follows. The test is conducted with the
REESS initially set at 90 to 95 percent
SOC 56 and at ambient temperatures
between 10 °C and 30 °C. The breakout
harness is attached on the traction side
of the REESS at the vehicle
manufacturer’s recommended
location(s) and attachment point(s), and
the battery tester/cycler is connected to
the breakout harnesses to supply the
charge current. Temperature probes are
connected to the REESS case to monitor
changes in the REESS temperature.
Temperature measurements may also be
53 Voltage can drift based on temperature. Higher
temperature can result in lower voltage.
54 Thermal runaway of a lithium-ion cell in a
REESS occurs when the thermal stability limit of
the cell chemistry is exceeded, and the cell releases
its energy via an exothermic reaction at an
uncontrolled rate such that the heat generated is
faster than that dissipated.
55 See Test reports in docket no. NHTSA–2021–
0029, available at www.regulations.gov. Detailed
test procedures are provided in the test reports of
the 2021 Chevrolet Bolt (NHTSA–2021–0029–0001),
2020 Nissan Leaf (NHTSA–2021–0029–0002), and
the 2020 Tesla Model 3 (NHTSA–2021–0029–0003).
56 Ranges in temperature and SOC are provided
for this and other test procedures for practicability
and ease of conducting the tests. In the overcharge
test, the REESS is initially set at a high SOC (90 to
95 percent) to enable fully charging the REESS in
a shorter period of time.
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obtained through communication with
the REESS control module.57
The vehicle is turned on and the
REESS is charged using the battery
tester/cycler in accordance with the
manufacturer’s recommended maximum
charge current 58 until one of the
following has occurred:
(a) the REESS overcharge protection
control terminates the charge current;
(b) the REESS temperature is 10 °C
above its maximum operating
temperature specified by the
manufacturer; 59 or,
(c) 12 hours have passed since the
start of charging the vehicle.
After the overcharge condition is
terminated, a standard cycle is
performed if possible. The test
concludes with a 1-hour observation
period in which the vehicle is observed
for any evidence of electrolyte leakage,
rupture, venting, fire, or explosion. At
the conclusion of the post-test
observation period, the electrical
isolation is determined in the same
manner as currently in FMVSS No. 305
S7.6 using a voltmeter to measure
voltages.
ddrumheller on DSK120RN23PROD with PROPOSALS3
ii. Over-Discharge Protection
Over-discharging a REESS, which
means discharging it below its lowest
state of charge specified by the
manufacturer, can lead to undesirable
aging, electrolyte leakage, swelling,
solid electrolyte interphase (SEI)
decomposition, internal short-circuit,
and damaged cell stability and safety on
subsequent recharges. Even though the
initial over-discharge response of
lithium-ion cells generally appears
benign, it can cause damage to cell
electrodes that can compromise cell
stability and safety on subsequent
recharge. Subsequent charging of an
over-discharged REESS may lead to fire
or explosion.
Vehicle controls or the BMS typically
prevent over-discharging when the
manufacturer specified minimum
operating SOC of the REESS is achieved.
GTR No. 20 includes a test to evaluate
the performance of vehicle controls to
prevent over-discharge of the REESS.
NHTSA tentatively concludes that GTR
No. 20’s over-discharge test is practical
and feasible based on the agency’s own
57 Commercial diagnostic tools or tools supplied
by the manufacturer may be used to read the
Temperature measurements within the REESS from
the vehicle’s Controller Area Network (CAN bus).
58 If the manufacturer does not provide an
appropriate charge current, then a charge rate (i.e.,
C-Rate) of C/3 current would be used.
59 The manufacturer would specify the procedure
for monitoring the temperature of the REESS during
testing. This could be measured by attaching
thermocouples to the casing of the REESS or
obtained from the CAN bus using appropriate tools.
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testing.60 NHTSA proposes to include
the over-discharge protection
requirement and test procedure in
FMVSS No. 305a.
The over-discharge test is performed
at ambient temperatures between 10 °C
and 30 °C on a complete vehicle. The
SOC of the REESS at the beginning of
the test is set at 10 to 15 percent.61 For
a vehicle with on-board energy
conversion systems (e.g., internal
combustion engine, fuel cell, etc.), the
fuel supply is set to the minimum
level 62 where active driving mode is
permitted. Similar to the overcharge
test, the breakout harness is attached on
the traction side of the REESS at the
vehicle manufacturer’s recommended
location(s) and attachment point(s), and
the battery tester/cycler is connected to
the breakout harness to discharge the
REESS.63 Temperature probes are
connected to the REESS case to monitor
changes in the REESS temperature.
Temperature measurements may also be
obtained through communication with
the REESS control module.
The vehicle is turned on and the
REESS is discharged using the battery
tester/cycler in accordance with the
manufacturer’s recommended
discharging rate 64 under normal
operating conditions until one of the
following has occurred:
(a) vehicle controls terminate the
discharge current,
(b) the temperature gradient of the
REESS is less than 4 °C 65 through two
hours, or
(c) if the vehicle is discharged to 25
percent of its nominal voltage level.
At the conclusion of the discharge
termination, one standard charge is
performed, followed by one standard
discharge. The test concludes with a 1hour observation period in which the
vehicle is observed for any evidence of
60 See Test reports in Docket No. NHTSA–2021–
0029, available at www.regulations.gov. Detailed
test procedures are provided in the test reports of
the 2021 Chevrolet Bolt (NHTSA–2021–0029–0001),
2020 Nissan Leaf (NHTSA–2021–0029–0002), and
the 2020 Tesla Model 3 (NHTSA–2021–0029–0003).
61 Ranges in temperature and SOC are provided
for this and other test procedures for practicability
and ease of conducting the tests. In this case, the
test is initiated with the REESS at a low SOC (10
to 15 percent) to enable discharging the REESS in
a shorter period of time.
62 Minimum level of fuel supply needed would be
provided by the manufacturer.
63 A discharge resistor may also be used for this
purpose.
64 If the manufacturer does not specify a discharge
rate, a power load of 1kW is used.
65 Temperature variation of 4 °C indicates stable
operation of the REESS. As noted earlier, the
manufacturer specifies the procedure for
monitoring the temperature of the REESS during
testing. This could be measured by attaching
thermocouples to the casing of the REESS or
obtained from the CAN bus using appropriate tools.
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electrolyte leakage, rupture, venting,
fire, or explosion. At the conclusion of
the observation period, the electrical
isolation is determined in a similar
manner as that in current FMVSS No.
305 S7.6 using a voltmeter to measure
voltages.
iii. Overcurrent Protection
As noted earlier, the vehicle and the
charging system communicate the level
of current needed to charge the REESS.
If there is a problem in the
communication or if the charging
system malfunctions, higher current
may be provided though not requested
by the vehicle. During direct current
(DC) fast-charging, failure of the external
charge equipment could cause overcurrent conditions in which the REESS
receives higher current than it was
designed to manage at a given state of
charge of the REESS. Overcurrent
conditions could result in heating of the
REESS, electrochemical damage to the
cells, and a risk of thermal runaway.
GTR No. 20 includes a test to evaluate
the performance of vehicle controls to
protect the REESS from overcurrent
conditions. NHTSA tentatively
concludes that GTR No. 20’s overcurrent
test is practical and feasible based on
the agency’s own testing.66 NHTSA
proposes to include the overcurrent
protection requirement in FMVSS No.
305a. In accordance with GTR No. 20,
NHTSA proposes to apply the
overcurrent test to vehicles that have
capability of charging by DC external
electricity supply. The test is
unnecessary for vehicles that only
charge by alternating current (AC)
supply because AC charging is slower
and the inverters for AC charging
manage any overcurrent. Also,
overcurrent issues have not been
observed in AC charging.
The overcurrent test is performed
with a complete vehicle. To avoid the
overcharge protection terminating the
over-current condition, the SOC of the
REESS is set between 40 to 50 percent.
The test is conducted at ambient
temperatures between 10 °C and 30 °C.
The breakout harness is attached on the
traction side of the REESS at the vehicle
manufacturer’s recommended
location(s) and attachment point(s), and
the battery tester/cycler is connected to
the breakout harnesses to supply the
charge current. Temperature probes are
connected to the REESS case to monitor
changes in the REESS temperature.
66 See Test reports in docket no. NHTSA–2021–
0029, available at www.regulations.gov. Detailed
test procedures are provided in the test reports of
the 2021 Chevrolet Bolt (NHTSA–2021–0029–0001),
2020 Nissan Leaf (NHTSA–2021–0029–0002), and
the 2020 Tesla Model 3 (NHTSA–2021–0029–0003).
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Temperature measurements may also be
obtained through communication with
the REESS control module. The vehicle
manufacturer specifies the highest
normal charge current and the overcurrent level that is applied. The battery
tester/cycler is programmed to supply
an over-current during charging at the
level specified by the manufacturer.
The vehicle is turned on and the
REESS is charged using the battery
tester/cycler in accordance with
manufacturer’s recommended charging
procedure with the highest normal
charge current specified by the
manufacturer.67 After charging is
initiated, an over-current specified by
the manufacturer 68 is supplied above
that requested by the vehicle. The
charge current is increased over the
course of 5 seconds from the highest
normal charge current to the overcurrent level. The charge current and
the overcurrent supply is continued
until one of the following has occurred:
(a) vehicle over-current protection
controls terminate the charging, or (b)
the temperature gradient of the REESS
is less than or equal to 4 °C for a twohour period.
If possible, a standard cycle is
performed using the connected breakout
harness and battery cycler. The test
concludes with an observation period of
one hour in which the vehicle is
observed for electrolyte leakage,
rupture, venting, fire, or explosion. At
the conclusion of the observation
period, the electrical isolation is
determined in a similar manner as that
in current FMVSS No. 305 S7.6, using
a voltmeter to measure voltages.
ddrumheller on DSK120RN23PROD with PROPOSALS3
iv. Over-Temperature Protection
While the impacts of overtemperature operation vary by
chemistry, most battery chemistries can
be negatively affected if operation by the
driver is attempted at high temperatures
(per the limits of a specific chemistry)
67 The manufacturer supplied information define
the constant current level and/or constant voltage
level combination to charge the REESS. If a charge
procedure is not specified, then a charge rate (i.e.,
C-Rate) of C/3 current is used.
68 If the vehicle manufacturer does not supply an
appropriate over-current level, the battery test/
cycler will be programmed to initially apply a 10
Ampere over-current. If charging is not terminated,
the over-current level of 20 amps will be applied.
Subsequently, the over-current supply is increased
in steps of 10 amperes.
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or if aggressive operation is attempted at
high temperatures (high-rate charging or
discharging). A temperature imbalance
or continued operation at elevated
temperatures may even lead to thermal
runaway of cells if appropriate
countermeasures, such as de-rating,69
are not taken.
Vehicle controls such as thermal
management systems or the BMS
continuously monitor temperature
conditions to prevent REESS operation
at elevated temperatures above the
upper temperature boundary for safe
REESS operations. GTR No. 20 includes
a test to evaluate the performance of
vehicle controls to prevent REESS
temperatures exceeding the upper
temperature boundary for safe REESS
operations. NHTSA tentatively
concludes that GTR No. 20’s overtemperature test is practical and feasible
based on the agency’s own testing.70
NHTSA proposes to include the overtemperature protection requirement and
test procedure in FMVSS No. 305a,
which aligns with GTR No. 20.
In the proposed FMVSS No. 305a, the
over-temperature test is performed on a
chassis dynamometer 71 with a complete
vehicle. The SOC of the REESS at the
beginning of the test is set between 90
to 95 percent. The test is conducted at
ambient temperatures between 10 °C
and 30 °C. For vehicles with on-board
energy conversion systems (e.g., internal
combustion engine, fuel cell, etc.), the
fuel system must have sufficient supply
to allow operation of the energy
conversion system for about one hour of
driving. The cooling system for the
REESS is disabled (or significantly
69 De-rating is the reduction of a battery’s
available power and is typically due to a state that
indicates an undesirable condition such as rapidly
increasing cell temperature, elevated temperatures,
or very cold cell temperatures. By temporarily
reducing a battery’s ability to provide and/or absorb
power, de-rating allows the battery to cool down (or
at least stop increasing in temperature) in situations
with elevated temperatures and reduces operation
when the battery is so cold that certain usage levels
could cause damage.
70 See Test reports in Docket No. NHTSA–2021–
0029, available at www.regulations.gov. Detailed
test procedures are provided in the test reports of
the 2021 Chevrolet Bolt (NHTSA–2021–0029–0001),
2020 Nissan Leaf (NHTSA–2021–0029–0002), and
the 2020 Tesla Model 3 (NHTSA–2021–0029–0003).
71 A chassis dynamometer is a mechanical device
that uses one or more fixed roller assemblies to
simulate different road conditions within a
controlled environment and is used for a wide
variety of vehicle testing.
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reduced for a REESS that will not
operate with the cooling system
disabled) per manufacturer-supplied
information.72 For REESSs that will not
operate if the cooling system is disabled,
the maximum amount of coolant is
removed to minimize the cooling
system’s operation for the test.
Temperature probes are connected to
the REESS case to monitor changes in
the REESS temperature. Temperature
measurements may also be obtained
through communication with the REESS
control module.
GTR No. 20 specifies that the vehicle
be soaked for at least 6 hours in a
thermally controlled chamber at 45 °C.
However, NHTSA’s testing 73
demonstrated that the presoaking of the
vehicle at elevated temperatures does
not raise the temperature of the REESS
as significantly as by driving the vehicle
under high acceleration and
deceleration drive modes. Therefore, to
reduce the test time and test burden, the
agency does not believe it needs to
specify presoaking of the vehicle.
The vehicle is installed on the chassis
dynamometer and is placed into driving
mode. The vehicle is driven on the
dynamometer using the vehicle
manufacturer-recommended appropriate
drive profile for discharge and charge of
the REESS that would raise the
temperature of the REESS (with cooling
system disabled or reduced function)
above its safe operating temperature
within one hour. If the vehicle
manufacturer does not supply an
appropriate drive profile, NHTSA will
drive the vehicle over back-to-back
aggressive acceleration (near 100%
pedal application) and decelerations
(near or above regenerative braking
limits) such as the one shown in Figure
3 below, where the vehicle is
accelerated to 80 mph and then
decelerated to 15 mph within 40
seconds.
72 Methods for disabling the cooling system may
include crimping the liquid cooling hose or in the
case of a refrigerant cooled package, removing the
refrigerant fluid. For REESS cooled by cabin air,
block the cabin air intakes used to provide cooling
air flow to the REESS.
73 System-Level RESS Safety and Protection Test
Procedure Development, Validation, and
Assessment-Final Report. DOT HS 812 782 October
2019. https://rosap.ntl.bts.gov/view/dot/42551.
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Average Wheel Speed (mph) vs Time (sec)- 10 minute Subsample
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Vehicle battery designs and controls
mitigate overheating of the REESS in
different ways: (1) Terminate discharge/
charge operations when the REESS
temperature reaches its operating
bounds; (2) Derate (reduce acceleration/
speed of the vehicle) to prevent the
REESS reaching its maximum operating
temperature; (3) REESS cell chemistries
are stable at higher REESS temperature.
In order to accommodate different
approaches to address hazards
associated with overheating of REESS,
GTR No. 20 provides three different
options for terminating the discharge/
charge cycles:
(a) the vehicle terminates the chargedischarge cycle,
(b) the REESS temperature gradient is
less than or equal to 4 °C for a two-hour
period, or
(c) 3 hours have elapsed from the time
of starting the discharge-charge cycles
on the chassis dynamometer.
In accordance with GTR No. 20, the
agency proposes to use the same three
options listed above to terminate the
discharge/charge cycle.
At the conclusion of the overtemperature evaluation, a standard cycle
is performed if possible. The test
concludes with a 1-hour observation
period in which the vehicle is observed
for electrolyte leakage, rupture, venting,
fire, or explosion. At the conclusion of
the observation period, the electrical
isolation is determined in a similar
manner as that in FMVSS No. 305 S7.6,
using a voltmeter to measure voltages.
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1
160
200
240
280
' ' ''
320
360
400
440
The purpose of the external shortcircuit protection test is to verify the
performance of the vehicle controls
(protection measure) against a shortcircuit occurring externally to the
REESS. During an external short-circuit
event, large amounts of instantaneous
current can be readily drawn generating
copious amounts of heat. Associated
safety risks include over-heating, gas
venting, or arcing that can occur under
fault conditions which can potentially
lead to fire or explosion.
Vehicle controls or the BMS typically
protect the REESS from an external
short-circuit. GTR No. 20 includes a test
to evaluate the performance of vehicle
controls to protect the REESS from an
external hard short-circuit (shorting
resistance less than 5 milliohms).
NHTSA tentatively concludes that GTR
No. 20’s external short-circuit test is
practical and feasible based on the
agency’s own testing.74 NHTSA
proposes to include the GTR No. 20
external short-circuit protection
requirement and test procedure in
FMVSS No. 305a.
The external short-circuit test is
performed on a complete vehicle. The
SOC of the REESS at the beginning of
the test is set at 90 to 95 percent SOC.
The test is conducted at ambient
temperatures between 10 °C and 30 °C.
The breakout harness is installed on the
vehicle at the manufacturer specified
location(s).75 Temperature probes are
74 See Test reports in Docket No. NHTSA–2021–
0029, available at www.regulations.gov. Detailed
test procedures are provided in the test reports of
the 2021 Chevrolet Bolt (NHTSA–2021–0029–0001),
2020 Nissan Leaf (NHTSA–2021–0029–0002), and
the 2020 Tesla Model 3 (NHTSA–2021–0029–0003).
75 If the manufacturer does not provide
information on the location to connect the breakout
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1
v. External Short-Circuit Protection
Figure 3—Drive Profile on
Dynamometer To Quickly Raise the
Temperature of the REESS. (For
Illustration Purposes Only)
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480
520
560
600
connected to the REESS case to monitor
changes in the REESS temperature.
Temperature measurements may also be
obtained through communication with
the REESS control module. The short
circuit contactor (with the contactors in
open position) is connected to the
breakout harnesses. The total resistance
of the equipment to create the external
short circuit (short circuit contactor and
breakout harnesses) is verified to be
between 2 to 5 milliohms.76 To begin
the short-circuit evaluation, the shortcircuit contactors are closed. The shortcircuit condition is continued until (1)
current is no longer present or (2) one
hour after the temperature probe on the
REESS has stabilized with a temperature
change of less than 4 °C for a two-hour
period.
If possible, a standard cycle is
performed after termination of the shortcircuit. Fuses that opened during the
short-circuit are not replaced, and the
standard cycle procedure is not
performed if it is not possible to charge
and discharge the vehicle.
The vehicle is observed for one hour
for electrolyte leakage, rupture, venting,
fire, or explosion. The external shortcircuit test concludes with an electrical
isolation determination in a similar
manner as that in current FMVSS No.
305a S7.6 using a voltmeter to measure
voltages.
vi. Low-Temperature Protection
Uncontrolled repeated operation at
low temperatures, especially charging
harness for the external short circuit test, the
breakout harnesses may be connected on either side
of the positive and negative terminals of the pack.
76 GTR No. 20 specifies the external short circuit
resistance not exceeding 5 milliohms. The agency
is specifying a range from 2 to 5 milliohms for ease
of conducting the tests and to ensure objectivity of
the test.
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for lithium-ion battery chemistries, may
result in lithium plating or cell damage
that could eventually lead to reduced
performance or degraded life during
subsequent operation. While single time
operation of REESS in very cold
temperatures would not lead to a severe
event, some REESS designs use special
chemical reactions which can damage
the REESS if it is charged at high rates
in very cold temperatures. A subsequent
high rate of charging of such a damaged
REESS may lead to fire or explosion.
Therefore, the rate of charging may need
to be terminated or limited in very cold
temperatures.
Currently, no practical test procedure
is available to evaluate the performance
of vehicle controls in low temperature
conditions because the effects of
repeated charging at very low
temperatures occur over a very long
period of time. Therefore, GTR No. 20
requires manufacturers to provide
documentation that includes a system
diagram, a written explanation on the
lower boundary temperature for safe
REESS operation, the method of
detecting REESS temperature, and the
action taken when the REESS
temperature is at or below the lower
boundary for safe REESS operation.
NHTSA proposes to include
documentation requirements based on
GTR No. 20 into FMVSS No. 305a.
NHTSA proposes that the manufacturer
provide documentation, upon NHTSA’s
request, to demonstrate how the vehicle
monitors and appropriately controls
REESS operations at low temperatures
at or below the lower temperature
boundary for safe REESS operation. The
proposed requirements would indicate
how manufacturers identify, verify, and
ensure vehicles have low-temperature
protections in place. Specifically, the
proposal requires the manufacturersupplied documentation for a specific
vehicle make, model, and model year
would include the following:
(1) A description of the lower
temperature boundary for safe REESS
operation in all vehicle operating
modes.
(2) A description and explanation of
C-rates at the lower temperature
boundary for safe REESS operation.
(3) A description of the method used
to detect REESS temperature.
(4) A system diagram with key
components and subsystems involved in
maintaining safe REESS charging and
discharging operation for temperatures
at or below the lower temperature
boundary for safe REESS operation.
(5) A description of how the vehicle
controls, ancillary equipment, and
design features were validated and
verified for maintaining safe REESS
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operations at or below the lower
temperature boundary for safe REESS
operation.
(6) A description of the final review/
audit process of the manufacturer, and
the accompanying results of the
manufacturer’s final assessment of risk
management, and risk mitigation
strategies.
NHTSA intends these documentation
measures to demonstrate that the
manufacturer has considered, assessed,
and mitigated identified risks for safe
operation of the vehicle. NHTSA
tentatively agrees with GTR No. 20 that
there is a safety need for low
temperature protections for the REESS.
Without protections, uncontrolled
repeated operation at low temperatures
poses an unreasonable risk of fire or
explosion. In the absence of information
enabling NHTSA to propose a practical
test procedure to evaluate the
performance of vehicle controls in low
temperature conditions, the agency is
proposing to require manufacturers to
submit documentation to NHTSA about
pertinent low temperature safety
hazards, describe their risk mitigation
strategies for the safety hazards, and
how they assessed the effectiveness of
their mitigation strategies.
NHTSA would review the
documentation to understand the safety
hazards associated with the particular
REESS in the vehicle, see whether the
manufacturer conducted an assessment
of the risks, and understand the
measures the manufacturer undertook to
mitigate those known risks. This
approach is intended to evolve over
time as battery technologies continue to
rapidly evolve. It is an interim measure
intended to assure that manufacturers
will identify and address the low
temperature safety risks of the REESS.
In section VI., NHTSA requests
comments on whether the proposed
document requirement would be better
placed in a general agency regulation
than in proposed FMVSS No. 305a.
2. Mitigating Risk of Thermal
Propagation Due to Internal Short
Within a Single Cell in the REESS
i. Safety Need
The potential for thermal runaway is
a characteristic of the lithium-ion cells
currently used in REESSs for electric
vehicle propulsion. Thermal runaway of
a lithium-ion cell in a REESS occurs
when the thermal stability limit of the
cell chemistry is exceeded, and the cell
releases its energy via an exothermic
reaction at an uncontrolled rate such
that heat is generated faster than it is
dissipated. The thermal runaway in a
single cell may propagate to the
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26719
surrounding cells through conductive,
convective, and radiative heat transfer
modes, causing reactions which create
smoke, fire or, in very rare
circumstances, explosion. Lithium-ion
cells have flammable electrolyte that
upon decomposition provides oxygen to
the fire caused by the thermal runaway,
which increases the likelihood of its
propagation to other cells and even
outside the REESS. The self-oxygenating
fires involving the cells in a REESS are
therefore difficult to extinguish. The
smoke, fire, toxic gas emissions, and
explosion resulting from the thermal
runaway can cause hazardous
conditions for vehicle occupants and
those near the vehicle.
One root-cause of single-cell thermal
runaway (SCTR) and propagation due to
an internal short-circuit relates to
problems within the cells. While this
NPRM contains many performance tests
for the safe operation of the REESS,
none of these tests would mitigate or
prevent thermal runaway due to an
internal short-circuit within a cell of the
REESS and subsequent fire propagation.
The mechanism of an internal short
circuit in a cell is complex and requires
further study. Currently, the risk of a
spontaneous internal short circuit is
heavily dependent on battery design,
such as use of non-flammable
electrolytes, ionic liquids, heat resistant
and puncture-proof separators, and
anode and cathode materials. However,
as discussed below, a performance test
that would establish a minimum
standard of performance for the
materials is not available now.
GTR No. 20 addresses the hazards
associated with SCTR due to an internal
short circuit through a documentation
approach that requires manufacturers to
provide (to the testing authority)
information on risk mitigation strategies
used in vehicle design to counteract the
safety risk. GTR No. 20 also requires a
warning system to allow vehicle
occupants sufficient time to egress the
vehicle before hazardous conditions are
present in the passenger compartment
due to SCTR within the REESS. GTR
No. 20 requires documentation of the
warning system, and requires operation
of the warning system only when the
vehicle propulsion system is turned on.
NHTSA tentatively generally agrees
that a documentation approach on risk
mitigation strategies currently has merit,
given there is no suitable performance
test to validate mitigation or prevention
of SCTR within a REESS. NHTSA is
proposing a documentation approach
based on GTR No. 20 but has focused
the GTR’s requirements to better address
this safety need pending development of
an objective performance test that can
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be applied to all REESSs in vehicles. In
section VI., NHTSA requests comments
on whether the proposed document
requirement would be better placed in
a general agency regulation than in
proposed FMVSS No. 305a.
NHTSA is not proposing to require a
warning system, or documentation of
the warning system, as specified in GTR
No. 20. As explained fully later in this
section, NHTSA believes such a
requirement would not mitigate the
safety hazards observed in the field.
ddrumheller on DSK120RN23PROD with PROPOSALS3
ii. GTR No. 20 Phase 1 Requirements
GTR No. 20 recognizes that, in
general, REESS cells are manufactured
with manufacturing controls to mitigate
safety problems. Based on current
manufacturing control processes, the
probability of manufacturing problems
within a cell is generally considered to
be less than one in a million.77 Since the
likelihood of two cells in a REESS going
into spontaneous single-cell thermal
runaway (SCTR) simultaneously is
significantly lower,78 the focus of GTR
No. 20 is to mitigate the hazards
associated with SCTR due to an internal
short-circuit within a single cell.
GTR No. 20 addresses the SCTR safety
hazard through a documentation
approach that requires manufacturers to
provide (to the testing authority on
request) information on risk mitigation
strategies used in vehicle design to
counteract the safety risk, and
documentation on a warning system
that warns occupants to egress the
vehicle. The documentation
requirements for risk mitigation
strategies are only generally described,
however. This is because during the
development of GTR No. 20, there was
no significant evidence of electric
vehicle fires due to SCTR and
propagation due to an internal shortcircuit. At that time, the thought was
that vehicle occupants would be
exposed to hazardous conditions if the
SCTR propagates outside of the REESS
to other parts of the vehicle. Therefore,
GTR No. 20 focuses primarily on the
warning and less on mitigating the risk
of the SCTR within the cell. The GTR
requires that a warning be provided to
77 A REESS consists of a number of cells (n) in
the range of 100 to 500. Therefore, the probability
of a single-cell thermal runaway and propagation
event due to an internal short-circuit is estimated
to be the product of the number of cells times one
in a million (n × 10¥6). https://
batteryuniversity.com/article/bu-304a-safetyconcerns-with-li-ion#:∼:text=Lithium
%2Dion%20batteries%20have%20a,than
%20those%20in%20consumer%20products.
78 The probability of two cells simultaneously
undergoing single-cell thermal runaway and
propagation due to an internal short-circuit is equal
to the product of the probability of a single-cell
thermal runaway (n2 × 10¥12).
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the driver 5 minutes before hazardous
conditions are present in the passenger
compartment due to SCTR and
subsequent fire propagation. Five
minutes was considered sufficient time
for vehicle occupants to egress the
vehicle before exposure to hazardous
conditions. Under the GTR,
manufacturers would satisfy the
requirement for a warning by providing
documentation that the vehicle provides
the required warning.
GTR No. 20 uses a documentation
approach for both the risk mitigation
strategies and the warning because an
objective test procedure is not available.
Existing methods of initiating thermal
runaway simulating an internal shortcircuit within a single cell in a REESS
are intrusive and dependent on the type
of cell chemistry and cell type.79
Additionally, different methods of
initiation could result in different
results.80 NHTSA funded research to
evaluate different thermal runaway
propagation test methods by examining
various existing methods of initiating
thermal runaway, including heating
element method, rapid heater method,
nail penetration, and laser method, on
batteries with a variety of chemistries,
formats, and configurations.81 The
research indicated that the thermal
runaway initiation methods may
influence the test results and the most
appropriate initiation method for a
battery may depend on battery
chemistries, formats, and
configurations.
The repeatability and reproducibility
of a potential performance test using
existing methods of thermal runaway
initiation, and whether such a test could
79 One common method of initiating a thermal
runaway is to heat a cell externally using a heating
element. This would require disassembly of the
casing of the REESS, adhering a heating element to
the surface of a cell, and adding thermocouples to
verify the heating element only provides heat to a
single cell and not to adjacent cells. The amount of
heat applied to initiate a thermal runaway depends
on the cell chemistry (more volatile chemistries
requiring less heat input), and the cell design/type
(thick wall cells needing more heat input). The
disassembly of the REESS, the addition of a heating
element, and the heat input is intrusive to the
REESS.
80 Another method of initiating a thermal
runaway in a cell is to penetrate a nail into a cell
in the REESS. The orientation of the nail
penetration depends on the cell design and in some
instances, nail penetration may not cause a thermal
runaway. While this method may not require the
REESS casing to be opened, the penetrating nail
compromises the casing and the cell structure.
Additionally, the depth of nail penetration may
result in differences in heat release that may not be
similar in repeat tests and in tests using a heating
element.
81 Lamb, J., Torres-Castro, L., Stanley J., Grosso,
C, Gray, L., ‘‘Evaluation of Multi-Cell Failure
Propagation,’’ Sandia Report SAND2020–2802,
March 2020. https://www.osti.gov/servlets/purl/
1605985.
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be conducted on all applicable vehicles,
are unknown. Due to the rapid
development of electric vehicle
propulsion technology, it was unclear
during development of the GTR if any
existing performance test could apply to
future vehicle designs without
restricting further enhancement of
electric vehicle propulsion systems.
Therefore, instead of specifying a
performance test for thermal runaway
and propagation due to an internal
short-circuit in a single cell of a REESS,
GTR No. 20 requires manufacturers to
submit documentation. Such
documentation must show risk
mitigation strategies in their vehicle
designs for reducing hazards to vehicle
occupants associated with thermal
runaway due to an internal short-circuit
in a single cell in the REESS. The
documentation must also detail how the
vehicle’s warning system activates a
warning at least 5 minutes before
hazardous conditions arise in the
passenger compartment.
Specifically, GTR No. 20 specifies the
following documentation requirements:
• A description of the warning
system.
• Parameters (such as voltage,
temperature, or current) that trigger the
warning indicator (telltale).
• A risk reduction analysis using
appropriate industry standard
methodology (for example, IEC 61508,82
MIL–STD 882E,83 ISO–26262,84 fault
analysis as in SAE J2929,85 or similar),
which documents the risk to vehicle
occupants caused by a single-cell
thermal runaway triggered by an
internal short-circuit leading to thermal
propagation and the expected risk
reduction resulting from
implementation of the identified risk
mitigation functions or characteristics.
• A system diagram of all relevant
physical systems and components
which contribute to the protection of
vehicle occupants from hazardous
effects caused by thermal propagation
triggered by a single-cell thermal
runaway event due to an internal shortcircuit.
82 IEC–61508:2010, ‘‘Functional Safety of
Electrical/Electronic/Programmable Electronic
Safety-related Systems’’. https://webstore.iec.ch/
searchform&q=IEC%2061508.
83 MIL–STD–882E:2012, ‘‘System Safety’’. https://
quicksearch.dla.mil/qsDocDetails.aspx?ident_
number=36027.
84 ISO–26262 series:2018, ‘‘Road vehicles—
Functional Safety’’. https://www.iso.org/
search.html?q=ISO-26262&hPP=10&idx=all_
en&p=0&hFR%5Bcategory%5D
%5B0%5D=standard.
85 SAE J2929:2013, ‘‘Safety Standard for Electric
and Hybrid Vehicle Propulsion Battery Systems
Utilizing Lithium-based Rechargeable Cells’’.
https://www.sae.org/standards/content/j2929_
201302/.
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• A diagram showing the functional
operation of the relevant systems and
components and identifying all relevant
risk mitigation functions or
characteristics.
• For each identified risk mitigation
function or characteristic:
Æ A description of its operation
strategy,
Æ Identification of the physical
system(s) or component(s) which
implements the function,
Æ One or more of the following
engineering documents relevant to the
manufacturers design which
demonstrates the effectiveness of the
risk mitigation function:
D Tests performed including
procedure used and conditions and
resulting data,
D Analysis or validated simulation
methodology and resulting data.
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iii. NHTSA Proposal
NHTSA tentatively agrees with GTR
No. 20’s rationale for the documentation
requirements for risk mitigation of
thermal propagation events resulting
from SCTR due to an internal shortcircuit within a cell in the REESS.
NHTSA tentatively concludes that due
to the rapidly evolving REESS
technology and control systems to
manage the performance condition and
safety of the REESS, a performance test
to validate mitigation of thermal
propagation resulting from SCTR within
the REESS is not currently feasible. A
performance test for a warning, when
the vehicle propulsion system is turned
on, that provides sufficient time for
vehicle occupants to egress the vehicle
before hazardous conditions arise in the
passenger compartment after a thermal
runaway is initiated in a cell of the
REESS would be unduly design
restrictive, not applicable to all vehicle/
REESS types, and not relevant to real
world incidents.86
This NPRM proposes a
documentation requirement for FMVSS
No. 305a to require manufacturers to
provide to NHTSA, upon NHTSA’s
request, information about their efforts
to identify and address potential safety
problems with SCTR and propagation
due to an internal short-circuit. The
information would be provided by a
manufacturer in accordance with
86 In most real-world incidents resulting in fire
due to thermal runaway of a single cell in the
REESS, the vehicle was parked, with propulsion
system turned off, and with no occupants in the
vehicle. In some cases, the vehicles were parked in
garages of homes. Therefore, a requirement for a
warning to vehicle occupants in the vehicle with
propulsion system turned on would not have
helped prevent the fire or mitigated hazards to
people in homes or in the vicinity of the burning
parked vehicle.
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NHTSA’s specified structure in four
parts. NHTSA’s proposed
documentation component structure is
based on elements from the GTR No. 20,
ISO–6469–1: Amendment 1 2022–11,87
and ISO–26262.88 The documentation
submitted by the manufacturer is
required to include all known risks to
vehicle occupants and bystanders, risk
assessment, risk management, and risk
mitigation strategies in three vehicle
operational modes (i.e., external
charging mode,89 active driving possible
mode,90 and parking mode 91). NHTSA’s
proposal goes beyond GTR No. 20’s
active driving possible mode to ensure
manufacturers consider all risks known
to it in three vehicle operational modes.
The assessment and validation of these
strategies may involve a combination of
physical testing and simulations at the
component level and/or full vehicle
level. The reporting requirements would
apply to REESSs of all types (including
REESS with non-flammable electrolyte).
The objective of the documentation is
for vehicle manufacturers to identify the
risks of single-cell thermal runaway and
propagation for their REESS type,
identify strategies to mitigate those
risks, and demonstrate how those
strategies work. The documentation
would accomplish the following goals:
• It would identify all risks known to
the manufacturer related to single-cell
thermal runaway and propagation due
to an internal short-circuit;
• It would discuss whether and how
each identified risk is managed and/or
mitigated by at least one risk mitigation
strategy;
• It would explain the reasons the
manufacturer believes each risk
87 ISO 6469–1:Third Edition 2019–04
Amendment 1 2022–11, ‘‘Electrically propelled
road vehicles—Safety specifications—Part 1:
Rechargeable energy storage system (RESS),’’
specifies safety requirements for REESS, including
test methodology for initiating thermal runaway in
a cell for the purpose of conducting a thermal
runaway propagation test and a format for reporting
on risk mitigation strategies of thermal propagation
resulting from a thermal runaway in a single cell
of an REESS due to an internal short within the cell.
88 ISO 26262: 2018, ‘‘Road vehicles—Functional
safety,’’ provides a comprehensive collection of
standards to manage and implement road vehicle
functional safety from concept phase to production
and operation. The standard provides guidelines for
overall risk management, individual component
development, production, operation, and service.
89 External charging mode is the vehicle
operational mode in which the charge connector is
connected to the vehicle charge inlet for the
purpose of charging the REESS.
90 Active driving possible mode is the vehicle
mode when application of pressure to the
accelerator pedal (or activation of an equivalent
control) or release of the brake system causes the
electric powertrain to move the vehicle.
91 Parking mode is the vehicle mode in which the
vehicle power is turned off, the vehicle propulsion
system and ancillary equipment such as the radio
are not operational, and the vehicle is stationary.
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mitigation strategy is effective (measures
taken to verify and/or validate them,
including any final review/audit
results); and,
• It would identify, describe, and
provide any review/audit process and
results that accompany the final
assessment of risk management and risk
mitigation strategies.
Proposed provisions to achieve the
above goals are discussed in detail
below.
The documentation requirement
proposed by NHTSA is divided into
four sections with more detailed
requirements than GTR No. 20. Under
the agency’s requirements, in Part I,
System Analysis, the vehicle
manufacturer would provide
information describing which
conditions specific to the vehicle could
lead to a SCTR event caused by an
internal short-circuit. The conditions
identified serve as the inputs to identify
the functions and failure modes for the
risk identification in Part II.
Part I would require the following
documentation:
• A system diagram and a description
of all relevant physical systems and
components of the REESS, including
information about the cell type and
electrical configuration, cell chemistry,
electrical capacity, voltage, current
limits during charging and discharging,
thermal limits of the components that
are critical for thermal propagation
safety;
• A system diagram, operational
description of sensors, components,
functional units relevant to single-cell
thermal runaway due to internal shortcircuit and thermal propagation, and the
interrelationship between the identified
sensors, components, and functional
units;
• A description of conditions under
which a single-cell thermal runaway
and propagation event due to an
internal short-circuit could occur;
• A description of how the identified
conditions are allocated to each
identified component, functional unit,
and subsystem;
• A description of the process used to
review the identified conditions and
their allocation to the identified sensors,
components, and functional units, for
completeness and validity; and
• A description of any system for
warning or notification prior to the
occurrence of thermal runaway in a cell,
including a description of the detection
technology and mitigation strategies, if
any.
Part II, Safety Risk Assessment and
Mitigation Process, provides a
description of all identified safety risks
and strategies to mitigate and manage
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these risks. Part II distinguishes between
primary and secondary risk mitigation
strategies. Primary risk mitigation
strategies mitigate the risk of SCTR due
to an internal short-circuit and the
occurrence of thermal propagation that
may result from SCTR. Primary risk
mitigation strategies include
manufacturing quality control to
mitigate defects in cells of REESS,
REESS design features such as heat
sinks, cell spacing, coolant, advanced
battery management system with
prognostics and diagnostics systems 92
to manage the health of the cells of an
REESS and detect a possible thermal
runaway condition before it occurs. In
contrast, secondary risk mitigation
strategies may not reduce the risk of
thermal runaway or thermal propagation
but reduce the hazards associated with
thermal propagation. Secondary risk
mitigation strategies include warning
systems to vehicle occupants/bystanders
and/or notification to emergency
personnel in the event of thermal
propagation (e.g., automatic notification
to 911 operators). NHTSA anticipates
that secondary risk mitigation strategies
would be employed as an addition to
primary risk mitigation strategies in the
overall safety strategy.
Part II would require the following
documentation:
• A description of safety risks and
safety risk mitigation strategies, and
how these were identified (e.g., Failure
Mode and Effects Analysis (FMEA), or
Failure Modes, Effects, and Criticality
Analysis (FMECA)); 93
• A description of how each risk
mitigation manages/mitigates the
identified safety risks.
In Part III, Verification and Validation
of Effective Risk Mitigation Strategies,
the manufacturer provides information
showing how they verify the
effectiveness of the identified mitigation
strategies in Part II to mitigate the
identified safety risks. The vehicle level
assessment examines how the entire
vehicle monitors and mitigates safety
risks. The vehicle level assessment is
the culmination of the verification/
validation results of each individual risk
mitigation strategy.
Part III would require the following
documentation:
92 Prognostic technologies predict the health of a
system or a component of a system in the future and
diagnostic technologies determine a specific
problem with a system or component of a system.
93 FMEA and FMECA are established
methodologies to identify failure modes and
postulate the effects of those failures on the system.
Refer to https://www.dau.edu/acquipedia-article/
failure-modes-effects-analysis-fmea-and-failuremodes-effects-criticality.
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• A summary of the process used to
verify each identified risk is addressed
by at least one risk mitigation strategy;
• A description of how each risk
mitigation strategy was verified and
validated for effectiveness; 94
• A description of the verification
and validation results for each risk
mitigation strategy; and
• A vehicle level assessment
evaluating the system response to safety
risks associated with the REESS.
Vehicle level assessment and validation
could be the use of physical tests and/
or validated models/simulations at a
component level scaled up to evaluate
the system response.
Part IV, Overall Evaluation of Risk
Mitigation, shall address:
• Results of any final review/audit
responsible for reviewing the technical
content, completeness, and verity of the
documentation submitted by the
manufacturer.
The risk-based methodology outlined
above is intended to mitigate the safety
hazards associated with SCTR and
propagation from an internal shortcircuit. The requirement is intended to
ensure that manufacturers are aware of
the safety risks at issue and have
considered safety risk mitigation
strategies. The documentation
submitted by the manufacturer will
inform NHTSA of the safety risk
mitigation strategies manufacturers have
utilized for the identified safety hazards,
enable NHTSA to oversee those safety
hazards, and inform future regulatory
measures.. This approach is battery
technology neutral, not design
restricted, and is intended to adapt over
time as battery technologies continue to
rapidly evolve. NHTSA seeks comment
on the documentation requirements
described above. In section VI., NHTSA
requests comments on whether the
proposed document requirement would
be better placed in a general agency
regulation than in proposed FMVSS No.
305a.
NHTSA’s Decision Not To Propose a
Warning Requirement
GTR No.20’s warning requirement
rationale is that the warning would
allow vehicle occupants sufficient time
to egress the vehicle before hazardous
conditions are present in the occupant
compartment. NHTSA does not agree
with GTR No.20’s rationale for a
warning requirement related to SCTR
due to an internal short-circuit within
94 Possible verification/validation methods for
Part III include (but are not limited to) fault
injection tests, software, and hardware performance
tests at component and/or system level, and system
level performance evaluation using validated
mathematical models.
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the cell. NHTSA is not proposing to
require such a warning system, or
documentation of the warning system,
as specified in GTR No. 20 because such
a requirement would not mitigate the
safety hazards observed in the field, as
described in detail below.
Field data and incidents related to
SCTR and propagation due to an
internal short-circuit in lithium-ion
REESSs are sparse and anecdotal.
However, when reviewing the limited
number of non-crash and non-abuse
related electric vehicle fire incidents in
the United States,95 the following trends
emerge:
• The vehicle operation mode is in
the usual parking mode.96
• The vehicle is parked in a garage
attached to a house, a parking garage, or
on the street.
• The state of charge (SOC) of the
REESS was generally in the upper range.
Fire statistics reports by South Korea
identified 35 electric vehicle fires since
2018, among which 20 electric vehicle
fires originated in the REESS of the
vehicles when the vehicle was parked
and the SOC was greater than 90
percent.97 In the electric vehicle fire
incidents in the United States and South
Korea, the vehicle fire propagated to
adjacent vehicles and structures with
release of copious amounts of smoke,
resulting in significant property damage.
The GTR No. 20 requirement for a
warning to the driver would not have
helped mitigate the electric vehicle fires
and would not have mitigated property
damage.
Accordingly, this NPRM does not
propose to require a warning to
occupants or documentation pertaining
to a warning, as such requirements
would not sufficiently address a safety
need. NHTSA believes the
documentation requirements in GTR
No. 20 for a warning to the driver are
not relevant to the field-observed
electric vehicle fires likely resulting
from SCTR. NHTSA believes that
vehicle designs using a risk mitigation
strategy to mitigate or prevent the
occurrence of SCTR incidents would
better address the risks and hazards
associated with spontaneous electric
95 E.g., Bolt EV Recall Information https://
experience.gm.com/recalls/bolt-ev.
96 Usual parking mode is the vehicle operational
mode in which the main software is ‘‘Off’’, the gear
selector is in ‘‘P’’ (park), the energy supply is
disconnected, the REESS power line is
disconnected, the cooling system is not operational,
the vehicle controls that manage safe operation of
the REESS (e.g., Battery Manage System) are not
energized, and the vehicle occupants are typically
not present.
97 EVS23–E1TP–0200 [KR] EV Fire Records of
Korea.pptx. https://wiki.unece.org/display/trans/
EVS+23rd+session.
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vehicle fires that originate within the
REESS than a warning to egress the
vehicle. This NPRM proceeds with
NHTSA’s preferred approach which
would require documentation
demonstrating that the manufacturer has
considered and developed risk
mitigation strategies to address SCTR in
developing their electric vehicles.
GTR No. 20 Phase 2 Test Procedure
Currently Under Consideration
The IWG is continuing work on
developing a test-based approach for
SCTR due to an internal short-circuit in
a single cell within the REESS. The plan
is for a future regulation to require that
the thermal propagation test procedure
fulfill the following conditions:
1. Triggering of thermal runaway at a
single-cell level must be repeatable,
reproducible, and practicable,
2. Judgment of thermal runaway
through common sensors, e.g., voltage
and temperature, needs to be practical,
repeatable, and reproducible, and
3. Judgment of whether consequent
thermal events involve severe thermal
propagation hazards, needs to be
unequivocal and evidence based.
NHTSA discusses this work in the
Appendix B to this preamble.
Comments are requested that could
assist the agency in future decisions on
this matter.
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3. Warning Requirements for REESS
Operations
As part of a risk-mitigation approach
addressing multiple aspects of electrical
system safety, NHTSA proposes
requiring: (a) a thermal event warning;
and (b) a vehicle control malfunction
warning for drivers. The thermal event
warning would be assessed by a
performance requirement, while the
vehicle control malfunction warning
would be a documentation requirement.
i. Thermal Event Warning
A ‘‘thermal event’’ presents an urgent
safety critical situation. The term refers
to a condition when the temperature
within the REESS is significantly higher
(as defined by the manufacturer) than
the maximum operating temperature
specified by the manufacturer. Thermal
events within REESS could occur due to
moisture and dust accumulation within
the REESS that cause a short circuit at
the connections or electronic
components within the REESS. A
thermal event within a battery pack can
be a safety critical event, as it can lead
to smoke, fire, and/or explosion. A
warning provided about a thermal event
within the REESS would reduce the
likelihood of occupant exposure to
smoke, fire, and/or explosion.
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GTR No. 20 requires the vehicle to
provide a warning to the driver in the
case of a ‘‘significant thermal event’’ in
the REESS (as specified by the
manufacturer) when the vehicle is in
active driving possible mode.98 The
GTR does not contain a performance test
for the warning but instead requires
manufacturers to provide
documentation on the parameters that
trigger the warning and a description of
the system for triggering the warning.
Specifically, the documentation
requirements include:
(1) Parameters and associated
threshold levels that are used to indicate
a thermal event (e.g., temperature,
temperature rise rate, SOC level, voltage
drop, electrical current, etc.) to trigger
the warning.
(2) A system diagram and written
explanation describing the sensors and
operation of the vehicle controls which
manage the REESS in the event of a
thermal event.
NHTSA Proposal
NHTSA proposes to include a
requirement for an audio and visual
warning to the driver if a thermal event
occurs in the REESS during the active
driving possible mode. Instead of a
documentation requirement as in the
current GTR No. 20, NHTSA proposes a
performance test to evaluate the
required warning of a thermal event
originating within the REESS.
NHTSA proposes to initiate the
thermal event in the REESS by inserting
a heater within the REESS that achieves
a peak temperature of 600°C within 30
seconds. In the proposed test procedure,
the REESS is removed from the vehicle,
if possible, and the REESS casing is
opened to attach the heater to a cell or
cells in the REESS in a manner to put
at least one cell in the REESS into
thermal runaway. In this test, there is no
need to restrict heating to a single cell
within the REESS as the test is verifying
activation of a warning when a thermal
event occurs in the REESS regardless of
the cause (e.g., an electric short between
electronic components in the REESS,
thermal runaway of multiple cells, etc.).
Following installation of the heater in
the REESS, the REESS casing is closed,
the REESS is re-installed in the vehicle,
and the vehicle propulsion system is
turned on. The heater within the REESS
is then activated. NHTSA proposes that
the audio-visual warning must be
98 Active driving possible mode means the
vehicle mode when application of pressure to the
accelerator pedal (or activation of an equivalent
control) or release of the brake system causes the
electric power train to move the vehicle.
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activated within three minutes 99 of
initiating the heater in the REESS.
NHTSA has tentatively decided not to
specify characteristics of the audiovisual warning to provide flexibility in
how manufacturers communicate this
safety critical information to vehicle
occupants so they quickly egress the
vehicle.
The proposed test is for evaluating
appropriate activation of a required
warning system when there is a thermal
event in the REESS that could be
hazardous to vehicle occupants.100
NHTSA tentatively concludes that the
proposed performance test to evaluate
the warning system would not be design
restrictive and can be conducted on all
applicable vehicles. Therefore, a
performance test is proposed instead of
adopting the documentation
requirement in GTR No. 20. NHTSA
seeks comment on the merits of the
proposed performance test to evaluate
the thermal event warning system
instead of the documentation
requirement in GTR No. 20. In addition,
NHTSA seeks input on the type of
heater, the heater characteristics (power,
peak temperature) and possible
locations of the heater within the REESS
to simulate a thermal event to trigger the
warning. While this NPRM does not
require specific features of the audiovisual warning itself, comments are
requested on what characteristics an
effective audio-visual warning should
have.
ii. Warning in the Event of Operational
Failure of REESS Vehicle Controls
NHTSA is proposing to require that
drivers be warned if there is a
malfunction of vehicle controls that
manage the safe operation of the REESS.
This NPRM proposes a documentation
approach for this type of warning,
similar to GTR No. 20.
GTR No. 20 specifies that when the
vehicle is in the active driving possible
mode, the vehicle shall provide a
warning telltale to the driver in the
event of a malfunction of the vehicle
controls that manage the safe operation
of the REESS. GTR No. 20 requires
manufacturers to provide
99 3 to 5 minutes is considered to be sufficient
time for able body individuals to evacuate light and
heavy passenger vehicles before the occurrence of
a hazardous event. https://one.nhtsa.gov/reports/
0900006480b01bbc.pdf.
100 This is unlike the risk management approach
for SCTR where the goal is to mitigate hazards of
thermal propagation (fire, smoke, gas emissions).
Because risk management strategies for mitigating
thermal propagation hazards due to SCTR differ
considerably in vehicle designs, an objective
performance test that can be conducted on all
applicable vehicles is not available and so a
documentation requirement is proposed.
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documentation demonstrating that a
warning to the driver will be provided
in the event of malfunction of one or
more aspects of vehicle controls that
manage REESS safe operation.
Specifically, vehicle manufacturers
shall make the following documentation
available to the testing authority:
(1) A system diagram that identifies
all the vehicle controls that manage
REESS operation. The diagram must
identify what components are used to
generate a warning telltale indicating
malfunction of vehicle controls to
conduct one or more basic operations.
(2) A written explanation describing
the basic operation of the vehicle
controls that manage REESS operation.
The explanation must identify the
components of the vehicle control
system, provide description of their
functions and capability to manage the
REESS, and provide a logic diagram and
description of conditions that would
lead to triggering the warning telltale.
NHTSA Proposal
Vehicle controls manage several
REESS operations, some of which are
safety critical. There are multiple
external fault scenarios 101 that could
trigger a vehicle control to take
corrective actions to ensure safe REESS
operations. This NPRM includes
performance requirements to address
these external fault scenarios that
assume proper functioning of the
vehicle controls that manage safe REESS
operations. However, if the vehicle
controls that manage safe REESS
operation are not functioning properly,
the REESS may not be adequately
protected from fault scenarios, which
could lead to REESS degradation and
eventually result in thermal propagation
and other safety hazards. Therefore, it is
important to notify the driver or front
row occupants in the event there is
malfunction of these vehicle controls
that manage safe REESS operations.
Due to the complexity and varied
designs of vehicle controls that manage
REESS safe operation, no single test
procedure could be developed that
would fully evaluate whether a warning
turns on in the event of operational
failure of vehicle controls. Therefore, in
accordance with GTR No. 20, this
NPRM proposes to require
manufacturers to provide a visual
warning to the driver (e.g., like a check
engine light) and documentation
demonstrating that the visual warning
will be provided in the event of
operational failure of one or more
101 These fault scenarios include overcharge,
over-discharge, overcurrent, external short-circuit,
and overheating of the REESS.
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aspects of vehicle controls that manage
REESS safe operation.
NHTSA proposes the GTR No. 20
requirements for a visual warning to the
driver of any malfunction of the REESS
vehicle controls, and manufacturer
documentation. In addition, NHTSA
proposes to include two additional
requirements that ensure manufacturers
have validated functionality of the
warning system:
(1) Any validation test results by the
vehicle manufacturer to confirm a visual
warning is displayed in the presence of
malfunction of the REESS operation
vehicle controls.
(2) A description of the final
manufacturer review or audit process
and results of any final review or audit
evaluating the technical content and the
completeness and verity of the
documentation submitted by the
manufacturer.
NHTSA tentatively concludes that a
documentation approach is merited to
demonstrate that the manufacturer has
considered the effectiveness of a visual
warning of the malfunction of the
REESS operational vehicle controls. In
the absence of information enabling
NHTSA to propose a practical test
procedure to evaluate the performance
of a warning, the documentation
approach ensures that manufacturers are
aware of the safety risks at issue and
have considered ways to address the
risks. NHTSA would review the
documentation to understand the visual
warning associated with the particular
REESS in the vehicle, see whether the
manufacturer conducted an assessment
of its effectiveness, and understand the
measures the manufacturer undertook to
validate such performance.
This approach is an interim measure
intended to assure that manufacturers
will identify, address, and validate the
effectiveness of their visual warnings
that help manage safe REESS operation.
The approach is intended to evolve over
time as battery technologies and
NHTSA’s information about the REESS
safety risk mitigation strategies evolve.
In section VI., NHTSA requests
comments on whether the proposed
document requirement would be better
placed in a general agency regulation
than in proposed FMVSS No. 305a.
4. Protection Against Water Exposure
NHTSA proposes to adopt GTR No.
20’s physical water test requirement,
where a vehicle shall maintain electrical
isolation resistance after the vehicle is
exposed to water under normal vehicle
operation, such as in a car wash or
while driving through a pool of standing
water. However, the agency is not
proposing to adopt GTR No. 20’s two
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other water exposure methods:
documentation measures and warning
requirements.
Environmental effects such as
exposure to water and moisture may
deteriorate the electrical isolation of
high voltage components in the
powertrain. This may first lead to an
electric system degradation and
eventually lead to an unsafe electrical
system for vehicle occupants, operators
(during charging) or by-standers. Under
extreme conditions, fire can originate
from compromised electrical
components due to water ingress. GTR
No. 20 contains water exposure shock
protection specifications in which a
vehicle shall maintain electrical
isolation resistance after the vehicle is
exposed to water under normal vehicle
operation, such as during a car wash or
driving through a pool of standing
water.
NHTSA begins by noting that GTR
No. 20 does not have specific
requirements to address vehicle fires
due to vehicle submersion such as
floods and storm surges, and this NPRM
is not covering that area. Floods are
considered as catastrophic events, and
as noted above, one of the principles for
developing GTR No. 20 was to address
unique safety risks posed by electric
vehicles and their components to ensure
a safety level equivalent to conventional
vehicles with internal combustion
engine (ICE). NHTSA continues to
research the area of REESS performance
post-submersions. This issue is
discussed in more detail later in this
section.
GTR No. 20 Requirements
GTR No. 20 contains water exposure
shock protection specifications in which
a vehicle shall maintain electrical
isolation resistance after the vehicle is
exposed to water under normal vehicle
operation. GTR No. 20 specifies three
compliance options contracting parties
may use in their regulations:
• Physical tests—(1) the vehicle is
subjected to normal washing using a
hose nozzle and conditions in
accordance with IPX5, after which (2)
the vehicle is driven in a freshwater
wade pool (10 cm depth) over a total
distance of 500 m at a speed of 20 km/
hr for approximately 1.5 minutes (min).
The electrical isolation of high voltage
sources in the electric powertrain are
verified at the conclusion of each test
and once again after 24 hours.
• Documentation—The vehicle
manufacturers provide documentation
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certifying to IPX5 102 level
waterproofing for protection of high
voltage components in the vehicle. IPX5
is a waterproof rating that ensures
protection against water ingress under
sustained low pressure water jet stream
(12.5 liters per minute at a pressure of
30 kilopascals (4.4 psi) from a distance
of 3 meters) from any angle. The
duration of the jet stream exposure is 1
minute per square meter surface area of
the high voltage component.
• Warning—The vehicle has an
electrical isolation loss warning system
that warns the driver when electrical
isolation falls below 100 ohms per volt
for DC electrical components or 500
ohms per volt for AC electrical
components. This option is available for
individual countries to adopt if they so
choose.
i. NHTSA Proposal
NHTSA tentatively concludes that the
GTR No. 20’s physical test option is a
practical and feasible means of
evaluating the effects of water exposure
under normal vehicle operating
conditions. It has advantages of a
performance standard in assessing
compliance over a documentation
approach. Thus, the agency is not
proposing the compliance option in
GTR No. 20 of providing documentation
on high voltage components meeting
IPX5 level of protection.
Regarding the electrical isolation loss
warning system option in GTR No. 20,
NHTSA believes the warning signals
alone are not sufficient for addressing
loss of electrical isolation concerns.
Where objective performance criteria are
available and are appropriate for all
types of vehicles to which the standard
applies, NHTSA believes objective
performance criteria should govern
when compared to the approach of
solely using a warning. The existence of
the visual warning cannot necessarily be
considered a safety prevention system,
as the root cause of the safety hazard
remains unaddressed, and the visual
warning may be ignored by the driver.
Although visual warning indicators
triggered from an isolation monitoring
system could help mitigate safety
concerns, NHTSA believes that this
approach is not sufficient to solely
mitigate a shock or fire hazard caused
by the effects of water exposure. Thus,
the agency does not propose this
alternative as a compliance option in
FMVSS No. 305a.
NHTSA Proposed Vehicle-Level
Physical Test Procedures
The proposed physical test procedure
is comprised of two series of tests,
informally referred to as the ‘‘vehicle
washing’’ test and the ‘‘driving through
standing water’’ test. Electrical isolation
is determined at the conclusion of each
test, and once again after 24 hours.
13
26725
A. Vehicle Washing Test
The washing test exposes the vehicle
to a stream of water such as when
washing a car. The vehicle external
surface, including the vehicle sides,
front, rear, top, and bottom is exposed
to the water stream. GTR No. 20
excludes the vehicle underbody from
exposure to the water stream. However,
since the vehicle underbody is often
exposed to water when the vehicle is
washed, NHTSA proposes to also
expose the vehicle underbody to the
water stream to make this test more
representative of vehicle washing. The
areas of the vehicle that are exposed to
the water stream in any possible
direction include border lines, i.e., a
seal of two parts such as flaps, glass
seals, outline of opening parts
(windows, doors, vehicle inlet cover),
outline of front grille and seals of lamps.
During the test, the vehicle is sprayed
from any practicable directions with a
stream of freshwater from a standard
test nozzle as shown in Figure 4 below.
The standard nozzle, with an internal
diameter is 6.3 mm, shall provide a
delivery rate of 11.9–13.2 liters/minute
(l/min) with water pressure at the
nozzle of 30–35 kilopascals (kPa) or
0.30–0.35 bar. These standard nozzle
specifications are from IEC 60529 for
IPX5 water jet nozzle.
20
Dimensions in millimetres
Dis 6.311llll asspecifiedm (a}above.
The vehicle surface is exposed to the
water stream from the standard nozzle
for a duration of 1 minute per square
meter or for 3 minutes, whichever is
greater. The distance from the nozzle to
the tested vehicle is 3 meters, which
may be reduced, if necessary, to ensure
the surface is wet when spraying
upwards.
After the ‘‘vehicle washing’’ test and
with the vehicle surface still wet,
electrical isolation is determined for
high voltage sources in the same manner
as that currently in S7.6 of FMVSS No.
305. The high voltage sources are
required to meet the electrical isolation
requirements as specified in S5.4.3 of
current FMVSS No. 305.
Comments are requested on the merits
of including the test in FMVSS No.
305a. NHTSA seeks comment on the
representativeness of the washing test,
including but not limited to the
proposed test conditions (e.g., 30–35
102 IEC 60529:1989/AMD2:2013, ‘‘Degrees of
protection provided by enclosures (IP Code).’’
https://webstore.iec.ch/publication/2446.
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Figure 4—Standard Nozzle (IEC 60529)
for IPX5 Water Exposure Test
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kPa versus 80–100 kPa water pressure
conditions, water salinity levels, and
water exposure durations, etc.).
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B. Driving Through Standing Water Test
NHTSA proposes that vehicles should
also be subjected to GTR No. 20’s
‘‘driving through standing water’’ test.
The vehicle is driven through a pool of
standing freshwater,103 10 centimeters
(cm) (4 inches) deep, for a total range of
500 meters (m), at a vehicle speed of 20
km/hr.104 The pool represents a lowlying portion of a road that can get
flooded in excessive rain. Meeting the
test is a reasonable indication that the
vehicle has safeguards to ensure
electrical safety when driven through
roads in inclement weather.
If the wade pool used is less than 500
m in length, then the vehicle is driven
through the wade pool several times.
The total time, including the periods
outside the wade pool, would have to be
less than 5 minutes. GTR No. 20
specifies a maximum test time of 10
minutes, but NHTSA believes that 5
minutes is preferable. Traversing 500 m
at 20 km/hr takes 90 seconds. A
maximum test duration of 10 minutes
would allow for an excessive amount of
time out of the water and may not be
equivalent to a continuous 500 m
exposure. NHTSA seeks comment on
the maximum duration of this test.
NHTSA also seeks comment on the
availability and geometric dimensions
of different types of wade pools (long
rectangular, circular) to accomplish this
type of test.
Just after the standing water test is
completed and with the vehicle still
wet, the vehicle would be required to
meet the electrical isolation
requirements now specified in FMVSS
No. 305 S5.4.3 when tested in the same
manner as described in S7.6 of current
FMVSS No. 305. The vehicle is also
required to meet the electrical isolation
requirements that are in S5.4.3 of
current FMVSS No. 305, 24 hours after
the washing test and the standing water
test are completed.
NHTSA seeks comment on the water
salinity requirements for the physical
tests as described above, including
tolerances for the test parameters listed
above.
103 Freshwater means water containing less than
1,000 milligrams per liter of dissolved solids, most
often salt.
104 NHTSA tentatively concludes that the 10 cm
(approximately four-inch) depth is reasonable, as
national weather advisories (https://
www.weather.gov/tsa/hydro_tadd) recommend not
driving on flooded roads with more than four
inches of water. Six inches of water on the road
could reach the bottom of most passenger cars
causing loss of control and possible stalling. A foot
of water can float many vehicles.
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ii. NHTSA’s Consideration of
Submersions
In the U.S., floods resulting from
Hurricane Sandy (2012), Hurricane
Harvey (2017) and Hurricane Ian (2022)
have led to electric vehicles submerged
in flood waters for varying periods of
time, with varying reports of vehicle
fires in the aftermath. In developing this
NPRM, the agency considered whether
it could propose requirements to
address these types of vehicle
submersions and the resulting risk of
fire. NHTSA analyzed field data from
these hurricanes and made the
following key observations of vehicle
fires resulting from the vehicle
submersions:
(1) Not all electric vehicles submerged
in floods catch on fire. The type of water
(water salinity), the level of submersion,
and duration of submersion are likely
factors;
(2) Fire and other hazards are more
likely after water exposure (days after
flood waters recede) rather than during
the exposure;
(3) Fire may not originate in the
REESS and may spread to the REESS
from another vehicle component; and
(4) While 12V systems may also short
circuit and result in vehicle fire, fires
involving lithium-ion REESS are more
difficult to extinguish and more
hazardous because of the selfoxygenating nature of the lithium-ion
cells and the energy density of the
REESS.
NHTSA evaluated the regulatory
approaches taken by other countries to
determine if such standards could assist
NHTSA in addressing the challenges
posed by the submersions and fires
resulting from Hurricanes Sandy,
Harvey, and Ian. NHTSA analyzed
China and Korea’s water exposure
requirements but determined the focus
of those standards do not appear to
address the safety matter at issue. Key
observations and findings from the field
data in the U.S. and the exploratory
investigation into the water exposure
posed by the hurricanes suggest that the
test procedure and parameters and the
performance requirements in China GB–
38031 105 and the Korean Motor Vehicle
105 GB–38031 water immersion test contains two
options. Option 1 is based on ISO–6469–1:2019
where the REESS is submerged in 1 meter of
seawater (salinity of 3.5 percent) for two hours. The
performance requirement for this test option is for
no fire or explosion of the REESS during the
submersion. Option 2 is based on ISO–20653, and
requires IPX7 level waterproofing. In this test
option, the REESS is completely submerged in
regular water for 30 minutes such that the lower
point of the battery is one meter below the surface
or the highest point is 150 mm below the surface
(for battery packs with a height greater than 850
mm). The performance requirement in this test
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Safety Standard (KMVSS) 106 may not be
representative of field events of vehicle
fires resulting from Hurricanes Sandy,
Harvey, and Ian water exposure. If the
standards are not representative of the
harm NHTSA wishes to address from
the hurricanes, the concern is the
countermeasures to meet the
performance test requirements of GB–
38031 and KMVSS may not be effective
at mitigating thermal events resulting
from the water exposure at issue.107
Specifically, in both standards, the
REESS is submerged in 3.5 percent
salinity water representing seawater for
a long period of time (two hours for GB–
38031 and one hour for KMVSS).
NHTSA’s exploratory investigation of
current REESS designs 108 suggests
submersion in lower salinity water for a
shorter duration may result in higher
risk of thermal event. Longer immersion
times in seawater salinity levels allow
the batteries to safely discharge under
water without adverse reactions such as
arcing, venting, or underwater fires.
Additionally, the requirements for no
fire and explosion in these two
standards are evaluated during the
REESS immersion and not after the
REESS is pulled out of the water. Such
a requirement is not relevant to the
electric vehicle fires observed after the
flood waters in Hurricane Sandy and
Hurricane Ian receded.
NHTSA acknowledges that the
batteries in conventional vehicles with
internal combustion engines (ICE) may
also catch fire due to submersion.
However, the post-submersion vehicle
fires after Hurricane Ian demonstrated
that electric vehicle fires are more
difficult to put out and therefore more
hazardous than ICE vehicle fires.
NHTSA believes that a better
understanding of the field incidences of
electric vehicle fires is needed before a
field relevant test and performance
requirements can be developed that
addresses the observed safety risks
option is for no water ingress, fire, or explosion,
and the REESS maintains an electrical isolation of
100 ohms per volt after submersion. Option 1 of
GB–38031 is intended for most current REESS
(open-type or partially sealed) while Option 2
would necessitate a fully sealed REESS.
106 KMVSS contains requirements for REESS,
including a water immersion test that has been
implemented in South Korea since 2009. In the
water immersion test, the REESS is fully submerged
in seawater (salinity of 3.5 percent) for one hour.
The performance requirement in this test is for the
REESS to not explode or catch on fire during the
immersion. EVS19–E4WI–0300 [KR] Water
Immersion Test.pptx. https://wiki.unece.org/
display/trans/EVS+19th+session.
107 For instance, NHTSA’s understanding is that
most of the vehicles involved in Hurricane Ian’s
post-submersion fires had met China GB–38031.
108 Li-Ion Battery Pack Immersion Exploratory
Investigation, DOT HS 813 136, July 2021. https://
rosap.ntl.bts.gov/view/dot/57013.
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associated with submersion of REESS
and high voltage components in events
such as floods.
The agency seeks comment on test
conditions and test procedures that
would address observed safety risks
associated with submersion of REESS
and high voltage components.
Going Forward
Shortly after Hurricane Ian, NHTSA
and other DOT agencies coordinated
with emergency personnel in Florida to
collect in-depth information on vehicle
fire incidences and REESSs involved in
the flooding.109 This activity and others
like it provided critical information that
informed approaches to better protect
vehicle owners, responders, and other
stakeholders in the future.
In the near term, as discussed in
sections below, this NPRM proposes to
require that electric vehicle
manufacturers submit standardized
emergency response information to a
NHTSA central depository, to assist first
and second responders to respond to
emergencies as quickly and safely as
possible. The agency tentatively
concludes that such a requirement
would be an important and achievable
near-term measure that NHTSA and the
industry can take to mitigate the harm
from these fires as work continues on
vehicle-based mitigation methods. As
part of NHTSA’s activity going forward,
NHTSA will document EV battery
conditions after catastrophic flooding
events and will commence new research
into mitigation methods. The agency
will obtain data to develop and improve
EV tests relevant to salt-water
immersion.
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5. Miscellaneous GTR No. 20 Provisions
Not Proposed
There are several GTR No. 20
provisions for REESS performance
during normal vehicle operations that
NHTSA has not included in this NPRM.
These provisions relate to requirements
for: vibration, thermal shock and
cycling, fire resistance, and low state-ofcharge (SOC). Below is a description of
the requirements and explanations of
why NHTSA is proposing not to include
the requirements. NHTSA requests
comments on these views.
i. REESS Vibration Requirements
GTR No. 20 contains a vibration
requirement and test procedure to verify
the safety performance of the REESS
109 NHTSA has purchased ten electric vehicles
damaged during Hurricane Ian and plans to perform
a teardown analysis to understand the root cause of
the vehicle fires. The teardown analysis will inform
the next steps to address the safety risks associated
with vehicle submersions.
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under a prescribed sinusoidal vibration
environment that applies a generic
vibration profile to the tested vehicle.
NHTSA believes the vibration profile
accelerations and frequencies are
unique for each vehicle model and so
applying a generic vibration profile to
all vehicle models may not be
appropriate. Additionally, the vibration
environment in the test specified in
GTR No. 20 is applied only in the
vertical direction while in real world
driving conditions, the REESS is subject
to vibration along all three orthogonal
axes. Therefore, the agency tentatively
concludes that the vibration test in GTR
No. 20 is not representative of the actual
vibration environment for different
vehicle models, or representative of
real-world conditions that the REESS
experiences.
Furthermore, vibration appears
sufficiently addressed through other
means. The market addresses this
matter, as manufacturers routinely
perform vibration testing to ensure
customer satisfaction and reliability.
Vehicle manufacturers assess the
durability of the vehicle and its
components (not just the REESS)
through various road conditions with
full vehicle simulation, either by driving
on a rough road test track or simulating
the lifetime fatigue on a vibration rig.
Further, at the component level, electric
vehicle batteries are currently subject to
similar vibration test requirements for
transportation under the United States
Hazardous Materials Regulations
(HMR) 110 but along all three orthogonal
axes and for frequencies up to 200
Hz.111 Thus, NHTSA believes that the
GTR No. 20 vibration test would not
address an additional safety need
beyond what is already provided by
HMR.
For the reasons stated in the
paragraph above, NHTSA is not
proposing the vibration test at a
component level or the vehicle level.112
Currently, during Phase 2 development
of GTR No. 20, there are discussions for
updating the vibration test to include
vibration in all three orthogonal axes
and at higher amplitudes and frequency
110 49 CFR parts 171 to 180, incorporated
requirements for lithium batteries from UN 38.3
‘‘Transport of dangerous goods: manual tests and
criteria.’’
111 49 CFR 173.185 incorporated the vibration test
38.3.4.3 from the UN’s ‘‘Recommendations on the
Transport of Dangerous Goods, Manual of Tests and
Criteria,’’ https://digitallibrary.un.org/record/
483552?ln=en.
112 NHTSA and Transport Canada discussed in
detail their positions for not including this
vibration test during the development of GTR No.
20. See https://wiki.unece.org/download/
attachments/117508721/EVS21-E3VP0101%5BOICA_UC_CA%5Dconsideration_of_
vibration.pdf?api=v2.
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26727
range. In Appendix B of this preamble,
the agency seeks public comment on the
work in Phase 2 on the vibration test.
ii. REESS Thermal Shock and Cycling
GTR No. 20’s thermal shock and
cycling requirement and test procedure
aim to verify that the REESS is robust
against thermal fatigue and contact
degradation caused by temperature
changes and potential incompatibilities
of materials with varying thermal
expansion characteristics.
At the component level, REESSs are
already subject to thermal cycling test
requirements for transportation under
the HMR. 49 CFR 173.185 requires
lithium-ion cells and batteries to
comply with the test requirements in
UN 38.3, including Test T2: Thermal
test, which is the basis of the GTR No.
20 thermal shock and cycling test. In the
UN38.3 Test T2, the REESS would be
subject to temperature changes from
¥40 °C to +75 °C. This temperature
range is greater than that prescribed in
GTR No. 20. To avoid redundancy,
NHTSA is not proposing the thermal
shock and cycling test for the REESS.
NHTSA tentatively concludes that
incorporating the GTR No. 20 thermal
shock and cycling test into FMVSS
would not address additional safety
needs beyond that already provided by
HMR and 49 CFR 173.185. The agency
seeks public comment on the safety
need of a REESS thermal shock and
cycling requirement, and requests
commenters provide data to substantiate
their comments and/or assertions.
iii. REESS Fire Resistance
This GTR No. 20 requirement is based
on UN Regulation No. 34, ‘‘Uniform
provision concerning the approval of
vehicles with regard to the prevention of
fire risks,’’ 113 which contains a fire
resistance requirement for liquid fueled
vehicle with plastic tanks. This test is
required for REESSs installed in a
vehicle at a height lower than 1.5 m
above the ground and contain
flammable electrolyte. During the test,
the REESS is placed on a grating table
positioned above the fire source in a
pan. The pan filled with fuel is placed
under the REESS in such a way that the
distance between the level of the fuel in
the pan and the bottom of the REESS
corresponds to the design height of the
REESS above the road surface at the
unladed mass. The REESS is exposed
directly to the flame for 70 seconds. A
screen made of refractory material is
then moved over the pan with the flame,
113 UN Regulation No. 34. https://unece.org/
fileadmin/DAM/trans/main/wp29/wp29regs/2013/
R034r2e.pdf.
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such that the REESS is indirectly
exposed to the flame for an additional
60 seconds. The screen and pan are then
moved away from the REESS. The
REESS is observed until the surface
temperature of the REESS has decreased
to the ambient temperature of the test
environment. During the test, the REESS
shall exhibit no evidence of explosion.
NHTSA tentatively concludes that the
short duration of the GTR No. 20 fire
resistance test would not address any
safety risks associated with explosion
resulting from external fire to the battery
pack. Transport Canada conducted full
vehicle gasoline pool fire tests of
electric powered vehicles and similar
vehicles with internal combustion
engines and found that there was no
explosion in tests of vehicles with
REESS and those without. The
Transport Canada tests indicated that
the short duration of the GTR No. 20
external fire test would not result in
explosion.114 During Phase 1 of the GTR
No. 20 discussions, the United States
and Canada noted that including the
short duration component level test in
GTR No. 20 would not address a safety
need and recommended removing it
from GTR No. 20.115 For these reasons,
NHTSA is tentatively not proposing the
short duration fire resistance test from
GTR No. 20. The agency seeks comment
on excluding this fire resistance
requirement from the FMVSS, and
requests commenters provide data to
substantiate their comments and/or
assertions.
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iv. Low State-of-Charge (SOC) Telltale
GTR No. 20 requires a telltale to the
driver in the event of low REESS
SOC.116 The agency is tentatively not
including this telltale requirement for
electric powered vehicles because there
is no corresponding low fuel warning
requirement for conventional vehicles
with internal combustion engines. Lowfuel telltales are presently provided in
all conventional vehicles due to
consumer demand. Similarly, all
electric-powered vehicles already
provide low SOC telltales due to
consumer demand. NHTSA seeks
comment on whether this GTR No. 20
requirement should be incorporated into
proposed FMVSS No. 305a, and if yes,
what the telltale should look like.
114 https://wiki.unece.org/download/attachments/
29884786/EVSTF-07-02e.pdf?api=v2.
115 https://wiki.unece.org/download/attachments/
29884786/EVSTF-07-02e.pdf?api=v2.
116 The GTR does not standardize the appearance
of the telltale.
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IV. Request for Comment on Applying
FMVSS No. 305a to Low-Speed
Vehicles
Current FMVSS No. 305 applies to
electric vehicles whose speed, attainable
over a distance of 1.6 kilometers (km) (1
mile) on a paved level surface, is more
than 40 km/h (25 miles per hour (mph)).
It does not apply to vehicles that travel
under 40 km/h (25 mph), such as lowspeed vehicles.117
There are low-speed vehicles that are
also electric-powered vehicles. NHTSA
requests comments on applying aspects
of FMVSS No. 305a to low-speed
vehicles to ensure a level of protection
against shock and fire, particularly
during normal vehicle operation, and to
assure the safe operation of the REESS.
The agency requests comment on the
possible applicability of FMVSS No.
305a to low-speed vehicles and its
relevant safety needs, including any
supporting research on low-speed
vehicles.
V. Emergency Response Information To
Assist First and Second Responders
Fires in electric vehicles are harder to
extinguish than fires in vehicles with
internal combustion engines and can
reignite. These risks are also dependent
on the specific vehicle design. Easy
access to pertinent vehicle specific and
emergency response information is vital
for first and second responders when
encountering electric vehicles. Safety is
impeded when first and secondary
responders are on scene but are delayed
in their mitigation efforts because
information on vehicle-specific safety
mitigation methods are not easily
accessible.
a. NTSB Report
In 2020, NTSB published a safety
report following a detailed investigation
of four electric vehicle fires.118 The
investigation identified safety risks to
first and second responders 119 from
117 ‘‘Low-speed vehicle’’ is defined in 49 CFR
571.3. See also FMVSS No. 500, ‘‘Low speed
vehicles,’’ 49 CFR 500.
118 Three of the vehicle fires occurred following
severe crashes that resulted in significant damage
to the REESS casing. One vehicle fire was caused
by internal failure of the REESS during normal
driving operations. ‘‘Safety risks to emergency
responders from lithium-ion battery fires in electric
vehicles,’’ Safety Report NTSB/SR–20/01, PB2020–
101011, National Transportation Safety Board,
https://www.ntsb.gov/safety/safety-studies/
Documents/SR2001.pdf.
119 The NTSB report states, ‘‘First responders in
this context refers to firefighters, but emergency
medical technicians, paramedics, and police
officers are also classified as first responders.
Second responders in this context refers to tow
truck drivers or tow yard operators, but they can
also include those responsible for temporary traffic
control or other support functions at a crash site.’’
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exposure to high voltage components
and from vehicle fire due to damaged
cells in the REESS that could reignite as
a result of stranded energy in the
REESS.120 The NTSB investigation
further identified the lack of a clear and
standardized format in vehicle
manufacturers’ emergency response
guides (ERGs) 121 and inadequacy in the
information provided in the ERGs for
first and second responders to minimize
safety risks posed by stranded energy in
the REESS while handling electric
vehicles.
NTSB issued recommendations to
vehicle manufacturers, first and second
responder organizations, and NHTSA.
NTSB recommended manufacturers of
electric vehicles to model their
emergency response guides on
International Standards Organization
(ISO)–17840 122 and SAE International
recommended practice SAE J2990,
‘‘Hybrid and EV first and second
responder recommended practice.’’ 123 It
recommended incorporating vehiclespecific information on (1)
extinguishing REESS fires, (2) mitigating
risk of REESS reignition, (3) mitigating
safety risks (electric shock and fire)
associated with stranded energy during
emergency response and transport of
damaged vehicle, and (4) storing
damaged electric vehicles.
NTSB recommended to the vehicle
manufacturers to follow the practices for
first and second emergency responders
120 Stranded energy is the energy remaining
inside the REESS after a crash or other incident.
Cells in a compromised REESS could undergo
thermal runaway at a later time and reignite the
vehicle fire after firefighters extinguish the initial
vehicle fire.
121 Emergency Response Guides (ERGs) contain
in-depth vehicle-specific information related to fire,
submersion, leakage of fluids, towing, and storage
of vehicles. The information is presented in a
specific format with color-coded sections in a
specific order to help first and second responders
quickly identify pertinent rescue information.
Rescue sheets contain abbreviated emergency
response information about a vehicle’s
construction. Rescue sheets are most likely to be
referenced first by emergency responders upon
arrival at the scene of a crash. ERGs contain more
information than rescue sheets.
122 ISO–17840, ‘‘Road vehicles—Information for
first and second responders,’’ consists of 4 parts: (1)
Part 1 (2015): Rescue sheet for passenger cars and
light commercial vehicles, (2) Part 2 (2019): Rescue
sheet for buses, coaches, and heavy commercial
vehicles, (3) Part 3 (2019): Emergency response
guide template, and (4) Part 4 (2018): Propulsion
energy identification. https://webstore.ansi.org/
standards/iso/iso178402015?gclid=Cj0KCQ
iAtbqdBhDvARIsAGYnXBMNT9mR9gjsrKxd5
kK8dK6V21Ql9bDr8q2OI0fncMQHHpX_D8bQCx
AaAhbUEALw_wcB.
123 SAE J2990 provides format and content
recommendations for emergency response guides
and quick reference sheets in accordance with ISO
17840. https://www.sae.org/standards/content/
j2990/2_202011/.
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available in SAE J2990 124 and ISO–
17840. SAE J2990 mainly refers to the
ISO–17840 for the emergency response
information. As indicated earlier, ISO–
17840 is comprised of four parts:
• ISO 17840–1:2022(E) standardizes
the content and layout of rescue sheets
for passenger cars and light commercial
vehicles.
• ISO 17840–2:2019(E) standardizes
the rescue sheets for buses, coaches, and
heavy commercial vehicles.
• ISO 17840–3:2019(E) establishes a
template and defines the general content
for manufacturers’ emergency response
guides for all vehicle types—longer
documents that give in-depth
‘‘necessary and useful information’’
about a vehicle for emergency incidents.
• ISO 17840–4:2018 defines the labels
and colors used to indicate the fuel or
energy used to propel a vehicle for both
the rescue sheets and the ERGs.
NTSB had two recommendations to
NHTSA. The first recommendation was
to factor the availability of a
manufacturer’s ERG and its adherence
to ISO 17840 and J2990 when
determining a vehicle’s U.S. New Car
Assessment Program (NCAP) score.125
The second recommendation was to
convene a coalition of stakeholders to
continue research and publish the
results on ways to mitigate or
deenergize the stranded energy in highvoltage lithium-ion batteries and to
reduce the hazards associated with
thermal runaway resulting from highspeed, high-severity crashes.
NHTSA responded to NTSB by a
letter dated April 2, 2021. Among other
things, the letter said that NHTSA will
be addressing risks to emergency
responders by working directly with the
emergency response community. The
agency explained that NHTSA has
partnered with the National Fire
Protection Association (NFPA) to
support the development of training to
emergency responders on handling and
managing fire incidents involving
alternative fuel vehicles, including
electric vehicles.126 This NPRM is one
124 SAE J2990 recommended practice provides
common procedures to help protect emergency
responders and personnel supporting towing and/
or recovery, storage, repair, and salvage after an
incident has occurred with an electric powertrain
vehicle.
125 NHTSA’s NCAP is a consumer information
program that evaluates the safety performance of
vehicles and provides comparative information on
new vehicles. NCAP also provides consumers with
information on the availability of new vehicle safety
features. This information is provided to assist
consumers with vehicle purchasing decisions and
to encourage safety improvements in vehicle
design.
126 https://www.nhtsa.gov/sites/nhtsa.gov/files/
2021-12/NHTSA-NTSB-Response-04-02-2021Stranded-Energy-Lithium-Ion-Batteries-NCAPImprovements-tag.pdf.
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result from our partnering with NFPA to
provide emergency response guides to
first and second responders.
NHTSA worked with other agencies
and stakeholders and issued interim
guidance in support of the development
of training for emergency responders. In
2012 and 2014, NHTSA provided
interim guidance to law enforcement,
emergency medical services personnel
and fire departments when
encountering electric or hybrid-electric
vehicles, to reduce the risk of shock
hazards and vehicle fires following
vehicle submersion.127 NHTSA also
provided separate interim guidance for
towing and recovery operators and
persons operating vehicle storage
facilities.128 NHTSA continues to lead
an inter-agency 129 effort to develop
updated guidance on best practices and
strategies for emergency personnel to
contain electric vehicle-related hazards
from field events, such as electric
vehicle fires resulting from storm surges
like those occurring during Hurricane
Ian.
b. NHTSA Proposal
The Information Must Be Provided
Current emergency response
information is voluntarily filed on an
NFPA website.130 Rather than factoring
the availability of ERGs as part of NCAP,
NHTSA tentatively believes it would be
more effective to address risks to
emergency responders by directly
requiring the standardized information.
The information would be available and
understandable to first and second
responders so they can refer quickly and
easily to identify pertinent vehiclespecific rescue information at the scene
of the crash or fire event, and respond
to the emergency quickly, effectively,
and safely.
The Information Must Be Standardized
To improve the ease and flow of
information and, ultimately, the safety
of persons involved, NHTSA is
proposing a requirement that vehicle
manufacturers submit the emergency
response information to NHTSA in a
standardized format. Currently, the
127 Interim Guidance for Electric and HybridElectric Vehicles Equipped with High-Voltage
Batteries (located at https://www.nhtsa.gov/sites/
nhtsa.gov/files/811575-interimguidehev-hv-batt_
lawenforce-ems-firedept-v2.pdf).
128 ‘‘Interim Guidance for Electric and HybridElectric Vehicles Equipped with High-Voltage
Batteries,’’ located at 811576-interimguidehev-hvbatt_towing-recovery-storage-v2.pdf (nhtsa.gov).
129 U.S. Department of Energy, the United States
Fire Administration, and the National Fire
Protection Association.
130 https://www.nfpa.org/Training-and-Events/Bytopic/Alternative-Fuel-Vehicle-Safety-Training/
Emergency-Response-Guides.
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ERGs and rescue sheets for alternative
fuel vehicles available on the NFPA
website is not in a standardized
format.131 The NTSB report indicated
that a standardized format for ERGs
would enhance emergency response as
well as protect first and second
responders. NHTSA tentatively believes
this NPRM’s proposed standardization
requirement would make the
information more understandable and
would be another means that would
help reduce response times and the
safety risks to emergency responders.
Proposed FMVSS No. 305a would
require that the rescue sheets must
follow the layout and format in ISO–
17840–1:2022(E) (for vehicles with a
GVWR less than or equal to 4,536 kg
(10,000 lb)) and the format in ISO–
17840–2:2019(E) (for vehicles with a
GVWR greater than 4,536 kg (10,000
lb)). ERGs must follow the template
layout and format of ISO–17840–
3:2019(E) and provide in-depth
information linked and aligned to the
corresponding rescue sheet to support
the quick and safe action of emergency
responders. The ERGs must also provide
in-depth information related to electric
vehicle fire, submersion, leakage of
fluids, towing, transportation, and
storage.
NHTSA seeks comment on the
proposed format and layout of rescue
sheets and ERGs in accordance with the
different parts of ISO–17840. Are there
main features of ISO–17840 that should
be considered instead of referring to
specific versions of the ISO–17840
parts? Are there specific features not
included in ISO–17840 that would
further enhance first and second
responders’ operations?
The Information Must Be VehicleSpecific
NHTSA tentatively believes that, due
to varying electric vehicle design and
development, emergency response
information must be vehicle-specific.
Currently, the ERGs and rescue sheets
on the NFPA website are not available
for all vehicle makes, models, and
model years. NHTSA tentatively
believes that the information is of
limited value because of this limited
availability. The agency tentatively
believes that requiring information on
all vehicles is necessary to best reduce
response times and the safety risks to
emergency responders.
131 https://www.nfpa.org/Training-and-Events/Bytopic/Alternative-Fuel-Vehicle-Safety-Training/
Emergency-Response-Guides.
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The Information Must Be Submitted to
NHTSA
NHTSA tentatively believes that easy
access to both short and long forms of
emergency response information are
essential to address the risk of
emergency responders. Therefore, as
part of this NPRM and the NHTSA’s
battery safety initiative,132 NHTSA is
proposing a provision in FMVSS No.
305a that would require vehicle
manufacturers to submit electronic
versions of ERGs and rescue sheets for
all vehicles to which FMVSS No. 305a
applies, prior to certification of the
vehicle, so that they are available in a
centralized location on NHTSA’s
website. The rationale of submission
prior to certification is to ensure the
pertinent information for first and
second responders are available by the
time the vehicles are placed on public
roads and potentially involved in
emergencies. The intent is for both the
ERGs and rescue sheets to be stored and
maintained at a centralized web location
(within NHTSA.gov), so that they are
always easily and quickly accessible to
all first and second responders.
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Other Issues Presented for Comment
• To align with NHTSA’s intent to
have both ERGs and rescue sheets
accessible in a centralized NHTSA web
location, NHTSA would like to migrate
the ERGs currently on the NFPA website
to NHTSA’s website. NHTSA requests
comments on whether electric vehicle
ERGs and rescue sheets that were
previously hosted on the NFPA website
should be included in NHTSA’s
centralized web location.
• NHTSA also requests comments on
whether the requirement described in
this section for ERGs and rescue sheets
would be better placed in a general
agency regulation than in proposed
FMVSS No. 305a. NHTSA discusses this
issue at length in section VI. of this
preamble regarding documentation
requirements pertaining to REESS safety
risks and risk mitigation strategies
identified by manufacturers. NHTSA
requests comments on the pros and cons
of having the ERGs and rescue sheet
requirements in a regulation rather than
in FMVSS No. 305a. Comments are
requested on the pros and cons of
placing the requirement for providing
ERG and rescue sheets to NHTSA to be
in a regulation rather than in FMVSS
No. 305a.
132 https://www.nhtsa.gov/battery-safetyinitiative.
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VI. Request for Comment on Placing the
Emergency Response Information and
Documentation Requirements in a
Regulation Rather Than in FMVSS No.
305a
NHTSA requests comments on
whether the proposed emergency
response information requirements
would be better placed in a general
agency regulation than in proposed
FMVSS No. 305a, given that the
documentation specifications are more
akin to a disclosure requirement
(disclosing information to NHTSA) than
a performance test or a consumer safety
information requirement.
NHTSA regulates motor vehicle safety
under many grants of authority. For
example, one is that NHTSA is
authorized by the Vehicle Safety Act to
issue FMVSS; a typical FMVSS specifies
minimum performance requirements
and may also include provisions
requiring manufacturers to provide
consumers safety information on
properly using a safety system or item
of equipment. Another is that the
Vehicle Safety Act authorizes NHTSA to
require manufacturers to retain certain
records and/or make information
available to NHTSA. Section 30166 of
the Act provides NHTSA the ability to
request and inspect manufacturer
records that are necessary to enforce the
prescribed regulations. NHTSA is also
authorized by delegation to issue
regulations to carry out the agency’s
duties of ensuring vehicle safety.133
Documentation requirements would be
authorized under these authorities.
However, NHTSA is mindful that the
mechanisms for enforcing a failure to
meet a documentation requirement
could differ depending on whether the
requirement is in an FMVSS or not.
Section 30118 of the Vehicle Safety Act
(49 U.S.C. 30118) provides that
whenever the Secretary of
Transportation (NHTSA by delegation)
determines that a vehicle does not
comply with an FMVSS, NHTSA (by
delegation) must require the vehicle’s
manufacturer to notify the owners,
purchasers and dealers of the vehicle or
equipment of the noncompliance and
remedy the noncompliance. There is an
exception to the recall requirement in
section 30120(h) which authorizes
NHTSA to exempt noncompliances
from recall provisions based on a
demonstration that the noncompliance
is inconsequential to safety. In the case
of a violation of a disclosure
133 49 U.S.C. 322(a). This provision states that the
Secretary of Transportation may prescribe
regulations to carry out the duties and powers of the
Secretary. The authority to implement the Vehicle
Safety Act has been delegated to NHTSA.
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requirement in a regulation other than
an FMVSS, the manufacturer could be
subject to injunctive remedies and/or
civil penalties,134 but would not be
subject to the recall notification and
remedy provision described above.
NHTSA requests comments on the pros
and cons of placing the proposed
emergency response information
requirement in a regulation rather than
in FMVSS No. 305a.
NHTSA also seeks comments on
whether the proposed risk mitigation
documentation requirements would be
better placed in a general agency
regulation. This NPRM proposes
manufacturers to document and submit
information, upon request, describing
identified safety risks, risk mitigation
strategies, and validation of those
strategies. NHTSA has similar
documentation requirements in FMVSS
No. 126, ‘‘Electronic stability control
systems for light vehicles’’ 135 and
FMVSS No. 226, ‘‘Ejection
Mitigation.’’ 136 NHTSA requests
comments on the pros and cons of
placing the proposed risk mitigation
documentation requirement in a
regulation rather than in FMVSS No.
305a.
VII. Proposed Compliance Dates
The proposed compliance dates are as
follows.
1. Regarding the proposed
requirements other than the emergency
response information to assist first and
second responders, the compliance date
would be two years after the publication
of the final rule in the Federal Register.
Small-volume manufacturers, final-stage
manufacturers, and alterers would be
provided an additional year to comply
with the final rule beyond the two-year
date identified above.137 We propose to
permit optional early compliance with
the final rule.
Under § 30111(d) of the Safety Act, a
standard may not become effective
before the 180th day after the standard
is prescribed or later than one year after
it is prescribed, unless NHTSA finds, for
good cause shown, that a different
effective date is in the public interest
and publishes the reasons for the
finding. NHTSA has tentatively
determined that a 2-year compliance
period is in the public interest because
all vehicle manufacturers need to gain
familiarity with the proposed REESS
requirements. There is already
widespread conformance to the
requirements so the 2-year period ought
134 See,
e.g., 49 U.S.C. 30165.
CFR 571.126 S5.6.
136 49 CFR 571.226 S4.2.4.
137 49 CFR 571.8(b).
135 49
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to provide sufficient time, but some
manufacturers may need time to assess
fleet performance, review their risk
management procedures and document
their mitigation strategies. Further,
heavy vehicle manufacturers would be
newly subject to electric system
integrity requirements having not been
subject to existing FMVSS No. 305.
They will need time to assess their
vehicles’ conformance to FMVSS No.
305a requirements, implement
appropriate design and production
changes, and assess and document risk
mitigation strategies.
2. Regarding requirements to provide
emergency response information to
assist first and second responders, the
proposed compliance date is one year
after publication of the final rule. Smallvolume manufacturers, final-stage
manufacturers, and alterers would be
provided an additional year to comply
with the final rule. Optional early
compliance would be permitted.
NHTSA believes the 1-year compliance
date for this proposed requirement is
long enough for manufacturers to
provide the information to NHTSA in
the required format. They are already
providing the information voluntarily to
the NFPA. The agency would like to
provide the information on NHTSA’s
website as soon as possible. If
manufacturers provide the information
in a year, NHTSA can begin the process
of posting the information shortly
thereafter.
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VIII. Rulemaking Analyses and Notices
Executive Order 12866, Executive Order
14094, Executive Order 13563, and DOT
Order 2100.6A
NHTSA has considered the impact of
this rulemaking action under Executive
Orders 12866, 14094, and 13563 and
DOT Order 2100.6A. This action was
not reviewed by the Office of
Management and Budget under E.O.
12866.
This NPRM proposes to update
FMVSS No. 305 to incorporate the
electrical safety requirements in GTR
No. 20 and issue FMVSS No. 305a with
the incorporated requirements. Most of
GTR No. 20 has already been adopted
into FMVSS No. 305; this NPRM
proposes to complete the process by
expanding FMVSS No. 305’s
applicability to heavy vehicles and by
adopting the GTR’s requirements for the
REESS. Since there is widespread
conformance with the requirements that
would apply to existing vehicles, we
anticipate no costs or benefits associated
with this rulemaking.
This NPRM also proposes a
requirement that electric vehicle
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manufacturers submit standardized
emergency response information to a
NHTSA central depository, to assist first
and second responders. A
comprehensive list of pertinent vehicle
specific rescue information at a central
location will enable first and second
responders to respond to emergencies as
quickly and safely as possible.
Currently, electric vehicle
manufacturers voluntarily upload
emergency response information to the
National Fire Protection Association’s
training site, so manufacturers are
already providing vehicle specific
emergency response information. With
this proposed rule, manufacturers
would submit ERGs and rescue sheets to
NHTSA instead. We anticipate no
additional costs by the manufacturers.
Regulatory Flexibility Act
NHTSA has considered the effects of
this NPRM under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq., as
amended by the Small Business
Regulatory Enforcement Fairness Act
(SBREFA) of 1996). I certify that this
NPRM, if promulgated, would not have
a significant economic impact on a
substantial number of small entities.
NHTSA is aware of 3 small
manufacturers of light and heavy
electric vehicles. NHTSA believes that
this proposed rule would not have a
significant economic impact on these
manufacturers for the following reasons.
First, small manufacturers of light
electric vehicles that might be affected
by this NPRM are already subject to the
electric vehicle safety requirements of
FMVSS No. 305 and have been
certifying compliance to the standard
for years. They are familiar with FMVSS
requirements for electric vehicle safety,
know how to assess the conformance of
their vehicles with the requirements,
and know how to certify their vehicles
to the FMVSS. The new proposed
requirements for the REESS are
manageable because the overcharge,
over-discharge, over-current, overtemperature, and external short-circuit
tests are non-destructive tests and can
be conducted in serial order. The
documentation requirements for safety
risk mitigation associated with charging
and discharging during cold
temperature, safety risk mitigation
associated with an internal short-circuit
in a single cell of a REESS, and warning
in the event of a malfunction of the
vehicle controls that manage REESS safe
operation are not design restrictive and
add minimal cost. The documentation
requirements simply ask manufacturers
to describe to NHTSA how they have
assessed certain safety risks and
mitigated them.
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26731
Second, there already is widespread
voluntarily compliance by the
manufacturers with GTR No. 20, which
is also aligned with industry standards.
Therefore, there will be only a minor
economic impact.
Finally, although the final
certification would be made by the
manufacturer, this proposal would
allow one additional year for small
volume manufacturers, final-stage
manufacturers and alterers to comply
with a final rule. This approach is
similar to the approach NHTSA has
taken in other rulemakings in
recognition of manufacturing
differences between larger and smaller
manufacturers. NHTSA anticipates that
EV components meeting FMVSS No.
305a would be developed by vehicle
designers and suppliers and integrated
into the fleets of larger vehicle
manufacturers first, before small
manufacturers. This NPRM recognizes
this and proposes to provide smaller
manufacturers flexibility, so they have
time to obtain the equipment and work
with the suppliers after the demands of
the larger manufacturers are met.
This NPRM would apply proposed
FMVSS No. 305a to heavy vehicles, so
this NPRM would also affect
manufacturers of vehicles of over 4,536
kg (10,000 lb) GVWR, some of which
may be final-stage manufacturers.138
According to the U.S. Census, there are
570 small businesses in body
manufacturing for light, medium, and
heavy-duty classes. This proposal could
affect a substantial number of final stage
manufacturers that are small businesses.
However, it is NHTSA’s understanding
that these small entities rarely make
modifications to a vehicle’s REESS
system and instead rely upon the passthrough certification provided by the
first-stage manufacturer, which is not
typically a small business. The same is
true for alterers, which are
manufacturers that obtain and alter a
complete vehicle prior to the vehicle’s
first sale to a consumer.139 Furthermore,
even if the final-stage manufacturer or
alterer must make the certification
independently, as explained above this
138 Final-stage manufacturers produce vehicles by
obtaining an incomplete vehicle (comprising the
chassis and other associated parts) manufactured by
an incomplete vehicle manufacturer, which is
typically a large manufacturer. The final-stage
manufacturer produces a vehicle by installing the
vehicle body on the incomplete vehicle. The finalstage manufacturer typically certifies a complete
vehicle by staying within manufacturing
instructions provided by the incomplete vehicle
manufacturer.
139 Alterers certify that the vehicle was altered by
them and as altered conforms to all applicable
FMVSS, bumper, and theft prevention standards
affected by the alteration.
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certification responsibility is
manageable. The proposed requirements
do not involve crash testing (except for
heavy school buses, as discussed
below), and conformance with the
requirements can be assessed relatively
simply in a laboratory setting. And
finally, this proposal would further
accommodate final-stage manufacturers
and alterers by providing them an
additional year before compliance is
required.140 For the reasons above,
NHTSA does not believe that the
economic impacts of this proposal on
small entities would be significant.
With regard to the proposed crash test
requirement for small manufacturers of
heavy school buses, the additional
requirement is for heavy school buses
with high voltage electric propulsion
systems to meet post-crash electrical
safety requirements when impacted by
the moving contoured barrier specified
in FMVSS No. 301. This requirement
does not require additional crash testing
and aligns the applicability of FMVSS
No. 305a with that of FMVSS Nos. 301
and 303. Per FMVSS No. 301 and
FMVSS No. 303, heavy school buses
(school buses with a GVWR greater than
4,536 kg) using conventional fuel or
compressed natural gas for propulsion
are required to maintain fuel system
integrity in a crash test where the
moving contoured barrier specified in
FMVSS No. 301 traveling at any speed
up to 48 km/h impacts the school bus
at any point and angle. These
requirements ensure post-crash safety to
maintain the current high safety
standards for school buses. Finally, this
proposal would accommodate small
manufacturers and final stage
manufacturers of heavy school buses by
providing them an additional year
before compliance is required. For the
reasons above, NHTSA does not believe
that the economic impacts of this
proposal on small entities would be
significant.
National Environmental Policy Act
NHTSA has analyzed this rulemaking
action for the purposes of the National
Environmental Policy Act (42 U.S.C.
4321 et seq.), as amended. The agency
has determined that implementation of
this action will not have an adverse
impact on the quality of the human
environment. As described earlier, the
proposal includes the current
requirements in FMVSS No. 305 but
would also expand the applicability of
the standard to heavy vehicles (vehicles
with a gross vehicle weight rating
(GVWR) greater than 4,536 kilograms
(kg) (10,000 lb)), add requirements to
140 See
49 CFR 571.8(b).
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mitigate post-crash vehicle fires, add an
optional method for assessing electrical
safety for capacitors included in the
electric powertrain, and include crash
test and post-crash safety requirements
for school buses with a GVWR greater
than 4,536 kg (10,000 lb). The proposal
would align the standard with electrical
safety requirements in the Global
Technical Regulation (GTR) No. 20,
‘‘Electric Vehicle Safety,’’ which has
been formally adopted by the UN World
Forum for Harmonization of Vehicle
Regulations. The proposal, with
expanded applicability and additional
requirements and test procedures,
would enable future updates to the
standard as battery technologies and
charging systems continue to evolve.
NHTSA expects the changes to new
and existing vehicles to be minimal, and
mitigating the hazards associated with
electric shock during parked conditions,
active drive-possible modes, external
charging, and post-crash events, as well
as risks associated with hazardous
conditions resulting from battery fires
and emissions, would result in a public
health and safety benefit. For these
reasons, the agency has determined that
implementation of this action will not
have any adverse impact on the quality
of the human environment.
Executive Order 13132 (Federalism)
NHTSA has examined this proposed
rule pursuant to Executive Order 13132
(64 FR 43255; Aug. 10, 1999) and
concluded that no additional
consultation with States, local
governments, or their representatives is
mandated beyond the rulemaking
process. The agency has concluded that
the proposal does not have sufficient
federalism implications to warrant
consultation with State and local
officials or the preparation of a
federalism summary impact statement.
The proposal does not have ‘‘substantial
direct effects on the States, on the
relationship between the national
government and the States, or on the
distribution of power and
responsibilities among the various
levels of government.’’
NHTSA rules can have preemptive
effect in two ways. First, the National
Traffic and Motor Vehicle Safety Act
contains an express preemption
provision: When a motor vehicle safety
standard is in effect under this chapter,
a State or a political subdivision of a
State may prescribe or continue in effect
a standard applicable to the same aspect
of performance of a motor vehicle or
motor vehicle equipment only if the
standard is identical to the standard
prescribed under this chapter. 49 U.S.C.
30103(b)(1). It is this statutory command
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that preempts any non-identical State
legislative and administrative law
address the same aspect of performance.
The express preemption provision
described above is subject to a savings
clause under which ‘‘[c]compliance
with a motor vehicle safety standard
prescribed under this chapter does not
exempt a person from liability at
common law.’’ 49 U.S.C. 30103(e).
Pursuant to this provision, State
common law tort causes of action
against motor vehicle manufacturers
that might otherwise be preempted by
the express preemption provision are
generally preserved. However, the
Supreme Court has recognized the
possibility, in some instances, of
implied preemption of State common
law tort causes of action by virtue of
NHTSA’s rules—even if not expressly
preempted.
This second way that NHTSA rules
can preempt is dependent upon the
existence of an actual conflict between
an FMVSS and the higher standard that
would effectively be imposed on motor
vehicle manufacturers if someone
obtained a State common law tort
judgment against the manufacturer—
notwithstanding the manufacturer’s
compliance with the NHTSA standard.
Because most NHTSA standards
established by an FMVSS are minimum
standards, a State common law tort
cause of action that seeks to impose a
higher standard on motor vehicle
manufacturers will generally not be
preempted. However, if and when such
a conflict does exist—for example, when
the standard at issue is both a minimum
and a maximum standard—the State
common law tort cause of action is
impliedly preempted. See Geier v.
American Honda Motor Co., 529 U.S.
861 (2000).
Pursuant to Executive Order 13132,
NHTSA has considered whether this
proposed rule could or should preempt
State common law causes of action. The
agency’s ability to announce its
conclusion regarding the preemptive
effect of one of its rules reduces the
likelihood that preemption will be an
issue in any subsequent tort litigation.
To this end, the agency has examined
the nature (e.g., the language and
structure of the regulatory text) and
objectives of this proposed rule and
does not foresee any potential State
requirements that might conflict with it.
NHTSA does not intend that this
proposed rule preempt state tort law
that would effectively impose a higher
standard on motor vehicle
manufacturers than that established by
this proposed rule. Establishment of a
higher standard by means of State tort
law would not conflict with the
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standards proposed in this NPRM.
Without any conflict, there could not be
any implied preemption of a State
common law tort cause of action.
Executive Order 12988 (Civil Justice
Reform)
With respect to the review of the
promulgation of a new regulation,
section 3(b) of Executive Order 12988,
‘‘Civil Justice Reform’’ (61 FR 4729; Feb.
7, 1996), requires that Executive
agencies make every reasonable effort to
ensure that the regulation: (1) Clearly
specifies the preemptive effect; (2)
clearly specifies the effect on existing
Federal law or regulation; (3) provides
a clear legal standard for affected
conduct, while promoting simplification
and burden reduction; (4) clearly
specifies the retroactive effect, if any; (5)
specifies whether administrative
proceedings are to be required before
parties file suit in court; (6) adequately
defines key terms; and (7) addresses
other important issues affecting clarity
and general draftsmanship under any
guidelines issued by the Attorney
General. This document is consistent
with that requirement.
Pursuant to this Order, NHTSA notes
as follows. The issue of preemption is
discussed above. NHTSA notes further
that there is no requirement that
individuals submit a petition for
reconsideration or pursue other
administrative proceedings before they
may file suit in court.
ddrumheller on DSK120RN23PROD with PROPOSALS3
Privacy Act
Please note that anyone is able to
search the electronic form of all
comments received into any of our
dockets by the name of the individual
submitting the comment (or signing the
comment, if submitted on behalf of an
association, business, labor union, etc.).
You may review DOT’s complete
Privacy Act Statement in the Federal
Register published on April 11, 2000
(65 FR 19477–78), or online at https://
www.dot.gov/privacy.html.
Paperwork Reduction Act
Under the procedures established by
the Paperwork Reduction Act of 1995
(PRA) (44 U.S.C. 3501, et. seq.), Federal
agencies must obtain approval from the
OMB for each collection of information
they conduct, sponsor, or require
through regulations. A person is not
required to respond to a collection of
information by a Federal agency unless
the collection displays a valid OMB
control number. The Information
Collection Request (ICR) for the
proposed new information collection
described below have been forwarded to
OMB for review and comment. In
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compliance with these requirements,
NHTSA asks for public comments on
the following proposed collections of
information for which the agency is
seeking approval from OMB.
There are two types of collection of
information that are part of the
proposed FMVSS No. 305a
requirements: (1) Electric Vehicles:
Rescue Sheets and Emergency Response
Guides and (2) Electric Vehicles: REESS
Thermal Propagation Safety Risk
Analysis and Mitigation Documentation.
Title: FMVSS No. 305a Electric
Vehicle Emergency Response
Information and Risk Mitigation
Documentation.
OMB Control Number: New.
Form Number: N/A.
Type of Request: Approval of a new
collection.
Type of Review Requested: Regular.
Requested Expiration Date of
Approval: 3 years from the date of
approval.
Summary of the Collection of
Information:
FMVSS No. 305a proposes electric
vehicle (EV) requirements for protection
from harmful electric shock, fire,
explosion, and gas venting during
normal vehicle operation and during
and after a crash. As part of the
proposed requirements, there are two
types of information collection that
would apply to all electric vehicle (EV)
manufacturers. First, before
certification, each manufacturer will be
required to submit emergency response
information, including rescue sheets
and emergency response guides (ERGs)
for each vehicle make, model, and
model year, so they are available in a
centralized location on NHTSA’s
website. The information would then be
readily available for first and second
responders so they can easily identify
pertinent vehicle-specific rescue
information at the scene of a vehicle
crash or fire event, and respond to the
emergency quickly, effectively, and
safely.
Second, each electric vehicle model
will be required to meet three proposed
documentation requirements and
manufacturers will be required to
submit to NHTSA, upon request,
documentation demonstrating risk
mitigation for certain safety hazards.
The documentation must describe safety
risk mitigation associated with charging
and discharging during cold
temperature, safety risk mitigation
associated with an internal short-circuit
in a single cell of a REESS, and warning
in the event of a malfunction of the
vehicle controls that manage REESS safe
operation.
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Description of the Need for the
Information and Proposed Use of the
Information:
First responders need detailed
information pertaining to an EV’s
electrical system layout in order to
safely work around the vehicle and
extricate injured passengers. Access to
vehicle-specific information in a clear,
standardized format help mitigate the
safety risks of high voltage components
and stranded energy in the Rechargeable
Electrical Energy Storage System
(REESS). The purpose of the
requirement is to make this information
readily available for first and second
responders for their safe handling of the
vehicle in emergencies and for towing
and storing operations. Rescue sheets
and ERGs communicate vehicle-specific
information related to fire, submersion,
and towing, as well as the location of
components in the vehicle that may
expose the vehicle occupants or rescue
personnel to risks. The information is
presented in a specific format with
color-coded sections in a specific order
to help first and second responders
quickly identify pertinent rescue
information. Rescue sheets contain
abbreviated emergency response
information about a vehicle’s
construction. Rescue sheets are most
likely to be referenced first by
emergency responders upon arrival at
the scene of a crash. ERGs contain more
information than rescue sheets.
Current emergency response
information is voluntarily filed on the
National Fire Protection Association
(NFPA) website, but they are not in
standardized format. The uploaded
rescue sheets and ERGs would be
standardized in layout and format and
be publicly available at NHTSA’s
website for quick access.
There are currently no objective test
procedures to evaluate REESS
mitigation of certain safety risks in a
manner that is not design restrictive.
Until test procedures and performance
criteria can be developed for all vehicle
powertrain architectures, the proposed
FMVSS No. 305a would require
manufacturers to compile and meet
three of the proposed documentation
requirements and submit
documentation to NHTSA, if requested,
that identifies all known safety hazards,
the risk mitigation strategies for the
safety hazards, and, if applicable,
describe how they provide a warning to
address a safety hazard. Given the
variation of battery design and designspecific risk mitigation systems, the
documentation is a means for
manufacturers to show that they have
identified and demonstrated safety risk
mitigation strategies, and for NHTSA to
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learn of and oversee the safety hazards.
This approach is battery technology
neutral, not design restrictive, and is
intended to evolve over time as battery
technologies continue to rapidly evolve.
These proposed documentation
requirements would address: (a) safety
risk mitigation associated with charging
and discharging during low
temperature; (b) the safety risks from
thermal propagation in the event of
SCTR due to an internal short-circuit of
a single cell; and (c) providing a
warning if there is a malfunction of
vehicle controls that manage REESS safe
operation.
Affected Public: Vehicle
manufacturers.
Frequency: Emergency response
information: as needed upon
certification; Risk mitigation
documentation: annually for
recordkeeping.
Number of Responses: It is anticipated
that an estimated 205 rescue sheets and
ERGs will be submitted each year and
all 205 unique models would be
compiling and maintaining the required
documentation annually.
Electric vehicle models encompass
battery-powered electric vehicle, plug-in
hybrid electric vehicle, hybrid electric
vehicle, and fuel cell electric vehicle
models. The combined number of
electric vehicle models is estimated to
be 205 unique models each year. Upon
certification, a total of 205 rescue sheets
and ERGs for all unique models will be
submitted. Out of the 205 EV models,
about 51 (25% of EV models) likely
already have rescue sheets and ERGs
that conform to the proposed
requirements. The number of new
rescue sheets and ERGs that would be
required to be compiled and submitted
to NHTSA before certification is
estimated to be 51 (25% of the
combined EV models sold each year).
NHTSA also anticipates updates to
existing or previously submitted rescue
sheets and ERGs for some vehicle
models. Updates may be necessary
when a vehicle model changes between
model years or there are revisions to an
existing model’s emergency response
information. It is estimated that
approximately 103 (50% of the 205
annual electric vehicle models) electric
vehicle models sold each year would
have updated or revised rescue sheets
and ERGs. Because rescue sheets and
emergency response guides often cover
several model years, the percentage of
models that would be needing new or
updates to existing or previously
submitted rescue sheets and ERGs are
likely to decrease after the second year
of the effective date.
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Estimated Total Annual Burden
Hours: 16,241 hours (2,506 hours for
emergency response information and
13,735 hours for risk mitigation
documentation).
For vehicle models that already have
rescue sheets and ERGs that conform to
the proposed requirements, it is
estimated to take 0.25 hour to submit
the required emergency response
information to NHTSA’s website. The
estimated burden hours for the 51 EV
models to submit their conformed
rescue sheets and ERGs is 13 hours (0.25
hour/model × 51 models).
For each new electric vehicle model,
it is anticipated that it will take
approximately 36 hours to complete the
vehicle-specific rescue sheet and
emergency response guide following the
required format and layout provided in
ISO–17840–1:2022, ISO–17840–2:2019,
and ISO–17840–3:2019. The estimated
total annual burden hours for new
rescue sheets and emergency response
guides is 1,849 hours (36.25 hours/
model × 51 models).
It is anticipated that it will take
approximately 6 hours to update the
rescue sheet and emergency response
guide for a vehicle model. The
estimated total annual burden hours for
updated rescue sheets and emergency
response guides is 644 hours (6.25
hours/model × 103 models). The
estimated total annual burden hours is
2,506 hours.
For each vehicle model, vehicle
manufacturers will need an estimated
67 hours to complete the three
documentation requirements (17 hours
to complete the documentation for low
temperature operation safety, 17 hours
for the documentation about warning in
the event of operational failure of
REESS vehicle controls, and 33 hours
for the documentation covering thermal
runaway due to internal short in a single
cell of the REESS). After the proposed
rule’s effective date, all 205 vehicle
models are expected to compile the
necessary information to meet the three
proposed documentation requirements.
The total estimated annual burden
hours for the three documentation
requirements is an estimate of 13,735
hours (205 vehicle models × 67 hours).
Estimated Total Annual Burden Cost:
$1,027,381 ($157,543 for emergency
response information and $869,838 for
risk mitigation documentation).
The preparation of information is
anticipated to be done by a technical
writer. The U.S. Bureau of Labor
Statistics (BLS) estimates the mean
hourly wage for technical writers in the
motor vehicle manufacturing industry
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as $44.71.141 The BLS estimates that
private industry workers’ wages account
for 70.6% of a worker’s total
compensation.142 Therefore, NHTSA
estimates the hourly labor costs to be
$63.33 ($44.71/hour/70.6%). The
submission of information is anticipated
to be done by an administrative
professional. The U.S. BLS estimates the
mean hourly wage for administrative
professional in the motor vehicle
manufacturing industry is $29.36.143
Therefore, NHTSA estimates the hourly
labor costs for submission to be $41.59
($29.36/hour/70.6%).
These estimates produce an annual
cost burden to manufacturers of
$116,804 (51 models × ((36 hours ×
$63.33) + (0.25 hour × $41.59)) for
generating and submitting the
emergency response information
documentation for new models, $40,209
(103 models × ((6 hours × $63.33) +
(0.25 hour × $41.59)) for updating and
submitting the documentation, and $530
(51 models × (0.25 hour × $41.59)) for
those EV models that already conform to
the proposed requirements for
submission. The total labor cost to
prepare and submit the emergency
response information documentation to
NHTSA’s website is estimated to be
$157,543 annually.
Because rescue sheets and emergency
response guides often cover several
model years, the percentage of models
that would be needing new or updates
to existing or previously submitted
rescue sheets and ERGs each year are
likely to decrease in subsequent years.
This would result in a reduction in
annual total burden hours and annual
total burden costs.
The preparation of the risk mitigation
documentation is also anticipated to be
done by a technical writer. The total
cost burden for manufacturers for
compiling and record keeping the three
documentation packets would be
$869,838 (205 vehicle models × (67
hours × $63.33)).
The estimated total annual burden
hours to manufacturers for the proposed
FMVSS No. 305a emergency response
information and documentation
requirements would be 16,241 hours.
141 See May 2022 National Industry-Specific
Occupational Employment and Wage Estimates,
NAICS 336100—Motor Vehicle Manufacturing,
available at https://www.bls.gov/oes/current/
naics4_336100.htm (accessed February 29, 2024).
142 See Table 1. Employer Costs for Employee
Compensation by ownership (Sept. 2023), available
at Table 1. By ownership—2023 Q03 Results
(bls.gov).
143 See May 2022 National Industry-Specific
Occupational Employment and Wage Estimates,
NAICS 336100—Motor Vehicle Manufacturing,
available at https://www.bls.gov/oes/current/
naics4_336100.htm (accessed February 29, 2024).
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The estimated total annual cost burden
to manufacturers for the proposed
FMVSS No. 305a emergency response
information and documentation
requirements would be $1,027,381.
Public Comments Invited: You are
asked to comment on any aspects of this
information collection, including (a)
whether the proposed collection of
information is necessary for the proper
performance of the functions of the
Department, including whether the
information will have practical utility;
(b) the accuracy of the Department’s
estimate of the burden of the proposed
information collection; (c) ways to
enhance the quality, utility and clarity
of the information to be collected; and
(d) ways to minimize the burden of the
collection of information on
respondents, including the use of
automated collection techniques or
other forms of information technology.
Please submit any comments,
identified by the docket number in the
heading of this document, by the
methods described in the ADDRESSES
section of this document to NHTSA and
OMB. Although comments may be
submitted during the entire comment
period, comments received within 30
days of publication are most useful.
National Technology Transfer and
Advancement Act
Section 12(d) of the National
Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law 104–
113, as amended by Public Law 107–107
(15 U.S.C. 272), directs the agency to
evaluate and use voluntary consensus
standards in its regulatory activities
unless doing so would be inconsistent
with applicable law or is otherwise
impractical. Voluntary consensus
standards are technical standards (e.g.,
materials specifications, test methods,
sampling procedures, and business
practices) that are developed or adopted
by voluntary consensus standards
bodies, such as the Society of
Automotive Engineers (SAE). The
NTTAA directs us to provide Congress
(through OMB) with explanations when
the agency decides not to use available
and potentially applicable voluntary
consensus standards.
This proposal to adopt GTR No. 20 is
consistent with the goals of the NTTAA.
This NPRM proposes to adopt a global
consensus standard. The GTR was
developed by a global regulatory body
and is designed to increase global
harmonization of differing vehicle
standards. The GTR leverages the
expertise of governments in developing
a vehicle standard to increase electric
vehicle safety, including the
performance of the REESS. NHTSA’s
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consideration of GTR No. 20 accords
with the principles of NTTAA as
NHTSA’s consideration of an
established, proven global technical
regulation has reduced the need for
NHTSA to expend significant agency
resources on the same safety need
addressed by GTR No. 20.
Unfunded Mandates Reform Act
Section 202 of the Unfunded
Mandates Reform Act of 1995 (UMRA),
Public Law 104–4, requires Federal
agencies to prepare a written assessment
of the costs, benefits, and other effects
of proposed or final rules that include
a Federal mandate likely to result in the
expenditure by State, local, or tribal
governments, in the aggregate, or by the
private sector, of more than $100
million annually (adjusted for inflation
with base year of 1995). Adjusting this
amount by the implicit gross domestic
product price deflator for the year 2022
results in $177 million (111.416/75.324
= 1.48). This NPRM would not result in
a cost of $177 million or more to either
State, local, or tribal governments, in the
aggregate, or the private sector. Thus,
this NPRM is not subject to the
requirements of sections 202 of the
UMRA.
Executive Order 13609 (Promoting
Regulatory Cooperation)
The policy statement in section 1 of
Executive Order 13609 provides, in part:
The regulatory approaches taken by
foreign governments may differ from
those taken by U.S. regulatory agencies
to address similar issues. In some cases,
the differences between the regulatory
approaches of U.S. agencies and those of
their foreign counterparts might not be
necessary and might impair the ability
of American businesses to export and
compete internationally. In meeting
shared challenges involving health,
safety, labor, security, environmental,
and other issues, international
regulatory cooperation can identify
approaches that are at least as protective
as those that are or would be adopted in
the absence of such cooperation.
International regulatory cooperation can
also reduce, eliminate, or prevent
unnecessary differences in regulatory
requirements.
The agency participated in the
development of GTR No. 20 to
harmonize the standards of electric
vehicle. As a signatory member, NHTSA
is proposing to incorporate electrical
safety requirements and options
specified in GTR No. 20 into FMVSS
No. 305a.
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26735
Incorporation by Reference
Under regulations issued by the Office
of the Federal Register (1 CFR 51.5(a)),
an agency must summarize in the
preamble of a proposed or final rule the
material it incorporates by reference and
discuss the ways the material is
reasonably available to interested
parties or how the agency worked to
make materials available to interested
parties.
NHTSA proposes to incorporate by
reference three documents into the Code
of Federal Regulations. The first
document is ISO 17840–1:2022 (E),
‘‘Road vehicles—Information for first
and second responders—Part 1: Rescue
sheet for passenger cars and light
commercial vehicles.’’ ISO 17840–
1:2022(E) standardizes the content and
layout of rescue sheets for passenger
cars and light commercial vehicles.
The second document is ISO 17840–
2:2019(E), ‘‘Road vehicles—Information
for first and second responders—Part 2:
Rescue sheet for buses, coaches and
heavy commercial vehicles.’’ ISO
17840–2:2019(E) standardizes the rescue
sheets for buses, coaches, and heavy
commercial vehicles.
The third document is ISO 17840–
3:2019(E), ‘‘Road vehicles—Information
for first and second responders—Part 3:
Emergency response guide template.’’
ISO 17840–3:2019(E) establishes a
template and defines the general content
for manufacturers’ emergency response
guides for all vehicle types.
All three documents would be
incorporated by reference solely to
specify the layout and format of the
rescue sheets and emergency response
guides. The ISO material is available for
review at NHTSA and is available for
purchase from ISO.144
Severability
The issue of severability of FMVSSs is
addressed in 49 CFR 571.9. It provides
that if any FMVSS or its application to
any person or circumstance is held
invalid, the remainder of the part and
the application of that standard to other
persons or circumstances is unaffected.
Comments are requested on the
severability of this proposed FMVSS.
Regulation Identifier Number
The Department of Transportation
assigns a regulation identifier number
(RIN) to each regulatory action listed in
the Unified Agenda of Federal
Regulations. The Regulatory Information
Service Center publishes the Unified
Agenda in April and October of each
year. You may use the RIN contained in
144 ISO standards may be purchased from the
ANSI webstore https://webstore.ansi.org/.
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the heading at the beginning of this
document to find this action in the
Unified Agenda.
Rulemaking Summary, 5 U.S.C.
553(b)(4)
As required by 5 U.S.C. 553(b)(4), a
summary of this rule can be found in
the Abstract section of the Department’s
Unified Agenda entry for this
rulemaking at https://www.reginfo.gov/
public/do/eAgendaViewRul
e?pubId=202304&RIN=2127-AM43.
Plain Language
Executive Order 12866 requires each
agency to write all rules in plain
language. Application of the principles
of plain language includes consideration
of the following questions:
• Have we organized the material to
suit the public’s needs?
• Are the requirements in the rule
clearly stated?
• Does the rule contain technical
language or jargon that isn’t clear?
• Would a different format (grouping
and order of sections, use of headings,
paragraphing) make the rule easier to
understand?
• Would more (but shorter) sections
be better?
• Could we improve clarity by adding
tables, lists, or diagrams?
• What else could we do to make the
rule easier to understand?
If you have any responses to these
questions, please write to us with your
views.
IX. Public Participation
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How long do I have to submit
comments?
Please see DATES section at the
beginning of this document.
How do I prepare and submit
comments?
• Your comments must be written in
English.
• To ensure that your comments are
correctly filed in the Docket, please
include the Docket Number shown at
the beginning of this document in your
comments.
• Your comments must not be more
than 15 pages long. (49 CFR 553.21). We
established this limit to encourage you
to write your primary comments in a
concise fashion. However, you may
attach necessary additional documents
to your comments. There is no limit on
the length of the attachments.
• If you are submitting comments
electronically as a PDF (Adobe) File,
NHTSA asks that the documents be
submitted using the Optical Character
Recognition (OCR) process, thus
allowing NHTSA to search and copy
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certain portions of your submissions.
Comments may be submitted to the
docket electronically by logging onto the
Docket Management System website at
https://www.regulations.gov. Follow the
online instructions for submitting
comments.
• You may also submit two copies of
your comments, including the
attachments, to Docket Management at
the address given above under
ADDRESSES.
Please note that pursuant to the Data
Quality Act, in order for substantive
data to be relied upon and used by the
agency, it must meet the information
quality standards set forth in the OMB
and DOT Data Quality Act guidelines.
Accordingly, we encourage you to
consult the guidelines in preparing your
comments. OMB’s guidelines may be
accessed at https://www.whitehouse.gov/
omb/fedreg/reproducible.html. DOT’s
guidelines may be accessed at https://
www.bts.gov/programs/statistical_
policy_and_research/data_quality_
guidelines.
How can I be sure that my comments
were received?
If you wish Docket Management to
notify you upon its receipt of your
comments, enclose a self-addressed,
stamped postcard in the envelope
containing your comments. Upon
receiving your comments, Docket
Management will return the postcard by
mail.
How do I submit confidential business
information?
You should submit a redacted ‘‘public
version’’ of your comment (including
redacted versions of any additional
documents or attachments) to the docket
using any of the methods identified
under ADDRESSES. This ‘‘public version’’
of your comment should contain only
the portions for which no claim of
confidential treatment is made and from
which those portions for which
confidential treatment is claimed has
been redacted. See below for further
instructions on how to do this.
You also need to submit a request for
confidential treatment directly to the
Office of Chief Counsel. Requests for
confidential treatment are governed by
49 CFR part 512. Your request must set
forth the information specified in Part
512. This includes the materials for
which confidentiality is being requested
(as explained in more detail below);
supporting information, pursuant to Part
512.8; and a certificate, pursuant to Part
512.4(b) and Part 512, Appendix A.
You are required to submit to the
Office of Chief Counsel one unredacted
‘‘confidential version’’ of the
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information for which you are seeking
confidential treatment. Pursuant to Part
512.6, the words ‘‘ENTIRE PAGE
CONFIDENTIAL BUSINESS
INFORMATION’’ or ‘‘CONFIDENTIAL
BUSINESS INFORMATION
CONTAINED WITHIN BRACKETS’’ (as
applicable) must appear at the top of
each page containing information
claimed to be confidential. In the latter
situation, where not all information on
the page is claimed to be confidential,
identify each item of information for
which confidentiality is requested
within brackets: ‘‘[ ].’’
You are also required to submit to the
Office of Chief Counsel one redacted
‘‘public version’’ of the information for
which you are seeking confidential
treatment. Pursuant to Part 512.5(a)(2),
the redacted ‘‘public version’’ should
include redactions of any information
for which you are seeking confidential
treatment (i.e., the only information that
should be unredacted is information for
which you are not seeking confidential
treatment).
NHTSA is currently treating
electronic submission as an acceptable
method for submitting confidential
business information to the agency
under Part 512. Please do not send a
hardcopy of a request for confidential
treatment to NHTSA’s headquarters.
The request should be sent to Dan
Rabinovitz in NHTSA’s Office of the
Chief Counsel (NCC) at
Daniel.Rabinovitz@dot.gov. You may
either submit your request via email or
request a secure file transfer link. If you
are submitting the request via email,
please also email a courtesy copy of the
request to K.Helena Sung in NCC at
Helena.Sung@dot.gov.
Will the agency consider late
comments?
We will consider all comments that
Docket Management receives before the
close of business on the comment
closing date indicated above under
DATES. To the extent possible, we will
also consider comments that Docket
Management receives after that date. If
Docket Management receives a comment
too late for us to consider in developing
the final rule, we will consider that
comment as an informal suggestion for
future rulemaking action.
How can I read the comments submitted
by other people?
You may read the comments received
by Docket Management at the address
given above under ADDRESSES. The
hours of the Docket are indicated above
in the same location. You may also see
the comments on the internet. To read
the comments on the internet, go to
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https://www.regulations.gov. Follow the
online instructions for accessing the
dockets.
Please note that, even after the
comment closing date, we will continue
to file relevant information in the
Docket as it becomes available. Further,
some people may submit late comments.
Accordingly, we recommend that you
periodically check the Docket for new
material.
X. Appendices to the Preamble
FMVSS No. 305, and the proposed FMVSS
No. 305a for light vehicles (LVs) and heavy
vehicles (HVs).
Appendix A. Table Comparing GTR No.
20, FMVSS No. 305, and FMVSS No.
305a
Table A below provides an overview of the
requirements presently in the GTR No. 20,
TABLE A—OVERVIEW OF SAFETY REQUIREMENTS IN GTR NO. 20, FMVSS NO. 305, AND THOSE PROPOSED IN THIS
NPRM
Requirement category
Requirement
GTR No. 20
FMVSS No. 305
Electrical Safety under Normal Vehicle
Operations.
Physical Barrier Protection Electrical
Isolation Isolation Monitoring
(FCEVs) Charging Safety Driver
Error Mitigation.
REESS Retention Electrolyte Leakage
Electrical Safety.
Yes for LV and HV
Yes for LV ............
Yes for LV and
HV.
Yes for LV ............
Yes for LV ............
Yes for LV and
heavy school
bus.
Fire Safety ...........................................
Low Voltage Electrical Isolation Physical Barrier Protection.
...............................
Yes for LV ............
No.
Yes for LV ............
Low Energy (Capacitors) .....................
Yes for LV ............
No .........................
Mechanical Crush Test instead of
crash test.
Mechanical Shock Test instead of
crash test.
Overcharge Over-Discharge OverCurrent Over-Temperature External
Short-Circuit Low-Temperature
Thermal Propagation Water Exposure REESS Venting.
Vibration Thermal Shock & Cycling
Fire Resistance.
Thermal Event Warning ......................
Yes for LV ............
No .........................
Only shock test for
HV.
Yes for LV and HV
No .........................
Yes for LV and
HV.
Yes for HV and LV
No .........................
No.
Yes for LV and HV
No .........................
Yes for LV and
HV.
...............................
No .........................
...............................
...............................
No.
...............................
No.
Post-Crash Safety .................................
Post-Crash Electrical Safety Compliance Options.
Optional Post-crash Component Level
REESS Tests.
REESS Safety Performance during
Normal Vehicle Operations.
Warning Requirements .........................
Emergency Response Information .......
Warning of Malfunction of Vehicle
Controls for REESS Operations.
Low SOC .............................................
Rescue Sheets ....................................
Emergency Response Guides (ERGs)
Appendix B. Request for Comment on
Phase 2 GTR No. 20 Approaches Under
Consideration by the IWG
1. Electrolyte Release and Venting From the
REESS
ddrumheller on DSK120RN23PROD with PROPOSALS3
NHTSA requests comment on the IWG’s
continuing work on venting. Phase 2 of GTR
No. 20 is considering more robust methods
to verify the occurrence and quantification of
electrolyte release 145 and/or venting.146 Two
possible approaches for detection of
145 EVS21–E2TG–0200 [EC]. Detection of
electrolyte leakage by gas detection techniques.
https://wiki.unece.org/display/trans/
EVS+21st+session.
146 Gas emissions in thermal runaway
propagation experiments, https://wiki.unece.org/
download/attachments/177242909/EVS25-E2TG0400%20%5BEC%5DGas%20
emissions%20in%20thermal%20
runaway%20propagation%20experiments
.pdf?api=v2.
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electrolyte release are under consideration:
(1) detection of solid and liquid Li-ion, and
(2) gas detection for the vapors released from
the liquid electrolyte and vented gases.
Chemosensors 147 are currently being
studied to detect the presence of Li-ion
resulting from electrolyte release. However,
no commercially available chemosensors
have been identified that could be used for
testing purposes to reliably detect electrolyte
leakage.
Common gas detection methods include
gas chromatography, fourier-transform
infrared spectroscopy (FTIR), and different
types of gas sensors. Emitted gases under
consideration include carbon dioxide (CO2),
carbon monoxide (CO), hydrogen (H2),
147 Chemosensors indicate the presence of Li-ion
through a color and fluorescence change.
Chemosensor means a molecule which is able to
simultaneously bind and signal the presence of
other species. F. Pina et al, J. Photochem. Photobiol.
A, 126 (1999), 65–69.
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FMVSS No. 305a
Yes for LV and
heavy school
bus.
Yes for LV and
heavy school
bus.
No.
Yes for LV and
HV.
oxygen (O2), light C1-C5 hydrocarbons, e.g.,
methane and ethane, and fluorine-containing
compounds such as hydrogen fluoride (HF)
and fluoro-organics such as e.g., ethylfluoride. However, practical, and costeffective methods of sampling the leakage/
emissions/venting and determining
acceptable exposure levels for different gases
are still under development.
NHTSA seeks comment on:
• How these detection methods
(chemosensors and gas detection methods)
may best be utilized in a vehicle level test
procedure for both normal operating
conditions and post-crash scenarios.
• How to best manage gases and
particulates emitted from the REESS for both
normal operating conditions and post-crash
scenarios.
• Which gases generated in and vented
from Li-ion batteries should be focused on for
all types of REESS chemistries and are
anticipated to remain relevant as REESS
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chemistry and technology changes in the
future.
• Practicable methods to verify the
occurrence of electrolyte release and venting
and to quantify the vented gases and vapors.
2. Single-Cell Thermal Runaway
The IWG is considering a test-based
approach during Phase 2 of GTR No. 20. GTR
No. 20 would require that the thermal
propagation test procedure fulfill the
following conditions:
• Triggering of thermal runaway at a
single-cell level must be repeatable,
reproducible, and practicable,
• Judgment of thermal runaway through
common sensors, e.g., voltage and
temperature, needs to be practical,
repeatable, and reproducible, and
• Judgement of whether consequent
thermal events involve severe thermal
propagation hazards, needs to be unequivocal
and evidence based.
The two main initiation methods under
consideration in Phase 2 are a localized rapid
external heating method and a nail
penetration method. The localized rapid
external heating method is comprised of a
film heater which is attached to an initiation
cell’s surface. The heater is turned on and set
to reach its maximum power, and only
turned off after thermal runaway occurs. In
the nail penetration method, a steel nail 3
mm in diameter or more, with a circular cone
is inserted into the initiation cell at a speed
of 0.1 ∼ 10 mm/s, which internally shortcircuits the cell, inducing thermal runaway.
Current GTR No. 20 specifies three
conditions in which thermal runaway can be
detected:
1. The measured voltage of the initiation
cell drops,
2. The measured temperature exceeds the
maximum operating temperature defined by
the manufacturer, and
3. The instantaneous rate of temperature
change (dT/dt) ≥1 °C/s of the measured
temperature.
Per GTR No. 20, thermal runaway can be
judged when both (1) and (3) are detected, or
both (2) and (3) are detected.
For the test procedure development, the
only operational mode originally considered
was the active driving possible mode. As
discussions continue in Phase 2, other
operational modes such as parking and
externally charging are also under
consideration. However, the test methods
and performance criteria are still under
development.
NHTSA conducted thermal runaway
propagation tests on four different electric
vehicle models using both the localized rapid
external heating method 148 and the nail
penetration (NP) method.149 The criteria for
identifying whether thermal runaway was
initiated as described in ISO–6469–1:2019/
DAM 1:2021(E) were used. Six tests were
conducted at the vehicle level (with REESS
installed in the vehicle) on four vehicle
makes and models as shown in Table B–1.
TABLE B–1—THERMAL RUNAWAY PROPAGATION TESTS USING TWO DIFFERENT METHODS OF INITIATING THERMAL
RUNAWAY ON A SINGLE CELL
Thermal runaway initiation method
Vehicle make, model, and model year
2019
2020
2020
2021
2021
2022
Localized external
rapid heater method
Chevrolet Bolt .............................................................................................
Nissan Leaf .................................................................................................
Tesla Model 3 .............................................................................................
Chevrolet Bolt .............................................................................................
Nissan Leaf .................................................................................................
Kia Niro .......................................................................................................
Nail penetration
method
X
X
X, X (Two tests)
X
X
X
X
X
Note—X represents a test was conducted.
Thermal runaway was initiated using the
localized heating method in tests with both
the 2019 and 2021 Chevrolet Bolt vehicles,
the 2020 Nissan Leaf, 2020 Tesla Model 3,
and the 2022 Kia Niro. Two tests using the
localized heating method were conducted on
the 2020 Tesla Model 3 because the first test
did not result in a thermal runaway. Tests
were conducted on the 2021 Chevrolet Bolt,
2021 Nissan Leaf, and the 2022 Kia Nero
using the nail penetration method for
initiating thermal runaway.
Significant information was needed from
the manufacturers on opening up the battery
pack and on selecting the cell for initiating
thermal runaway using both methods. The
selection of the cell for initiating thermal
runaway was not random and was based on
which cells were accessible; the cells were
not necessarily those that are more likely to
cause thermal propagation if a thermal
runaway was initiated. Copious amounts of
smoke were released within and outside of
the passenger cabin before flames were
observed. Some of the gas emissions include
hydrogen (flammable) and carbon monoxide
(toxic). All vehicles tested have REESSs with
pouch cells except for the Tesla Model 3,
whose REESS has cylindrical cells. In the
first Tesla Model 3, the initial heater was
unsuccessful in transferring heat into the
target cell due to lack of back pressure on the
heater. In the second test, the target cell went
into thermal runaway but experienced a side
wall rupture towards the outside of the
battery pack.150 The timing of the smoke
emissions and the thermal propagation was
not the same for the two methods of initiating
thermal runaway in a single cell of the
REESS. The results of the tests and the timing
of various events are shown in Table B–2
below.
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TABLE B–2—SINGLE-CELL THERMAL RUNAWAY AND PROPAGATION TEST RESULTS—TIMING OF EVENTS
External
smoke
(min:sec)
Smoke
in cabin
(min:sec)
Warning observed
(min:sec)
Venting
observed
(min:sec)
CO in ppm
(min:sec)
22:29
08:17
No ...........................
Yes (00:51) .............
Yes ...........
Yes ...........
03:10
11:58
Yes (00:27) .............
Yes ...........
04:45
01:10
31:09
24:48
Yes (00:45) .............
Yes (00:34) .............
Yes ...........
Yes ...........
N/A
N/A
N/A
N/A
No ...........................
No ...........................
No ............
Yes ...........
N/A.
>100 ppm (02:20),
>1500 ppm (03:30).
>100 ppm (07:30),
>1200 ppm (08:58).
N/A.
>100 ppm (10:10),
>800 ppm (21:30).
N/A.
N/A.
Method
Vehicle
TRIM ........................
TRIM ........................
2019 Chevrolet Bolt ................
2021 Chevrolet Bolt ................
00:15
00:17
00:38
01:10
NP ............................
2021 Chevrolet Bolt ................
00:07
TRIM ........................
NP ............................
2020 Nissan Leaf ...................
2021 Nissan Leaf ....................
00:25
00:05
TRIM ........................
TRIM ........................
2020 Tesla Model 3 ................
2021 Tesla Model 3 ................
N/A
00:28
148 Thermal Runaway Initiation Method (TRIM)
heater developed by the National Research Council
(NRC) Canada.
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External
flame
(min:sec)
149 The testers used a generic nail similar to that
specified in the ISO–6469–1:2019/DAM 1
1:2021(E).
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150 Side wall rupture does not represent thermal
runaway events observed in the field.
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TABLE B–2—SINGLE-CELL THERMAL RUNAWAY AND PROPAGATION TEST RESULTS—TIMING OF EVENTS—Continued
External
smoke
(min:sec)
Method
Vehicle
TRIM ........................
NP ............................
2022 Kia Niro ..........................
2022 Kia Niro ..........................
For the localized rapid external heating
method, the heating element parameter may
vary depending on the different battery
chemistries or cell type (e.g., large prismatic
cells versus cylindrical cells).151 More stable
chemistries will require higher heat inputs
than less stable chemistries. Calorimetric
testing may need to be implemented to
provide insights on what heating input
parameters would be representative to avoid
penalizing more stable cell chemistries, since
they may require higher heat inputs to
induce thermal runaway. The nail
penetration method may be implemented in
lieu of the localized rapid external heating
method for more stable chemistries. It
remains unclear whether the two initiation
methods under consideration are equivalent
in stringency. NHTSA’s research results
indicate that the timing of thermal
propagation is different for the different
thermal runaway initiation methods for the
same vehicle models. The rapid heating and
nail penetration thermal runaway initiation
methods can be applied to only some cells
in the REESS or REESS subsystem; only the
cells that can be accessed and modified
without impinging on adjacent cells in the
pack can be triggered in these tests.152
Additionally, the criteria for assessing
whether thermal runaway has occurred in a
cell needs further development.
Part of the performance criteria for a
thermal runaway propagation test under
consideration is for some form of warning to
vehicle occupants and/or bystanders outside
the vehicle in the event of thermal
propagation within and outside the REESS.
However, NHTSA considers warning to be a
secondary mitigation strategy which would
not prevent the thermal propagation from
occurring in the first place. Thermal
propagation resulting in EV fires are difficult
to extinguish and may cause significant
damage to adjacent structures and may pose
a safety risk to people nearby, even when a
warning is provided. In comparison, in the
agency’s view, the proposed documentation
requirements provide a holistic risk
mitigation of thermal propagation events
resulting from single-cell thermal runaway
due to an internal short-circuit within the
cell. This risk mitigation would include of a
cell in an REESS significantly before thermal
runaway occurs to allow for appropriate
action to be taken. Vehicle manufacturers are
currently incorporating such technologies
151 ISO 6469–1:2019/DAM1:2021(E), ‘‘Electrically
propelled road vehicles—Safety specifications—
Part 1: Rechargeable energy storage system (RESS)—
Draft Amendment 1.’’
152 NHTSA’s testing experience indicates that
these testable cells are generally located along the
edges of a module. The result of single-cell thermal
runaway will vary with location based on heat
transfer to adjacent cells and other components.
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Smoke
in cabin
(min:sec)
01:01
07:16
External
flame
(min:sec)
03:57
14:40
177:03
59:31
No ...........................
No ...........................
into the BMS to predict and evaluate the
status of individual cells and mitigate the
occurrence of single cell thermal runaway
(SCTR) in the first place.
NHTSA seeks comment on the proposed
reporting requirements to mitigate the risk of
SCTR due to an internal short-circuit in a
single cell of the REESS and the performance
test under consideration in GTR No. 20 Phase
2.
3. REESS Vibration Requirements
Currently, during Phase 2 development of
GTR No. 20, there are discussions for
updating the vibration test to include
vibration in all three orthogonal axes and at
higher amplitudes and frequency range.
NHTSA seeks comment on the safety need
that would warrant an update to a more
stringent vibration test than that already in
UN 38.3 Test T3.153 NHTSA seeks comment
from vehicle manufacturers on practices they
have implemented to avoid reliability issues
and assure customer satisfaction in the field.
List of Subjects in 49 CFR Part 571
Imports, Incorporation by Reference,
Motor vehicles, Motor vehicle safety.
Proposed Regulatory Text
In consideration of the foregoing,
NHTSA proposes to amend 49 CFR part
571 as set forth below.
PART 571—FEDERAL MOTOR
VEHICLE SAFETY STANDARDS
1. The authority citation for part 571
continues to read as follows:
■
Authority: 49 U.S.C. 322, 30111, 30115,
30117, and 30166; delegation of authority at
49 CFR 1.95.
2. Section 571.5 is amended by adding
paragraphs (i)(5), (i)(6), and (i)(7), to
read as follows:
■
§ 571.5
Matter incorporated by reference.
*
*
*
*
*
(i) * * *
* * *
(5) ISO 17840–1:2022 (E), ‘‘Road
vehicles—Information for first and
second responders—Part 1: Rescue sheet
for passenger cars and light commercial
vehicles,’’ Second Edition, February
2022, into § 571.305a.
153 The vibration load spectrum in GTR No. 20
was derived from UN 38.3.4.3 ‘‘Recommendation
on the Transport of Dangerous Goods, Manual of
Tests and Criteria.’’ https://unece.org/fileadmin/
DAM/trans/danger/publi/manual/Rev7/Manual_
Rev7_E.pdf.
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Venting
observed
(min:sec)
Warning observed
(min:sec)
Yes ...........
Yes ...........
I
CO in ppm
(min:sec)
25 ppm (05:25).
>100 ppm (14:20).
I
(6) ISO 17840–2:2019 (E), ‘‘Road
vehicles—Information for first and
second responders—Part 2: Rescue sheet
for buses, coaches and heavy
commercial vehicles,’’ First edition,
April 2019, into § 571.305a.
(7) ISO 17840–3:2019 (E), ’’ Road
vehicles—Information for first and
second responders—Part 3: Emergency
response guide template,’’ First Edition,
April 2019, into § 571.305a.
*
*
*
*
*
■ 3. Section 571.305a is added to read
as follows:
§ 571.305a Standard No. 305a; ElectricPowered Vehicles: Electric Powertrain
Integrity; Mandatory applicability begins on
(this date will be the compliance date of the
final rule).
S1. Scope. This standard specifies
requirements for protection from
harmful electric shock, fire, explosion,
and gas venting during normal vehicle
operation and during and after a crash.
S2. Purpose. The purpose of this
standard is to reduce deaths and injuries
during normal vehicle operations and
during and after a crash that occur
because of electrolyte leakage, intrusion
of electric energy storage/conversion
devices into the occupant compartment,
electric shock, fire, explosion, and gas
venting, including deaths and injuries
due to driver error.
S3. Application. This standard
applies to passenger cars, multipurpose
passenger vehicles, trucks, and buses
that use electrical propulsion
components with working voltages
greater than 60 volts direct current
(VDC) or 30 volts alternating current
(VAC), and whose speed attainable over
a distance of 1.6 km on a paved level
surface is more than 40 km/h.
S4. Definitions.
Active driving possible mode means
the vehicle mode when application of
pressure to the accelerator pedal (or
activation of an equivalent control) or
release of the brake system causes the
electric power train to move the vehicle.
Automatic disconnect means a device
that when triggered, conductively
separates a high voltage source from the
electric power train or the rest of the
electric power train.
Breakout harness means connector
wires that are connected for testing
purposes to the REESS on the traction
side of the automatic disconnect.
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Capacitor means a device used to
store electrical energy, consisting of one
or more pairs of conductors separated
by an insulator: x-capacitors are
connected between electrical mains or
neutral and y-capacitors are connected
between a main to ground.
Charge connector is a conductive
device that, by insertion into a vehicle
charge inlet, establishes an electrical
connection of the vehicle to an external
electric power supply for the purpose of
transferring energy.
Chassis dynamometer means a
mechanical device that uses one or more
fixed roller assemblies to simulate
different road conditions within a
controlled environment and is used for
a wide variety of vehicle testing.
Connector means a device providing
mechanical connection and
disconnection of high voltage electrical
conductors to a suitable mating
component, including its housing.
n C Rate means the constant current
of the REESS, which takes 1/n hours to
charge or discharge the REESS between
0 and 100 percent state of charge.
Direct contact is the contact of any
person or persons with high voltage live
parts.
Electric energy storage device means a
high voltage source that stores energy
for vehicle propulsion. This includes,
but is not limited to, a high voltage
battery or battery pack, rechargeable
energy storage device, and capacitor
module.
Electric energy storage/conversion
device means a high voltage source that
stores or converts energy for vehicle
propulsion. This includes, but is not
limited to, a high voltage battery or
battery pack, fuel cell stack,
rechargeable energy storage device, and
capacitor module.
Electric energy storage/conversion
system means an assembly of electrical
components that stores or converts
electrical energy for vehicle propulsion.
This includes, but is not limited to, high
voltage batteries or battery packs, fuel
cell stacks, rechargeable energy storage
systems, capacitor modules, inverters,
interconnects, and venting systems.
Electric power train means an
assembly of electrically connected
components which includes, but is not
limited to, electric energy storage/
conversion systems and propulsion
systems.
Electrical chassis means conductive
parts of the vehicle whose electrical
potential is taken as reference and
which are:
(1) conductively linked together, and
(2) not high voltage sources during
normal vehicle operation.
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Electrical isolation of a high voltage
source in the vehicle means the
electrical resistance between the high
voltage source and any of the vehicle’s
electrical chassis divided by the
working voltage of the high voltage
source.
Electrical protection barrier is the part
providing protection against direct
contact with high voltage live parts from
any direction of access.
Electrolyte leakage means the escape
of liquid electrolyte from the REESS.
Emergency response guide means a
document containing in-depth vehiclespecific information related to fire,
submersion, leakage of fluids, towing,
and storage of vehicles for first and
second responders.
Exposed conductive part is the
conductive part that can be touched
under the provisions of the IPXXB
protection degree and that is not
normally energized, but that can become
electrically energized under isolation
fault conditions. This includes parts
under a cover if the cover can be
removed without using tools.
External Charging mode means the
vehicle mode when the REESS is
charging with external electric power
supply connected through the charge
connector to the vehicle charge inlet.
External electric power supply is a
power supply external to the vehicle
that provides electric power to charge
the electric energy storage device in the
vehicle through the charge connector.
First responder means a person with
specialized training such as a law
enforcement officer, paramedic,
emergency medical technician, and/or
firefighter.
Fuel cell system is a system
containing the fuel cell stack(s), air
processing system, fuel flow control
system, exhaust system, thermal
management system, and water
management system.
High voltage live part means a live
part of a high voltage source.
High voltage source means any
electric component which is contained
in the electric power train or
conductively connected to the electric
power train and has a working voltage
greater than 30 VAC or 60 VDC.
Indirect contact is the contact of any
person or persons with exposed
conductive parts.
Live part is a conductive part of the
vehicle that is electrically energized
under normal vehicle operation.
Luggage compartment is the space in
the vehicle for luggage accommodation,
separated from the passenger
compartment by the front or rear
bulkhead and bounded by a roof, hood
or trunk lid, floor, and side walls, as
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well as by electrical protection barriers
provided for protecting the occupants
from direct contact with high voltage
live parts.
Normal vehicle operation includes
operating modes and conditions that
can reasonably be encountered during
typical operation of the vehicle, such as
driving, parking, and standing in traffic,
as well as charging using chargers that
are compatible with the specific
charging ports installed on the vehicle.
It does not include conditions where the
vehicle is damaged, either by a crash or
road debris, subjected to fire or water
submersion, or in a state where service
and/or maintenance is needed or being
performed.
Parking mode is the vehicle mode in
which the vehicle power is turned off,
the vehicle propulsion system and
ancillary equipment such as the radio
are not operational, and the vehicle is
stationary.
Passenger compartment is the space
for occupant accommodation that is
bounded by the roof, floor, side walls,
doors, outside glazing, front bulkhead
and rear bulkhead or rear gate, as well
as electrical protection barriers provided
for protecting the occupants from direct
contact with high voltage live parts.
Propulsion system means an assembly
of electric or electro-mechanical
components or circuits that propel the
vehicle using the energy that is supplied
by a high voltage source. This includes,
but is not limited to, electric motors,
inverters/converters, and electronic
controllers.
Protection degree IPXXB is protection
from contact with high voltage live
parts. It is tested by probing electrical
protection barriers with the jointed test
finger probe, IPXXB, in Figure 7b.
Protection degree IPXXD is protection
from contact with high voltage live
parts. It is tested by probing electrical
protection barriers with the test wire
probe, IPXXD, in Figure 7a.
Rechargeable Electrical Energy
Storage System (REESS) means the
rechargeable electric energy storage
system that provides electric energy for
electrical propulsion.
Rescue sheet means an abbreviated
version of an emergency response guide
that gives quick information about a
vehicle’s construction, intended for use
by first and second responders at the
scene of a crash.
Rupture means an opening through
the casing of the REESS that would
permit the IPXXB test probe to penetrate
and contact live parts.
Second responder means a worker
who supports first responders by
cleaning up a site, towing vehicles, and/
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or supporting services after an event
requiring first responders.
Service disconnect is the device for
deactivation of an electrical circuit
when conducting checks and services of
the vehicle electrical propulsion system.
State of charge (SOC) means the
available electrical charge in a tested
device expressed as a percentage of its
rated capacity.
Thermal event means the condition
when the temperature within the REESS
is significantly higher than the
maximum operating temperature.
Thermal runaway means an
uncontrolled increase of cell
temperature caused by exothermic
reactions inside the cell.
Thermal propagation means the
sequential occurrence of thermal
runaway within a REESS triggered by
thermal runaway of a cell in the REESS.
VAC means volts of alternating
current (AC) expressed using the root
mean square value.
VDC means volts of direct current
(DC).
Vehicle charge inlet is the device on
the electric vehicle into which the
charge connector is inserted for the
purpose of transferring energy and
exchanging information from an
external electric power supply.
Venting means the release of
excessive internal pressure from cell or
battery in a manner intended by design
to preclude rupture or explosion.
Working voltage means the highest
root mean square voltage of the voltage
source, which may occur across its
terminals or between its terminals and
any conductive parts in open circuit
conditions or under normal operating
conditions.
S5. General Requirements.
S5.1 Vehicles of GVWR of 4,536
kilograms (kg) or less (light vehicles).
Each vehicle with a GVWR of 4,536 kg
or less shall meet the requirements set
forth in S6 (normal vehicle operation
safety), S8 (post-crash safety), S11
(vehicle controls managing REESS safe
operations), S13.2 (thermal event in
REESS warning), S14 (water exposure
safety), and S15 (emergency response
information).
S5.2 Vehicles with a GVWR greater
than 4,536 kg other than school buses
(heavy vehicles other than school
buses). Each heavy vehicle with a
GVWR greater than 4,536 kg, other than
school buses, shall meet the
requirements set forth in S6 (normal
vehicle operation safety), S11 (vehicle
controls managing REESS safe
operations), S13.2 (thermal event in
REESS warning), S14 (water exposure
safety), and S15 (emergency response
information).
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S5.3 School buses with a GVWR
greater than 4,536 kg. Each school bus
with a GVWR greater than 4,536 kg shall
meet the requirements set forth in S6
(normal vehicle operation safety), S8
(post-crash safety), S11 (vehicle controls
managing REESS safe operations), S13.2
(thermal event in REESS warning), S14
(water exposure safety), and S15
(emergency response information).
S6. Normal vehicle operation safety.
Each vehicle to which this standard
applies must meet the requirements in
S6.1 to S6.6, when tested according to
the relevant provisions in S7.
S6.1 Protection against direct
contact.
S6.1.1 Marking. The symbol shown
in Figure 6 shall be present on or near
electric energy storage devices. The
symbol in Figure 6 shall also be visible
on electrical protection barriers which,
when removed, expose live parts of high
voltage sources. The symbol shall be
yellow and the bordering and the arrow
shall be black.
S6.1.1.1 The marking is not required
for electrical protection barriers that
cannot be physically accessed, opened,
or removed without the use of tools.
Markings are not required for electrical
connectors or the vehicle charge inlet.
S6.1.2 High voltage cables. Cables
for high voltage sources which are not
located within electrical protection
barriers shall be identified by having an
outer covering with the color orange.
S6.1.3 Service disconnect. For a
service disconnect which can be
opened, disassembled, or removed
without tools, protection degree IPXXB
shall be provided when tested under
procedures specified in S7.3.1 using the
IPXXB test probe shown in Figures 7a
and 7b.
S6.1.4 Protection degree of high
voltage live parts.
(a) Protection degree IPXXD shall be
provided for high voltage live parts
inside the passenger or luggage
compartment when tested according to
the procedures specified in S7.3.1 using
the IPXXD test probe shown in Figure
7a.
(b) Protection degree IPXXB shall be
provided for high voltage live parts in
areas other than the passenger or
luggage compartment when tested
according to the procedures specified in
S7.3.1 using the IPXXB test probe
shown in Figures 7a and 7b.
S6.1.5 Connectors. All connectors
shall provide direct contact protection
by:
(a) Meeting the requirements specified
in S6.1.4 when the connector is
connected to its corresponding mating
component; and,
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(b) If a connector can be separated
from its mating component without the
use of a tool, meeting at least one of the
following conditions from (b)(1), (2), or
(3) of this section:
(1) The connector meets the
requirements of S6.1.4 when separated
from its mating component;
(2) The voltage of the live parts
becomes less than or equal to 60 VDC
or 30 VAC within one second after the
connector is separated from its mating
component; or,
(3) The connector requires at least two
distinct actions to separate from its
mating component and there are other
components that must be removed in
order to separate the connector from its
mating component and these other
components cannot be removed without
the use of tools.
S6.1.6 Vehicle charge inlet. Direct
contact protection for a vehicle charge
inlet shall be provided by meeting the
requirements specified in S6.1.4 when
the charge connector is connected to the
vehicle inlet and by meeting at least one
of the requirements of subparagraphs (a)
or (b).
(a) The vehicle charge inlet meets the
requirements of S6.1.4 when the charge
connector is not connected to it; or
(b) The voltage of the high voltage live
parts becomes equal to or less than 60
VDC or equal to or less than 30 VAC
within 1 second after the charge
connector is separated from the vehicle
charge inlet.
S6.2 Protection against indirect
contact.
S6.2.1 The resistance between all
exposed conductive parts of electrical
protection barriers and the electrical
chassis shall be less than 0.1 ohms
when tested according to the procedures
specified in S7.3.2
S6.2.2 The resistance between any
two simultaneously reachable exposed
conductive parts of the electrical
protection barriers that are less than 2.5
meters from each other shall be less
than 0.2 ohms when tested according to
the procedures specified in S7.3.2.
S6.3 Electrical isolation.
S6.3.1 Electrical isolation of AC and
DC high voltage sources. The electrical
isolation of a high voltage source,
determined in accordance with the
procedure specified in S7.2 must be
greater than or equal to one of the
following:
(a) 500 ohms/volt for an AC high
voltage source;
(b) 100 ohms/volt for an AC high
voltage source if it is conductively
connected to a DC high voltage source,
but only if the AC high voltage source
meets the requirements for protection
against direct contact in S6.1.4 and the
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protection from indirect contact in S6.2;
or
(c) 100 ohms/volt for a DC high
voltage source.
S6.3.2 Exclusion of high voltage
sources from electrical isolation
requirements. A high voltage source that
is conductively connected to an electric
component which is conductively
connected to the electrical chassis and
has a working voltage less than or equal
to 60 VDC, is not required to meet the
electrical isolation requirements in
S6.3.1 if the voltage between the high
voltage source and the electrical chassis
is less than or equal to 30 VAC or 60
VDC.
S6.3.3 Electrical isolation of high
voltage sources for charging the electric
energy storage device. For the vehicle
charge inlet intended to be conductively
connected to the AC external electric
power supply, the electric isolation
between the electrical chassis and the
high voltage sources that are
conductively connected to the vehicle
charge inlet during charging of the
electric energy storage device shall be
greater than or equal to 500 ohms/volt
when the charge connector is
disconnected. The electrical isolation is
measured at the high voltage live parts
of the vehicle charge inlet and
determined in accordance with the
procedure specified in S7.2. During the
measurement, the electric energy storage
device may be disconnected.
S6.4 Electrical isolation monitoring.
DC high voltage sources of vehicles with
a fuel cell system shall be monitored by
an electrical isolation monitoring
system that displays a warning for loss
of isolation when tested according to
S7.4. The system must monitor its own
readiness and the visual warning
display must be provided to the driver.
For a vehicle with autonomous driving
systems and without manually-operated
driving controls, the visual warning
must be provided to all the front row
occupants.
S6.5 Electric shock protection
during charging. For motor vehicles
with an electric energy storage device
that can be charged through a
conductive connection with a grounded
external electric power supply, a device
to enable conductive connection of the
electrical chassis to the earth ground
shall be provided. This device shall
enable connection to the earth ground
before exterior voltage is applied to the
vehicle and retain the connection until
after the exterior voltage is removed
from the vehicle.
S6.6 Mitigating driver error.
S6.6.1 Indicator of active driving
possible mode. At least a momentary
indication shall be given to the driver
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each time the vehicle is first placed in
active driving possible mode after
manual activation of the propulsion
system. This requirement does not
apply under conditions where an
internal combustion engine directly or
indirectly provides the vehicle’s
propulsion power when the vehicle is
first placed in the active driving
possible mode after manual activation of
the propulsion system.
S6.6.2 Indicator of active driving
possible mode when leaving the vehicle.
When leaving the vehicle, the driver
shall be informed by an auditory or
visual signal if the vehicle is still in the
active driving possible mode.
S6.6.3 Prevent drive-away. If the onboard electric energy storage device can
be externally charged, vehicle
movement of more than 150 mm by its
own propulsion system shall not be
possible as long as the charge connector
of the external electric power supply is
physically connected to the vehicle
charge inlet in a manner that would
permit charging of the electric energy
storage device.
S7. Electrical safety test procedures
for normal vehicle operation safety. The
following provisions specify the test
procedures associated with the
requirements of S6.
S7.1 Voltage measurements. For the
purpose of determining the voltage level
of the high voltage source, voltage is
measured as shown in Figure 1 using a
voltmeter that has an internal resistance
of at least 10 MW. All post-crash voltage
measurements for determining electrical
isolation of high voltage sources
specified in S8.2(a), the voltage levels
specified in S8.2(b), and the energy in
capacitors specified in S8.2(d) are made
between 10 to 60 seconds after impact.
S7.1.1 For a high voltage source that
has an automatic disconnect that is
physically contained within itself, the
voltage measurement after the test is
made from the side of the automatic
disconnect connected to the electric
power train or to the rest of the electric
power train if the high voltage source is
a component contained in the power
train. For a high voltage source that has
an automatic disconnect that is not
physically contained within itself, the
voltage measurement after the test is
made from both the high voltage source
side of the automatic disconnect and
from the side of the automatic
disconnect connected to the electric
power train or to the rest of the electric
power train if the high voltage source is
a component contained in the power
train.
S7.1.2 Voltage Vb is measured
across the two terminals of the voltage
source. Before a vehicle crash test, Vb is
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equal to or greater than the working
voltage as specified by the vehicle
manufacturer.
S7.1.3 Voltage V1 is measured
between the negative side of the high
voltage source and the electrical chassis
as shown in Figure 2. Voltage V2 is
measured between the positive side of
the high voltage source and the
electrical chassis as shown in Figure 3.
S7.2 Test method for determining
electrical isolation. Measure the voltages
V1, V2, and Vb as shown in Figure 1 in
accordance with S7.1
S7.2.1 If V1 is greater than or equal
to V2, insert a known resistance (Ro)
between the negative side of the high
voltage source and the electrical chassis.
With the Ro installed, measure the
voltage (V1′) as shown in Figure 4
between the negative side of the high
voltage source and the electrical chassis.
Calculate the electrical isolation
resistance (Ri) according to the formula
shown. Divide Ri (in ohms) by the
working voltage of the high voltage
source (in volts) to obtain the electrical
isolation (in ohms/volt).
S7.2.2 If V2 is greater than V1, insert
a known resistance (Ro) between the
positive side of the high voltage source
and the electrical chassis. With the Ro
installed, measure the voltage (V2′) as
shown in Figure 5 between the positive
side of the high voltage source and the
electrical chassis. Calculate the
electrical isolation resistance (Ri)
according to the formula shown. Divide
Ri (in ohms) by the working voltage of
the high voltage source (in volts) to
obtain the electrical isolation (in ohms/
volt).
S7.3 Test methods for evaluating
physical barrier protection.
S7.3.1 Test method to evaluate
protection from direct contact with high
voltage sources.
(a) Any parts surrounding the high
voltage components are opened,
disassembled, or removed without the
use of tools.
(b) The selected access probe is
inserted into any gaps or openings of the
electrical protection barrier with a test
force between 9 Newton to 11 Newton
with the IPXXB probe or 1 Newton to
2 Newton with the IPXXD probe. If the
probe partly or fully penetrates into the
electrical protection barrier, it is placed
in every possible position to evaluate
contact with high voltage live parts. If
partial or full penetration into the
electrical protection barrier occurs with
the IPXXB probe, the IPXXB probe shall
be placed as follows: starting from the
straight position, both joints of the test
finger are rotated progressively through
an angle of up to 90 degrees with
respect to the axis of the adjoining
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section of the test finger and are placed
in every possible position.
(c) A low voltage supply (of not less
than 40 V and not more than 50 V) in
series with a suitable lamp may be
connected between the access probe and
any high voltage live parts inside the
electrical protection barrier to indicate
whether high voltage live parts were
contacted.
(d) A mirror or fiberscope may be
used to inspect whether the access
probe touches high voltage live parts
inside the electrical protection barrier.
(e) Protection degree IPXXD or IPXXB
is verified when the following
conditions are met:
(1) The access probe does not touch
high voltage live parts. The IPXXB
access probe may be manipulated as
specified in S7.3.1(b) for evaluating
contact with high voltage live parts. The
methods specified in S7.3.1(c) or
S7.3.1(d) may be used to aid the
evaluation. If method S7.3.1(c) is used
for verifying protection degree IPXXB or
IPXXD, the lamp shall not light up.
(2) The stop face of the access probe
does not fully penetrate into the
electrical protection barrier.
S7.3.2 Test method to evaluate
protection against indirect contact with
high voltage sources. Any parts
surrounding the high voltage
components are opened, disassembled,
or removed without the use of tools. At
the option of the manufacturer,
protection against indirect contact with
high voltage sources shall be
determined using the test method in
subparagraph (a) or subparagraph (b).
(a) Test method using a resistance
tester. The resistance tester is connected
to the measuring points (the electrical
chassis and any exposed conductive
part of electrical protection barriers or
any two simultaneously reachable
exposed conductive parts of electrical
protection barriers that are less than 2.5
meters from each other), and the
resistance is measured using a
resistance tester that can supply current
levels of at least 0.2 Amperes with a
resolution of 0.01 ohms or less. The
resistance between two exposed
conductive parts of electrical protection
barriers that are less than 2.5 meters
from each other may be calculated using
the separately measured resistances of
the relevant parts of the electric path.
(b) Test method using a DC power
supply, voltmeter, and ammeter.
(1) Connect the DC power supply,
voltmeter, and ammeter to the
measuring points (the electrical chassis
and any exposed conductive part or any
two simultaneously reachable exposed
conductive parts that are less than 2.5
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meters from each other) as shown in
Figure 8.
(2) Adjust the voltage of the DC power
supply so that the current flow becomes
more than 0.2 Amperes.
(3) Measure the current I and the
voltage V shown in Figure 8.
(4) Calculate the resistance R
according to the formula, R=V/I.
(5) The resistance between two
simultaneously reachable exposed
conductive parts of electrical protection
barriers that are less than 2.5 meters
from each other may be calculated using
the separately measured resistances of
the relevant parts of the electric path.
S7.3.3 Test method to determine
voltage between exposed conductive
parts of electrical protection barriers
and the electrical chassis and between
exposed conductive parts of electrical
protection barriers.
(a) Any parts surrounding the high
voltage components are opened,
disassembled, or removed without the
use of tools.
(b) Connect the voltmeter to the
measuring points (exposed conductive
part of an electrical protection barrier
and the electrical chassis or any two
simultaneously reachable exposed
conductive parts of electrical protection
barriers that are less than 2.5 meters
from each other).
(c) Measure the voltage.
(d) The voltage between two
simultaneously reachable exposed
conductive parts of electrical protection
barriers that are less than 2.5 meters
from each other may be calculated using
the separately measured voltages
between the relevant electrical
protection barriers and the electrical
chassis.
S7.4 Test method for evaluating onboard electrical isolation monitoring
system.
Prior to any impact test, the
requirements of S6.4 for the on-board
electrical isolation monitoring system
shall be tested using the following
procedure.
(a) The electric energy storage device
is at the state-of-charge specified in
S7.1.
(b) The switch or device that provides
power from the electric energy storage/
conversion system to the propulsion
system is in the activated position or the
ready-to-drive position.
(c) Determine the isolation resistance,
Ri, of the high voltage source with the
electrical isolation monitoring system
using the procedure outlined in S7.2.
(d) Insert a resistor with resistance Ro
equal to or greater than 1/(1/(95 times
the working voltage of the high voltage
source)—1/Ri) and less than 1/(1/(100
times the working voltage of the high
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voltage source)—1/Ri) between the
positive terminal of the high voltage
source and the electrical chassis.
(e) The electrical isolation monitoring
system indicator shall provide a visual
warning to the driver. For a vehicle with
autonomous driving systems and
without manually-operated driving
controls, the visual warning must be
provided to all the front row occupants.
S7.5 Test method for determining
post-crash energy in capacitors.
(a) Prior to the crash tests, the vehicle
manufacturer must identify the
capacitors, type of capacitors (xcapacitors and y-capacitors) and their
respective capacitance (Cx and Cy) in
the electric power train for which the
low energy compliance option for postcrash electrical safety in S8.2(d) is
applied.
(b) Voltages Vb, V1, and V2 are
measured across the capacitors in
accordance with S7.1.
(c) The energy in a x-capacitor is
equal to 0.5 × Cx × Vb2
(d) The energy in a y-capacitor is
equal to 0.5 × Cy × (V12 + V22).
S8. Post-crash safety. Each vehicle
with a GVWR of 4,536 kg or less to
which this standard applies, must meet
the requirements in S8.1, S8.2, S8.3, and
S8.4 when tested according to S9 under
the conditions of S10. Each school bus
with a GVWR greater than 4,536 kg to
which this standard applies, must meet
the requirements in S8.1, S8.2, S8.3, and
S8.4 when tested according to S9.5
under the conditions of S10.
S8.1 Fire safety. Starting from the
time of impact and continuing until one
hour after the completion of the
sequence of tests specified in S9 of this
standard, there shall be no evidence of
fire or explosion in any part of the
vehicle. The assessment of fire or
explosion is verified by visual
inspection without disassembly of the
REESS or vehicle.
S8.2 Electrical safety. After each test
specified in S9 of this standard, each
high voltage source in a vehicle must
meet one of the following electrical
safety requirements: electrical isolation
requirements of subparagraph (a), the
voltage level requirements of
subparagraph (b), or the physical barrier
protection requirements of
subparagraph (c). High voltage
capacitors in the electric power train
may also meet electrical safety
requirements using the low-energy
requirements of subparagraph (d).
(a) The electrical isolation of the high
voltage source, determined in
accordance with the procedure specified
in S7.2, must be greater than or equal to
one of the following:
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(1) 500 ohms/volt for an AC high
voltage source; or
(2) 100 ohms/volt for an AC high
voltage source if it is conductively
connected to a DC high voltage source,
but only if the AC high voltage source
meets the physical barrier protection
requirements specified in S8.3(c)(1) and
S8.3(c)(2); or
(3) 100 ohms/volt for a DC high
voltage source.
(b) The voltages V1, V2, and Vb of the
high voltage source, measured according
to the procedure specified in S7.1, must
be less than or equal to 30 VAC for AC
components or 60 VDC for DC
components.
(c) Protection against electric shock by
direct and indirect contact (physical
barrier protection) shall be
demonstrated by meeting the following
three conditions:
(1) The high voltage source (AC or
DC) meets the protection degree IPXXB
when tested according to the procedure
specified in S7.3.1 using the IPXXB test
probe shown in Figures 7a and 7b;
(2) The resistance between exposed
conductive parts of the electrical
protection barrier of the high voltage
source and the electrical chassis is less
than 0.1 ohms when tested according to
the procedures specified in S7.3.2. In
addition, the resistance between an
exposed conductive part of the electrical
protection barrier of the high voltage
source and any other simultaneously
reachable exposed conductive parts of
electrical protection barriers within 2.5
meters of it must be less than 0.2 ohms
when tested using the test procedures
specified in S7.3.2; and
(3) The voltage between exposed
conductive parts of the electrical
protection barrier of the high voltage
source and the electrical chassis is less
than or equal to 30 VAC or 60 VDC as
measured in accordance with S7.3.3. In
addition, the voltage between an
exposed conductive part of the electrical
protection barrier of the high voltage
source and any other simultaneously
reachable exposed conductive parts of
electrical protection barriers within 2.5
meters of it must be less than or equal
to 30 VAC or 60 VDC as measured in
accordance with S7.3.3.
(d) The total energy of unidirectional
single impulse currents from capacitors
shall be less than 0.2 Joules when
determined in accordance with the
procedure specified in S7.5.
S8.3 Electric energy storage/
conversion device retention. During and
after each test specified in S9 of this
standard:
(a) Electric energy storage/conversion
devices shall remain attached to the
vehicle by at least one component
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anchorage, bracket, or any structure that
transfers loads from the device to the
vehicle structure, and
(b) Electric energy storage/conversion
devices located outside the occupant
compartment shall not enter the
occupant compartment.
S8.4 Electrolyte leakage from
electric energy storage devices. Not
more than 5.0 liters of electrolyte shall
leak from electric energy storage
devices, and no visible trace of
electrolyte shall leak into the passenger
compartment. Leakage is measured from
the time of the impact until 30 minutes
thereafter, and throughout any static
rollover after a barrier impact test,
specified in S9 of this standard.
S9. Crash test specifications. A test
vehicle with a GVWR less than or equal
to 4,536 kg, under the conditions of S10,
is subject to any one single barrier crash
test of S9.1, S9.2, or S9.3, followed by
the static rollover test of S9.4. A school
bus with a GVWR greater than 4,536 kg,
under the conditions of S10, is subject
to the contoured barrier crash test of
S9.5. A particular vehicle need not meet
further test requirements after having
been subjected to a single barrier crash/
static rollover test sequence.
S9.1 Frontal barrier crash. The test
vehicle, with test dummies in
accordance with S6.1 of 571.301 of this
chapter, traveling longitudinally
forward at any speed up to and
including 48 km/h, impacts a fixed
collision barrier that is perpendicular to
the line of travel of the vehicle, or at an
angle up to 30 degrees in either
direction from the perpendicular to the
line of travel of the vehicle.
S9.2 Rear moving barrier impact.
The test vehicle, with test dummies in
accordance with S6.1 of 571.301 of this
chapter, is impacted from the rear by a
barrier that conforms to S7.3(b) of
571.301 of this chapter and that is
moving at any speed between 79 and 81
km/h.
S9.3 Side moving deformable barrier
impact. The test vehicle, with the
appropriate 49 CFR part 572 test
dummies specified in 571.214 at
positions required for testing by S7.1.1,
S7.2.1, or S7.2.2 of Standard 214, is
impacted laterally on either side by a
moving deformable barrier moving at
any speed between 52.0 km/h and 54.0
km/h.
S9. 4 Post-impact test static rollover.
After each crash test specified in S9.1,
S9.2, and S9.3, without any alteration of
the vehicle, the vehicle is rotated on its
longitudinal axis to each successive
increment of 90 degrees under the test
conditions of S10.3.
S9.5 Moving contoured barrier
crash. The test vehicle, under the
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conditions of S10.1 and S10.2, is
impacted at any point and at any angle
by the moving contoured barrier
assembly, specified in S7.5 and S7.6 in
571.301 of this chapter, traveling
longitudinally forward at any speed up
to and including 48 km/h.
S10. Crash test conditions.
S10.1 State-of-charge. The electric
energy storage device(s) shall be at the
state-of-charge specified in either
subparagraph (a), (b), or (c):
(a) At the maximum state-of-charge in
accordance with the vehicle
manufacturer’s recommended charging
procedures, as stated in the vehicle
owner’s manual or on a label that is
permanently affixed to the vehicle; or
(b) If the manufacturer has made no
recommendation for charging
procedures in the owner’s manual or on
a label permanently affixed to the
vehicle, at a state-of-charge of not less
than 95 percent of the maximum
capacity of the electric energy storage
device(s); or
(c) If the electric energy storage
device(s) is/are rechargeable only by an
energy source on the vehicle, at any
state-of-charge within the normal
operating voltage defined by the vehicle
manufacturer.
S10.2 Vehicle conditions. The
switch or device that provides power
from the electric energy storage/
conversion system to the propulsion
system is in the activated position or the
ready-to-drive position. Bypass any
devices or systems that do not allow the
propulsion system to be energized at the
time of impact when the vehicle
ignition is on and the vehicle is in
neutral.
S10.2.1 The parking brake is
disengaged and the vehicle drive system
is in the neutral position. In a test
conducted under S9.3, the parking brake
is set.
S10.2.2 Tires are inflated to the
manufacturer’s specifications.
S10.2.3 The vehicle, including test
devices and instrumentation, is loaded
as follows:
(a) A passenger car is loaded to its
unloaded vehicle weight plus its rated
cargo and luggage capacity weight,
secured in the luggage compartment,
plus the necessary test dummies as
specified in S9, restrained only by
means that are installed in the vehicle
for protection at its seating position.
(b) A multipurpose passenger vehicle,
truck, or bus, with a GVWR of 4,536 kg
(10,000 lb) or less, is loaded to its
unloaded vehicle weight plus the
necessary dummies, as specified in S9,
plus 136 kg or its rated GVWR,
whichever is less, secured in the load
carrying area and distributed as nearly
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as possible in proportion to its GVWR.
For the purpose of this standard,
unloaded vehicle weight does not
include the weight of work-performing
accessories. Each dummy is restrained
only by means that are installed in the
vehicle for protection at its seating
position.
S10.3 Static rollover test conditions.
The vehicle is rotated about its
longitudinal axis, with the axis kept
horizontal, to each successive increment
of 90°, 180°, and 270° at a uniform rate,
with 90° of rotation taking place in any
time interval from 1 to 3 minutes. After
reaching each 90° increment the vehicle
is held in that position for 5 minutes.
S10.4 Rear moving barrier impact
test conditions. The conditions of
S7.3(b) and S7.6 of 571.301 of this
chapter apply to the conducting of the
rear moving deformable barrier impact
test specified in S9.2.
S10.5 Side moving deformable
barrier impact test conditions. The
conditions of S8.9, S8.10, and S8.11 of
571.214 of this chapter apply to the
conduct of the side moving deformable
barrier impact test specified in S9.3.
S11. Vehicle controls managing
REESS safe operations. Each vehicle to
which the standard applies shall meet
the requirements in S11.1, S11.2, and
S11.3, when tested according to S12.
S11.1 When tested in accordance
with the overcharge test in S12.1, the
over-discharge test in S12.2, the
overcurrent test in S12.3, the hightemperature test in S12.4, and the shortcircuit test in accordance with S12.5,
each vehicle shall meet the following:
(a) During the test, there shall be no
evidence of electrolyte leakage, rupture,
venting, fire, or explosion of the REESS
as verified by visual inspection without
disassembly of the vehicle.
(b) The isolation resistance of the high
voltage sources measured after the test
shall not be less than 100 ohms/volt
when determined in accordance with
S7.2.
S11.2 The vehicle manufacturer
must make available to the agency, upon
request, documentation in accordance
with S12.7 that demonstrates whether
the vehicle is equipped with controls for
REESS operations at or below the lower
boundary REESS temperature threshold
for safe REESS operations specified by
the manufacturer.
S11.3 The vehicle manufacturer
must make available to the agency, upon
request, documentation in accordance
with S12.8 that demonstrates the
activation of a visual warning, when the
vehicle is in active driving possible
mode to indicate operational failure of
the vehicle controls that manage the safe
operation of the REESS. The warning
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system shall monitor its own readiness
and the visual warning must be
provided to the driver. For a vehicle
with autonomous driving systems and
without manually operated driving
controls, the visual warning must be
provided to all the front row occupants.
S12. Test methods and
documentation for evaluating vehicle
controls managing REESS safe
operations.
S12.1 Overcharge test. The
overcharge test is conducted at ambient
temperatures between 10 °C and 30 °C,
with the vehicle REESS initially set
between 90 to 95 percent SOC. The
following steps are conducted to
evaluate the vehicle’s overcharge
protection controls:
(a) A breakout harness is connected to
the traction side of the REESS.
Manufacturer may specify an
appropriate location(s) and attachment
point(s) to connect the breakout harness.
(b) Temperature probes are connected
to the REESS outer casing to monitor
changes in REESS temperature.
Temperature measurements may also be
obtained through communication with
the REESS control module.
(c) The external charge/discharge
equipment, with maximum voltage and
current set at least 10 percent higher
than the REESS voltage and current
limits, is connected to the breakout
harness.
(d) The vehicle switch or device that
provides power to the vehicle controls
that manage REESS operations is set to
the activated position.
(e) The REESS is charged with the
external charge/discharge equipment
with the maximum charge current
specified by the manufacturer. If the
manufacturer does not specify an
appropriate charge current, then a
charge rate of 1⁄3C is used.
(f) Charging is continued until the
following occurs:
(1) The overcharge protection control
terminates the charge current;
(2) The REESS temperature is 10 °C
above the manufacturer specified
maximum operating temperature of the
REESS; or
(3) 12 hours have passed since the
start of charging the vehicle.
(g) After the charge current is
terminated, if charge and discharge is
permitted by the vehicle controls, a
standard cycle is performed in
accordance with S12.6.
(h) After the completion of the
standard cycle, or if the standard cycle
was not performed, after charging is
terminated, the vehicle is observed for
1 hour for evidence of electrolyte
leakage, rupture, venting, fire, or
explosion of the REESS.
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(i) At the conclusion of the test,
electrical isolation of the REESS is
determined in accordance with S7.2.
S12.2 Over-discharge test. The overdischarge test is conducted at ambient
temperatures between 10 °C and 30 °C,
with the vehicle REESS initially set
between 10 and 15 percent SOC. For a
vehicle with on-board energy
conversion systems such as an internal
combustion engine or a fuel cell, the
fuel supply is set to the minimum level
where active driving possible mode is
permitted. The following steps are
conducted to evaluate the vehicle’s
over-discharge protection controls:
(a) A breakout harness is connected to
the traction side of the REESS.
Manufacturer may specify an
appropriate location(s) and attachment
point(s) to connect the breakout harness.
(b) Temperature probes are connected
to the REESS outer casing to monitor
changes in REESS temperature.
Temperature measurements may also be
obtained through communication with
the REESS control module.
(c) The external charge/discharge
equipment, with maximum voltage and
current set at least 10 percent higher
than the REESS voltage and current
limits, is connected to the breakout
harness.
(d) The vehicle switch or device that
provides power from the REESS to the
electric power train is set to the
activated position or the active driving
possible mode.
(e) The REESS is discharged with the
external charge/discharge equipment
with the maximum discharge rate under
normal operating conditions specified
by the manufacturer. If the manufacturer
does not specify an appropriate
discharge rate, a power load of 1kW is
used.
(f) Discharging is continued until the
following occurs:
(1) The over-discharge protection
control terminates the discharge current;
(2) The temperature gradient of the
REESS is less than 4 °C through 2 hours
from the start of discharge; or
(3) the vehicle is discharged to 25
percent of its nominal voltage level.
(g) After the discharge current is
terminated, a standard cycle is
performed in accordance with S12.6, if
charge and discharge is permitted by the
vehicle controls.
(h) After the completion of the
standard cycle, or if the standard cycle
was not performed, after discharging is
terminated, the vehicle is observed for
1 hour for evidence of electrolyte
leakage, rupture, venting, fire, or
explosion of the REESS.
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(i) At the conclusion of the test,
electrical isolation of the REESS is
determined in accordance with S7.2.
S12.3 Overcurrent test. The
overcurrent test is only conducted on
vehicles that have the capability of
charging by DC external electricity
supply. The test is conducted at ambient
temperatures between 10 °C and 30 °C,
with the vehicle REESS initially set
between 40 to 50 percent SOC. The
following steps are conducted to
evaluate the vehicle’s over-current
protection controls:
(a) A breakout harness is connected to
the traction side of the REESS.
Manufacturer may specify an
appropriate location(s) and attachment
point(s) to connect the breakout harness.
(b) Temperature probes are connected
to the REESS outer casing to monitor
changes in REESS temperature.
Temperature measurements may also be
obtained through communication with
the REESS control module.
(c) The external charge/discharge
equipment, with maximum voltage and
current set at least 10 percent higher
than the REESS voltage and current
limits, is connected to the breakout
harness.
(d) The vehicle switch or device that
provides power to the vehicle controls
that manage REESS operations is set to
the activated position.
(e) The REESS is charged with the
external charge/discharge equipment
with the maximum charge current
specified by the manufacturer. If the
manufacturer does not specify an
appropriate charge current, then a
charge rate of 1⁄3C is used.
(f) After charging is initiated, the
overcurrent specified by the
manufacturer is supplied over the
course of 5 seconds from the maximum
charge current level to the over-current
level. If the vehicle manufacturer does
not supply an overcurrent level, a 10
Ampere over-current is supplied over 5
seconds. If charging is not terminated,
the over-current supply is increased in
steps of 10 Amperes.
(g) Charging at the over-current level
is continued until the following occurs:
(1) The over-current protection
control terminates the charge current; or
(2) The temperature gradient of the
REESS is less than 4 °C through 2 hours
from the first overcurrent input;
(h) After the charge current is
terminated, if charge and discharge is
permitted by the vehicle controls, a
standard cycle is performed in
accordance with S12.6.
(i) After the completion of the
standard cycle or if the standard cycle
was not performed, after charging is
terminated, the vehicle is observed for
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1 hour for evidence of electrolyte
leakage, rupture, venting, fire, or
explosion of the REESS.
(j) At the conclusion of the test,
electrical isolation of the REESS is
determined in accordance with S7.2.
S12.4 Over-temperature test. The
overtemperature test is conducted at
ambient temperatures between 10 °C
and 30 °C on a chassis-dynamometer
with the vehicle REESS initially set
between 90 to 95 percent SOC. For a
vehicle with on-board energy
conversion systems such as an internal
combustion engine or a fuel cell, the
fuel supply is set to allow operation for
about one hour of driving. The
following steps are conducted to
evaluate the vehicle’s high temperature
protection controls:
(a) The cooling system of the REESS
is disabled using manufacturer supplied
information. For an REESS that will not
operate if the cooling system is disabled,
the cooling operation is significantly
reduced. If manufacturer does not
supply information to disable or
significantly reduce the cooling system,
methods such as crimping the liquid
cooling hose, removing refrigerant fluid,
or blocking cabin air intakes for air
cooled REESS are applied.
(b) Temperature probes are connected
to the REESS outer casing to monitor
changes in REESS temperature.
Temperature measurements may also be
obtained through communication with
the REESS control module.
(c) The vehicle is installed on a
chassis dynamometer and the vehicle
switch or device that provides power
from the REESS to the electric power
train is set to the activated position or
the active driving possible mode.
(d) The vehicle is driven on the
dynamometer using an appropriate
vehicle manufacturer supplied drive
profile and charging information for
discharge and charge of the REESS to
raise the REESS temperature to its upper
boundary safe operating temperature
within one hour. If an appropriate
manufacturer supplied drive profile is
not available, the vehicle is repeatedly
accelerated to 80 mph and then
decelerated to 15 mph within 40
seconds. If the manufacturer does not
supply a charge profile, then a charge
rate greater than 1⁄3C current is used.
(e) The discharge/charge procedure on
the chassis-dynamometer is continued
until the following occurs:
(1) The vehicle terminates the
discharge/charge cycle;
(2) The temperature gradient of the
REESS is less than 4 °C through 2 hours
from the start of the discharge/charge
cycle; or
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(3) 3 hours have passed since the start
of discharge/charge cycles.
(g) After the discharge and charge
procedure is terminated, if charge and
discharge is permitted by the vehicle
controls, a standard cycle is performed
in accordance with S12.6.
(h) After the completion of the
standard cycle, or if the standard cycle
is not performed, after the discharge and
charge procedure is terminated, the
vehicle is observed for 1 hour for
evidence of electrolyte leakage, rupture,
venting, fire, or explosion of the REESS.
(i) At the conclusion of the test,
electrical isolation of the REESS is
determined in accordance with S7.2.
S12.5 External Short circuit test. The
short circuit test is conducted at
ambient conditions with the vehicle
REESS initially set between 90 to 95
percent SOC. The following steps are
conducted to evaluate the vehicle’s
overcharge protection controls:
(a) A breakout harness is connected to
the REESS. Manufacturer may specify
an appropriate location(s) and
attachment point(s) to connect the
breakout harness.
(b) Temperature probes are connected
to the REESS outer casing to monitor
changes in REESS temperature.
Temperature measurements may also be
obtained through communication with
the REESS control module.
(c) The vehicle switch or device that
provides power to the vehicle controls
that manage REESS operations is set to
the activated position.
(d) The short circuit contactor (with
the contactors in open position) is
connected to the breakout harnesses.
The total resistance of the equipment to
create the external short circuit (short
circuit contactor and breakout
harnesses) is verified to be between 2 to
5 milliohms.
(e) The short circuit contactor is
closed to initiate the short-circuit.
(f) The short circuit condition is
continued until the following occurs:
(1) Short circuit current is terminated;
or
(2) The temperature gradient of the
REESS is less than 4 °C through 2 hours
from the start of initiating the short
circuit condition.
(g) After the short circuit current is
terminated, if charge and discharge is
permitted by the vehicle controls, a
standard cycle is performed in
accordance with S12.6.
(h) After the completion of the
standard cycle, or if the standard cycle
was not performed, after short circuit
current is terminated, the vehicle is
observed for 1 hour for evidence of
electrolyte leakage, rupture, venting,
fire, or explosion of the REESS.
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(i) At the conclusion of the test,
electrical isolation of the REESS is
determined in accordance with S7.2.
S12.6 Standard cycle. The standard
cycle is conducted at ambient
temperatures between 10 °C and 30 °C
and starts with a standard discharge
followed by a standard charge. The
discharge and charge procedures would
follow manufacturer supplied
information. The charge procedure is
initiated 15 minutes after discharge is
terminated.
(a) If the manufacturer does not
provide a discharge procedure, the
vehicle is discharged with 1C current
until discharge is terminated by vehicle
controls.
(b) If the manufacturer does not
provide a charge procedure, the vehicle
is charged with 1⁄3C current until
terminated by vehicle controls.
S12.7 Documentation for low
temperature operation safety. At
NHTSA’s request, each manufacturer
shall submit documentation that
includes the following:
(a) The make, model, model year, and
production dates of the vehicles to
which the submitted documentation
applies.
(b) The lower temperature boundary
for safe REESS operation in all vehicle
operating modes.
(c) A description and explanation of
charge and discharge rates at the lower
temperature boundary for safe REESS
operation.
(d) A description of the method used
to detect REESS temperature.
(e) A system diagram with key
components and subsystems involved in
maintaining safe REESS charging and
discharging operation for temperatures
at or below the lower temperature
boundary for safe REESS operation.
(f) A description of how the vehicle
controls, ancillary equipment, and
design features were validated and
verified for maintaining safe REESS
operations at or below the lower
temperature boundary for safe REESS
operation.
(g) Overall evaluation: A description
of the final manufacturer review/audit
process and results of any final review
or audit evaluating the technical content
and the completeness and verity of
S12.7(a) to S12.7(f).
S12.8 Documentation and visual
warning in the event of operational
failure of vehicle controls.
(a) During the vehicle’s active driving
mode, the vehicle shall provide a visual
warning to the driver when there is a
vehicle control malfunction.
(b) At NHTSA’s request, each
manufacturer shall submit
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documentation that includes the
following:
(1) The make, model, model year, and
production dates of the vehicles to
which the submitted documentation
applies.
(2) A system diagram that identifies
all the vehicle controls that manage
REESS operation. The diagram must
identify what components are used to
generate a visual warning indicating
malfunction of vehicle controls to
conduct one or more basic operations.
(3) A written explanation describing
the basic operation of the vehicle
controls that manage REESS operation.
The explanation must identify the
components of the vehicle control
system, provide description of their
functions and capability to manage the
REESS, and provide a logic diagram and
description of conditions that would
lead to triggering the telltale activation.
(4) Validation results from tests to
confirm the display of a visual warning
in the presence of a malfunction of the
vehicle controls which manage safe
operation of the REESS.
(5) Overall evaluation: A description
of the final manufacturer review/audit
process and results of the final review
or audit which evaluated the technical
content and the completeness and verity
of S12.8(b)(1) to S12.8(b)(4).
S13. REESS thermal propagation
safety.
S13.1 Thermal runaway due to
internal short in a single cell of the
REESS. The vehicle manufacturer shall
make available to the agency, upon
request, documentation demonstrating
how the vehicle and its REESS are
designed to mitigate the safety risks
associated with thermal propagation
resulting from a single cell thermal
runaway due to an internal short within
the cell. The documentation shall
demonstrate thermal propagation safety
risk mitigation for the vehicle in
external charging mode, active driving
possible mode, and parking mode. The
documentation shall include the
following:
(a) The make, model, model year, and
production dates of the vehicles to
which the submitted documentation
applies.
(b) Part I: System analysis. This part
of the documentation shall identify the
conditions which could lead to singlecell thermal runaway due to an internal
short-circuit in different vehicle
operational modes and allocate
applicable functional units,
components, subsystems to each
identified condition. This part shall
include:
(1) A system diagram and a
description of all relevant physical
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systems and components of the REESS,
including information about the cell
type and electrical configuration, cell
chemistry, electrical capacity, voltage,
current limits during charging and
discharging, thermal limits of the
components that are critical for thermal
propagation safety.
(2) A system diagram, operational
description of sensors, components,
functional units relevant to single-cell
thermal runaway due to internal shortcircuit and thermal propagation, and the
interrelationship between the identified
sensors, components, and functional
units;
(3) A description of conditions under
which a single-cell thermal runaway
and propagation event due to an
internal short-circuit could occur;
(4) A description of how the
identified conditions were allocated to
each identified component, functional
unit, and subsystem;
(5) A description of the process used
to review the identified conditions and
their allocation to the identified sensors,
components, and functional units, for
completeness and validity; and
(6) A description of the warning or
notification system before the thermal
runaway occurred, including a
description of the detection technology
and mitigation strategies, if any.
(c) Part II: Safety risk assessment and
mitigation process. This part of the
documentation shall identify thermal
propagation safety risk mitigation
strategies for identified conditions
leading to single cell thermal runaway
in Part I and include:
(1) A description of the safety risks
and safety risk mitigation strategies, and
how these were identified, and
(2) A description of how each risk
mitigation strategy manages, mitigates,
or prevents the identified safety risks.
(3) Safety risk mitigation strategies
identified should include those that
mitigate the risk of single cell thermal
runaway due to an internal short and
mitigate the occurrence of thermal
propagation due to single-cell thermal
runaway resulting from an internal
short-circuit within the cell.
(d) Part III: Verification and validation
of risk mitigation strategies. This part of
the documentation pertains to
verification that the manufacturer
identified safety risks and considered
safety risk mitigation strategies and
include:
(1) A description of how each risk
mitigation strategy was verified and
validated for effectiveness,
(2) A description of the verification
and validation results for each risk
mitigation strategy, and
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(3) A description of and results from
the vehicle level assessment.
(e) Part IV: Overall evaluation of risk
mitigation. This part of the
documentation summarizes the vehicle
design and manufacturing strategies and
their validation to mitigate the safety
risks associated with thermal
propagation due single cell thermal
runaway resulting from internal short
within a cell. This part shall include a
description of the final manufacturer
review/audit process and results of the
final review or audit evaluating the
technical content and the completeness
and verity of S13.1(a) to S13.1(d).
S13.2 Warning in the case of
thermal event in REESS. The vehicle
shall provide a warning to the driver of
a thermal event in the REESS. The
warning shall activate within three
minutes of activating a heater within the
REESS when tested in accordance with
S13.3. The warning shall consist of
auditory and visual signals that remain
active for at least 5 minutes. The
thermal event warning system must
monitor its own readiness and the
warning must be provided to the driver.
S13.3 Test procedure for evaluating
warning for thermal event in REESS.
The thermal event warning test is
conducted at ambient temperatures
between 10 °C and 30 °C with the
vehicle REESS initially set between 90
to 95 percent SOC. The following steps
are conducted to evaluate the warning
in the case of thermal event in the
REESS:
(a) If possible, the REESS is removed
from the vehicle.
(b) The REESS casing is opened.
(c) A heater that achieves a peak
temperature of 600 °C within 30 seconds
is attached to one or more cells in the
REESS in a manner to put at least one
cell in the REESS into thermal runaway.
(d) The REESS casing is closed and
the REESS is reinstalled into the vehicle
(if initially removed in (a)).
(e) Vehicle stops to prevent vehicle
rollaway are installed.
(f) The vehicle is placed in active
driving possible mode.
(g) The heater within the REESS is
activated to achieve 600 °C within 30
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seconds. The heater shall remain
operational until thermal runaway is
initiated in at least one cell.
(h) The time for the activation of the
warning to the front row occupant (if
any) from the time of activation of the
heater is noted.
(i) The test is terminated after
activation of the warning or after four
minutes of activating the heater in the
REESS, whichever comes first.
S14. Water exposure safety. Each
vehicle to which the standard applies
shall maintain electrical isolation as
specified in S6.3.1 and S6.3.2 at these
times: (a) just after exposure to water in
each of the two tests specified below
and with the vehicle still wet; and (b)
after a minimum of 24 hours after
completing each of the tests specified
below.
S14.1 Vehicle washing test. The
vehicle is sprayed from any direction
with a stream of freshwater from a
standard test nozzle shown in Figure 9
that has a nozzle internal diameter of
6.3 millimeters, delivery rate of 11.9 to
13.2 liters/minute, and water pressure at
the nozzle between 30 kPa to 35 kPa.
(a) During the washing, the distance
from the nozzle to the vehicle surface is
3.0 to 3.2 meters. The distance of the
nozzle from the vehicle surface may be
reduced, if necessary, to ensure the
surface is wet when spraying upwards.
The washing test duration per square
meter of the vehicle surface area is 60
to 75 seconds, with a minimum total
test duration of 3 minutes.
(b) The vehicle external surface,
including the vehicle sides, front, rear,
top, and bottom is exposed to the water
stream. Border lines on the vehicle such
glass seals, outline of opening parts
(doors, windows, vehicle inlet cover),
outline of front grille, seals of vehicle
lamps are exposed to the water stream
from any direction.
(c) At the conclusion of the normal
washing test, with the vehicle still wet,
electrical isolation is determined in
accordance with S7.2.
S14.2 Driving through standing
water test. The vehicle is driven through
a wade pool of at least 10 centimeters
but not more than 15 centimeters depth
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of freshwater for a distance of 500
meters at a minimum speed of 12 mph
(20 km/h) but not more than 15 mph (24
km/h).
(a) If the wade pool is less than 500
m in length, then the vehicle shall be
driven through it several times for a
total distance of 500 m. The total time,
including the period outside of the
wade pool, shall be less than 5 minutes.
(b) At the conclusion of the standing
water test, with the vehicle still wet,
electrical isolation is determined in
accordance with S7.2.
S15. Rescue Sheets and Emergency
Response Guides.
S15.1 Rescue Sheets. Prior to vehicle
certification per 49 CFR part 567,
vehicle manufacturers shall submit
rescue sheets to NHTSA.
(a) For vehicles with a GVWR less
than or equal to 4,536 kg to which the
standard applies, submitted rescue
sheets shall follow the layout and
format in ISO–17840–1:2022(E).
(b) For vehicles with a GVWR greater
than 4,536 kg to which the standard
applies, the submitted rescue sheets
shall follow the layout and format in
ISO–17840–2:2019(E).
(c) The rescue sheets shall provide
information for first responders to
extricate occupants.
S15.2 Emergency Response Guides.
Prior to vehicle certification per 49 CFR
part 567, vehicle manufacturers shall
submit to NHTSA Emergency Response
Guides (ERGs) in accordance with the
template layout and format in ISO–
17840–3:2019(E) for vehicles to which
this standard applies.
(a) The ERGs shall provide in-depth
information linked and aligned to the
corresponding rescue sheet to support
the quick and safe action of first
responders and second responders.
(b) The ERGs shall provide in-depth
information related to electric vehicle
fire, submersion, leakage of fluids,
towing, transportation, and storage.
(c) The ERGs shall provide
information to assist first responders in
extricating occupants.
Figures to FMVSS No. 305a
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Electrical Chassis
Energy Conversion System
Energy Storage System
V2
r------------------
+
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System
Vb
t
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Figure 1. Voltage Measurements of the
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Electrical Chassis
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of the High Voltage Source and
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Figure 6. Marking of High Voltage
Sources
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Jointed test finger
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(050x20)
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Figure 7a. Access Probes for the Tests
of Direct Contact Protection. Access
Probe IPXXB (Top) and Access Probe
IPXXD (Bottom)
Federal Register / Vol. 89, No. 73 / Monday, April 15, 2024 / Proposed Rules
26753
Access probe
{Dimensions in mm)
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075
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Material: metal, except where otherwise specified
Linear dimensions in millimeters
Tolerances on dimensions vvithout specific tolerance:
on angles, 0/10 degrees
on linear dimensions:
up to 25 mm: 0/-0.05 mm
over 25 mm: :i:0.2 mm
Both joints shall pennit movement in the same plane and the same direction through
an angle of 90° with a 0° to + I0° tolerance.
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Connection to Exposed Conductive Parts
I
Exposed Conductive
Parts
D.C.
Power
Supply
V
Electrical Chassis
Connection to Electrical Chassis
Figure 8. Connection To Determine
Resistance Between Exposed
Conductive Parts of Electrical
Protection Barrier and Electrical
Chassis
4
6
13
20
5
Dimensions in millimetr'es
Dis 6.3 mm as specified in (a) above.
Figure 9. Standard Nozzle for IPX5
Water Exposure Test
Issued in Washington, DC, under authority
delegated in 49 CFR 1.95 and 501.5.
Sophie Shulman,
Deputy Administrator.
[FR Doc. 2024–07646 Filed 4–12–24; 8:45 am]
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BILLING CODE 4910–59–C
]]>Agencies
[Federal Register Volume 89, Number 73 (Monday, April 15, 2024)]
[Proposed Rules]
[Pages 26704-26754]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-07646]
[[Page 26703]]
Vol. 89
Monday,
No. 73
April 15, 2024
Part V
Department of Transportation
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National Highway Traffic Safety Administration
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49 CFR Part 571
Federal Motor Vehicle Safety Standards; FMVSS No. 305a Electric-Powered
Vehicles: Electric Powertrain Integrity Global Technical Regulation No.
20, Incorporation by Reference; Proposed Rule
Federal Register / Vol. 89 , No. 73 / Monday, April 15, 2024 /
Proposed Rules
[[Page 26704]]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-2024-0012]
RIN 2127-AM43
Federal Motor Vehicle Safety Standards; FMVSS No. 305a Electric-
Powered Vehicles: Electric Powertrain Integrity Global Technical
Regulation No. 20, Incorporation by Reference
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: Consistent with a Global Technical Regulation on electric
vehicle safety, NHTSA proposes to establish Federal Motor Vehicle
Safety Standard (FMVSS) No. 305a to replace FMVSS No. 305, ``Electric-
powered vehicles: Electrolyte spillage and electrical shock
protection.'' Among other improvements, FMVSS No. 305a would apply to
light and heavy vehicles and would have performance and risk mitigation
requirements for the propulsion battery. Relating to a National
Transportation Safety Board recommendation, FMVSS No. 305a would also
require manufacturers to submit standardized emergency response
information for inclusion on NHTSA's website that would assist first
and second responders handling electric vehicles.
DATES: Comments should be submitted no later than June 14, 2024.
Proposed compliance date: We propose that the compliance date for
the proposed requirements be two years after the date of publication of
the final rule in the Federal Register. Small-volume manufacturers,
final-stage manufacturers, and alterers would be provided an additional
year to comply with the rule beyond the date identified above. We
propose to permit optional early compliance with the rule. After FMVSS
No. 305a is finalized, NHTSA intends to sunset FMVSS No. 305.
ADDRESSES: You may submit comments identified by the docket number in
the heading of this document or by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments on
the electronic docket site by clicking on ``Help'' or ``FAQ.''
Mail: Docket Management Facility. M-30, U.S. Department of
Transportation, 1200 New Jersey Avenue SE, West Building, Ground Floor,
Room W12-140, Washington, DC 20590.
Hand Delivery: U.S. Department of Transportation, 1200 New
Jersey Avenue SE, West Building, Ground Floor, Room W12-140,
Washington, DC 20590 between 9 a.m. and 5 p.m. Eastern Time, Monday
through Friday, except Federal Holidays.
Fax: 202-493-2251.
Instructions: All submissions must include the agency name and
docket number. Note that all comments received will be posted without
change to https://www.regulations.gov, including any personal
information provided. Please see the Privacy Act discussion below. We
will consider all comments received before the close of business on the
comment closing date indicated above. To the extent possible, we will
also consider comments filed after the closing date.
Docket: For access to the docket to read background documents or
comments received, go to www.regulations.gov at any time or to 1200 New
Jersey Avenue SE, West Building Ground Floor, Room W12-140, Washington,
DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except
Federal Holidays. Telephone: 202-366-9826.
Confidential Business Information: If you claim that any of the
information in your comment (including any additional documents or
attachments) constitutes confidential business information within the
meaning of 5 U.S.C. 552(b)(4) or is protected from disclosure pursuant
to 18 U.S.C. 1905, please see the detailed instructions given under the
Public Participation heading of the SUPPLEMENTARY INFORMATION section
of this document.
Privacy Act: In accordance with 5 U.S.C. 553(c), DOT solicits
comments from the public to better inform its decision-making process.
DOT posts these comments, without edit, including any personal
information the commenter provides, to www.regulations.gov, as
described in the system of records notice (DOT/ALL-14 FDMS), which can
be reviewed at www.transportation.gov/privacy. In order to facilitate
comment tracking and response, we encourage commenters to provide their
name, or the name of their organization; however, submission of names
is completely optional. Whether or not commenters identify themselves,
all timely comments will be fully considered.
FOR FURTHER INFORMATION CONTACT: For technical issues, you may contact
Ms. Lina Valivullah, Office of Crashworthiness Standards; Telephone:
202-366-8786; Email: [email protected]; Facsimile: (202) 493-
2739. For legal issues, you may contact Ms. K. Helena Sung, Office of
Chief Counsel; Telephone: 202-366-2992; Email: [email protected];
Facsimile: (202) 366-3820. The mailing address of these officials is:
National Highway Traffic Safety Administration, 1200 New Jersey Avenue
SE, Washington, DC 20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
II. Background
a. Overview of FMVSS No. 305
b. Overview of GTR No. 20
1. The GTR Process
2. GTR No. 20
III. Proposals Based on GTR No. 20
a. Expanding Applicability of FMVSS No. 305a to Heavy Vehicles
1. Heavy School Buses
2. Heavy Vehicles Other Than School Buses
i. Request for Comment; Mechanical Integrity Test
ii. Request for Comment; Mechanical Shock Test
b. General Specifications Relating To Crash Testing
1. Low Energy Option for Capacitors
2. Assessing Fire or Explosion in Vehicle Post-Crash Test
3. Assessing Post-Crash Voltage Measurements
4. Electrolyte Spillage Versus Leakage
c. REESS Requirements Applicable to All Vehicles
1. Vehicle Controls for Safe REESS Operation
i. Overcharge Protection
ii. Over-Discharge Protection
iii. Overcurrent Protection
iv. Over-Temperature Protection
v. External Short-Circuit Protection
vi. Low-Temperature Protection
2. Mitigating Risk of Thermal Propagation Due to Internal Short
Within a Single Cell in the REESS
i. Safety Need
ii. GTR No. 20 Phase 1 Requirements
iii. NHTSA Proposal
3. Warning Requirements for REESS Operations
i. Thermal Event Warning
ii. Warning in the Event of Operational Failure of REESS Vehicle
Controls
4. Protection Against Water Exposure
i. NHTSA Proposal
A. Vehicle Washing Test
B. Driving Through Standing Water Test
ii. NHTSA's Consideration of Submersions
5. Miscellaneous GTR No. 20 Provisions Not Proposed
i. REESS Vibration Requirements
ii. REESS Thermal Shock and Cycling
iii. REESS Fire Resistance
iv. Low State-of-Charge (SOC) Telltale
IV. Request for Comment on Applying FMVSS No. 305a to Low-Speed
Vehicles
V. Emergency Response Information To Assist First and Second
Responders
[[Page 26705]]
VI. Request for Comment on Placing the Emergency Response
Information and Documentation Requirements in a Regulation Rather
Than in FMVSS No. 305a
VII. Proposed Compliance Dates
VIII. Rulemaking Analyses and Notices
IX. Public Participation
X. Appendices to the Preamble
Appendix A. Table Comparing GTR No. 20, FMVSS No. 305, and FMVSS No.
305a
Appendix B. Request for Comment on Phase 2 GTR No. 20 Approaches
Under Consideration by the IWG
I. Executive Summary
NHTSA is issuing this NPRM to achieve two goals. First, NHTSA
proposes to establish FMVSS No. 305a, ``Electric-powered Vehicles:
Electric Powertrain Integrity,'' to upgrade and replace existing FMVSS
No. 305. Proposed FMVSS No. 305a would have all the requirements of
FMVSS No. 305, but the proposed standard would expand its applicability
to vehicles with a gross vehicle weight rating (GVWR) greater than
4,536 kilograms (kg) (10,000 pounds (lb)) and add requirements and test
procedures covering new aspects of electric vehicle safety, such as the
performance and risk mitigation requirements for the propulsion
battery, referred to as the Rechargeable Electrical Energy Storage
System (REESS). NHTSA is also proposing requirements to ensure first
and second responders have access to vehicle-specific information about
extinguishing REESS fires and mitigating safety risks associated with
stranded energy \1\ when responding to emergencies. The restructured
and upgraded FMVSS No. 305a will facilitate future updates to the
standard as battery technologies and charging systems continue to
evolve. After FMVSS No. 305a is finalized, NHTSA intends to sunset
FMVSS No. 305.
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\1\ Stranded energy is the energy remaining inside the REESS
after a crash or other incident.
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The second goal is to further NHTSA's effort to harmonize the
Federal Motor Vehicle Safety Standards under the Economic Commission
for Europe 1998 Global Agreement (``1998 Agreement''). The efforts of
the U.S. and other contracting parties to the 1998 Agreement culminated
in the establishment of Global Technical Regulation (GTR) No. 20,
``Electric Vehicle Safety.'' \2\ FMVSS No. 305 already incorporates a
substantial portion of GTR No. 20's requirements due to a previous
NHTSA rulemaking. In 2017, NHTSA amended FMVSS No. 305 to include
electrical safety requirements from GTR No. 13, ``Hydrogen and fuel
cell vehicles,'' pertaining to electric vehicle performance during
normal vehicle operation and post-crash.\3\ Because GTR No. 13's
provisions for electric vehicles were later incorporated into what
would become GTR No. 20, the 2017 final rule that adopted GTR No. 13's
provisions adopted what later became many of the requirements of GTR
No. 20. That 2017 rulemaking, however, did not expand the applicability
of FMVSS No. 305 to include heavy vehicles nor did it include
requirements for the REESS. This NPRM proposes these and other GTR No.
20 requirements.
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\2\ GTR No. 20, https://unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29gen/wp29registry/ECE-TRANS-180a20e.pdf.
\3\ GTR No. 13 only applied to light vehicles. Normal vehicle
operations include operating modes and conditions that can
reasonably be encountered during typical operation of the vehicle,
such as driving, parking, standing in traffic with vehicle in drive
mode, and charging. Final rule, 82 FR 44950, September 27, 2017.
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High Level Summary of the Proposal
FMVSS No. 305 currently only applies to passenger cars and to
multipurpose passenger vehicles, trucks, and buses with a GVWR of 4,536
kg (10,000 lb) or less (``light vehicles''). Consistent with GTR No.
20, proposed FMVSS No. 305a expands the current applicability of FMVSS
No. 305 to vehicles with a GVWR greater than 4,536 kg (10,000 lb)
(``heavy vehicles''). Under proposed FMVSS No. 305a:
Light vehicles would be subject to requirements carried
over from FMVSS No. 305 that ensure the safety of the electrical system
during normal vehicle operations and after a crash (post-crash).\4\
They would also be subject to new requirements for the REESS.
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\4\ Current FMVSS No. 305 light vehicle post-crash test
requirements (front, side, and rear crashes) are aligned with FMVSS
No. 301's light vehicle post-crash test requirements.
---------------------------------------------------------------------------
Heavy vehicles would be subject to the requirements for
electrical system safety during normal vehicle operations and to
requirements for the REESS. However, except for heavy school buses,
they would not be subject to post-crash requirements. This proposed
exclusion of heavy vehicles, other than school buses, from crash tests,
aligns with similar exclusions in FMVSS No. 301, ``Fuel system
integrity,'' for conventional fuel vehicles and FMVSS No. 303, ``Fuel
system integrity of compressed natural gas vehicles,'' for compressed
natural gas vehicles.
Heavy school buses (GVWRs greater than 4,536 kg (10,000
lb)) \5\ would be subject to the requirements for electrical system
safety during normal vehicle operations and to the requirements for the
REESS, and would have to meet post-crash test requirements to ensure
the vehicles protect against unreasonable risk of electric shock and
risk of fire after a crash. The post-crash tests are the same tests
described in FMVSS No. 301 for heavy school buses (impacted at any
point and at any angle by a moving contoured barrier).
---------------------------------------------------------------------------
\5\ In the school bus safety area, stakeholders, including
NHTSA, commonly refer to buses with a GVWR over 4,536 kg (10,000 lb)
as ``large'' school buses.
---------------------------------------------------------------------------
The post-crash requirements of proposed FMVSS No. 305a for light
vehicles and heavy school buses include electric shock protection
(there are four compliance options--low voltage, electrical isolation,
protective barrier, and low energy for capacitors \6\); REESS
retention; electrolyte leakage; and fire safety. The requirements for
REESS retention and electrolyte leakage are already in FMVSS No. 305,
but this NPRM proposes to enhance some provisions consistent with GTR
No. 20. For example, current FMVSS No. 305 does not specify that there
must be no fire or explosion after a crash test. Electric vehicles may
catch fire long after a collision or other occurrence resulting in a
fault condition. To account for the potential delayed response, NHTSA
is proposing to prohibit fire or explosion for a one-hour post-test
period.
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\6\ FMVSS No. 305 already includes the first three compliance
options for electrical shock protection but not the low energy
option that is available for capacitors in GTR No. 20. This NPRM
would complete the alignment by proposing the low energy option for
capacitors in FMVSS No. 305a. NHTSA had considered this option years
ago and had decided against it. As explained in detail in sections
below, NHTSA has changed its view on the matter after further
considering data and analysis from the GTR.
---------------------------------------------------------------------------
A substantial portion of this NPRM focuses on safety provisions for
the propulsion battery, the REESS. For what would be the first time in
an FMVSS, proposed FMVSS No. 305a includes comprehensive performance
requirements and risk mitigation strategies for the REESS. These REESS
requirements would apply to all vehicles, regardless of GVWR. A REESS
provides electric energy for propulsion and may include necessary
ancillary systems for physical support, thermal management, electronic
controls, and casings. The proposed requirements set a level of
protection of the REESS against external fault inputs, ensure the REESS
operations are within the manufacturer-specified functional range, and
increase the likelihood of safe operation of the REESS and other
electrical systems of the vehicle during
[[Page 26706]]
and after water exposure during normal vehicle operations.\7\
---------------------------------------------------------------------------
\7\ ``Normal vehicle operation'' means situations such as
driving through a pool of standing water or exposing the vehicle to
an automated car wash. This NPRM does not propose requirements to
address vehicle fires due to vehicle submersions in floods and storm
surges, as GTR No. 20 does not have specific requirements to address
this area. NHTSA is researching this latter area.
---------------------------------------------------------------------------
Proposed FMVSS No. 305a addresses some aspects of REESS safety
through documentation measures, consistent with GTR No. 20.
``Documentation measures'' means a list of information provided by
manufacturers, at NHTSA's request, that demonstrate that they
considered, assessed, and mitigated identified risks for safe operation
of the vehicle. These proposed documentation requirements would
address: (a) safety risk mitigation associated with charging and
discharging during low temperature; (b) the safety risks from thermal
propagation in the event of single-cell thermal runaway \8\ (SCTR) due
to an internal short-circuit of a single cell; and (c) providing a
warning if there is a malfunction of vehicle controls that manage REESS
safe operation. The GTR takes a documentation approach on these aspects
of safety because of the rapidly evolving electric vehicle technologies
and the variety of available REESS and electric vehicle designs. The
Informal Working Group experts that drafted the GTR determined there
currently are no objective test procedures to evaluate safety risk
mitigation designs or the operations of warnings of a malfunction of
vehicle controls in a manner that is not design restrictive.
---------------------------------------------------------------------------
\8\ Thermal runaway means an uncontrolled increase of cell
temperature caused by exothermic reactions inside the cell.
---------------------------------------------------------------------------
NHTSA tentatively agrees with this approach given the current state
of knowledge. Thus, until test procedures and performance criteria can
be developed for all vehicle powertrain architectures, proposed FMVSS
No. 305a would require manufacturers to submit documentation to NHTSA,
at NHTSA's request, that identify all known safety hazards, describe
their risk mitigation strategies for the safety hazards, and, if
applicable, describe how they provide a warning to address a safety
hazard.\9\ The purpose of the documentation approach is two-fold. Given
the variation of battery design and design specific risk mitigation
systems, the documentation requirement would be a means of assuring
that each manufacturer has identified safety risks and safety risk
mitigation strategies. The requirement provides a means for NHTSA to
learn of the risks associated with the REESS, understand how the
manufacturer is addressing the risks, and oversee those safety hazards.
This approach is battery technology neutral, not design restrictive,
and is intended to evolve over time as battery technologies continue to
rapidly evolve. It is an interim measure intended to assure that
manufacturers will identify and address the safety risks of the REESS
until such time objective performance standards can be developed that
can be applied to all applicable REESS designs. NHTSA would also
acquire information from the submissions to learn about the safety of
the REESS and potentially develop the future performance standards for
FMVSS No. 305a. The proposed documentation requirements are based on
the approach of GTR No. 20, but NHTSA proposes to focus the GTR's
documentation requirements to enable the agency to obtain more targeted
information from manufacturers.\10\
---------------------------------------------------------------------------
\9\ Section 30166 of the Vehicle Safety Act authorizes the
Secretary of Transportation (NHTSA by delegation) the ability to
request and inspect manufacturer records that are necessary to
enforce the prescribed regulations.
\10\ Given the proposed documentation specifications are more
akin to disclosure requirements that could be issued under general
NHTSA regulation rather than pursuant to an FMVSS with specified
test procedures, the agency also requests comment on whether the
proposed documentation requirements would be better placed in a
general agency regulation than in the proposed FMVSS No. 305a.
---------------------------------------------------------------------------
As part of NHTSA's battery initiative \11\ and in response to a
2020 NTSB recommendation,\12\ this NPRM proposes to include in FMVSS
No. 305a a requirement that vehicle manufacturers submit to NHTSA
emergency response guides (ERGs) and rescue sheets for each vehicle
make, model, and model year. The purpose of the requirement is to
provide information to first \13\ and second \14\ responders regarding
the safe handling of the vehicle in emergencies and for towing and
storing operations. The uploaded ERGs and rescue sheets would be
publicly available on NHTSA's website for easy searchable access. ERGs
and rescue sheets communicate vehicle-specific information related to
fire, submersion, and towing, as well as the location of components in
the vehicle that may expose the vehicle occupants or rescue personnel
to risks, the nature of a specific function or danger, and devices or
measures which inhibit a dangerous state.
---------------------------------------------------------------------------
\11\ https://www.nhtsa.gov/battery-safety-initiative.
\12\ ``Safety risks to emergency responders from lithium-ion
battery fires in electric vehicles,'' Safety Report NTSB/SR-20/01,
PB2020-101011, National Transportation Safety Board, https://www.ntsb.gov/safety/safety-studies/Documents/SR2001.pdf.
\13\ ``First responder'' means a person with specialized
training such as a law enforcement officer, paramedic, emergency
medical technician, and/or firefighter, who is typically one of the
first to arrive and provide assistance at the scene of an emergency.
\14\ ``Second responder'' means a worker who supports first
responders by cleaning up a site, towing vehicles, and/or returning
services after an event requiring first responders.
---------------------------------------------------------------------------
NHTSA would require standardized formatting of the information. The
ERG and rescue sheet requirements would meet the layout and format
specified in ISO-17840, ``Road vehicles--Information for first and
second responders,'' which standardize color-coded sections in a
specific order to help first and second responders quickly identify
pertinent vehicle-specific rescue information. The standardized
information would be available and understandable to first and second
responders so they can easily refer to vehicle-specific rescue
information en route to or at the scene of a crash or fire event and
respond to the emergency quickly and safely.
NHTSA believes there are no notable costs associated with this
NPRM. This proposal closely mirrors the electrical safety provisions of
GTR No. 20, which have been voluntarily implemented by manufacturers in
this country. The agency believes that the proposed safety standards
are widely implemented by manufacturers of light and heavy electric
vehicles and heavy electric school buses. Manufacturers are also
already providing emergency response information to the National Fire
Protection Association (NFPA); under proposed FMVSS No. 305a they would
just have to standardize the format and submit the information to
NHTSA.\15\
---------------------------------------------------------------------------
\15\ Similar to the issue discussed above regarding having the
proposed documentation requirements in a general regulation rather
than in FMVSS No. 305a, the agency also requests comment on whether
the proposed ERG and rescue sheet requirements would be better
placed in a general agency regulation than in proposed FMVSS No.
305a.
---------------------------------------------------------------------------
Lastly, current FMVSS No. 305 does not apply to vehicles that
travel under 40 km/h (25 mph), such as low-speed vehicles.\16\ Given
there are low-speed vehicles that are also electric-powered vehicles,
NHTSA requests comments on the possibility of applying aspects of FMVSS
No. 305a to low-speed vehicles to ensure a level of protection against
shock and fire, particularly during normal vehicle operation, and to
assure the safe operation of the REESS.
---------------------------------------------------------------------------
\16\ ``Low-speed vehicle'' is defined in 49 CFR 571.3. See also
FMVSS No. 500, ``Low speed vehicles,'' 49 CFR 500.
---------------------------------------------------------------------------
II. Background
a. Overview of FMVSS No. 305
The purpose of FMVSS No. 305, ``Electric-powered vehicles:
electrolyte
[[Page 26707]]
spillage and electrical shock protection,'' is to reduce deaths and
injuries from electrical shock. The standard applies only to light
vehicles (vehicles with a GVWR less than or equal to 4,536 (kg) (10,000
(lb)). The standard's requirements reduce the risk of harmful electric
shock: (a) during normal vehicle operation; \17\ and (b) in post-crash
situations (to protect vehicle occupants, and rescue workers and others
who may come in contact with the vehicle after a crash). The standard's
requirements for the former protect against direct and indirect contact
of high voltage sources during everyday operation of the vehicles. The
focus of this ``in-use'' testing (unlike ``post-crash'' testing,
discussed below) deals with performance criteria that would be assessed
without first exposing the vehicle to a crash test.
---------------------------------------------------------------------------
\17\ Normal vehicle operation includes operating modes and
conditions that can reasonably be encountered during typical
operation of the vehicle, such as driving, parking, and standing in
traffic, as well as charging using chargers that are compatible with
the specific charging ports installed on the vehicle. It does not
include conditions where the vehicle is damaged, either by a crash
or road debris, subjected to fire or water submersion, or in a state
where service and/or maintenance is needed or being performed.
---------------------------------------------------------------------------
Normal Vehicle Operations. FMVSS No. 305 requires vehicles to
provide the following measures to protect against electric shock during
normal vehicle operations. Vehicles must prevent direct contact of high
voltage sources (those operating with voltage greater than 30 VAC or 60
VDC) \18\; prevent indirect contact of high voltage sources;
electrically isolate high voltage sources from the electric chassis
(500 ohms/volt or higher for alternating current (AC) and 100 ohms/volt
or higher for direct current (DC) sources); mitigate risk of driver
error (indicate to the driver when the vehicle is in possible active
driving mode at startup and when the driver is leaving the vehicle, and
prevent vehicle movement by its own propulsion system when the vehicle
charging system is connected to the external electric power supply).
---------------------------------------------------------------------------
\18\ VAC--volts of alternating current; VDC--volts of direct
current.
---------------------------------------------------------------------------
Post-Crash Protections. For post-crash protections, FMVSS No. 305
requires vehicles to meet the following provisions during and after the
crash tests specified in the standard. FMVSS No. 305 limits electrolyte
spillage from propulsion batteries and requires the REESS to remain
attached to the vehicle and not enter the passenger compartment. The
standard requires that during and after a crash test, high voltage
sources in a vehicle must be either electrically isolated from the
vehicle's chassis; of a voltage below specified levels considered safe
from electric shock hazards; or prevented from direct or indirect
contact by occupants or emergency services personnel by use of physical
barriers. The standard specifies that the post-crash requirements must
be met after crash tests involving: a frontal impact up to and
including 48 kilometer per hour (km/h) (30 mile per hour (mph)) into a
fixed collision barrier; an impact of a moving barrier at 80 km/h (50
mph) into the rear of the vehicle; an impact of a moving barrier at 53
km/h (33 mph) into the side of the vehicle; and under static rollover
conditions after each such impact.
FMVSS No. 305 already has many of GTR No. 20's requirements for
light vehicles, including requirements for electrical safety during
normal vehicle operation; post-crash electrolyte spillage; post-crash
REESS retention; and most of the GTR's post-crash electrical safety
options for high voltage sources.
b. Overview of GTR No. 20
1. The GTR Process
The United States is a contracting party to the ``1998 Agreement''
(the Agreement concerning the Establishing of Global Technical
Regulations for Wheeled Vehicles, Equipment and Parts which can be
fitted and/or be used on Wheeled Vehicles). This agreement entered into
force in 2000 and is administered by the UN Economic Commission for
Europe's (UN ECE's) World Forum for the Harmonization of Vehicle
Regulations (WP.29). The purpose of this agreement is to establish
Global Technical Regulations (GTRs).
In March 2012, UNECE WP.29 formally adopted the proposal to
establish GTR No. 20 at its one-hundred-and-fifty-eighth session. NHTSA
chaired the development of GTR No. 20 and voted in favor of
establishing GTR No. 20.
As a Contracting Party Member to the 1998 Global Agreement who
voted in favor of GTR No. 20, NHTSA is obligated to initiate the
process used in the U.S. to adopt the GTR as an agency regulation. By
issuing this NPRM, NHTSA is initiating the process to consider adoption
of GTR No. 20. As noted above, under the terms of the 1998 Agreement,
NHTSA is not obligated to adopt the GTR after initiating this process.
In deciding whether to adopt a GTR as an FMVSS, NHTSA follows the
requirements for NHTSA rulemaking, including the Administrative
Procedure Act, the National Traffic and Motor Vehicle Safety Act
(Vehicle Safety Act), Presidential Executive Orders, and DOT and NHTSA
policies, procedures, and regulations. Among other things, FMVSSs
issued under the Vehicle Safety Act ``shall be practicable, meet the
need for motor vehicle safety, and be stated in objective terms.'' \19\
---------------------------------------------------------------------------
\19\ 49 U.S.C. 30111.
---------------------------------------------------------------------------
2. GTR No. 20
GTR No. 20 establishes performance-orientated requirements that
reduce potential safety risks of electric vehicles (EVs) while in use
and after a crash event. The GTR includes provisions that address
electrical shock associated with high voltage circuits of EVs and
potential hazards associated with lithium-ion batteries and/or other
REESS. One of the principles for developing GTR No. 20 was to address
unique safety risks posed by electric vehicles and their components to
ensure a safety level equivalent to conventional vehicles with internal
combustion engines.
The requirements in GTR No. 20 were developed in Phase 1 of the
GTR. GTR No. 20 was developed in phases due to the differing stages at
which technologies have been developed and evaluated. The informal
working group (IWG) that developed the GTR determined that Phase 1
would address issues relating to the safe operation of the rechargeable
electrical energy storage system (REESS), and for mitigating risks of
fire and other safety risks associated with the REESS. In Phase 2,
which is on-going, the IWG is addressing issues involving long-term
research and verification.\20\ This NPRM pertains to the adoption of
the GTR as developed in Phase 1.
---------------------------------------------------------------------------
\20\ In Appendix B to this preamble, NHTSA requests comments on
some issues under development in Phase 2.
---------------------------------------------------------------------------
GTR No. 20 applies to all electric-powered vehicles regardless of
GVWR, in contrast to FMVSS No. 305, which only applies to light
vehicles. FMVSS No. 305 currently includes the majority of GTR No. 20's
requirements and applies these to light vehicles. GTR No. 20 also has
safety requirements for the REESS beyond those in FMVSS No. 305. These
additional requirements in GTR No. 20 for the REESS include:
Safe operation of REESS under the following exposures
during normal vehicle operations:
[cir] REESS protection under external fault conditions and extreme
operating temperatures:
--External short circuit
--Overcharge
--Over-discharge
[[Page 26708]]
--Overcurrent
--High operating temperature
--Low operating temperature
[cir] Management of REESS emitted gases
[cir] Water exposure during vehicle washing and driving through 10-
centimeter (cm) deep water on roadway.
[cir] Thermal shock and cycling (-40 [deg]C to 60 [deg]C) * \21\
---------------------------------------------------------------------------
\21\ The asterisk notes that this NPRM is not proposing to adopt
the GTR No. 20 requirement.
---------------------------------------------------------------------------
[cir] Resistance to short duration external gasoline pool fire *
[cir] Vibration environment during normal vehicle operations *
Warning systems for REESS safe operation in case of:
[cir] Low energy content in REESS * \22\
---------------------------------------------------------------------------
\22\ This NPRM does not propose to require a warning for low
energy in REESS. There is no such warning requirement for
conventional fuel vehicles in the event of low-fuel, yet all
conventional fuel vehicles have a low fuel indicator because it is a
consumer convenience feature. The agency expects that, similarly, a
low energy in REESS indicator will be voluntarily provided in all
electric-powered vehicles.
---------------------------------------------------------------------------
[cir] REESS control operational failure
[cir] Thermal runaway propagation due to single cell short circuit in
REESS
[cir] Thermal event in REESS
Installation (location) of REESS on the vehicle \23\
---------------------------------------------------------------------------
\23\ This requirement is intended for countries with type
approval systems where a generic REESS can be approved separate from
the vehicle. A vehicle with a pre-approved REESS that complies with
the REESS installation requirement would not have to undergo post-
crash safety assessment for approval. This installation requirement
would not apply in the U.S. with a self-certification system.
This NPRM proposes to complete the alignment of FMVSS No. 305 with
GTR No. 20 by extending the standard's electrical safety requirements
to heavy vehicles. This NPRM also proposes to adopt the above
requirements for the REESS to light and heavy vehicles, except as noted
by an asterisk, because requirements for thermal shock and cycling,
resistance to short duration external pool fire, and vibration
environment are already included under United States Hazardous
Materials Regulations (HMR), 49 CFR parts 171 to 180, in accordance
with the international lithium battery transportation requirements of
UN 38.3, ``Transport of dangerous goods: Manual of tests and
criteria.'' To avoid redundancy, NHTSA is not proposing adding these
requirements into FMVSS No. 305a. NHTSA explains the bases for the
proposals and, for provisions not proposed, the reasons the agency has
not proposed them in this NPRM.
GTR No. 20 includes post-crash requirements but does not specify
the crash tests for post-crash evaluation. Instead, the GTR allows
contracting parties to apply the crash tests in their regulations.
Further, the GTR allows contracting parties to permit regulated
entities to comply with post-crash requirements without conducting
vehicle crash tests. In place of crash tests, a contracting party may
specify tests for ``mechanical integrity'' and ``mechanical shock'' of
the REESS. The mechanical integrity test uses a quasi-static load of
100 kN on the REESS to evaluate the safety performance of the REESS
under contact loads that may occur during vehicle crash. The mechanical
shock test accelerates the REESS on a sled system to evaluate the
safety performance of the REESS and the integrity of the REESS mounting
structures to the vehicle under inertial loads that may occur. NHTSA
discusses its assessment of the component level mechanical integrity
and mechanical shock test procedures and requests comment on these
issues later in this NPRM.
III. Proposals Based on GTR No. 20
a. Expanding Applicability of FMVSS No. 305a to Heavy Vehicles
NHTSA proposes to harmonize the application of FMVSS No. 305a with
GTR No. 20. Currently, FMVSS No. 305 applies to electric-powered
vehicles with a GVWR less than or equal to 4,536 kg (10,000 lb); it
does not apply to electric vehicles with a GVWR greater than 4,536 kg
(10,000 lb). GTR No. 20 applies to both light and heavy electric
vehicles. NHTSA proposes to apply FMVSS No. 305a to both light and
heavy electric vehicles. The fundamentals for protecting against an
electrical shock for light vehicles are the same as for heavy vehicles.
A failure of a high voltage system may cause injurious electric shock
to the human body.
Specifically, NHTSA proposes to apply FMVSS No. 305a to all
passenger cars, multipurpose passenger vehicles, trucks, and buses,
regardless of their GVWR, that use electrical propulsion components
with working voltages greater than or equal to 60 VDC or 30 VAC, and
whose speed attainable over a distance of 1.6 kilometers (km) (1 mile)
on a paved level surface is more than 40 km/h (25 miles per hour
(mph)).\24\ The NPRM proposes to carry over the current requirements
for light vehicles in FMVSS No. 305 to FMVSS No. 305a, except some
provisions as enhanced by this NPRM if adopted by a final rule. To sum,
light vehicles would have to meet the requirements for normal vehicle
operations and the requirements proposed in this NPRM for the REESS.
Further, they would have to meet requirements for post-crash
protections following a crash test. Under proposed FMVSS No. 305a,
heavy school buses would have to meet the requirements for normal
vehicle operations and for the REESS, and, following a specific crash
test, requirements for post-crash protections. The agency is not
adopting the provision in GTR No. 20 that conducts mechanical integrity
and mechanical shock tests (component-level) for light vehicles and for
heavy school buses. NHTSA believes that post-crash safety is better
evaluated at a system level in a crash test than in component-level
tests. Currently there are crash tests for light vehicles and school
buses, thus, NHTSA proposes to conduct post-crash safety after the
specified crash tests.
---------------------------------------------------------------------------
\24\ Current FMVSS No. 305 does not apply to these vehicles that
travel under 40 km/h (25 mph).
---------------------------------------------------------------------------
Heavy vehicles other than heavy school buses would be subject to
the requirements for normal vehicle operations described above and the
requirements for the REESS. They would not be subject to crash testing
requirements because the agency does not know of a crash test that
would be appropriate for the vehicles at this time. However, while
NHTSA does not have a sufficient basis to proceed currently with
dynamic or quasi-static requirements for heavy vehicles other than
school buses, this NPRM requests comment on this issue. NHTSA is
interested in the merits of component-level tests that are
representative of impact loads in heavy vehicle crashes and the
appropriateness of applying the tests to different weight classes of
heavy vehicles. Even in the absence of post-crash testing requirements,
NHTSA tentatively concludes that meeting requirements for normal
vehicle operations and for the REESS, as a starting point, will enhance
the safety of these heavy electric vehicles.
1. Heavy School Buses
NHTSA proposes to distinguish heavy school buses from other types
of heavy vehicles and subject them to crash testing because the school
vehicles will be carrying children. This NPRM proposes to assess the
post-crash safety of heavy school buses (school buses with a GVWR
greater than 4,536 kg (10,000 lb)) in a dynamic moving contoured
barrier test. This proposal would be consistent with current school bus
safety standards. FMVSS No. 301, ``Fuel system integrity,'' and FMVSS
No. 303, ``Fuel system integrity of compressed natural gas vehicles,''
require heavy school buses using
[[Page 26709]]
conventional fuel or compressed natural gas for propulsion,
respectively, to maintain fuel system integrity in a crash test where a
moving contoured barrier traveling at any speed up to 48 km/h (30 mph)
impacts the school bus at any point and angle. These standards set this
high level of safety for heavy school buses even though FMVSS Nos. 301
and 303 do not apply to other types of heavy vehicles.
NHTSA recognizes that FMVSS No. 305 currently does not apply to nor
has a crash test requirement for heavy school buses. When FMVSS No. 305
was first promulgated in September 2000, NHTSA decided not to apply
proposed FMVSS No. 305 to heavy school buses. NHTSA made this decision
after agreeing with commenters that applying the standard to the
vehicles at that time could have substantial effect, in terms of cost
and weight, on heavy school buses and potentially restrict further
development.\25\ The prevailing technology at that time was a series of
conventional lead-acid batteries as the energy source for propulsion.
Since the 1990s and early 2000s, battery technology and electric
powertrains have evolved to include nickel metal hydride and lithium-
ion batteries for electric vehicles. The weight and cost concerns
raised for electric school buses in 2000 are no longer obstacles with
current lithium-ion battery technologies because of their high energy
density and their widespread use. Several school bus manufacturers are
currently manufacturing and offering for sale heavy school buses with
high voltage electric propulsion systems. Given the development of the
technology and practicability of designing and producing heavy electric
school buses, NHTSA tentatively concludes it is appropriate to adopt
requirements to ensure post-crash safety of heavy electric school buses
and maintain the current high level of safety of heavy school buses.
---------------------------------------------------------------------------
\25\ Final rule, 65 FR 57980, September 27, 2000.
---------------------------------------------------------------------------
NHTSA is proposing to include in FMVSS No. 305a a requirement that
heavy school buses with high voltage electric propulsion systems meet
the requirements for normal vehicle operations (assessed prior to a
crash test) and the proposed post-crash electrical safety requirements
when impacted by the moving contoured barrier specified in FMVSS No.
301. The crash test requirement would align FMVSS No. 305a's
requirements for heavy school buses with those of FMVSS Nos. 301 and
303. Due to the number of electric school bus manufacturers and sales
since 2000, NHTSA tentatively concludes that meeting the proposed
standard would have no substantial effect on cost and weight due to
widespread use of lithium-ion battery and conformance to the proposed
post-crash safety requirements.\26\
---------------------------------------------------------------------------
\26\ Currently, all major school bus manufacturers (Blue Bird,
IC Bus, Thomas Built) are offering large and small electric school
buses (see AFDC-electric school bus) and many school districts have
introduced electric powered school buses in their fleets. As of June
2023, there are 2,277 electric school buses that are either on
order, delivered or operating in the U.S. In total, there are now
5,982 committed electric school buses in the U.S. https://
www.wri.org/insights/where-electric-school-buses-
us#:~:text=As%20of%20June%202023%2C%20there,more%20buses%20since%20Ju
ne%202022.
---------------------------------------------------------------------------
2. Heavy Vehicles Other Than School Buses
There are currently no heavy vehicle crash tests in FMVSS. Heavy
vehicles are typically made to order with different configurations \27\
based on the operational needs of the purchaser and are produced in low
volume. Conducting crash tests of various design configurations from a
small volume of representative vehicles would be cost prohibitive.
There could also be practicability constraints for conducting crash
tests on higher weight classes of heavy vehicles.
---------------------------------------------------------------------------
\27\ These differences include the number of fuel containers and
battery packs and the location and attachment of fuel lines and fuel
containers.
---------------------------------------------------------------------------
In this NPRM, NHTSA has proposed requirements to ensure post-crash
safety using full vehicle crash tests for light vehicles and heavy
school buses. Such full vehicle crash tests evaluate post-crash safety
at a system level, so NHTSA is not considering component-level tests of
the REESS for those vehicles. However, since there are no full vehicle
crash tests currently in FMVSSs for heavy vehicles (other than heavy
school buses), NHTSA seeks comment on considerations for component-
level tests (other than the mechanical integrity and mechanical shock
tests in GTR No. 20) that are representative of impact loads in heavy
vehicle crashes and that can be applied to different weight classes of
heavy vehicles.
i. Request for Comment; Mechanical Integrity Test
There are currently no crash tests specified in the FMVSSs \28\ for
evaluating the integrity of the fuel system or propulsion system of
heavy vehicles other than heavy school buses. GTR No. 20 provides an
option for evaluating post-crash safety of light vehicles by way of a
mechanical integrity test (crush test) of the REESS as an item of
vehicle equipment, instead of a full vehicle crash test as in FMVSS No.
305. The loads in the mechanical integrity requirements in the GTR No.
20 were derived from REESS contact loads measured in light passenger
vehicle crash tests per UN Regulations ECE R. No. 12, ``Uniform
provisions concerning the approval of vehicles with regard to the
protection of the driver against the steering mechanism in the event of
impact,'' ECE R.94, ``Uniform provisions concerning the approval of
vehicles with regard to the protection of the occupants in the event of
a frontal collision,'' and ECE R.95, ``Uniform provisions concerning
the approval of vehicles with regard to the protection of occupants in
the event of a lateral collision,'' using electric and hybrid-electric
vehicles available on the market.
---------------------------------------------------------------------------
\28\ FMVSS No. 301, ``Fuel system integrity,'' and FMVSS No.
303, ``Fuel system integrity of compressed natural gas vehicles,''
only applies to light vehicles and to heavy school buses.
---------------------------------------------------------------------------
In the mechanical integrity test, a quasi-static load is applied to
the charged REESS \29\ along with any subsystem components (including
crush protection systems specified by the manufacturer) along the
longitudinal axis of the vehicle (along the direction of vehicle
travel) or the lateral axis (perpendicular to the longitudinal axis). A
peak load of 100 kN is applied within 3 minutes and maintained for at
least 100 milliseconds. During the integrity test, the REESS is
required to have no evidence of electrolyte leakage, fire, or
explosion. The REESS is required to have electric isolation of at least
100 ohms/volt or provide protection level IPXXB against direct contact
of high voltage sources.\30\
---------------------------------------------------------------------------
\29\ The REESS is charged to 95 percent state-of-charge for
REESS designed to be externally charged and charged to no less than
90 percent of state-of-charge for REESS designed to be charged only
by an energy source on the vehicle.
\30\ IPXXB and IPXXD ``protection levels'' refer to the ability
of the physical barriers to prevent entrance of a probe into the
enclosure, to ensure no direct contact with high voltage sources.
``IPXXB'' is a probe representing a small human finger. ``IPXXD'' is
a slender wire probe. Protection degrees IPXXD and IPXXB are
International Electrotechnical Commission specifications for
protection from direct contact of high voltage sources.
---------------------------------------------------------------------------
Because there are no full vehicle crash tests currently in FMVSSs
for heavy vehicles (other than heavy school buses), NHTSA seeks comment
on a mechanical integrity test for REESS on heavy vehicles to evaluate
post-crash safety at a component-level. As noted above, the current
quasi-static loads of the integrity test specified in GTR No. 20 are
specific to light vehicles. NHTSA seeks comment on the parameters for a
[[Page 26710]]
possible quasi-static crush test for the REESS on heavy vehicles.\31\
The agency requests feedback on the merits of the integrity test in
assessing post-crash safety for heavy vehicle REESS. NHTSA seeks
comment on the practicability of such a test and on the specifics of
subsystem components that should be included with the REESS while
conducting the crush test. NHTSA requests that commenters provide data
to substantiate their assertions.
---------------------------------------------------------------------------
\31\ NHTSA's research evaluated the crush resistance of REESS
using a displacement-based loading method. See Ford Safety
Performance of Rechargeable Energy Storage Systems, Appendix A, DOT
HS 812 756, July 2019. https://rosap.ntl.bts.gov/view/dot/41840.
---------------------------------------------------------------------------
ii. Request for Comment; Mechanical Shock Test
NHTSA seeks comment to inform our research on a mechanical shock
test for REESS on heavy vehicles to evaluate post-crash safety at a
component level. The aim of the mechanical shock requirement in GTR No.
20 is to verify the safety performance of the REESS under inertial
loads which may occur during an impact. The requirement evaluates
specifically the performance of the REESS mountings and fixtures to the
vehicle.
The mechanical shock test is conducted with the REESS along with
any subsystem components installed on a sled system using the mounting
structures that are used for installing the REESS to the vehicle. The
REESS is decelerated or accelerated with an acceleration profile within
the acceleration corridor in Figure 1 and in accordance with
acceleration magnitudes in Table 1 through Table 3 for different
vehicle GVWRs. The test concludes with an observation period of one
hour at the ambient temperature conditions of the test environment.
[GRAPHIC] [TIFF OMITTED] TP15AP24.044
Figure 1--Generic Description of Test Pulses--Mechanical Shock Test
Table 1--Mechanical Shock Test--Acceleration Values for Vehicles With a GVWR Less Than or Equal to 3,500 kg
(7,716 lbs)
----------------------------------------------------------------------------------------------------------------
Acceleration (g)
Point Time (ms) -------------------------------
Longitudinal Transverse
----------------------------------------------------------------------------------------------------------------
A............................................................... 20 0 0
B............................................................... 50 20 8
C............................................................... 65 20 8
D............................................................... 100 0 0
E............................................................... 0 10 4.5
F............................................................... 50 28 15
G............................................................... 80 28 15
H............................................................... 120 0 0
----------------------------------------------------------------------------------------------------------------
Table 2--Mechanical Shock Test--Acceleration Values for Vehicles With a GVWR Greater Than 3,500 kg (7,716 lbs)
and Less Than or Equal to 12,000 kg (26,455 lbs)
----------------------------------------------------------------------------------------------------------------
Acceleration (g)
Point Time (ms) -------------------------------
Longitudinal Transverse
----------------------------------------------------------------------------------------------------------------
A............................................................... 20 0 0
B............................................................... 50 10 5
C............................................................... 65 10 5
D............................................................... 100 0 0
[[Page 26711]]
E............................................................... 0 5 2.5
F............................................................... 50 17 10
G............................................................... 80 17 10
H............................................................... 120 0 0
----------------------------------------------------------------------------------------------------------------
Table 3--Mechanical Shock Test--Acceleration Values for Vehicles With a GVWR Greater Than 12,000 kg (26,455 lbs)
----------------------------------------------------------------------------------------------------------------
Acceleration (g)
Point Time (ms) -------------------------------
Longitudinal Transverse
----------------------------------------------------------------------------------------------------------------
A............................................................... 20 0 0
B............................................................... 50 6.6 5
C............................................................... 65 6.6 5
D............................................................... 100 0 0
E............................................................... 0 4 2.5
F............................................................... 50 12 10
G............................................................... 80 12 10
H............................................................... 120 0 0
----------------------------------------------------------------------------------------------------------------
During the mechanical shock test, the REESS is required to have no
evidence of electrolyte leakage, fire, or explosion. The REESS is
required to have electric isolation of at least 100 ohms/volt or have
protection degree IPXXB.
Since there are no full vehicle crash tests currently in FMVSSs for
heavy vehicles (other than heavy school buses) to evaluate post-crash
safety at a system level, NHTSA seeks comment to inform possible future
research on a mechanical shock test for REESS on heavy vehicles to
evaluate post-crash safety at a component level. Among other matters,
NHTSA requests comment on the following apparent limitations of the GTR
test. The mechanical shock test in GTR No. 20 aims primarily at
evaluating the safety performance of the REESS mounting fixture, which
does not appear to address a safety need presently observed in the
field.\32\ Furthermore, the accelerations captured in the GTR No. 20
for the mechanical shock requirement may be too low, according to a
technical study performed by the Transportation Research
Laboratory.\33\ The aim of the technical study was to review the
appropriateness of the crash pulses used in current European
regulations. This study determined that the crash pulse requirements in
a number of the EU regulations (including R67, R100, and R110) are not
representative of current vehicles. (These are among the reasons NHTSA
is not proposing the mechanical shock test in GTR No. 20 for heavy
vehicles in this NPRM.)
---------------------------------------------------------------------------
\32\ Under the Vehicle Safety Act, the FMVSSs must, among other
things, be practicable, meet the need for motor vehicle safety, and
be stated in objective terms. (49 U.S.C. 30111(a).)
\33\ European Commission, Directorate-General for Internal
Market, Industry, Entrepreneurship and SMEs, Edwards, M., Hylands,
N., Grubor, D., et al., Technical study to review the
appropriateness of crash pulses used in current EU legislation:
final report, Section 4.4, Publications Office, 2021, https://data.europa.eu/doi/10.2873/58935.
---------------------------------------------------------------------------
NHTSA seeks comment on the relevance of the mechanical shock test
for heavy vehicles. NHTSA seeks comment on how the mechanical shock
test would be performed on heavy vehicle REESSs, the appropriate
accelerations levels that would be representative of acceleration
levels observed in the field or in crash tests, and appropriate
requirements which the REESS would need to meet in a mechanical shock
test.
NHTSA seeks comment on the best approach or test method for
evaluating post-crash safety for electric vehicles with a GVWR greater
than 4,536 kg (10,000 lb). Specifically, NHTSA seeks comment and
recommendations on other applicable safety tests and corresponding
objective performance criteria to evaluate the propulsion system crash
safety performance of vehicles with a GVWR greater than 4,536 kg
(10,000 lb). NHTSA seeks comment on whether the moving contoured
barrier crash test proposed for heavy school buses in the above section
in this preamble can or should be applied to all heavy vehicles.
b. General Specifications Relating To Crash Testing
This NPRM proposes several general provisions from GTR No. 20 that
would apply to various testing and performance requirements. NHTSA
highlights the following proposals below. These provisions pertain to
light vehicles and heavy school buses subject to the crash testing
requirements of proposed FMVSS No. 305a.
1. Low Energy Option for Capacitors
Currently, FMVSS No. 305 S5.3 requires that vehicles meet one of
the following three criteria post-crash: electrical isolation; absence
of high voltage; or physical barrier protection. This NPRM proposes a
low energy option for capacitors in the electric powertrain in FMVSS
No. 305a.
Capacitors store electrical energy and may be connected directly to
the chassis in some electric power trains. In fuel cell electric
vehicles (FCEVs), the high-voltage systems may contain capacitors that
are connected to high voltage buses and are not electrically isolated.
Such capacitors may be high voltage sources post-crash (because a
charged capacitor may not discharge quickly) and may not be able to
comply with post-crash electrical safety requirements using the direct
and indirect contact protection option or the electrical isolation.
However, capacitors may not pose a safety hazard when contacted, even
though they may be high voltage sources post-crash, because they are
low energy high voltage sources.
[[Page 26712]]
NHTSA has previously considered this issue. In a 2007 NPRM
responding to petitions for rulemaking from what were then the Alliance
of Automobile Manufacturers (Alliance) and the Association of
International Automobile Manufacturers (AIAM),\34\ NHTSA sought
comments regarding a request of the petitioners to include 0.2 Joule
(J) as an appropriate low energy threshold for electrical safety
compliance post-crash for high voltage sources.\35\ The petitioners
believed that the low energy option was non-harmful, and argued in
their subsequent comments to the NPRM \36\ that the option is necessary
due to the presence of x- and y-capacitors in the powertrain of fuel
cell vehicles. After evaluating the comments, NHTSA ultimately
disagreed with the petitioners and decided against a low energy option
for post-crash electrical safety because the agency was not convinced
that a low energy option was needed and had concerns about the possible
disparity between the level of safety provided by 0.2 J of energy and
the electrical isolation requirement.\37\ At that time a safety need
for a low energy option was not yet clear and the agency expressed
concerns regarding the practicality of measuring the residual energy in
a crash test environment.
---------------------------------------------------------------------------
\34\ In January 2020, the two industry associations merged to
form the Alliance for Automotive Innovation (generally referred to
as the Auto Innovators).
\35\ 72 FR 57260, October 9, 2007.
\36\ NHTSA-2007-28517-0004.
\37\ Final rule, 75 FR 33515, 33519; June 14, 2010.
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NHTSA is reconsidering this issue in this NPRM. GTR No. 20 contains
a detailed analysis of the 0.2 Joules energy limit for the low energy
post-crash electrical safety compliance option. While the 2007 NPRM
considered a low energy post-crash electrical safety compliance option
for any high voltage source in the powertrain, GTR No. 20 only provides
this option to capacitors in the powertrain.
NHTSA conducted an analysis using human body resistance charts,
long and short duration capacitance discharge pulse profiles, and the
graphs of physiological effects of AC and DC body current by duration
of exposure from two International Electrotechnical Commission (IEC)
technical publications,\38\ to determine safe energy levels for the
human body. NHTSA has submitted a technical memorandum to the docket
for this NPRM that provides details and results of the agency's
analysis.
---------------------------------------------------------------------------
\38\ IEC 60479-1 and 60479-2 Effects of Current on Human Beings
and Livestock--Part 1: General Aspects, Part 2: Special Aspects,
2005-07, Reference Nos. CEI/IEC/TS 60479-1:2018 and CEI/IEC/TS
60479-2:2019. https://webstore.iec.ch/publication/62980; https://webstore.iec.ch/publication/63392 (last accessed September 26,
2023).
---------------------------------------------------------------------------
Based on the analysis results, NHTSA tentatively concludes that a
post-crash electrical safety compliance option for capacitors based on
an electrical energy of 0.2 Joules or less provides adequate safety
from electrical shock and long-term harmful effects on the human body.
Providing this post-crash compliance option would allow for practicable
powertrain designs for battery electric and fuel cell vehicles without
any reduction in safety. Automotive high-voltage systems typically
utilize a number of capacitors connected to high voltage buses, and it
is not always practical to discharge every capacitor post-crash. NHTSA
tentatively believes that by providing this compliance option for a
safe energy limit, vehicle manufacturers would have the flexibility to
design products that assure safety. NHTSA seeks comments on the
parameters (human body resistance, discharge profiles) used in the
analysis and the analysis method.
2. Assessing Fire or Explosion in Vehicle Post-Crash Test
After a real-world crash, passengers within the vehicle need time
to safely egress from the vehicle or be rescued by first responders.
During this time, passengers should not be exposed to hazards such as
fire or explosion of the REESS, which may hinder their egress or
rescue.
GTR No. 20 requires that for a period of one hour after a crash
test, there shall be no evidence of fire or explosion of the REESS.
However, such a requirement is not currently in FMVSS No. 305. In
accordance with GTR No. 20, NHTSA proposes to include in FMVSS No. 305a
a requirement that there be no evidence of fire or explosion for the
duration of one hour after the crash test for heavy school buses, and
for the duration of one hour after each crash test and subsequent
quasi-static rollover test for light vehicles. The assessment of fire
or explosion would be verified by inspection without removal of the
REESS or any parts of the vehicle.
3. Assessing Post-Crash Voltage Measurements
This NPRM proposes to clear up a source of ambiguity in FMVSS No.
305. FMVSS No. 305 requires that the post-crash voltage measurements be
made at least 5 seconds after the vehicle comes to rest. However, at
times it is not entirely clear when the vehicle comes to rest because
there is always some vibration and slight vehicle motion post-crash.
For consistency with the GTR No. 20 test procedure, NHTSA proposes that
the voltage measurements in FMVSS No. 305a would be made between 10
seconds and 60 seconds after the impact. The agency tentatively
believes that 10 seconds after impact is sufficient time for voltage
measurement and 60 seconds after impact is early enough that any high
voltage arcing would be detected. NHTSA seeks comment on this approach.
4. Electrolyte Spillage Versus Leakage
Currently, FMVSS No. 305 S5.1 addresses ``electrolyte spillage from
propulsion batteries.'' The standard specifies that following a crash
test, not more than 5.0 liters of electrolyte from propulsion batteries
shall spill outside the passenger compartment, and that no visible
trace of electrolyte shall spill into the passenger compartment. NHTSA
proposes to use terms related to ``leakage'' instead of spillage. When
the electrolyte spillage \39\ requirement was originally adopted in
2000, EV propulsion batteries were envisioned to be a series of lead-
acid batteries. Lead-acid batteries at the time had large quantities of
liquid electrolyte that could spill out of the battery if the battery
structure were compromised in a crash. At that time, it was appropriate
to eliminate the term ``leakage'' due to its synonymity to
``spillage,'' to avoid questions of whether different meanings were
intended by the different words.
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\39\ Per Section B, ``S5.1 Electrolyte Spillage from Propulsion
Batteries,'' NHTSA stated in 65 FR 57980 that ``leakage'' is
synonymous for ``spillage.'' Both words indicate the escape of
electrolyte from the battery.
---------------------------------------------------------------------------
Current EV propulsion batteries, however, are lithium-ion
batteries. The cells of lithium-ion batteries have small quantity of
electrolyte that could leak out of the battery casing rather than
spill. Thus, NHTSA proposes to use the term ``electrolyte leakage,''
which is more relevant than ``electrolyte spillage'' for these
batteries.
NHTSA seeks comment on the inclusion of a post-crash electrolyte
leakage requirement in FMVSS No. 305a and the necessity and relevance
of such a requirement for current EVs. Specifically, NHTSA seeks
comment on whether this requirement is still relevant given today's
propulsion battery technologies and if it is still necessary based on
the safety incidents observed in the field or in crash tests. NHTSA
seeks comment on whether a 5-liter maximum amount of electrolyte
permitted to be leaked is still relevant and requests commenters to
provide data based on safety incidents observed in the field or in
crash tests to
[[Page 26713]]
substantiate their assertions.\40\ NHTSA seeks comment on and
recommendations regarding electrolyte leakage detection methods and how
these detection methods can discern between the presence of electrolyte
and the presence of other liquids such as coolant.
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\40\ GTR No. 20 requires that the electrolyte leaking from the
REESS during and after the crash test is no more than 7 percent by
volume of the REESS electrolyte. However, there is no practical way
of measuring the quantity by volume of the electrolyte in the REESS.
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c. REESS Requirements Applicable to All Vehicles
This section of the NPRM addresses REESS safety performance
requirements during normal vehicle operation. The REESS requirements
would apply to all vehicles subject to FMVSS No. 305a.
Introduction
Currently, FMVSS No. 305 does not have any requirements for the
safe operation of the REESS and for mitigating risks of fire and other
safety risks associated with it. This NPRM's proposed requirements
would protect the REESS against external fault inputs, ensure the REESS
operations are within the manufacturer-specified functional range,
provide protection from thermal propagation in the event of single-cell
thermal runaway (SCTR) due to an internal short-circuit, provide a
warning if there is a thermal event within the REESS or a malfunction
of vehicle controls that manage REESS safe operation, and ensure safe
REESS operation during and after water exposure.
While REESS is a general term to represent any rechargeable
electrical energy storage system, currently all electric powered
vehicles use REESS with lithium-ion chemistry. Therefore, the current
safety hazards associated with REESS identified in literature and in
the field are those specific to lithium-ion chemistry REESS. However,
the proposed requirements in this NPRM will apply regardless of REESS
chemistry.
REESSs are designed and manufactured to operate safely within a
range of operating parameters, including temperature ranges, charge
levels, and current levels. If the REESS is subjected to fault
conditions outside these operating ranges such as overcharge, over-
discharge, overcurrent, over-temperature, external short-circuit, or
low temperature, these conditions can result in damage to the cells.
Cell damage increases the risk of hazardous conditions such as
electrolyte leakage, reduced electrical isolation, and fire in the
REESS (thermal runaway). Manufacturers include controls in electric
vehicles to manage REESS operation to ensure they stay within the
specified safe operating range, thereby mitigating damage to the REESS.
The system that monitors and controls the REESS is referred to as the
battery management system (BMS). NHTSA proposes requirements to assure
that the BMS has controls that protect the REESS against these faults
by, e.g., stopping the vehicle from charging to prevent overcharge.
Performance Criteria For Normal Vehicle Operations--General
The performance criteria specified in GTR No. 20 for each of the
vehicle control performance tests specify no evidence of electrolyte
leakage, rupture (applicable to high voltage REESSs only), venting
(applicable to REESSs other than open-type traction batteries \41\),
fire, or explosion. For high voltage REESSs, the electrical isolation
is required to be greater than or equal to 100 ohms per volt, for a DC
high voltage source. This NPRM proposes the same performance criteria
to protect the REESS against external faults, such as a fault in an
external charger that could result in the charger supplying greater
current than requested by the vehicle and/or charging the REESS beyond
full state of charge.\42\
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\41\ Open-type traction batteries are a type of battery which
are filled with liquid and generate hydrogen gas that is released
into the atmosphere.
\42\ The control pilot pin of the charger communicates with the
vehicle during charging. Based on the state of charge (SOC), the
vehicle requests a certain level of current and the vehicle charger
provides that level. Other external faults could arise when
attempting to drive the vehicle beyond the lowest safe operating SOC
of the REESS (over-discharge of the REESS), driving fast up a steep
hill for a long period of time that could cause the REESS to heat
beyond its highest safe operating temperature, and charging a REESS
at very cold temperatures that could cause lithium plating.
---------------------------------------------------------------------------
Under proposed FMVSS No. 305a, the evidence of electrolyte leakage,
venting,\43\ or rupture is verified by visual inspection without
disassembly of any part of the vehicle. Visible smoke during and after
the test, and/or the presence of soot and/or electrolyte residue in
post-test visual inspection are indicators of venting and electrolyte
leakage. The overcharge, over-discharge, overcurrent, over-temperature,
and external short-circuit test procedures specify that the agency
would perform a standard cycle after completing exposure to each of the
external faults, provided that the vehicle permits charging and
discharging at that time. A standard cycle, as specified in GTR No. 20
and proposed FMVSS No. 305a, consists of a standard discharge and
followed by a standard charge. If the vehicle is operable after
exposure to the external fault, running the standard cycle after
exposure to the external fault condition--while observing the vehicle
for one hour for evidence of electrolyte leakage, rupture, venting,
fire, or explosion, followed by voltage measurements for determining
electrical isolation--would ensure that continuing operating the
vehicle would not result in safety hazards.
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\43\ NHTSA elaborates on the proposed venting requirement at the
end of this section.
---------------------------------------------------------------------------
The vehicle might not permit charging and discharging after
detecting a dangerous condition; NHTSA considers this a safety feature
and that such a test outcome would not amount to an apparent
noncompliance. The inability to perform a standard cycle after exposure
to the external fault does not terminate the test. If the vehicle does
not permit charging and discharging after exposure to an external
fault, then the standard cycle is simply not performed and the test
proceeds. Specifically, the test ends with the vehicle observed for one
hour for evidence of electrolyte leakage, rupture, venting, fire, or
explosion, followed by voltage measurements for determining electrical
isolation.
The standard cycle would be conducted with the breakout harness
connected to the manufacturer-specified location(s) on the traction
side of the REESS \44\ on the vehicle's electric power train. The REESS
is charged and discharged using a high voltage battery tester/cycler
(with appropriate power and voltage ranges) which is connected to the
vehicle through the breakout harness, as shown in Figure 2 below (for
illustration purposes only).
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\44\ The manufacturer is required by proposed FMVSS No. 305a to
specify the location for connecting the breakout harness and may
also provide appropriate breakout harnesses for testing the vehicle.
If the manufacturer does not provide a breakout harness, NHTSA would
use a generic breakout harness to connect to the traction side of
the REESS.
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[[Page 26714]]
[GRAPHIC] [TIFF OMITTED] TP15AP24.045
Figure 2--Connection of the Breakout Harness & Laboratory Test
Equipment to the Vehicle
NHTSA proposes that the discharge and charge rates for the standard
cycle would be provided by the vehicle manufacturer. NHTSA proposes
that, if the discharge rate is not specified by the manufacturer, NHTSA
would use a discharge rate (C-Rate) of 1C current. A ``nC Rate'' is the
magnitude of constant current that would charge or discharge the REESS
in 1/n hour between 0 percent state of charge (SOC) and 100 percent
SOC. Discharge would continue until automatically terminated by vehicle
controls at the manufacturer-specified minimum operating SOC of the
REESS. After discharge, the standard cycle would include a 15-minute
rest period before the charging procedure commences. If a charge
procedure is not specified, then a charge rate (i.e., C-Rate) of \1/3\C
current would be used. Charging is continued until automatically
terminated by vehicle controls at the manufacturer-specified maximum
operating SOC of the REESS.
REESS Venting
Venting is the release of excessive internal pressure from a cell
or REESS in a manner intended by design to preclude rupture or
explosion. Venting during normal vehicle use may be associated with (a)
combustion and/or decomposition of electrolyte, or (b) vaporization of
the electrolyte. In case of condition (a), the emissions from the cells
may increase the risk to vehicle occupants if they are exposed to such
substances. In case of condition (b), the amount of the gases released
is considered less likely to pose a safety risk to the occupants.
Venting in the case of condition (a) may result in the release of gases
and particulates from the REESS, thereby potentially exposing vehicle
occupants to the emissions (gases and particulate matter).\45\ Hazards
associated with toxicity, corrosiveness, and flammability of the gases
emitted from the REESS and associated human health exposure limits vary
considerably. As noted above, NHTSA proposes to include a provision in
FMVSS No. 305a to limit the safety risks to vehicle occupants due to
venting during normal vehicle operations. The provision is based on GTR
No. 20 requirements described below.
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\45\ Gases generated in and vented from lithium-ion (Li-ion)
batteries typically include carbon dioxide (CO2), carbon
monoxide (CO), hydrogen (H2), oxygen (O2),
light C1-C5 hydrocarbons, e.g., methane and
ethane, and fluorine-containing compounds such as hydrogen fluoride
(HF) and fluoro-organics, e.g., ethyl-fluoride.
---------------------------------------------------------------------------
GTR No. 20 specifies that under normal vehicle operation, the
vehicle occupants are not exposed to any hazardous environment caused
by venting from the REESS. To avoid human harm that may occur due to
potential toxic or corrosive emissions, GTR No. 20 specifies that there
be no venting from the REESS for the following normal vehicle
operations tests: vibration, thermal shock and cycling, external short
circuit protection, overcharge protection, over-discharge protection,
over-temperature protection and overcurrent protection. GTR No. 20
includes a no-fire requirement in these tests which addresses the issue
of vented gas flammability. During the development of GTR No. 20, a
robust and repeatable method to verify the occurrence of
[[Page 26715]]
venting and the potential exposure of vehicle occupants to various
gases from the venting was sought, but no suitable method was found.
Visual inspection was found to be the best approach at this time for
verifying the occurrence of venting for assessing the influence of
vented gases on vehicle occupants. Therefore, GTR No. 20 specifies that
evidence of venting in these tests is verified by visual inspection
(evidence of soot, electrolyte residues) without disassembling any part
of the REESS.
NHTSA proposes to use a similar approach in FMVSS No. 305a to
evaluate the safety risks to vehicle occupants resulting from venting
from the REESS. The agency acknowledges that research is needed to
develop a repeatable, reproducible, and practical method to verify the
occurrence of various vented gases and the potential exposure and harm
to vehicle occupants. However, NHTSA tentatively concludes that in the
absence of such a method, the requirement that there must be no fire,
electrolyte leakage or venting during the tests evaluating vehicle
controls for safe REESS operation (external short-circuit protection,
overcharge protection, over-discharge protection, over-temperature, and
overcurrent protection) would reduce some safety risks to vehicle
occupants due to venting from the REESS. The evidence of venting in
these tests would be verified by visual inspection (evidence of soot,
electrolyte residues) without disassembling any part of the REESS.
NHTSA also requests comment in an Appendix to this preamble on the
IWG's continuing work on venting in Phase 2 of the GTR.
1. Vehicle Controls for Safe REESS Operation
This NPRM proposes the following performance requirements and
associated test procedures for vehicles to ensure they have controls
managing safe REESS operations. There are some minor differences
between the GTR No. 20 test procedures and those proposed in this NPRM
that are based on the lessons learned from NHTSA's test program. Those
differences pertain to the ease of conducting the test.\46\
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\46\ For example, the state of charge of the REESS at the
beginning of the test differed in some instances from that in GTR
No. 20 to enable completing the test more readily.
---------------------------------------------------------------------------
NHTSA funded research to validate a collection of test procedures
that assess safety hazards to electric vehicles while being charged or
when the REESS exceeds its recommended operational
limits.47 48 The research independently evaluated, refined,
and validated vehicle-level test procedures that could be robustly
applied to a wide range of vehicle technologies and battery
configurations. Based on the results of NHTSA's research, the agency
proposes to conduct full vehicle-level tests using a breakout harness
connected to a battery tester/cycler \49\ to evaluate vehicle controls
for safe REESS operation, rather than conducting the tests on the REESS
as a separate component. NHTSA is proposing vehicle-level testing
because evaluating REESS safe operation at the vehicle level would
evaluate the entire vehicle system and the associated vehicle controls,
whereas conducting the tests at the equipment level would not evaluate
all the relevant vehicle controls or any interaction or interference
between vehicle controls.
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\47\ DC Charging Safety Evaluation Procedure Development,
Validation, And Assessment, and Preliminary AC Charging Evaluation
Procedure--DOT HS 812 754 and DOT HS 812 778--July 2019. https://rosap.ntl.bts.gov/view/dot/41933.
\48\ System-Level RESS Safety and Protection Test Procedure
Development, Validation, and Assessment--Final Report--DOT HS 812
782 October 2019 https://rosap.ntl.bts.gov/view/dot/42551.
\49\ A battery tester/cycler is equipment that can be used for
charging and discharging REESS and for conducting specialized tests
on the REESS. An example of a battery tester with hybrid and battery
electric vehicles is the NHR 9300 battery test system (NHR 9300).
---------------------------------------------------------------------------
NHTSA evaluated the GTR No. 20 test procedures for feasibility,
practicability, and objectivity by conducting the test procedures on a
2019 Chevy Bolt, 2020 Tesla Model 3, and 2020 Nissan Leaf S
Plus.50 51 52 NHTSA's test program demonstrated the ease of
conducting tests at a vehicle level using breakout harnesses connected
to a battery cycler/tester for the external inputs to the REESS without
having to remove the REESS from the vehicle to conduct component level
tests. The proposed test procedures for overcharge, over-discharge,
overcurrent, over-temperature, and external short-circuit tests are
non-destructive tests intended to evaluate vehicle controls to protect
the REESS and can be conducted in serial order on the same vehicle.
---------------------------------------------------------------------------
\50\ NHTSA Test Report on the 2020 Tesla Model 3 Standard Range
4-Door Sedan can be accessed here: https://downloads.regulations.gov/NHTSA-2021-0029-0003/attachment_2.pdf.
\51\ NHTSA Test Report on the 2020 Nissan Leaf S Plus (62kWh
Battery) 5-Door Hatchback can be accessed here: https://downloads.regulations.gov/NHTSA-2021-0029-0002/attachment_2.pdf.
\52\ NHTSA Test Report on the 2019 Chevy Bolt can be accessed
here: https://downloads.regulations.gov/NHTSA-2021-0029-0001/attachment_2.pdf.
---------------------------------------------------------------------------
i. Overcharge Protection
A battery pack experiences an overcharge when a charger forces its
state of charge (SOC) level to rise above 100 percent. Overcharge of a
REESS can occur because of a failure of the charging system, such as a
fault in an external charger, a fault in the vehicle's regenerative
braking system, a sensor failure, or a voltage reference drift.\53\
Overcharge can lead to swelling of an electrochemical cell, lithium
plating, stability degradation, or over-heating, and ultimately can
lead to thermal runaway.\54\ Severe events such as fire or explosion
may occur. Therefore, vehicle controls to ensure the REESS does not get
overcharged are important for long-term safe operation of the REESS.
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\53\ Voltage can drift based on temperature. Higher temperature
can result in lower voltage.
\54\ Thermal runaway of a lithium-ion cell in a REESS occurs
when the thermal stability limit of the cell chemistry is exceeded,
and the cell releases its energy via an exothermic reaction at an
uncontrolled rate such that the heat generated is faster than that
dissipated.
---------------------------------------------------------------------------
Vehicle level controls or the BMS typically prevent charging when
the manufacturer-specified maximum operating SOC of the REESS is
achieved. GTR No. 20 includes a test to evaluate the performance of
vehicle controls to prevent overcharge of the REESS. NHTSA tentatively
concludes that GTR No. 20's overcharge test is practical and feasible
based on the agency's own testing.\55\ NHTSA proposes to include the
overcharge protection requirement and test procedure in FMVSS No. 305a.
---------------------------------------------------------------------------
\55\ See Test reports in docket no. NHTSA-2021-0029, available
at www.regulations.gov. Detailed test procedures are provided in the
test reports of the 2021 Chevrolet Bolt (NHTSA-2021-0029-0001), 2020
Nissan Leaf (NHTSA-2021-0029-0002), and the 2020 Tesla Model 3
(NHTSA-2021-0029-0003).
---------------------------------------------------------------------------
The proposed overcharge test would be performed on a complete
vehicle as follows. The test is conducted with the REESS initially set
at 90 to 95 percent SOC \56\ and at ambient temperatures between 10
[deg]C and 30 [deg]C. The breakout harness is attached on the traction
side of the REESS at the vehicle manufacturer's recommended location(s)
and attachment point(s), and the battery tester/cycler is connected to
the breakout harnesses to supply the charge current. Temperature probes
are connected to the REESS case to monitor changes in the REESS
temperature. Temperature measurements may also be
[[Page 26716]]
obtained through communication with the REESS control module.\57\
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\56\ Ranges in temperature and SOC are provided for this and
other test procedures for practicability and ease of conducting the
tests. In the overcharge test, the REESS is initially set at a high
SOC (90 to 95 percent) to enable fully charging the REESS in a
shorter period of time.
\57\ Commercial diagnostic tools or tools supplied by the
manufacturer may be used to read the Temperature measurements within
the REESS from the vehicle's Controller Area Network (CAN bus).
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The vehicle is turned on and the REESS is charged using the battery
tester/cycler in accordance with the manufacturer's recommended maximum
charge current \58\ until one of the following has occurred:
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\58\ If the manufacturer does not provide an appropriate charge
current, then a charge rate (i.e., C-Rate) of C/3 current would be
used.
---------------------------------------------------------------------------
(a) the REESS overcharge protection control terminates the charge
current;
(b) the REESS temperature is 10 [deg]C above its maximum operating
temperature specified by the manufacturer; \59\ or,
---------------------------------------------------------------------------
\59\ The manufacturer would specify the procedure for monitoring
the temperature of the REESS during testing. This could be measured
by attaching thermocouples to the casing of the REESS or obtained
from the CAN bus using appropriate tools.
---------------------------------------------------------------------------
(c) 12 hours have passed since the start of charging the vehicle.
After the overcharge condition is terminated, a standard cycle is
performed if possible. The test concludes with a 1-hour observation
period in which the vehicle is observed for any evidence of electrolyte
leakage, rupture, venting, fire, or explosion. At the conclusion of the
post-test observation period, the electrical isolation is determined in
the same manner as currently in FMVSS No. 305 S7.6 using a voltmeter to
measure voltages.
ii. Over-Discharge Protection
Over-discharging a REESS, which means discharging it below its
lowest state of charge specified by the manufacturer, can lead to
undesirable aging, electrolyte leakage, swelling, solid electrolyte
interphase (SEI) decomposition, internal short-circuit, and damaged
cell stability and safety on subsequent recharges. Even though the
initial over-discharge response of lithium-ion cells generally appears
benign, it can cause damage to cell electrodes that can compromise cell
stability and safety on subsequent recharge. Subsequent charging of an
over-discharged REESS may lead to fire or explosion.
Vehicle controls or the BMS typically prevent over-discharging when
the manufacturer specified minimum operating SOC of the REESS is
achieved. GTR No. 20 includes a test to evaluate the performance of
vehicle controls to prevent over-discharge of the REESS. NHTSA
tentatively concludes that GTR No. 20's over-discharge test is
practical and feasible based on the agency's own testing.\60\ NHTSA
proposes to include the over-discharge protection requirement and test
procedure in FMVSS No. 305a.
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\60\ See Test reports in Docket No. NHTSA-2021-0029, available
at www.regulations.gov. Detailed test procedures are provided in the
test reports of the 2021 Chevrolet Bolt (NHTSA-2021-0029-0001), 2020
Nissan Leaf (NHTSA-2021-0029-0002), and the 2020 Tesla Model 3
(NHTSA-2021-0029-0003).
---------------------------------------------------------------------------
The over-discharge test is performed at ambient temperatures
between 10 [deg]C and 30 [deg]C on a complete vehicle. The SOC of the
REESS at the beginning of the test is set at 10 to 15 percent.\61\ For
a vehicle with on-board energy conversion systems (e.g., internal
combustion engine, fuel cell, etc.), the fuel supply is set to the
minimum level \62\ where active driving mode is permitted. Similar to
the overcharge test, the breakout harness is attached on the traction
side of the REESS at the vehicle manufacturer's recommended location(s)
and attachment point(s), and the battery tester/cycler is connected to
the breakout harness to discharge the REESS.\63\ Temperature probes are
connected to the REESS case to monitor changes in the REESS
temperature. Temperature measurements may also be obtained through
communication with the REESS control module.
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\61\ Ranges in temperature and SOC are provided for this and
other test procedures for practicability and ease of conducting the
tests. In this case, the test is initiated with the REESS at a low
SOC (10 to 15 percent) to enable discharging the REESS in a shorter
period of time.
\62\ Minimum level of fuel supply needed would be provided by
the manufacturer.
\63\ A discharge resistor may also be used for this purpose.
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The vehicle is turned on and the REESS is discharged using the
battery tester/cycler in accordance with the manufacturer's recommended
discharging rate \64\ under normal operating conditions until one of
the following has occurred:
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\64\ If the manufacturer does not specify a discharge rate, a
power load of 1kW is used.
---------------------------------------------------------------------------
(a) vehicle controls terminate the discharge current,
(b) the temperature gradient of the REESS is less than 4 [deg]C
\65\ through two hours, or
---------------------------------------------------------------------------
\65\ Temperature variation of 4 [deg]C indicates stable
operation of the REESS. As noted earlier, the manufacturer specifies
the procedure for monitoring the temperature of the REESS during
testing. This could be measured by attaching thermocouples to the
casing of the REESS or obtained from the CAN bus using appropriate
tools.
---------------------------------------------------------------------------
(c) if the vehicle is discharged to 25 percent of its nominal
voltage level.
At the conclusion of the discharge termination, one standard charge
is performed, followed by one standard discharge. The test concludes
with a 1-hour observation period in which the vehicle is observed for
any evidence of electrolyte leakage, rupture, venting, fire, or
explosion. At the conclusion of the observation period, the electrical
isolation is determined in a similar manner as that in current FMVSS
No. 305 S7.6 using a voltmeter to measure voltages.
iii. Overcurrent Protection
As noted earlier, the vehicle and the charging system communicate
the level of current needed to charge the REESS. If there is a problem
in the communication or if the charging system malfunctions, higher
current may be provided though not requested by the vehicle. During
direct current (DC) fast-charging, failure of the external charge
equipment could cause over-current conditions in which the REESS
receives higher current than it was designed to manage at a given state
of charge of the REESS. Overcurrent conditions could result in heating
of the REESS, electrochemical damage to the cells, and a risk of
thermal runaway.
GTR No. 20 includes a test to evaluate the performance of vehicle
controls to protect the REESS from overcurrent conditions. NHTSA
tentatively concludes that GTR No. 20's overcurrent test is practical
and feasible based on the agency's own testing.\66\ NHTSA proposes to
include the overcurrent protection requirement in FMVSS No. 305a. In
accordance with GTR No. 20, NHTSA proposes to apply the overcurrent
test to vehicles that have capability of charging by DC external
electricity supply. The test is unnecessary for vehicles that only
charge by alternating current (AC) supply because AC charging is slower
and the inverters for AC charging manage any overcurrent. Also,
overcurrent issues have not been observed in AC charging.
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\66\ See Test reports in docket no. NHTSA-2021-0029, available
at www.regulations.gov. Detailed test procedures are provided in the
test reports of the 2021 Chevrolet Bolt (NHTSA-2021-0029-0001), 2020
Nissan Leaf (NHTSA-2021-0029-0002), and the 2020 Tesla Model 3
(NHTSA-2021-0029-0003).
---------------------------------------------------------------------------
The overcurrent test is performed with a complete vehicle. To avoid
the overcharge protection terminating the over-current condition, the
SOC of the REESS is set between 40 to 50 percent. The test is conducted
at ambient temperatures between 10 [deg]C and 30 [deg]C. The breakout
harness is attached on the traction side of the REESS at the vehicle
manufacturer's recommended location(s) and attachment point(s), and the
battery tester/cycler is connected to the breakout harnesses to supply
the charge current. Temperature probes are connected to the REESS case
to monitor changes in the REESS temperature.
[[Page 26717]]
Temperature measurements may also be obtained through communication
with the REESS control module. The vehicle manufacturer specifies the
highest normal charge current and the over-current level that is
applied. The battery tester/cycler is programmed to supply an over-
current during charging at the level specified by the manufacturer.
The vehicle is turned on and the REESS is charged using the battery
tester/cycler in accordance with manufacturer's recommended charging
procedure with the highest normal charge current specified by the
manufacturer.\67\ After charging is initiated, an over-current
specified by the manufacturer \68\ is supplied above that requested by
the vehicle. The charge current is increased over the course of 5
seconds from the highest normal charge current to the over-current
level. The charge current and the overcurrent supply is continued until
one of the following has occurred: (a) vehicle over-current protection
controls terminate the charging, or (b) the temperature gradient of the
REESS is less than or equal to 4 [deg]C for a two-hour period.
---------------------------------------------------------------------------
\67\ The manufacturer supplied information define the constant
current level and/or constant voltage level combination to charge
the REESS. If a charge procedure is not specified, then a charge
rate (i.e., C-Rate) of C/3 current is used.
\68\ If the vehicle manufacturer does not supply an appropriate
over-current level, the battery test/cycler will be programmed to
initially apply a 10 Ampere over-current. If charging is not
terminated, the over-current level of 20 amps will be applied.
Subsequently, the over-current supply is increased in steps of 10
amperes.
---------------------------------------------------------------------------
If possible, a standard cycle is performed using the connected
breakout harness and battery cycler. The test concludes with an
observation period of one hour in which the vehicle is observed for
electrolyte leakage, rupture, venting, fire, or explosion. At the
conclusion of the observation period, the electrical isolation is
determined in a similar manner as that in current FMVSS No. 305 S7.6,
using a voltmeter to measure voltages.
iv. Over-Temperature Protection
While the impacts of over-temperature operation vary by chemistry,
most battery chemistries can be negatively affected if operation by the
driver is attempted at high temperatures (per the limits of a specific
chemistry) or if aggressive operation is attempted at high temperatures
(high-rate charging or discharging). A temperature imbalance or
continued operation at elevated temperatures may even lead to thermal
runaway of cells if appropriate countermeasures, such as de-rating,\69\
are not taken.
---------------------------------------------------------------------------
\69\ De-rating is the reduction of a battery's available power
and is typically due to a state that indicates an undesirable
condition such as rapidly increasing cell temperature, elevated
temperatures, or very cold cell temperatures. By temporarily
reducing a battery's ability to provide and/or absorb power, de-
rating allows the battery to cool down (or at least stop increasing
in temperature) in situations with elevated temperatures and reduces
operation when the battery is so cold that certain usage levels
could cause damage.
---------------------------------------------------------------------------
Vehicle controls such as thermal management systems or the BMS
continuously monitor temperature conditions to prevent REESS operation
at elevated temperatures above the upper temperature boundary for safe
REESS operations. GTR No. 20 includes a test to evaluate the
performance of vehicle controls to prevent REESS temperatures exceeding
the upper temperature boundary for safe REESS operations. NHTSA
tentatively concludes that GTR No. 20's over-temperature test is
practical and feasible based on the agency's own testing.\70\ NHTSA
proposes to include the over-temperature protection requirement and
test procedure in FMVSS No. 305a, which aligns with GTR No. 20.
---------------------------------------------------------------------------
\70\ See Test reports in Docket No. NHTSA-2021-0029, available
at www.regulations.gov. Detailed test procedures are provided in the
test reports of the 2021 Chevrolet Bolt (NHTSA-2021-0029-0001), 2020
Nissan Leaf (NHTSA-2021-0029-0002), and the 2020 Tesla Model 3
(NHTSA-2021-0029-0003).
---------------------------------------------------------------------------
In the proposed FMVSS No. 305a, the over-temperature test is
performed on a chassis dynamometer \71\ with a complete vehicle. The
SOC of the REESS at the beginning of the test is set between 90 to 95
percent. The test is conducted at ambient temperatures between 10
[deg]C and 30 [deg]C. For vehicles with on-board energy conversion
systems (e.g., internal combustion engine, fuel cell, etc.), the fuel
system must have sufficient supply to allow operation of the energy
conversion system for about one hour of driving. The cooling system for
the REESS is disabled (or significantly reduced for a REESS that will
not operate with the cooling system disabled) per manufacturer-supplied
information.\72\ For REESSs that will not operate if the cooling system
is disabled, the maximum amount of coolant is removed to minimize the
cooling system's operation for the test.
---------------------------------------------------------------------------
\71\ A chassis dynamometer is a mechanical device that uses one
or more fixed roller assemblies to simulate different road
conditions within a controlled environment and is used for a wide
variety of vehicle testing.
\72\ Methods for disabling the cooling system may include
crimping the liquid cooling hose or in the case of a refrigerant
cooled package, removing the refrigerant fluid. For REESS cooled by
cabin air, block the cabin air intakes used to provide cooling air
flow to the REESS.
---------------------------------------------------------------------------
Temperature probes are connected to the REESS case to monitor
changes in the REESS temperature. Temperature measurements may also be
obtained through communication with the REESS control module.
GTR No. 20 specifies that the vehicle be soaked for at least 6
hours in a thermally controlled chamber at 45 [deg]C. However, NHTSA's
testing \73\ demonstrated that the presoaking of the vehicle at
elevated temperatures does not raise the temperature of the REESS as
significantly as by driving the vehicle under high acceleration and
deceleration drive modes. Therefore, to reduce the test time and test
burden, the agency does not believe it needs to specify presoaking of
the vehicle.
---------------------------------------------------------------------------
\73\ System-Level RESS Safety and Protection Test Procedure
Development, Validation, and Assessment-Final Report. DOT HS 812 782
October 2019. https://rosap.ntl.bts.gov/view/dot/42551.
---------------------------------------------------------------------------
The vehicle is installed on the chassis dynamometer and is placed
into driving mode. The vehicle is driven on the dynamometer using the
vehicle manufacturer-recommended appropriate drive profile for
discharge and charge of the REESS that would raise the temperature of
the REESS (with cooling system disabled or reduced function) above its
safe operating temperature within one hour. If the vehicle manufacturer
does not supply an appropriate drive profile, NHTSA will drive the
vehicle over back-to-back aggressive acceleration (near 100% pedal
application) and decelerations (near or above regenerative braking
limits) such as the one shown in Figure 3 below, where the vehicle is
accelerated to 80 mph and then decelerated to 15 mph within 40 seconds.
[[Page 26718]]
[GRAPHIC] [TIFF OMITTED] TP15AP24.046
Figure 3--Drive Profile on Dynamometer To Quickly Raise the Temperature
of the REESS. (For Illustration Purposes Only)
Vehicle battery designs and controls mitigate overheating of the
REESS in different ways: (1) Terminate discharge/charge operations when
the REESS temperature reaches its operating bounds; (2) Derate (reduce
acceleration/speed of the vehicle) to prevent the REESS reaching its
maximum operating temperature; (3) REESS cell chemistries are stable at
higher REESS temperature. In order to accommodate different approaches
to address hazards associated with overheating of REESS, GTR No. 20
provides three different options for terminating the discharge/charge
cycles:
(a) the vehicle terminates the charge-discharge cycle,
(b) the REESS temperature gradient is less than or equal to 4
[deg]C for a two-hour period, or
(c) 3 hours have elapsed from the time of starting the discharge-
charge cycles on the chassis dynamometer.
In accordance with GTR No. 20, the agency proposes to use the same
three options listed above to terminate the discharge/charge cycle.
At the conclusion of the over-temperature evaluation, a standard
cycle is performed if possible. The test concludes with a 1-hour
observation period in which the vehicle is observed for electrolyte
leakage, rupture, venting, fire, or explosion. At the conclusion of the
observation period, the electrical isolation is determined in a similar
manner as that in FMVSS No. 305 S7.6, using a voltmeter to measure
voltages.
v. External Short-Circuit Protection
The purpose of the external short-circuit protection test is to
verify the performance of the vehicle controls (protection measure)
against a short-circuit occurring externally to the REESS. During an
external short-circuit event, large amounts of instantaneous current
can be readily drawn generating copious amounts of heat. Associated
safety risks include over-heating, gas venting, or arcing that can
occur under fault conditions which can potentially lead to fire or
explosion.
Vehicle controls or the BMS typically protect the REESS from an
external short-circuit. GTR No. 20 includes a test to evaluate the
performance of vehicle controls to protect the REESS from an external
hard short-circuit (shorting resistance less than 5 milliohms). NHTSA
tentatively concludes that GTR No. 20's external short-circuit test is
practical and feasible based on the agency's own testing.\74\ NHTSA
proposes to include the GTR No. 20 external short-circuit protection
requirement and test procedure in FMVSS No. 305a.
---------------------------------------------------------------------------
\74\ See Test reports in Docket No. NHTSA-2021-0029, available
at www.regulations.gov. Detailed test procedures are provided in the
test reports of the 2021 Chevrolet Bolt (NHTSA-2021-0029-0001), 2020
Nissan Leaf (NHTSA-2021-0029-0002), and the 2020 Tesla Model 3
(NHTSA-2021-0029-0003).
---------------------------------------------------------------------------
The external short-circuit test is performed on a complete vehicle.
The SOC of the REESS at the beginning of the test is set at 90 to 95
percent SOC. The test is conducted at ambient temperatures between 10
[deg]C and 30 [deg]C. The breakout harness is installed on the vehicle
at the manufacturer specified location(s).\75\ Temperature probes are
connected to the REESS case to monitor changes in the REESS
temperature. Temperature measurements may also be obtained through
communication with the REESS control module. The short circuit
contactor (with the contactors in open position) is connected to the
breakout harnesses. The total resistance of the equipment to create the
external short circuit (short circuit contactor and breakout harnesses)
is verified to be between 2 to 5 milliohms.\76\ To begin the short-
circuit evaluation, the short-circuit contactors are closed. The short-
circuit condition is continued until (1) current is no longer present
or (2) one hour after the temperature probe on the REESS has stabilized
with a temperature change of less than 4 [deg]C for a two-hour period.
---------------------------------------------------------------------------
\75\ If the manufacturer does not provide information on the
location to connect the breakout harness for the external short
circuit test, the breakout harnesses may be connected on either side
of the positive and negative terminals of the pack.
\76\ GTR No. 20 specifies the external short circuit resistance
not exceeding 5 milliohms. The agency is specifying a range from 2
to 5 milliohms for ease of conducting the tests and to ensure
objectivity of the test.
---------------------------------------------------------------------------
If possible, a standard cycle is performed after termination of the
short-circuit. Fuses that opened during the short-circuit are not
replaced, and the standard cycle procedure is not performed if it is
not possible to charge and discharge the vehicle.
The vehicle is observed for one hour for electrolyte leakage,
rupture, venting, fire, or explosion. The external short-circuit test
concludes with an electrical isolation determination in a similar
manner as that in current FMVSS No. 305a S7.6 using a voltmeter to
measure voltages.
vi. Low-Temperature Protection
Uncontrolled repeated operation at low temperatures, especially
charging
[[Page 26719]]
for lithium-ion battery chemistries, may result in lithium plating or
cell damage that could eventually lead to reduced performance or
degraded life during subsequent operation. While single time operation
of REESS in very cold temperatures would not lead to a severe event,
some REESS designs use special chemical reactions which can damage the
REESS if it is charged at high rates in very cold temperatures. A
subsequent high rate of charging of such a damaged REESS may lead to
fire or explosion. Therefore, the rate of charging may need to be
terminated or limited in very cold temperatures.
Currently, no practical test procedure is available to evaluate the
performance of vehicle controls in low temperature conditions because
the effects of repeated charging at very low temperatures occur over a
very long period of time. Therefore, GTR No. 20 requires manufacturers
to provide documentation that includes a system diagram, a written
explanation on the lower boundary temperature for safe REESS operation,
the method of detecting REESS temperature, and the action taken when
the REESS temperature is at or below the lower boundary for safe REESS
operation.
NHTSA proposes to include documentation requirements based on GTR
No. 20 into FMVSS No. 305a. NHTSA proposes that the manufacturer
provide documentation, upon NHTSA's request, to demonstrate how the
vehicle monitors and appropriately controls REESS operations at low
temperatures at or below the lower temperature boundary for safe REESS
operation. The proposed requirements would indicate how manufacturers
identify, verify, and ensure vehicles have low-temperature protections
in place. Specifically, the proposal requires the manufacturer-supplied
documentation for a specific vehicle make, model, and model year would
include the following:
(1) A description of the lower temperature boundary for safe REESS
operation in all vehicle operating modes.
(2) A description and explanation of C-rates at the lower
temperature boundary for safe REESS operation.
(3) A description of the method used to detect REESS temperature.
(4) A system diagram with key components and subsystems involved in
maintaining safe REESS charging and discharging operation for
temperatures at or below the lower temperature boundary for safe REESS
operation.
(5) A description of how the vehicle controls, ancillary equipment,
and design features were validated and verified for maintaining safe
REESS operations at or below the lower temperature boundary for safe
REESS operation.
(6) A description of the final review/audit process of the
manufacturer, and the accompanying results of the manufacturer's final
assessment of risk management, and risk mitigation strategies.
NHTSA intends these documentation measures to demonstrate that the
manufacturer has considered, assessed, and mitigated identified risks
for safe operation of the vehicle. NHTSA tentatively agrees with GTR
No. 20 that there is a safety need for low temperature protections for
the REESS. Without protections, uncontrolled repeated operation at low
temperatures poses an unreasonable risk of fire or explosion. In the
absence of information enabling NHTSA to propose a practical test
procedure to evaluate the performance of vehicle controls in low
temperature conditions, the agency is proposing to require
manufacturers to submit documentation to NHTSA about pertinent low
temperature safety hazards, describe their risk mitigation strategies
for the safety hazards, and how they assessed the effectiveness of
their mitigation strategies.
NHTSA would review the documentation to understand the safety
hazards associated with the particular REESS in the vehicle, see
whether the manufacturer conducted an assessment of the risks, and
understand the measures the manufacturer undertook to mitigate those
known risks. This approach is intended to evolve over time as battery
technologies continue to rapidly evolve. It is an interim measure
intended to assure that manufacturers will identify and address the low
temperature safety risks of the REESS. In section VI., NHTSA requests
comments on whether the proposed document requirement would be better
placed in a general agency regulation than in proposed FMVSS No. 305a.
2. Mitigating Risk of Thermal Propagation Due to Internal Short Within
a Single Cell in the REESS
i. Safety Need
The potential for thermal runaway is a characteristic of the
lithium-ion cells currently used in REESSs for electric vehicle
propulsion. Thermal runaway of a lithium-ion cell in a REESS occurs
when the thermal stability limit of the cell chemistry is exceeded, and
the cell releases its energy via an exothermic reaction at an
uncontrolled rate such that heat is generated faster than it is
dissipated. The thermal runaway in a single cell may propagate to the
surrounding cells through conductive, convective, and radiative heat
transfer modes, causing reactions which create smoke, fire or, in very
rare circumstances, explosion. Lithium-ion cells have flammable
electrolyte that upon decomposition provides oxygen to the fire caused
by the thermal runaway, which increases the likelihood of its
propagation to other cells and even outside the REESS. The self-
oxygenating fires involving the cells in a REESS are therefore
difficult to extinguish. The smoke, fire, toxic gas emissions, and
explosion resulting from the thermal runaway can cause hazardous
conditions for vehicle occupants and those near the vehicle.
One root-cause of single-cell thermal runaway (SCTR) and
propagation due to an internal short-circuit relates to problems within
the cells. While this NPRM contains many performance tests for the safe
operation of the REESS, none of these tests would mitigate or prevent
thermal runaway due to an internal short-circuit within a cell of the
REESS and subsequent fire propagation. The mechanism of an internal
short circuit in a cell is complex and requires further study.
Currently, the risk of a spontaneous internal short circuit is heavily
dependent on battery design, such as use of non-flammable electrolytes,
ionic liquids, heat resistant and puncture-proof separators, and anode
and cathode materials. However, as discussed below, a performance test
that would establish a minimum standard of performance for the
materials is not available now.
GTR No. 20 addresses the hazards associated with SCTR due to an
internal short circuit through a documentation approach that requires
manufacturers to provide (to the testing authority) information on risk
mitigation strategies used in vehicle design to counteract the safety
risk. GTR No. 20 also requires a warning system to allow vehicle
occupants sufficient time to egress the vehicle before hazardous
conditions are present in the passenger compartment due to SCTR within
the REESS. GTR No. 20 requires documentation of the warning system, and
requires operation of the warning system only when the vehicle
propulsion system is turned on.
NHTSA tentatively generally agrees that a documentation approach on
risk mitigation strategies currently has merit, given there is no
suitable performance test to validate mitigation or prevention of SCTR
within a REESS. NHTSA is proposing a documentation approach based on
GTR No. 20 but has focused the GTR's requirements to better address
this safety need pending development of an objective performance test
that can
[[Page 26720]]
be applied to all REESSs in vehicles. In section VI., NHTSA requests
comments on whether the proposed document requirement would be better
placed in a general agency regulation than in proposed FMVSS No. 305a.
NHTSA is not proposing to require a warning system, or
documentation of the warning system, as specified in GTR No. 20. As
explained fully later in this section, NHTSA believes such a
requirement would not mitigate the safety hazards observed in the
field.
ii. GTR No. 20 Phase 1 Requirements
GTR No. 20 recognizes that, in general, REESS cells are
manufactured with manufacturing controls to mitigate safety problems.
Based on current manufacturing control processes, the probability of
manufacturing problems within a cell is generally considered to be less
than one in a million.\77\ Since the likelihood of two cells in a REESS
going into spontaneous single-cell thermal runaway (SCTR)
simultaneously is significantly lower,\78\ the focus of GTR No. 20 is
to mitigate the hazards associated with SCTR due to an internal short-
circuit within a single cell.
---------------------------------------------------------------------------
\77\ A REESS consists of a number of cells (n) in the range of
100 to 500. Therefore, the probability of a single-cell thermal
runaway and propagation event due to an internal short-circuit is
estimated to be the product of the number of cells times one in a
million (n x 10-6). https://batteryuniversity.com/
article/bu-304a-safety-concerns-with-li-
ion#:~:text=Lithium%2Dion%20batteries%20have%20a,than%20those%20in%20
consumer%20products.
\78\ The probability of two cells simultaneously undergoing
single-cell thermal runaway and propagation due to an internal
short-circuit is equal to the product of the probability of a
single-cell thermal runaway (n\2\ x 10-12).
---------------------------------------------------------------------------
GTR No. 20 addresses the SCTR safety hazard through a documentation
approach that requires manufacturers to provide (to the testing
authority on request) information on risk mitigation strategies used in
vehicle design to counteract the safety risk, and documentation on a
warning system that warns occupants to egress the vehicle. The
documentation requirements for risk mitigation strategies are only
generally described, however. This is because during the development of
GTR No. 20, there was no significant evidence of electric vehicle fires
due to SCTR and propagation due to an internal short-circuit. At that
time, the thought was that vehicle occupants would be exposed to
hazardous conditions if the SCTR propagates outside of the REESS to
other parts of the vehicle. Therefore, GTR No. 20 focuses primarily on
the warning and less on mitigating the risk of the SCTR within the
cell. The GTR requires that a warning be provided to the driver 5
minutes before hazardous conditions are present in the passenger
compartment due to SCTR and subsequent fire propagation. Five minutes
was considered sufficient time for vehicle occupants to egress the
vehicle before exposure to hazardous conditions. Under the GTR,
manufacturers would satisfy the requirement for a warning by providing
documentation that the vehicle provides the required warning.
GTR No. 20 uses a documentation approach for both the risk
mitigation strategies and the warning because an objective test
procedure is not available. Existing methods of initiating thermal
runaway simulating an internal short-circuit within a single cell in a
REESS are intrusive and dependent on the type of cell chemistry and
cell type.\79\ Additionally, different methods of initiation could
result in different results.\80\ NHTSA funded research to evaluate
different thermal runaway propagation test methods by examining various
existing methods of initiating thermal runaway, including heating
element method, rapid heater method, nail penetration, and laser
method, on batteries with a variety of chemistries, formats, and
configurations.\81\ The research indicated that the thermal runaway
initiation methods may influence the test results and the most
appropriate initiation method for a battery may depend on battery
chemistries, formats, and configurations.
---------------------------------------------------------------------------
\79\ One common method of initiating a thermal runaway is to
heat a cell externally using a heating element. This would require
disassembly of the casing of the REESS, adhering a heating element
to the surface of a cell, and adding thermocouples to verify the
heating element only provides heat to a single cell and not to
adjacent cells. The amount of heat applied to initiate a thermal
runaway depends on the cell chemistry (more volatile chemistries
requiring less heat input), and the cell design/type (thick wall
cells needing more heat input). The disassembly of the REESS, the
addition of a heating element, and the heat input is intrusive to
the REESS.
\80\ Another method of initiating a thermal runaway in a cell is
to penetrate a nail into a cell in the REESS. The orientation of the
nail penetration depends on the cell design and in some instances,
nail penetration may not cause a thermal runaway. While this method
may not require the REESS casing to be opened, the penetrating nail
compromises the casing and the cell structure. Additionally, the
depth of nail penetration may result in differences in heat release
that may not be similar in repeat tests and in tests using a heating
element.
\81\ Lamb, J., Torres-Castro, L., Stanley J., Grosso, C, Gray,
L., ``Evaluation of Multi-Cell Failure Propagation,'' Sandia Report
SAND2020-2802, March 2020. https://www.osti.gov/servlets/purl/1605985.
---------------------------------------------------------------------------
The repeatability and reproducibility of a potential performance
test using existing methods of thermal runaway initiation, and whether
such a test could be conducted on all applicable vehicles, are unknown.
Due to the rapid development of electric vehicle propulsion technology,
it was unclear during development of the GTR if any existing
performance test could apply to future vehicle designs without
restricting further enhancement of electric vehicle propulsion systems.
Therefore, instead of specifying a performance test for thermal runaway
and propagation due to an internal short-circuit in a single cell of a
REESS, GTR No. 20 requires manufacturers to submit documentation. Such
documentation must show risk mitigation strategies in their vehicle
designs for reducing hazards to vehicle occupants associated with
thermal runaway due to an internal short-circuit in a single cell in
the REESS. The documentation must also detail how the vehicle's warning
system activates a warning at least 5 minutes before hazardous
conditions arise in the passenger compartment.
Specifically, GTR No. 20 specifies the following documentation
requirements:
A description of the warning system.
Parameters (such as voltage, temperature, or current) that
trigger the warning indicator (telltale).
A risk reduction analysis using appropriate industry
standard methodology (for example, IEC 61508,\82\ MIL-STD 882E,\83\
ISO-26262,\84\ fault analysis as in SAE J2929,\85\ or similar), which
documents the risk to vehicle occupants caused by a single-cell thermal
runaway triggered by an internal short-circuit leading to thermal
propagation and the expected risk reduction resulting from
implementation of the identified risk mitigation functions or
characteristics.
---------------------------------------------------------------------------
\82\ IEC-61508:2010, ``Functional Safety of Electrical/
Electronic/Programmable Electronic Safety-related Systems''. https://webstore.iec.ch/searchform&q=IEC%2061508.
\83\ MIL-STD-882E:2012, ``System Safety''. https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=36027.
\84\ ISO-26262 series:2018, ``Road vehicles--Functional
Safety''. https://www.iso.org/search.html?q=ISO-26262&hPP=10&idx=all_en&p=0&hFR%5Bcategory%5D%5B0%5D=standard.
\85\ SAE J2929:2013, ``Safety Standard for Electric and Hybrid
Vehicle Propulsion Battery Systems Utilizing Lithium-based
Rechargeable Cells''. https://www.sae.org/standards/content/j2929_201302/.
---------------------------------------------------------------------------
A system diagram of all relevant physical systems and
components which contribute to the protection of vehicle occupants from
hazardous effects caused by thermal propagation triggered by a single-
cell thermal runaway event due to an internal short-circuit.
[[Page 26721]]
A diagram showing the functional operation of the relevant
systems and components and identifying all relevant risk mitigation
functions or characteristics.
For each identified risk mitigation function or
characteristic:
[cir] A description of its operation strategy,
[cir] Identification of the physical system(s) or component(s)
which implements the function,
[cir] One or more of the following engineering documents relevant
to the manufacturers design which demonstrates the effectiveness of the
risk mitigation function:
[ssquf] Tests performed including procedure used and conditions and
resulting data,
[ssquf] Analysis or validated simulation methodology and resulting
data.
iii. NHTSA Proposal
NHTSA tentatively agrees with GTR No. 20's rationale for the
documentation requirements for risk mitigation of thermal propagation
events resulting from SCTR due to an internal short-circuit within a
cell in the REESS. NHTSA tentatively concludes that due to the rapidly
evolving REESS technology and control systems to manage the performance
condition and safety of the REESS, a performance test to validate
mitigation of thermal propagation resulting from SCTR within the REESS
is not currently feasible. A performance test for a warning, when the
vehicle propulsion system is turned on, that provides sufficient time
for vehicle occupants to egress the vehicle before hazardous conditions
arise in the passenger compartment after a thermal runaway is initiated
in a cell of the REESS would be unduly design restrictive, not
applicable to all vehicle/REESS types, and not relevant to real world
incidents.\86\
---------------------------------------------------------------------------
\86\ In most real-world incidents resulting in fire due to
thermal runaway of a single cell in the REESS, the vehicle was
parked, with propulsion system turned off, and with no occupants in
the vehicle. In some cases, the vehicles were parked in garages of
homes. Therefore, a requirement for a warning to vehicle occupants
in the vehicle with propulsion system turned on would not have
helped prevent the fire or mitigated hazards to people in homes or
in the vicinity of the burning parked vehicle.
---------------------------------------------------------------------------
This NPRM proposes a documentation requirement for FMVSS No. 305a
to require manufacturers to provide to NHTSA, upon NHTSA's request,
information about their efforts to identify and address potential
safety problems with SCTR and propagation due to an internal short-
circuit. The information would be provided by a manufacturer in
accordance with NHTSA's specified structure in four parts. NHTSA's
proposed documentation component structure is based on elements from
the GTR No. 20, ISO-6469-1: Amendment 1 2022-11,\87\ and ISO-26262.\88\
The documentation submitted by the manufacturer is required to include
all known risks to vehicle occupants and bystanders, risk assessment,
risk management, and risk mitigation strategies in three vehicle
operational modes (i.e., external charging mode,\89\ active driving
possible mode,\90\ and parking mode \91\). NHTSA's proposal goes beyond
GTR No. 20's active driving possible mode to ensure manufacturers
consider all risks known to it in three vehicle operational modes. The
assessment and validation of these strategies may involve a combination
of physical testing and simulations at the component level and/or full
vehicle level. The reporting requirements would apply to REESSs of all
types (including REESS with non-flammable electrolyte).
---------------------------------------------------------------------------
\87\ ISO 6469-1:Third Edition 2019-04 Amendment 1 2022-11,
``Electrically propelled road vehicles--Safety specifications--Part
1: Rechargeable energy storage system (RESS),'' specifies safety
requirements for REESS, including test methodology for initiating
thermal runaway in a cell for the purpose of conducting a thermal
runaway propagation test and a format for reporting on risk
mitigation strategies of thermal propagation resulting from a
thermal runaway in a single cell of an REESS due to an internal
short within the cell.
\88\ ISO 26262: 2018, ``Road vehicles--Functional safety,''
provides a comprehensive collection of standards to manage and
implement road vehicle functional safety from concept phase to
production and operation. The standard provides guidelines for
overall risk management, individual component development,
production, operation, and service.
\89\ External charging mode is the vehicle operational mode in
which the charge connector is connected to the vehicle charge inlet
for the purpose of charging the REESS.
\90\ Active driving possible mode is the vehicle mode when
application of pressure to the accelerator pedal (or activation of
an equivalent control) or release of the brake system causes the
electric powertrain to move the vehicle.
\91\ Parking mode is the vehicle mode in which the vehicle power
is turned off, the vehicle propulsion system and ancillary equipment
such as the radio are not operational, and the vehicle is
stationary.
---------------------------------------------------------------------------
The objective of the documentation is for vehicle manufacturers to
identify the risks of single-cell thermal runaway and propagation for
their REESS type, identify strategies to mitigate those risks, and
demonstrate how those strategies work. The documentation would
accomplish the following goals:
It would identify all risks known to the manufacturer
related to single-cell thermal runaway and propagation due to an
internal short-circuit;
It would discuss whether and how each identified risk is
managed and/or mitigated by at least one risk mitigation strategy;
It would explain the reasons the manufacturer believes
each risk mitigation strategy is effective (measures taken to verify
and/or validate them, including any final review/audit results); and,
It would identify, describe, and provide any review/audit
process and results that accompany the final assessment of risk
management and risk mitigation strategies.
Proposed provisions to achieve the above goals are discussed in
detail below.
The documentation requirement proposed by NHTSA is divided into
four sections with more detailed requirements than GTR No. 20. Under
the agency's requirements, in Part I, System Analysis, the vehicle
manufacturer would provide information describing which conditions
specific to the vehicle could lead to a SCTR event caused by an
internal short-circuit. The conditions identified serve as the inputs
to identify the functions and failure modes for the risk identification
in Part II.
Part I would require the following documentation:
A system diagram and a description of all relevant
physical systems and components of the REESS, including information
about the cell type and electrical configuration, cell chemistry,
electrical capacity, voltage, current limits during charging and
discharging, thermal limits of the components that are critical for
thermal propagation safety;
A system diagram, operational description of sensors,
components, functional units relevant to single-cell thermal runaway
due to internal short-circuit and thermal propagation, and the
interrelationship between the identified sensors, components, and
functional units;
A description of conditions under which a single-cell
thermal runaway and propagation event due to an internal short-circuit
could occur;
A description of how the identified conditions are
allocated to each identified component, functional unit, and subsystem;
A description of the process used to review the identified
conditions and their allocation to the identified sensors, components,
and functional units, for completeness and validity; and
A description of any system for warning or notification
prior to the occurrence of thermal runaway in a cell, including a
description of the detection technology and mitigation strategies, if
any.
Part II, Safety Risk Assessment and Mitigation Process, provides a
description of all identified safety risks and strategies to mitigate
and manage
[[Page 26722]]
these risks. Part II distinguishes between primary and secondary risk
mitigation strategies. Primary risk mitigation strategies mitigate the
risk of SCTR due to an internal short-circuit and the occurrence of
thermal propagation that may result from SCTR. Primary risk mitigation
strategies include manufacturing quality control to mitigate defects in
cells of REESS, REESS design features such as heat sinks, cell spacing,
coolant, advanced battery management system with prognostics and
diagnostics systems \92\ to manage the health of the cells of an REESS
and detect a possible thermal runaway condition before it occurs. In
contrast, secondary risk mitigation strategies may not reduce the risk
of thermal runaway or thermal propagation but reduce the hazards
associated with thermal propagation. Secondary risk mitigation
strategies include warning systems to vehicle occupants/bystanders and/
or notification to emergency personnel in the event of thermal
propagation (e.g., automatic notification to 911 operators). NHTSA
anticipates that secondary risk mitigation strategies would be employed
as an addition to primary risk mitigation strategies in the overall
safety strategy.
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\92\ Prognostic technologies predict the health of a system or a
component of a system in the future and diagnostic technologies
determine a specific problem with a system or component of a system.
---------------------------------------------------------------------------
Part II would require the following documentation:
A description of safety risks and safety risk mitigation
strategies, and how these were identified (e.g., Failure Mode and
Effects Analysis (FMEA), or Failure Modes, Effects, and Criticality
Analysis (FMECA)); \93\
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\93\ FMEA and FMECA are established methodologies to identify
failure modes and postulate the effects of those failures on the
system. Refer to https://www.dau.edu/acquipedia-article/failure-modes-effects-analysis-fmea-and-failure-modes-effects-criticality.
---------------------------------------------------------------------------
A description of how each risk mitigation manages/
mitigates the identified safety risks.
In Part III, Verification and Validation of Effective Risk
Mitigation Strategies, the manufacturer provides information showing
how they verify the effectiveness of the identified mitigation
strategies in Part II to mitigate the identified safety risks. The
vehicle level assessment examines how the entire vehicle monitors and
mitigates safety risks. The vehicle level assessment is the culmination
of the verification/validation results of each individual risk
mitigation strategy.
Part III would require the following documentation:
A summary of the process used to verify each identified
risk is addressed by at least one risk mitigation strategy;
A description of how each risk mitigation strategy was
verified and validated for effectiveness; \94\
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\94\ Possible verification/validation methods for Part III
include (but are not limited to) fault injection tests, software,
and hardware performance tests at component and/or system level, and
system level performance evaluation using validated mathematical
models.
---------------------------------------------------------------------------
A description of the verification and validation results
for each risk mitigation strategy; and
A vehicle level assessment evaluating the system response
to safety risks associated with the REESS. Vehicle level assessment and
validation could be the use of physical tests and/or validated models/
simulations at a component level scaled up to evaluate the system
response.
Part IV, Overall Evaluation of Risk Mitigation, shall address:
Results of any final review/audit responsible for
reviewing the technical content, completeness, and verity of the
documentation submitted by the manufacturer.
The risk-based methodology outlined above is intended to mitigate
the safety hazards associated with SCTR and propagation from an
internal short-circuit. The requirement is intended to ensure that
manufacturers are aware of the safety risks at issue and have
considered safety risk mitigation strategies. The documentation
submitted by the manufacturer will inform NHTSA of the safety risk
mitigation strategies manufacturers have utilized for the identified
safety hazards, enable NHTSA to oversee those safety hazards, and
inform future regulatory measures.. This approach is battery technology
neutral, not design restricted, and is intended to adapt over time as
battery technologies continue to rapidly evolve. NHTSA seeks comment on
the documentation requirements described above. In section VI., NHTSA
requests comments on whether the proposed document requirement would be
better placed in a general agency regulation than in proposed FMVSS No.
305a.
NHTSA's Decision Not To Propose a Warning Requirement
GTR No.20's warning requirement rationale is that the warning would
allow vehicle occupants sufficient time to egress the vehicle before
hazardous conditions are present in the occupant compartment. NHTSA
does not agree with GTR No.20's rationale for a warning requirement
related to SCTR due to an internal short-circuit within the cell. NHTSA
is not proposing to require such a warning system, or documentation of
the warning system, as specified in GTR No. 20 because such a
requirement would not mitigate the safety hazards observed in the
field, as described in detail below.
Field data and incidents related to SCTR and propagation due to an
internal short-circuit in lithium-ion REESSs are sparse and anecdotal.
However, when reviewing the limited number of non-crash and non-abuse
related electric vehicle fire incidents in the United States,\95\ the
following trends emerge:
---------------------------------------------------------------------------
\95\ E.g., Bolt EV Recall Information https://experience.gm.com/recalls/bolt-ev.
---------------------------------------------------------------------------
The vehicle operation mode is in the usual parking
mode.\96\
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\96\ Usual parking mode is the vehicle operational mode in which
the main software is ``Off'', the gear selector is in ``P'' (park),
the energy supply is disconnected, the REESS power line is
disconnected, the cooling system is not operational, the vehicle
controls that manage safe operation of the REESS (e.g., Battery
Manage System) are not energized, and the vehicle occupants are
typically not present.
---------------------------------------------------------------------------
The vehicle is parked in a garage attached to a house, a
parking garage, or on the street.
The state of charge (SOC) of the REESS was generally in
the upper range.
Fire statistics reports by South Korea identified 35 electric
vehicle fires since 2018, among which 20 electric vehicle fires
originated in the REESS of the vehicles when the vehicle was parked and
the SOC was greater than 90 percent.\97\ In the electric vehicle fire
incidents in the United States and South Korea, the vehicle fire
propagated to adjacent vehicles and structures with release of copious
amounts of smoke, resulting in significant property damage. The GTR No.
20 requirement for a warning to the driver would not have helped
mitigate the electric vehicle fires and would not have mitigated
property damage.
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\97\ EVS23-E1TP-0200 [KR] EV Fire Records of Korea.pptx. https://wiki.unece.org/display/trans/EVS+23rd+session.
---------------------------------------------------------------------------
Accordingly, this NPRM does not propose to require a warning to
occupants or documentation pertaining to a warning, as such
requirements would not sufficiently address a safety need. NHTSA
believes the documentation requirements in GTR No. 20 for a warning to
the driver are not relevant to the field-observed electric vehicle
fires likely resulting from SCTR. NHTSA believes that vehicle designs
using a risk mitigation strategy to mitigate or prevent the occurrence
of SCTR incidents would better address the risks and hazards associated
with spontaneous electric
[[Page 26723]]
vehicle fires that originate within the REESS than a warning to egress
the vehicle. This NPRM proceeds with NHTSA's preferred approach which
would require documentation demonstrating that the manufacturer has
considered and developed risk mitigation strategies to address SCTR in
developing their electric vehicles.
GTR No. 20 Phase 2 Test Procedure Currently Under Consideration
The IWG is continuing work on developing a test-based approach for
SCTR due to an internal short-circuit in a single cell within the
REESS. The plan is for a future regulation to require that the thermal
propagation test procedure fulfill the following conditions:
1. Triggering of thermal runaway at a single-cell level must be
repeatable, reproducible, and practicable,
2. Judgment of thermal runaway through common sensors, e.g.,
voltage and temperature, needs to be practical, repeatable, and
reproducible, and
3. Judgment of whether consequent thermal events involve severe
thermal propagation hazards, needs to be unequivocal and evidence
based.
NHTSA discusses this work in the Appendix B to this preamble.
Comments are requested that could assist the agency in future decisions
on this matter.
3. Warning Requirements for REESS Operations
As part of a risk-mitigation approach addressing multiple aspects
of electrical system safety, NHTSA proposes requiring: (a) a thermal
event warning; and (b) a vehicle control malfunction warning for
drivers. The thermal event warning would be assessed by a performance
requirement, while the vehicle control malfunction warning would be a
documentation requirement.
i. Thermal Event Warning
A ``thermal event'' presents an urgent safety critical situation.
The term refers to a condition when the temperature within the REESS is
significantly higher (as defined by the manufacturer) than the maximum
operating temperature specified by the manufacturer. Thermal events
within REESS could occur due to moisture and dust accumulation within
the REESS that cause a short circuit at the connections or electronic
components within the REESS. A thermal event within a battery pack can
be a safety critical event, as it can lead to smoke, fire, and/or
explosion. A warning provided about a thermal event within the REESS
would reduce the likelihood of occupant exposure to smoke, fire, and/or
explosion.
GTR No. 20 requires the vehicle to provide a warning to the driver
in the case of a ``significant thermal event'' in the REESS (as
specified by the manufacturer) when the vehicle is in active driving
possible mode.\98\ The GTR does not contain a performance test for the
warning but instead requires manufacturers to provide documentation on
the parameters that trigger the warning and a description of the system
for triggering the warning. Specifically, the documentation
requirements include:
---------------------------------------------------------------------------
\98\ Active driving possible mode means the vehicle mode when
application of pressure to the accelerator pedal (or activation of
an equivalent control) or release of the brake system causes the
electric power train to move the vehicle.
---------------------------------------------------------------------------
(1) Parameters and associated threshold levels that are used to
indicate a thermal event (e.g., temperature, temperature rise rate, SOC
level, voltage drop, electrical current, etc.) to trigger the warning.
(2) A system diagram and written explanation describing the sensors
and operation of the vehicle controls which manage the REESS in the
event of a thermal event.
NHTSA Proposal
NHTSA proposes to include a requirement for an audio and visual
warning to the driver if a thermal event occurs in the REESS during the
active driving possible mode. Instead of a documentation requirement as
in the current GTR No. 20, NHTSA proposes a performance test to
evaluate the required warning of a thermal event originating within the
REESS.
NHTSA proposes to initiate the thermal event in the REESS by
inserting a heater within the REESS that achieves a peak temperature of
600[deg]C within 30 seconds. In the proposed test procedure, the REESS
is removed from the vehicle, if possible, and the REESS casing is
opened to attach the heater to a cell or cells in the REESS in a manner
to put at least one cell in the REESS into thermal runaway. In this
test, there is no need to restrict heating to a single cell within the
REESS as the test is verifying activation of a warning when a thermal
event occurs in the REESS regardless of the cause (e.g., an electric
short between electronic components in the REESS, thermal runaway of
multiple cells, etc.). Following installation of the heater in the
REESS, the REESS casing is closed, the REESS is re-installed in the
vehicle, and the vehicle propulsion system is turned on. The heater
within the REESS is then activated. NHTSA proposes that the audio-
visual warning must be activated within three minutes \99\ of
initiating the heater in the REESS. NHTSA has tentatively decided not
to specify characteristics of the audio-visual warning to provide
flexibility in how manufacturers communicate this safety critical
information to vehicle occupants so they quickly egress the vehicle.
---------------------------------------------------------------------------
\99\ 3 to 5 minutes is considered to be sufficient time for able
body individuals to evacuate light and heavy passenger vehicles
before the occurrence of a hazardous event. https://one.nhtsa.gov/reports/0900006480b01bbc.pdf.
---------------------------------------------------------------------------
The proposed test is for evaluating appropriate activation of a
required warning system when there is a thermal event in the REESS that
could be hazardous to vehicle occupants.\100\ NHTSA tentatively
concludes that the proposed performance test to evaluate the warning
system would not be design restrictive and can be conducted on all
applicable vehicles. Therefore, a performance test is proposed instead
of adopting the documentation requirement in GTR No. 20. NHTSA seeks
comment on the merits of the proposed performance test to evaluate the
thermal event warning system instead of the documentation requirement
in GTR No. 20. In addition, NHTSA seeks input on the type of heater,
the heater characteristics (power, peak temperature) and possible
locations of the heater within the REESS to simulate a thermal event to
trigger the warning. While this NPRM does not require specific features
of the audio-visual warning itself, comments are requested on what
characteristics an effective audio-visual warning should have.
---------------------------------------------------------------------------
\100\ This is unlike the risk management approach for SCTR where
the goal is to mitigate hazards of thermal propagation (fire, smoke,
gas emissions). Because risk management strategies for mitigating
thermal propagation hazards due to SCTR differ considerably in
vehicle designs, an objective performance test that can be conducted
on all applicable vehicles is not available and so a documentation
requirement is proposed.
---------------------------------------------------------------------------
ii. Warning in the Event of Operational Failure of REESS Vehicle
Controls
NHTSA is proposing to require that drivers be warned if there is a
malfunction of vehicle controls that manage the safe operation of the
REESS. This NPRM proposes a documentation approach for this type of
warning, similar to GTR No. 20.
GTR No. 20 specifies that when the vehicle is in the active driving
possible mode, the vehicle shall provide a warning telltale to the
driver in the event of a malfunction of the vehicle controls that
manage the safe operation of the REESS. GTR No. 20 requires
manufacturers to provide
[[Page 26724]]
documentation demonstrating that a warning to the driver will be
provided in the event of malfunction of one or more aspects of vehicle
controls that manage REESS safe operation. Specifically, vehicle
manufacturers shall make the following documentation available to the
testing authority:
(1) A system diagram that identifies all the vehicle controls that
manage REESS operation. The diagram must identify what components are
used to generate a warning telltale indicating malfunction of vehicle
controls to conduct one or more basic operations.
(2) A written explanation describing the basic operation of the
vehicle controls that manage REESS operation. The explanation must
identify the components of the vehicle control system, provide
description of their functions and capability to manage the REESS, and
provide a logic diagram and description of conditions that would lead
to triggering the warning telltale.
NHTSA Proposal
Vehicle controls manage several REESS operations, some of which are
safety critical. There are multiple external fault scenarios \101\ that
could trigger a vehicle control to take corrective actions to ensure
safe REESS operations. This NPRM includes performance requirements to
address these external fault scenarios that assume proper functioning
of the vehicle controls that manage safe REESS operations. However, if
the vehicle controls that manage safe REESS operation are not
functioning properly, the REESS may not be adequately protected from
fault scenarios, which could lead to REESS degradation and eventually
result in thermal propagation and other safety hazards. Therefore, it
is important to notify the driver or front row occupants in the event
there is malfunction of these vehicle controls that manage safe REESS
operations.
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\101\ These fault scenarios include overcharge, over-discharge,
overcurrent, external short-circuit, and overheating of the REESS.
---------------------------------------------------------------------------
Due to the complexity and varied designs of vehicle controls that
manage REESS safe operation, no single test procedure could be
developed that would fully evaluate whether a warning turns on in the
event of operational failure of vehicle controls. Therefore, in
accordance with GTR No. 20, this NPRM proposes to require manufacturers
to provide a visual warning to the driver (e.g., like a check engine
light) and documentation demonstrating that the visual warning will be
provided in the event of operational failure of one or more aspects of
vehicle controls that manage REESS safe operation.
NHTSA proposes the GTR No. 20 requirements for a visual warning to
the driver of any malfunction of the REESS vehicle controls, and
manufacturer documentation. In addition, NHTSA proposes to include two
additional requirements that ensure manufacturers have validated
functionality of the warning system:
(1) Any validation test results by the vehicle manufacturer to
confirm a visual warning is displayed in the presence of malfunction of
the REESS operation vehicle controls.
(2) A description of the final manufacturer review or audit process
and results of any final review or audit evaluating the technical
content and the completeness and verity of the documentation submitted
by the manufacturer.
NHTSA tentatively concludes that a documentation approach is
merited to demonstrate that the manufacturer has considered the
effectiveness of a visual warning of the malfunction of the REESS
operational vehicle controls. In the absence of information enabling
NHTSA to propose a practical test procedure to evaluate the performance
of a warning, the documentation approach ensures that manufacturers are
aware of the safety risks at issue and have considered ways to address
the risks. NHTSA would review the documentation to understand the
visual warning associated with the particular REESS in the vehicle, see
whether the manufacturer conducted an assessment of its effectiveness,
and understand the measures the manufacturer undertook to validate such
performance.
This approach is an interim measure intended to assure that
manufacturers will identify, address, and validate the effectiveness of
their visual warnings that help manage safe REESS operation. The
approach is intended to evolve over time as battery technologies and
NHTSA's information about the REESS safety risk mitigation strategies
evolve. In section VI., NHTSA requests comments on whether the proposed
document requirement would be better placed in a general agency
regulation than in proposed FMVSS No. 305a.
4. Protection Against Water Exposure
NHTSA proposes to adopt GTR No. 20's physical water test
requirement, where a vehicle shall maintain electrical isolation
resistance after the vehicle is exposed to water under normal vehicle
operation, such as in a car wash or while driving through a pool of
standing water. However, the agency is not proposing to adopt GTR No.
20's two other water exposure methods: documentation measures and
warning requirements.
Environmental effects such as exposure to water and moisture may
deteriorate the electrical isolation of high voltage components in the
powertrain. This may first lead to an electric system degradation and
eventually lead to an unsafe electrical system for vehicle occupants,
operators (during charging) or by-standers. Under extreme conditions,
fire can originate from compromised electrical components due to water
ingress. GTR No. 20 contains water exposure shock protection
specifications in which a vehicle shall maintain electrical isolation
resistance after the vehicle is exposed to water under normal vehicle
operation, such as during a car wash or driving through a pool of
standing water.
NHTSA begins by noting that GTR No. 20 does not have specific
requirements to address vehicle fires due to vehicle submersion such as
floods and storm surges, and this NPRM is not covering that area.
Floods are considered as catastrophic events, and as noted above, one
of the principles for developing GTR No. 20 was to address unique
safety risks posed by electric vehicles and their components to ensure
a safety level equivalent to conventional vehicles with internal
combustion engine (ICE). NHTSA continues to research the area of REESS
performance post-submersions. This issue is discussed in more detail
later in this section.
GTR No. 20 Requirements
GTR No. 20 contains water exposure shock protection specifications
in which a vehicle shall maintain electrical isolation resistance after
the vehicle is exposed to water under normal vehicle operation. GTR No.
20 specifies three compliance options contracting parties may use in
their regulations:
Physical tests--(1) the vehicle is subjected to normal
washing using a hose nozzle and conditions in accordance with IPX5,
after which (2) the vehicle is driven in a freshwater wade pool (10 cm
depth) over a total distance of 500 m at a speed of 20 km/hr for
approximately 1.5 minutes (min). The electrical isolation of high
voltage sources in the electric powertrain are verified at the
conclusion of each test and once again after 24 hours.
Documentation--The vehicle manufacturers provide
documentation
[[Page 26725]]
certifying to IPX5 \102\ level waterproofing for protection of high
voltage components in the vehicle. IPX5 is a waterproof rating that
ensures protection against water ingress under sustained low pressure
water jet stream (12.5 liters per minute at a pressure of 30
kilopascals (4.4 psi) from a distance of 3 meters) from any angle. The
duration of the jet stream exposure is 1 minute per square meter
surface area of the high voltage component.
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\102\ IEC 60529:1989/AMD2:2013, ``Degrees of protection provided
by enclosures (IP Code).'' https://webstore.iec.ch/publication/2446.
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Warning--The vehicle has an electrical isolation loss
warning system that warns the driver when electrical isolation falls
below 100 ohms per volt for DC electrical components or 500 ohms per
volt for AC electrical components. This option is available for
individual countries to adopt if they so choose.
i. NHTSA Proposal
NHTSA tentatively concludes that the GTR No. 20's physical test
option is a practical and feasible means of evaluating the effects of
water exposure under normal vehicle operating conditions. It has
advantages of a performance standard in assessing compliance over a
documentation approach. Thus, the agency is not proposing the
compliance option in GTR No. 20 of providing documentation on high
voltage components meeting IPX5 level of protection.
Regarding the electrical isolation loss warning system option in
GTR No. 20, NHTSA believes the warning signals alone are not sufficient
for addressing loss of electrical isolation concerns. Where objective
performance criteria are available and are appropriate for all types of
vehicles to which the standard applies, NHTSA believes objective
performance criteria should govern when compared to the approach of
solely using a warning. The existence of the visual warning cannot
necessarily be considered a safety prevention system, as the root cause
of the safety hazard remains unaddressed, and the visual warning may be
ignored by the driver. Although visual warning indicators triggered
from an isolation monitoring system could help mitigate safety
concerns, NHTSA believes that this approach is not sufficient to solely
mitigate a shock or fire hazard caused by the effects of water
exposure. Thus, the agency does not propose this alternative as a
compliance option in FMVSS No. 305a.
NHTSA Proposed Vehicle-Level Physical Test Procedures
The proposed physical test procedure is comprised of two series of
tests, informally referred to as the ``vehicle washing'' test and the
``driving through standing water'' test. Electrical isolation is
determined at the conclusion of each test, and once again after 24
hours.
A. Vehicle Washing Test
The washing test exposes the vehicle to a stream of water such as
when washing a car. The vehicle external surface, including the vehicle
sides, front, rear, top, and bottom is exposed to the water stream. GTR
No. 20 excludes the vehicle underbody from exposure to the water
stream. However, since the vehicle underbody is often exposed to water
when the vehicle is washed, NHTSA proposes to also expose the vehicle
underbody to the water stream to make this test more representative of
vehicle washing. The areas of the vehicle that are exposed to the water
stream in any possible direction include border lines, i.e., a seal of
two parts such as flaps, glass seals, outline of opening parts
(windows, doors, vehicle inlet cover), outline of front grille and
seals of lamps.
During the test, the vehicle is sprayed from any practicable
directions with a stream of freshwater from a standard test nozzle as
shown in Figure 4 below. The standard nozzle, with an internal diameter
is 6.3 mm, shall provide a delivery rate of 11.9-13.2 liters/minute (l/
min) with water pressure at the nozzle of 30-35 kilopascals (kPa) or
0.30-0.35 bar. These standard nozzle specifications are from IEC 60529
for IPX5 water jet nozzle.
[GRAPHIC] [TIFF OMITTED] TP15AP24.047
Figure 4--Standard Nozzle (IEC 60529) for IPX5 Water Exposure Test
The vehicle surface is exposed to the water stream from the
standard nozzle for a duration of 1 minute per square meter or for 3
minutes, whichever is greater. The distance from the nozzle to the
tested vehicle is 3 meters, which may be reduced, if necessary, to
ensure the surface is wet when spraying upwards.
After the ``vehicle washing'' test and with the vehicle surface
still wet, electrical isolation is determined for high voltage sources
in the same manner as that currently in S7.6 of FMVSS No. 305. The high
voltage sources are required to meet the electrical isolation
requirements as specified in S5.4.3 of current FMVSS No. 305.
Comments are requested on the merits of including the test in FMVSS
No. 305a. NHTSA seeks comment on the representativeness of the washing
test, including but not limited to the proposed test conditions (e.g.,
30-35
[[Page 26726]]
kPa versus 80-100 kPa water pressure conditions, water salinity levels,
and water exposure durations, etc.).
B. Driving Through Standing Water Test
NHTSA proposes that vehicles should also be subjected to GTR No.
20's ``driving through standing water'' test. The vehicle is driven
through a pool of standing freshwater,\103\ 10 centimeters (cm) (4
inches) deep, for a total range of 500 meters (m), at a vehicle speed
of 20 km/hr.\104\ The pool represents a low-lying portion of a road
that can get flooded in excessive rain. Meeting the test is a
reasonable indication that the vehicle has safeguards to ensure
electrical safety when driven through roads in inclement weather.
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\103\ Freshwater means water containing less than 1,000
milligrams per liter of dissolved solids, most often salt.
\104\ NHTSA tentatively concludes that the 10 cm (approximately
four-inch) depth is reasonable, as national weather advisories
(https://www.weather.gov/tsa/hydro_tadd) recommend not driving on
flooded roads with more than four inches of water. Six inches of
water on the road could reach the bottom of most passenger cars
causing loss of control and possible stalling. A foot of water can
float many vehicles.
---------------------------------------------------------------------------
If the wade pool used is less than 500 m in length, then the
vehicle is driven through the wade pool several times. The total time,
including the periods outside the wade pool, would have to be less than
5 minutes. GTR No. 20 specifies a maximum test time of 10 minutes, but
NHTSA believes that 5 minutes is preferable. Traversing 500 m at 20 km/
hr takes 90 seconds. A maximum test duration of 10 minutes would allow
for an excessive amount of time out of the water and may not be
equivalent to a continuous 500 m exposure. NHTSA seeks comment on the
maximum duration of this test. NHTSA also seeks comment on the
availability and geometric dimensions of different types of wade pools
(long rectangular, circular) to accomplish this type of test.
Just after the standing water test is completed and with the
vehicle still wet, the vehicle would be required to meet the electrical
isolation requirements now specified in FMVSS No. 305 S5.4.3 when
tested in the same manner as described in S7.6 of current FMVSS No.
305. The vehicle is also required to meet the electrical isolation
requirements that are in S5.4.3 of current FMVSS No. 305, 24 hours
after the washing test and the standing water test are completed.
NHTSA seeks comment on the water salinity requirements for the
physical tests as described above, including tolerances for the test
parameters listed above.
ii. NHTSA's Consideration of Submersions
In the U.S., floods resulting from Hurricane Sandy (2012),
Hurricane Harvey (2017) and Hurricane Ian (2022) have led to electric
vehicles submerged in flood waters for varying periods of time, with
varying reports of vehicle fires in the aftermath. In developing this
NPRM, the agency considered whether it could propose requirements to
address these types of vehicle submersions and the resulting risk of
fire. NHTSA analyzed field data from these hurricanes and made the
following key observations of vehicle fires resulting from the vehicle
submersions:
(1) Not all electric vehicles submerged in floods catch on fire.
The type of water (water salinity), the level of submersion, and
duration of submersion are likely factors;
(2) Fire and other hazards are more likely after water exposure
(days after flood waters recede) rather than during the exposure;
(3) Fire may not originate in the REESS and may spread to the REESS
from another vehicle component; and
(4) While 12V systems may also short circuit and result in vehicle
fire, fires involving lithium-ion REESS are more difficult to
extinguish and more hazardous because of the self-oxygenating nature of
the lithium-ion cells and the energy density of the REESS.
NHTSA evaluated the regulatory approaches taken by other countries
to determine if such standards could assist NHTSA in addressing the
challenges posed by the submersions and fires resulting from Hurricanes
Sandy, Harvey, and Ian. NHTSA analyzed China and Korea's water exposure
requirements but determined the focus of those standards do not appear
to address the safety matter at issue. Key observations and findings
from the field data in the U.S. and the exploratory investigation into
the water exposure posed by the hurricanes suggest that the test
procedure and parameters and the performance requirements in China GB-
38031 \105\ and the Korean Motor Vehicle Safety Standard (KMVSS) \106\
may not be representative of field events of vehicle fires resulting
from Hurricanes Sandy, Harvey, and Ian water exposure. If the standards
are not representative of the harm NHTSA wishes to address from the
hurricanes, the concern is the countermeasures to meet the performance
test requirements of GB-38031 and KMVSS may not be effective at
mitigating thermal events resulting from the water exposure at
issue.\107\
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\105\ GB-38031 water immersion test contains two options. Option
1 is based on ISO-6469-1:2019 where the REESS is submerged in 1
meter of seawater (salinity of 3.5 percent) for two hours. The
performance requirement for this test option is for no fire or
explosion of the REESS during the submersion. Option 2 is based on
ISO-20653, and requires IPX7 level waterproofing. In this test
option, the REESS is completely submerged in regular water for 30
minutes such that the lower point of the battery is one meter below
the surface or the highest point is 150 mm below the surface (for
battery packs with a height greater than 850 mm). The performance
requirement in this test option is for no water ingress, fire, or
explosion, and the REESS maintains an electrical isolation of 100
ohms per volt after submersion. Option 1 of GB-38031 is intended for
most current REESS (open-type or partially sealed) while Option 2
would necessitate a fully sealed REESS.
\106\ KMVSS contains requirements for REESS, including a water
immersion test that has been implemented in South Korea since 2009.
In the water immersion test, the REESS is fully submerged in
seawater (salinity of 3.5 percent) for one hour. The performance
requirement in this test is for the REESS to not explode or catch on
fire during the immersion. EVS19-E4WI-0300 [KR] Water Immersion
Test.pptx. https://wiki.unece.org/display/trans/EVS+19th+session.
\107\ For instance, NHTSA's understanding is that most of the
vehicles involved in Hurricane Ian's post-submersion fires had met
China GB-38031.
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Specifically, in both standards, the REESS is submerged in 3.5
percent salinity water representing seawater for a long period of time
(two hours for GB-38031 and one hour for KMVSS). NHTSA's exploratory
investigation of current REESS designs \108\ suggests submersion in
lower salinity water for a shorter duration may result in higher risk
of thermal event. Longer immersion times in seawater salinity levels
allow the batteries to safely discharge under water without adverse
reactions such as arcing, venting, or underwater fires. Additionally,
the requirements for no fire and explosion in these two standards are
evaluated during the REESS immersion and not after the REESS is pulled
out of the water. Such a requirement is not relevant to the electric
vehicle fires observed after the flood waters in Hurricane Sandy and
Hurricane Ian receded.
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\108\ Li-Ion Battery Pack Immersion Exploratory Investigation,
DOT HS 813 136, July 2021. https://rosap.ntl.bts.gov/view/dot/57013.
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NHTSA acknowledges that the batteries in conventional vehicles with
internal combustion engines (ICE) may also catch fire due to
submersion. However, the post-submersion vehicle fires after Hurricane
Ian demonstrated that electric vehicle fires are more difficult to put
out and therefore more hazardous than ICE vehicle fires. NHTSA believes
that a better understanding of the field incidences of electric vehicle
fires is needed before a field relevant test and performance
requirements can be developed that addresses the observed safety risks
[[Page 26727]]
associated with submersion of REESS and high voltage components in
events such as floods.
The agency seeks comment on test conditions and test procedures
that would address observed safety risks associated with submersion of
REESS and high voltage components.
Going Forward
Shortly after Hurricane Ian, NHTSA and other DOT agencies
coordinated with emergency personnel in Florida to collect in-depth
information on vehicle fire incidences and REESSs involved in the
flooding.\109\ This activity and others like it provided critical
information that informed approaches to better protect vehicle owners,
responders, and other stakeholders in the future.
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\109\ NHTSA has purchased ten electric vehicles damaged during
Hurricane Ian and plans to perform a teardown analysis to understand
the root cause of the vehicle fires. The teardown analysis will
inform the next steps to address the safety risks associated with
vehicle submersions.
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In the near term, as discussed in sections below, this NPRM
proposes to require that electric vehicle manufacturers submit
standardized emergency response information to a NHTSA central
depository, to assist first and second responders to respond to
emergencies as quickly and safely as possible. The agency tentatively
concludes that such a requirement would be an important and achievable
near-term measure that NHTSA and the industry can take to mitigate the
harm from these fires as work continues on vehicle-based mitigation
methods. As part of NHTSA's activity going forward, NHTSA will document
EV battery conditions after catastrophic flooding events and will
commence new research into mitigation methods. The agency will obtain
data to develop and improve EV tests relevant to salt-water immersion.
5. Miscellaneous GTR No. 20 Provisions Not Proposed
There are several GTR No. 20 provisions for REESS performance
during normal vehicle operations that NHTSA has not included in this
NPRM. These provisions relate to requirements for: vibration, thermal
shock and cycling, fire resistance, and low state-of-charge (SOC).
Below is a description of the requirements and explanations of why
NHTSA is proposing not to include the requirements. NHTSA requests
comments on these views.
i. REESS Vibration Requirements
GTR No. 20 contains a vibration requirement and test procedure to
verify the safety performance of the REESS under a prescribed
sinusoidal vibration environment that applies a generic vibration
profile to the tested vehicle. NHTSA believes the vibration profile
accelerations and frequencies are unique for each vehicle model and so
applying a generic vibration profile to all vehicle models may not be
appropriate. Additionally, the vibration environment in the test
specified in GTR No. 20 is applied only in the vertical direction while
in real world driving conditions, the REESS is subject to vibration
along all three orthogonal axes. Therefore, the agency tentatively
concludes that the vibration test in GTR No. 20 is not representative
of the actual vibration environment for different vehicle models, or
representative of real-world conditions that the REESS experiences.
Furthermore, vibration appears sufficiently addressed through other
means. The market addresses this matter, as manufacturers routinely
perform vibration testing to ensure customer satisfaction and
reliability. Vehicle manufacturers assess the durability of the vehicle
and its components (not just the REESS) through various road conditions
with full vehicle simulation, either by driving on a rough road test
track or simulating the lifetime fatigue on a vibration rig. Further,
at the component level, electric vehicle batteries are currently
subject to similar vibration test requirements for transportation under
the United States Hazardous Materials Regulations (HMR) \110\ but along
all three orthogonal axes and for frequencies up to 200 Hz.\111\ Thus,
NHTSA believes that the GTR No. 20 vibration test would not address an
additional safety need beyond what is already provided by HMR.
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\110\ 49 CFR parts 171 to 180, incorporated requirements for
lithium batteries from UN 38.3 ``Transport of dangerous goods:
manual tests and criteria.''
\111\ 49 CFR 173.185 incorporated the vibration test 38.3.4.3
from the UN's ``Recommendations on the Transport of Dangerous Goods,
Manual of Tests and Criteria,'' https://digitallibrary.un.org/record/483552?ln=en.
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For the reasons stated in the paragraph above, NHTSA is not
proposing the vibration test at a component level or the vehicle
level.\112\ Currently, during Phase 2 development of GTR No. 20, there
are discussions for updating the vibration test to include vibration in
all three orthogonal axes and at higher amplitudes and frequency range.
In Appendix B of this preamble, the agency seeks public comment on the
work in Phase 2 on the vibration test.
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\112\ NHTSA and Transport Canada discussed in detail their
positions for not including this vibration test during the
development of GTR No. 20. See https://wiki.unece.org/download/attachments/117508721/EVS21-E3VP-0101%5BOICA_UC_CA%5Dconsideration_of_vibration.pdf?api=v2.
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ii. REESS Thermal Shock and Cycling
GTR No. 20's thermal shock and cycling requirement and test
procedure aim to verify that the REESS is robust against thermal
fatigue and contact degradation caused by temperature changes and
potential incompatibilities of materials with varying thermal expansion
characteristics.
At the component level, REESSs are already subject to thermal
cycling test requirements for transportation under the HMR. 49 CFR
173.185 requires lithium-ion cells and batteries to comply with the
test requirements in UN 38.3, including Test T2: Thermal test, which is
the basis of the GTR No. 20 thermal shock and cycling test. In the
UN38.3 Test T2, the REESS would be subject to temperature changes from
-40 [deg]C to +75 [deg]C. This temperature range is greater than that
prescribed in GTR No. 20. To avoid redundancy, NHTSA is not proposing
the thermal shock and cycling test for the REESS. NHTSA tentatively
concludes that incorporating the GTR No. 20 thermal shock and cycling
test into FMVSS would not address additional safety needs beyond that
already provided by HMR and 49 CFR 173.185. The agency seeks public
comment on the safety need of a REESS thermal shock and cycling
requirement, and requests commenters provide data to substantiate their
comments and/or assertions.
iii. REESS Fire Resistance
This GTR No. 20 requirement is based on UN Regulation No. 34,
``Uniform provision concerning the approval of vehicles with regard to
the prevention of fire risks,'' \113\ which contains a fire resistance
requirement for liquid fueled vehicle with plastic tanks. This test is
required for REESSs installed in a vehicle at a height lower than 1.5 m
above the ground and contain flammable electrolyte. During the test,
the REESS is placed on a grating table positioned above the fire source
in a pan. The pan filled with fuel is placed under the REESS in such a
way that the distance between the level of the fuel in the pan and the
bottom of the REESS corresponds to the design height of the REESS above
the road surface at the unladed mass. The REESS is exposed directly to
the flame for 70 seconds. A screen made of refractory material is then
moved over the pan with the flame,
[[Page 26728]]
such that the REESS is indirectly exposed to the flame for an
additional 60 seconds. The screen and pan are then moved away from the
REESS. The REESS is observed until the surface temperature of the REESS
has decreased to the ambient temperature of the test environment.
During the test, the REESS shall exhibit no evidence of explosion.
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\113\ UN Regulation No. 34. https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2013/R034r2e.pdf.
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NHTSA tentatively concludes that the short duration of the GTR No.
20 fire resistance test would not address any safety risks associated
with explosion resulting from external fire to the battery pack.
Transport Canada conducted full vehicle gasoline pool fire tests of
electric powered vehicles and similar vehicles with internal combustion
engines and found that there was no explosion in tests of vehicles with
REESS and those without. The Transport Canada tests indicated that the
short duration of the GTR No. 20 external fire test would not result in
explosion.\114\ During Phase 1 of the GTR No. 20 discussions, the
United States and Canada noted that including the short duration
component level test in GTR No. 20 would not address a safety need and
recommended removing it from GTR No. 20.\115\ For these reasons, NHTSA
is tentatively not proposing the short duration fire resistance test
from GTR No. 20. The agency seeks comment on excluding this fire
resistance requirement from the FMVSS, and requests commenters provide
data to substantiate their comments and/or assertions.
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\114\ https://wiki.unece.org/download/attachments/29884786/EVSTF-07-02e.pdf?api=v2.
\115\ https://wiki.unece.org/download/attachments/29884786/EVSTF-07-02e.pdf?api=v2.
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iv. Low State-of-Charge (SOC) Telltale
GTR No. 20 requires a telltale to the driver in the event of low
REESS SOC.\116\ The agency is tentatively not including this telltale
requirement for electric powered vehicles because there is no
corresponding low fuel warning requirement for conventional vehicles
with internal combustion engines. Low-fuel telltales are presently
provided in all conventional vehicles due to consumer demand.
Similarly, all electric-powered vehicles already provide low SOC
telltales due to consumer demand. NHTSA seeks comment on whether this
GTR No. 20 requirement should be incorporated into proposed FMVSS No.
305a, and if yes, what the telltale should look like.
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\116\ The GTR does not standardize the appearance of the
telltale.
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IV. Request for Comment on Applying FMVSS No. 305a to Low-Speed
Vehicles
Current FMVSS No. 305 applies to electric vehicles whose speed,
attainable over a distance of 1.6 kilometers (km) (1 mile) on a paved
level surface, is more than 40 km/h (25 miles per hour (mph)). It does
not apply to vehicles that travel under 40 km/h (25 mph), such as low-
speed vehicles.\117\
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\117\ ``Low-speed vehicle'' is defined in 49 CFR 571.3. See also
FMVSS No. 500, ``Low speed vehicles,'' 49 CFR 500.
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There are low-speed vehicles that are also electric-powered
vehicles. NHTSA requests comments on applying aspects of FMVSS No. 305a
to low-speed vehicles to ensure a level of protection against shock and
fire, particularly during normal vehicle operation, and to assure the
safe operation of the REESS. The agency requests comment on the
possible applicability of FMVSS No. 305a to low-speed vehicles and its
relevant safety needs, including any supporting research on low-speed
vehicles.
V. Emergency Response Information To Assist First and Second Responders
Fires in electric vehicles are harder to extinguish than fires in
vehicles with internal combustion engines and can reignite. These risks
are also dependent on the specific vehicle design. Easy access to
pertinent vehicle specific and emergency response information is vital
for first and second responders when encountering electric vehicles.
Safety is impeded when first and secondary responders are on scene but
are delayed in their mitigation efforts because information on vehicle-
specific safety mitigation methods are not easily accessible.
a. NTSB Report
In 2020, NTSB published a safety report following a detailed
investigation of four electric vehicle fires.\118\ The investigation
identified safety risks to first and second responders \119\ from
exposure to high voltage components and from vehicle fire due to
damaged cells in the REESS that could reignite as a result of stranded
energy in the REESS.\120\ The NTSB investigation further identified the
lack of a clear and standardized format in vehicle manufacturers'
emergency response guides (ERGs) \121\ and inadequacy in the
information provided in the ERGs for first and second responders to
minimize safety risks posed by stranded energy in the REESS while
handling electric vehicles.
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\118\ Three of the vehicle fires occurred following severe
crashes that resulted in significant damage to the REESS casing. One
vehicle fire was caused by internal failure of the REESS during
normal driving operations. ``Safety risks to emergency responders
from lithium-ion battery fires in electric vehicles,'' Safety Report
NTSB/SR-20/01, PB2020-101011, National Transportation Safety Board,
https://www.ntsb.gov/safety/safety-studies/Documents/SR2001.pdf.
\119\ The NTSB report states, ``First responders in this context
refers to firefighters, but emergency medical technicians,
paramedics, and police officers are also classified as first
responders. Second responders in this context refers to tow truck
drivers or tow yard operators, but they can also include those
responsible for temporary traffic control or other support functions
at a crash site.''
\120\ Stranded energy is the energy remaining inside the REESS
after a crash or other incident. Cells in a compromised REESS could
undergo thermal runaway at a later time and reignite the vehicle
fire after firefighters extinguish the initial vehicle fire.
\121\ Emergency Response Guides (ERGs) contain in-depth vehicle-
specific information related to fire, submersion, leakage of fluids,
towing, and storage of vehicles. The information is presented in a
specific format with color-coded sections in a specific order to
help first and second responders quickly identify pertinent rescue
information. Rescue sheets contain abbreviated emergency response
information about a vehicle's construction. Rescue sheets are most
likely to be referenced first by emergency responders upon arrival
at the scene of a crash. ERGs contain more information than rescue
sheets.
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NTSB issued recommendations to vehicle manufacturers, first and
second responder organizations, and NHTSA. NTSB recommended
manufacturers of electric vehicles to model their emergency response
guides on International Standards Organization (ISO)-17840 \122\ and
SAE International recommended practice SAE J2990, ``Hybrid and EV first
and second responder recommended practice.'' \123\ It recommended
incorporating vehicle-specific information on (1) extinguishing REESS
fires, (2) mitigating risk of REESS reignition, (3) mitigating safety
risks (electric shock and fire) associated with stranded energy during
emergency response and transport of damaged vehicle, and (4) storing
damaged electric vehicles.
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\122\ ISO-17840, ``Road vehicles--Information for first and
second responders,'' consists of 4 parts: (1) Part 1 (2015): Rescue
sheet for passenger cars and light commercial vehicles, (2) Part 2
(2019): Rescue sheet for buses, coaches, and heavy commercial
vehicles, (3) Part 3 (2019): Emergency response guide template, and
(4) Part 4 (2018): Propulsion energy identification. https://webstore.ansi.org/standards/iso/iso178402015?gclid=Cj0KCQiAtbqdBhDvARIsAGYnXBMNT9mR9gjsrKxd5kK8dK6V21Ql9bDr8q2OI0fncMQHHpX_D8bQCxAaAhbUEALw_wcB.
\123\ SAE J2990 provides format and content recommendations for
emergency response guides and quick reference sheets in accordance
with ISO 17840. https://www.sae.org/standards/content/j2990/2_202011/.
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NTSB recommended to the vehicle manufacturers to follow the
practices for first and second emergency responders
[[Page 26729]]
available in SAE J2990 \124\ and ISO-17840. SAE J2990 mainly refers to
the ISO-17840 for the emergency response information. As indicated
earlier, ISO-17840 is comprised of four parts:
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\124\ SAE J2990 recommended practice provides common procedures
to help protect emergency responders and personnel supporting towing
and/or recovery, storage, repair, and salvage after an incident has
occurred with an electric powertrain vehicle.
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ISO 17840-1:2022(E) standardizes the content and layout of
rescue sheets for passenger cars and light commercial vehicles.
ISO 17840-2:2019(E) standardizes the rescue sheets for
buses, coaches, and heavy commercial vehicles.
ISO 17840-3:2019(E) establishes a template and defines the
general content for manufacturers' emergency response guides for all
vehicle types--longer documents that give in-depth ``necessary and
useful information'' about a vehicle for emergency incidents.
ISO 17840-4:2018 defines the labels and colors used to
indicate the fuel or energy used to propel a vehicle for both the
rescue sheets and the ERGs.
NTSB had two recommendations to NHTSA. The first recommendation was
to factor the availability of a manufacturer's ERG and its adherence to
ISO 17840 and J2990 when determining a vehicle's U.S. New Car
Assessment Program (NCAP) score.\125\ The second recommendation was to
convene a coalition of stakeholders to continue research and publish
the results on ways to mitigate or deenergize the stranded energy in
high-voltage lithium-ion batteries and to reduce the hazards associated
with thermal runaway resulting from high-speed, high-severity crashes.
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\125\ NHTSA's NCAP is a consumer information program that
evaluates the safety performance of vehicles and provides
comparative information on new vehicles. NCAP also provides
consumers with information on the availability of new vehicle safety
features. This information is provided to assist consumers with
vehicle purchasing decisions and to encourage safety improvements in
vehicle design.
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NHTSA responded to NTSB by a letter dated April 2, 2021. Among
other things, the letter said that NHTSA will be addressing risks to
emergency responders by working directly with the emergency response
community. The agency explained that NHTSA has partnered with the
National Fire Protection Association (NFPA) to support the development
of training to emergency responders on handling and managing fire
incidents involving alternative fuel vehicles, including electric
vehicles.\126\ This NPRM is one result from our partnering with NFPA to
provide emergency response guides to first and second responders.
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\126\ https://www.nhtsa.gov/sites/nhtsa.gov/files/2021-12/NHTSA-NTSB-Response-04-02-2021-Stranded-Energy-Lithium-Ion-Batteries-NCAP-Improvements-tag.pdf.
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NHTSA worked with other agencies and stakeholders and issued
interim guidance in support of the development of training for
emergency responders. In 2012 and 2014, NHTSA provided interim guidance
to law enforcement, emergency medical services personnel and fire
departments when encountering electric or hybrid-electric vehicles, to
reduce the risk of shock hazards and vehicle fires following vehicle
submersion.\127\ NHTSA also provided separate interim guidance for
towing and recovery operators and persons operating vehicle storage
facilities.\128\ NHTSA continues to lead an inter-agency \129\ effort
to develop updated guidance on best practices and strategies for
emergency personnel to contain electric vehicle-related hazards from
field events, such as electric vehicle fires resulting from storm
surges like those occurring during Hurricane Ian.
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\127\ Interim Guidance for Electric and Hybrid-Electric Vehicles
Equipped with High-Voltage Batteries (located at https://www.nhtsa.gov/sites/nhtsa.gov/files/811575-interimguidehev-hv-batt_lawenforce-ems-firedept-v2.pdf).
\128\ ``Interim Guidance for Electric and Hybrid-Electric
Vehicles Equipped with High-Voltage Batteries,'' located at 811576-
interimguidehev-hv-batt_towing-recovery-storage-v2.pdf (nhtsa.gov).
\129\ U.S. Department of Energy, the United States Fire
Administration, and the National Fire Protection Association.
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b. NHTSA Proposal
The Information Must Be Provided
Current emergency response information is voluntarily filed on an
NFPA website.\130\ Rather than factoring the availability of ERGs as
part of NCAP, NHTSA tentatively believes it would be more effective to
address risks to emergency responders by directly requiring the
standardized information. The information would be available and
understandable to first and second responders so they can refer quickly
and easily to identify pertinent vehicle-specific rescue information at
the scene of the crash or fire event, and respond to the emergency
quickly, effectively, and safely.
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\130\ https://www.nfpa.org/Training-and-Events/By-topic/Alternative-Fuel-Vehicle-Safety-Training/Emergency-Response-Guides.
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The Information Must Be Standardized
To improve the ease and flow of information and, ultimately, the
safety of persons involved, NHTSA is proposing a requirement that
vehicle manufacturers submit the emergency response information to
NHTSA in a standardized format. Currently, the ERGs and rescue sheets
for alternative fuel vehicles available on the NFPA website is not in a
standardized format.\131\ The NTSB report indicated that a standardized
format for ERGs would enhance emergency response as well as protect
first and second responders. NHTSA tentatively believes this NPRM's
proposed standardization requirement would make the information more
understandable and would be another means that would help reduce
response times and the safety risks to emergency responders.
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\131\ https://www.nfpa.org/Training-and-Events/By-topic/Alternative-Fuel-Vehicle-Safety-Training/Emergency-Response-Guides.
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Proposed FMVSS No. 305a would require that the rescue sheets must
follow the layout and format in ISO-17840-1:2022(E) (for vehicles with
a GVWR less than or equal to 4,536 kg (10,000 lb)) and the format in
ISO-17840-2:2019(E) (for vehicles with a GVWR greater than 4,536 kg
(10,000 lb)). ERGs must follow the template layout and format of ISO-
17840-3:2019(E) and provide in-depth information linked and aligned to
the corresponding rescue sheet to support the quick and safe action of
emergency responders. The ERGs must also provide in-depth information
related to electric vehicle fire, submersion, leakage of fluids,
towing, transportation, and storage.
NHTSA seeks comment on the proposed format and layout of rescue
sheets and ERGs in accordance with the different parts of ISO-17840.
Are there main features of ISO-17840 that should be considered instead
of referring to specific versions of the ISO-17840 parts? Are there
specific features not included in ISO-17840 that would further enhance
first and second responders' operations?
The Information Must Be Vehicle-Specific
NHTSA tentatively believes that, due to varying electric vehicle
design and development, emergency response information must be vehicle-
specific. Currently, the ERGs and rescue sheets on the NFPA website are
not available for all vehicle makes, models, and model years. NHTSA
tentatively believes that the information is of limited value because
of this limited availability. The agency tentatively believes that
requiring information on all vehicles is necessary to best reduce
response times and the safety risks to emergency responders.
[[Page 26730]]
The Information Must Be Submitted to NHTSA
NHTSA tentatively believes that easy access to both short and long
forms of emergency response information are essential to address the
risk of emergency responders. Therefore, as part of this NPRM and the
NHTSA's battery safety initiative,\132\ NHTSA is proposing a provision
in FMVSS No. 305a that would require vehicle manufacturers to submit
electronic versions of ERGs and rescue sheets for all vehicles to which
FMVSS No. 305a applies, prior to certification of the vehicle, so that
they are available in a centralized location on NHTSA's website. The
rationale of submission prior to certification is to ensure the
pertinent information for first and second responders are available by
the time the vehicles are placed on public roads and potentially
involved in emergencies. The intent is for both the ERGs and rescue
sheets to be stored and maintained at a centralized web location
(within NHTSA.gov), so that they are always easily and quickly
accessible to all first and second responders.
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\132\ https://www.nhtsa.gov/battery-safety-initiative.
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Other Issues Presented for Comment
To align with NHTSA's intent to have both ERGs and rescue
sheets accessible in a centralized NHTSA web location, NHTSA would like
to migrate the ERGs currently on the NFPA website to NHTSA's website.
NHTSA requests comments on whether electric vehicle ERGs and rescue
sheets that were previously hosted on the NFPA website should be
included in NHTSA's centralized web location.
NHTSA also requests comments on whether the requirement
described in this section for ERGs and rescue sheets would be better
placed in a general agency regulation than in proposed FMVSS No. 305a.
NHTSA discusses this issue at length in section VI. of this preamble
regarding documentation requirements pertaining to REESS safety risks
and risk mitigation strategies identified by manufacturers. NHTSA
requests comments on the pros and cons of having the ERGs and rescue
sheet requirements in a regulation rather than in FMVSS No. 305a.
Comments are requested on the pros and cons of placing the requirement
for providing ERG and rescue sheets to NHTSA to be in a regulation
rather than in FMVSS No. 305a.
VI. Request for Comment on Placing the Emergency Response Information
and Documentation Requirements in a Regulation Rather Than in FMVSS No.
305a
NHTSA requests comments on whether the proposed emergency response
information requirements would be better placed in a general agency
regulation than in proposed FMVSS No. 305a, given that the
documentation specifications are more akin to a disclosure requirement
(disclosing information to NHTSA) than a performance test or a consumer
safety information requirement.
NHTSA regulates motor vehicle safety under many grants of
authority. For example, one is that NHTSA is authorized by the Vehicle
Safety Act to issue FMVSS; a typical FMVSS specifies minimum
performance requirements and may also include provisions requiring
manufacturers to provide consumers safety information on properly using
a safety system or item of equipment. Another is that the Vehicle
Safety Act authorizes NHTSA to require manufacturers to retain certain
records and/or make information available to NHTSA. Section 30166 of
the Act provides NHTSA the ability to request and inspect manufacturer
records that are necessary to enforce the prescribed regulations. NHTSA
is also authorized by delegation to issue regulations to carry out the
agency's duties of ensuring vehicle safety.\133\ Documentation
requirements would be authorized under these authorities.
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\133\ 49 U.S.C. 322(a). This provision states that the Secretary
of Transportation may prescribe regulations to carry out the duties
and powers of the Secretary. The authority to implement the Vehicle
Safety Act has been delegated to NHTSA.
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However, NHTSA is mindful that the mechanisms for enforcing a
failure to meet a documentation requirement could differ depending on
whether the requirement is in an FMVSS or not. Section 30118 of the
Vehicle Safety Act (49 U.S.C. 30118) provides that whenever the
Secretary of Transportation (NHTSA by delegation) determines that a
vehicle does not comply with an FMVSS, NHTSA (by delegation) must
require the vehicle's manufacturer to notify the owners, purchasers and
dealers of the vehicle or equipment of the noncompliance and remedy the
noncompliance. There is an exception to the recall requirement in
section 30120(h) which authorizes NHTSA to exempt noncompliances from
recall provisions based on a demonstration that the noncompliance is
inconsequential to safety. In the case of a violation of a disclosure
requirement in a regulation other than an FMVSS, the manufacturer could
be subject to injunctive remedies and/or civil penalties,\134\ but
would not be subject to the recall notification and remedy provision
described above. NHTSA requests comments on the pros and cons of
placing the proposed emergency response information requirement in a
regulation rather than in FMVSS No. 305a.
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\134\ See, e.g., 49 U.S.C. 30165.
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NHTSA also seeks comments on whether the proposed risk mitigation
documentation requirements would be better placed in a general agency
regulation. This NPRM proposes manufacturers to document and submit
information, upon request, describing identified safety risks, risk
mitigation strategies, and validation of those strategies. NHTSA has
similar documentation requirements in FMVSS No. 126, ``Electronic
stability control systems for light vehicles'' \135\ and FMVSS No. 226,
``Ejection Mitigation.'' \136\ NHTSA requests comments on the pros and
cons of placing the proposed risk mitigation documentation requirement
in a regulation rather than in FMVSS No. 305a.
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\135\ 49 CFR 571.126 S5.6.
\136\ 49 CFR 571.226 S4.2.4.
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VII. Proposed Compliance Dates
The proposed compliance dates are as follows.
1. Regarding the proposed requirements other than the emergency
response information to assist first and second responders, the
compliance date would be two years after the publication of the final
rule in the Federal Register. Small-volume manufacturers, final-stage
manufacturers, and alterers would be provided an additional year to
comply with the final rule beyond the two-year date identified
above.\137\ We propose to permit optional early compliance with the
final rule.
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\137\ 49 CFR 571.8(b).
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Under Sec. 30111(d) of the Safety Act, a standard may not become
effective before the 180th day after the standard is prescribed or
later than one year after it is prescribed, unless NHTSA finds, for
good cause shown, that a different effective date is in the public
interest and publishes the reasons for the finding. NHTSA has
tentatively determined that a 2-year compliance period is in the public
interest because all vehicle manufacturers need to gain familiarity
with the proposed REESS requirements. There is already widespread
conformance to the requirements so the 2-year period ought
[[Page 26731]]
to provide sufficient time, but some manufacturers may need time to
assess fleet performance, review their risk management procedures and
document their mitigation strategies. Further, heavy vehicle
manufacturers would be newly subject to electric system integrity
requirements having not been subject to existing FMVSS No. 305. They
will need time to assess their vehicles' conformance to FMVSS No. 305a
requirements, implement appropriate design and production changes, and
assess and document risk mitigation strategies.
2. Regarding requirements to provide emergency response information
to assist first and second responders, the proposed compliance date is
one year after publication of the final rule. Small-volume
manufacturers, final-stage manufacturers, and alterers would be
provided an additional year to comply with the final rule. Optional
early compliance would be permitted. NHTSA believes the 1-year
compliance date for this proposed requirement is long enough for
manufacturers to provide the information to NHTSA in the required
format. They are already providing the information voluntarily to the
NFPA. The agency would like to provide the information on NHTSA's
website as soon as possible. If manufacturers provide the information
in a year, NHTSA can begin the process of posting the information
shortly thereafter.
VIII. Rulemaking Analyses and Notices
Executive Order 12866, Executive Order 14094, Executive Order 13563,
and DOT Order 2100.6A
NHTSA has considered the impact of this rulemaking action under
Executive Orders 12866, 14094, and 13563 and DOT Order 2100.6A. This
action was not reviewed by the Office of Management and Budget under
E.O. 12866.
This NPRM proposes to update FMVSS No. 305 to incorporate the
electrical safety requirements in GTR No. 20 and issue FMVSS No. 305a
with the incorporated requirements. Most of GTR No. 20 has already been
adopted into FMVSS No. 305; this NPRM proposes to complete the process
by expanding FMVSS No. 305's applicability to heavy vehicles and by
adopting the GTR's requirements for the REESS. Since there is
widespread conformance with the requirements that would apply to
existing vehicles, we anticipate no costs or benefits associated with
this rulemaking.
This NPRM also proposes a requirement that electric vehicle
manufacturers submit standardized emergency response information to a
NHTSA central depository, to assist first and second responders. A
comprehensive list of pertinent vehicle specific rescue information at
a central location will enable first and second responders to respond
to emergencies as quickly and safely as possible. Currently, electric
vehicle manufacturers voluntarily upload emergency response information
to the National Fire Protection Association's training site, so
manufacturers are already providing vehicle specific emergency response
information. With this proposed rule, manufacturers would submit ERGs
and rescue sheets to NHTSA instead. We anticipate no additional costs
by the manufacturers.
Regulatory Flexibility Act
NHTSA has considered the effects of this NPRM under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq., as amended by the Small Business
Regulatory Enforcement Fairness Act (SBREFA) of 1996). I certify that
this NPRM, if promulgated, would not have a significant economic impact
on a substantial number of small entities. NHTSA is aware of 3 small
manufacturers of light and heavy electric vehicles. NHTSA believes that
this proposed rule would not have a significant economic impact on
these manufacturers for the following reasons. First, small
manufacturers of light electric vehicles that might be affected by this
NPRM are already subject to the electric vehicle safety requirements of
FMVSS No. 305 and have been certifying compliance to the standard for
years. They are familiar with FMVSS requirements for electric vehicle
safety, know how to assess the conformance of their vehicles with the
requirements, and know how to certify their vehicles to the FMVSS. The
new proposed requirements for the REESS are manageable because the
overcharge, over-discharge, over-current, over-temperature, and
external short-circuit tests are non-destructive tests and can be
conducted in serial order. The documentation requirements for safety
risk mitigation associated with charging and discharging during cold
temperature, safety risk mitigation associated with an internal short-
circuit in a single cell of a REESS, and warning in the event of a
malfunction of the vehicle controls that manage REESS safe operation
are not design restrictive and add minimal cost. The documentation
requirements simply ask manufacturers to describe to NHTSA how they
have assessed certain safety risks and mitigated them.
Second, there already is widespread voluntarily compliance by the
manufacturers with GTR No. 20, which is also aligned with industry
standards. Therefore, there will be only a minor economic impact.
Finally, although the final certification would be made by the
manufacturer, this proposal would allow one additional year for small
volume manufacturers, final-stage manufacturers and alterers to comply
with a final rule. This approach is similar to the approach NHTSA has
taken in other rulemakings in recognition of manufacturing differences
between larger and smaller manufacturers. NHTSA anticipates that EV
components meeting FMVSS No. 305a would be developed by vehicle
designers and suppliers and integrated into the fleets of larger
vehicle manufacturers first, before small manufacturers. This NPRM
recognizes this and proposes to provide smaller manufacturers
flexibility, so they have time to obtain the equipment and work with
the suppliers after the demands of the larger manufacturers are met.
This NPRM would apply proposed FMVSS No. 305a to heavy vehicles, so
this NPRM would also affect manufacturers of vehicles of over 4,536 kg
(10,000 lb) GVWR, some of which may be final-stage manufacturers.\138\
According to the U.S. Census, there are 570 small businesses in body
manufacturing for light, medium, and heavy-duty classes. This proposal
could affect a substantial number of final stage manufacturers that are
small businesses. However, it is NHTSA's understanding that these small
entities rarely make modifications to a vehicle's REESS system and
instead rely upon the pass-through certification provided by the first-
stage manufacturer, which is not typically a small business. The same
is true for alterers, which are manufacturers that obtain and alter a
complete vehicle prior to the vehicle's first sale to a consumer.\139\
Furthermore, even if the final-stage manufacturer or alterer must make
the certification independently, as explained above this
[[Page 26732]]
certification responsibility is manageable. The proposed requirements
do not involve crash testing (except for heavy school buses, as
discussed below), and conformance with the requirements can be assessed
relatively simply in a laboratory setting. And finally, this proposal
would further accommodate final-stage manufacturers and alterers by
providing them an additional year before compliance is required.\140\
For the reasons above, NHTSA does not believe that the economic impacts
of this proposal on small entities would be significant.
---------------------------------------------------------------------------
\138\ Final-stage manufacturers produce vehicles by obtaining an
incomplete vehicle (comprising the chassis and other associated
parts) manufactured by an incomplete vehicle manufacturer, which is
typically a large manufacturer. The final-stage manufacturer
produces a vehicle by installing the vehicle body on the incomplete
vehicle. The final-stage manufacturer typically certifies a complete
vehicle by staying within manufacturing instructions provided by the
incomplete vehicle manufacturer.
\139\ Alterers certify that the vehicle was altered by them and
as altered conforms to all applicable FMVSS, bumper, and theft
prevention standards affected by the alteration.
\140\ See 49 CFR 571.8(b).
---------------------------------------------------------------------------
With regard to the proposed crash test requirement for small
manufacturers of heavy school buses, the additional requirement is for
heavy school buses with high voltage electric propulsion systems to
meet post-crash electrical safety requirements when impacted by the
moving contoured barrier specified in FMVSS No. 301. This requirement
does not require additional crash testing and aligns the applicability
of FMVSS No. 305a with that of FMVSS Nos. 301 and 303. Per FMVSS No.
301 and FMVSS No. 303, heavy school buses (school buses with a GVWR
greater than 4,536 kg) using conventional fuel or compressed natural
gas for propulsion are required to maintain fuel system integrity in a
crash test where the moving contoured barrier specified in FMVSS No.
301 traveling at any speed up to 48 km/h impacts the school bus at any
point and angle. These requirements ensure post-crash safety to
maintain the current high safety standards for school buses. Finally,
this proposal would accommodate small manufacturers and final stage
manufacturers of heavy school buses by providing them an additional
year before compliance is required. For the reasons above, NHTSA does
not believe that the economic impacts of this proposal on small
entities would be significant.
National Environmental Policy Act
NHTSA has analyzed this rulemaking action for the purposes of the
National Environmental Policy Act (42 U.S.C. 4321 et seq.), as amended.
The agency has determined that implementation of this action will not
have an adverse impact on the quality of the human environment. As
described earlier, the proposal includes the current requirements in
FMVSS No. 305 but would also expand the applicability of the standard
to heavy vehicles (vehicles with a gross vehicle weight rating (GVWR)
greater than 4,536 kilograms (kg) (10,000 lb)), add requirements to
mitigate post-crash vehicle fires, add an optional method for assessing
electrical safety for capacitors included in the electric powertrain,
and include crash test and post-crash safety requirements for school
buses with a GVWR greater than 4,536 kg (10,000 lb). The proposal would
align the standard with electrical safety requirements in the Global
Technical Regulation (GTR) No. 20, ``Electric Vehicle Safety,'' which
has been formally adopted by the UN World Forum for Harmonization of
Vehicle Regulations. The proposal, with expanded applicability and
additional requirements and test procedures, would enable future
updates to the standard as battery technologies and charging systems
continue to evolve.
NHTSA expects the changes to new and existing vehicles to be
minimal, and mitigating the hazards associated with electric shock
during parked conditions, active drive-possible modes, external
charging, and post-crash events, as well as risks associated with
hazardous conditions resulting from battery fires and emissions, would
result in a public health and safety benefit. For these reasons, the
agency has determined that implementation of this action will not have
any adverse impact on the quality of the human environment.
Executive Order 13132 (Federalism)
NHTSA has examined this proposed rule pursuant to Executive Order
13132 (64 FR 43255; Aug. 10, 1999) and concluded that no additional
consultation with States, local governments, or their representatives
is mandated beyond the rulemaking process. The agency has concluded
that the proposal does not have sufficient federalism implications to
warrant consultation with State and local officials or the preparation
of a federalism summary impact statement. The proposal does not have
``substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government.''
NHTSA rules can have preemptive effect in two ways. First, the
National Traffic and Motor Vehicle Safety Act contains an express
preemption provision: When a motor vehicle safety standard is in effect
under this chapter, a State or a political subdivision of a State may
prescribe or continue in effect a standard applicable to the same
aspect of performance of a motor vehicle or motor vehicle equipment
only if the standard is identical to the standard prescribed under this
chapter. 49 U.S.C. 30103(b)(1). It is this statutory command that
preempts any non-identical State legislative and administrative law
address the same aspect of performance.
The express preemption provision described above is subject to a
savings clause under which ``[c]compliance with a motor vehicle safety
standard prescribed under this chapter does not exempt a person from
liability at common law.'' 49 U.S.C. 30103(e). Pursuant to this
provision, State common law tort causes of action against motor vehicle
manufacturers that might otherwise be preempted by the express
preemption provision are generally preserved. However, the Supreme
Court has recognized the possibility, in some instances, of implied
preemption of State common law tort causes of action by virtue of
NHTSA's rules--even if not expressly preempted.
This second way that NHTSA rules can preempt is dependent upon the
existence of an actual conflict between an FMVSS and the higher
standard that would effectively be imposed on motor vehicle
manufacturers if someone obtained a State common law tort judgment
against the manufacturer--notwithstanding the manufacturer's compliance
with the NHTSA standard. Because most NHTSA standards established by an
FMVSS are minimum standards, a State common law tort cause of action
that seeks to impose a higher standard on motor vehicle manufacturers
will generally not be preempted. However, if and when such a conflict
does exist--for example, when the standard at issue is both a minimum
and a maximum standard--the State common law tort cause of action is
impliedly preempted. See Geier v. American Honda Motor Co., 529 U.S.
861 (2000).
Pursuant to Executive Order 13132, NHTSA has considered whether
this proposed rule could or should preempt State common law causes of
action. The agency's ability to announce its conclusion regarding the
preemptive effect of one of its rules reduces the likelihood that
preemption will be an issue in any subsequent tort litigation.
To this end, the agency has examined the nature (e.g., the language
and structure of the regulatory text) and objectives of this proposed
rule and does not foresee any potential State requirements that might
conflict with it. NHTSA does not intend that this proposed rule preempt
state tort law that would effectively impose a higher standard on motor
vehicle manufacturers than that established by this proposed rule.
Establishment of a higher standard by means of State tort law would not
conflict with the
[[Page 26733]]
standards proposed in this NPRM. Without any conflict, there could not
be any implied preemption of a State common law tort cause of action.
Executive Order 12988 (Civil Justice Reform)
With respect to the review of the promulgation of a new regulation,
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR
4729; Feb. 7, 1996), requires that Executive agencies make every
reasonable effort to ensure that the regulation: (1) Clearly specifies
the preemptive effect; (2) clearly specifies the effect on existing
Federal law or regulation; (3) provides a clear legal standard for
affected conduct, while promoting simplification and burden reduction;
(4) clearly specifies the retroactive effect, if any; (5) specifies
whether administrative proceedings are to be required before parties
file suit in court; (6) adequately defines key terms; and (7) addresses
other important issues affecting clarity and general draftsmanship
under any guidelines issued by the Attorney General. This document is
consistent with that requirement.
Pursuant to this Order, NHTSA notes as follows. The issue of
preemption is discussed above. NHTSA notes further that there is no
requirement that individuals submit a petition for reconsideration or
pursue other administrative proceedings before they may file suit in
court.
Privacy Act
Please note that anyone is able to search the electronic form of
all comments received into any of our dockets by the name of the
individual submitting the comment (or signing the comment, if submitted
on behalf of an association, business, labor union, etc.). You may
review DOT's complete Privacy Act Statement in the Federal Register
published on April 11, 2000 (65 FR 19477-78), or online at https://www.dot.gov/privacy.html.
Paperwork Reduction Act
Under the procedures established by the Paperwork Reduction Act of
1995 (PRA) (44 U.S.C. 3501, et. seq.), Federal agencies must obtain
approval from the OMB for each collection of information they conduct,
sponsor, or require through regulations. A person is not required to
respond to a collection of information by a Federal agency unless the
collection displays a valid OMB control number. The Information
Collection Request (ICR) for the proposed new information collection
described below have been forwarded to OMB for review and comment. In
compliance with these requirements, NHTSA asks for public comments on
the following proposed collections of information for which the agency
is seeking approval from OMB.
There are two types of collection of information that are part of
the proposed FMVSS No. 305a requirements: (1) Electric Vehicles: Rescue
Sheets and Emergency Response Guides and (2) Electric Vehicles: REESS
Thermal Propagation Safety Risk Analysis and Mitigation Documentation.
Title: FMVSS No. 305a Electric Vehicle Emergency Response
Information and Risk Mitigation Documentation.
OMB Control Number: New.
Form Number: N/A.
Type of Request: Approval of a new collection.
Type of Review Requested: Regular.
Requested Expiration Date of Approval: 3 years from the date of
approval.
Summary of the Collection of Information:
FMVSS No. 305a proposes electric vehicle (EV) requirements for
protection from harmful electric shock, fire, explosion, and gas
venting during normal vehicle operation and during and after a crash.
As part of the proposed requirements, there are two types of
information collection that would apply to all electric vehicle (EV)
manufacturers. First, before certification, each manufacturer will be
required to submit emergency response information, including rescue
sheets and emergency response guides (ERGs) for each vehicle make,
model, and model year, so they are available in a centralized location
on NHTSA's website. The information would then be readily available for
first and second responders so they can easily identify pertinent
vehicle-specific rescue information at the scene of a vehicle crash or
fire event, and respond to the emergency quickly, effectively, and
safely.
Second, each electric vehicle model will be required to meet three
proposed documentation requirements and manufacturers will be required
to submit to NHTSA, upon request, documentation demonstrating risk
mitigation for certain safety hazards. The documentation must describe
safety risk mitigation associated with charging and discharging during
cold temperature, safety risk mitigation associated with an internal
short-circuit in a single cell of a REESS, and warning in the event of
a malfunction of the vehicle controls that manage REESS safe operation.
Description of the Need for the Information and Proposed Use of the
Information:
First responders need detailed information pertaining to an EV's
electrical system layout in order to safely work around the vehicle and
extricate injured passengers. Access to vehicle-specific information in
a clear, standardized format help mitigate the safety risks of high
voltage components and stranded energy in the Rechargeable Electrical
Energy Storage System (REESS). The purpose of the requirement is to
make this information readily available for first and second responders
for their safe handling of the vehicle in emergencies and for towing
and storing operations. Rescue sheets and ERGs communicate vehicle-
specific information related to fire, submersion, and towing, as well
as the location of components in the vehicle that may expose the
vehicle occupants or rescue personnel to risks. The information is
presented in a specific format with color-coded sections in a specific
order to help first and second responders quickly identify pertinent
rescue information. Rescue sheets contain abbreviated emergency
response information about a vehicle's construction. Rescue sheets are
most likely to be referenced first by emergency responders upon arrival
at the scene of a crash. ERGs contain more information than rescue
sheets.
Current emergency response information is voluntarily filed on the
National Fire Protection Association (NFPA) website, but they are not
in standardized format. The uploaded rescue sheets and ERGs would be
standardized in layout and format and be publicly available at NHTSA's
website for quick access.
There are currently no objective test procedures to evaluate REESS
mitigation of certain safety risks in a manner that is not design
restrictive. Until test procedures and performance criteria can be
developed for all vehicle powertrain architectures, the proposed FMVSS
No. 305a would require manufacturers to compile and meet three of the
proposed documentation requirements and submit documentation to NHTSA,
if requested, that identifies all known safety hazards, the risk
mitigation strategies for the safety hazards, and, if applicable,
describe how they provide a warning to address a safety hazard. Given
the variation of battery design and design-specific risk mitigation
systems, the documentation is a means for manufacturers to show that
they have identified and demonstrated safety risk mitigation
strategies, and for NHTSA to
[[Page 26734]]
learn of and oversee the safety hazards. This approach is battery
technology neutral, not design restrictive, and is intended to evolve
over time as battery technologies continue to rapidly evolve. These
proposed documentation requirements would address: (a) safety risk
mitigation associated with charging and discharging during low
temperature; (b) the safety risks from thermal propagation in the event
of SCTR due to an internal short-circuit of a single cell; and (c)
providing a warning if there is a malfunction of vehicle controls that
manage REESS safe operation.
Affected Public: Vehicle manufacturers.
Frequency: Emergency response information: as needed upon
certification; Risk mitigation documentation: annually for
recordkeeping.
Number of Responses: It is anticipated that an estimated 205 rescue
sheets and ERGs will be submitted each year and all 205 unique models
would be compiling and maintaining the required documentation annually.
Electric vehicle models encompass battery-powered electric vehicle,
plug-in hybrid electric vehicle, hybrid electric vehicle, and fuel cell
electric vehicle models. The combined number of electric vehicle models
is estimated to be 205 unique models each year. Upon certification, a
total of 205 rescue sheets and ERGs for all unique models will be
submitted. Out of the 205 EV models, about 51 (25% of EV models) likely
already have rescue sheets and ERGs that conform to the proposed
requirements. The number of new rescue sheets and ERGs that would be
required to be compiled and submitted to NHTSA before certification is
estimated to be 51 (25% of the combined EV models sold each year).
NHTSA also anticipates updates to existing or previously submitted
rescue sheets and ERGs for some vehicle models. Updates may be
necessary when a vehicle model changes between model years or there are
revisions to an existing model's emergency response information. It is
estimated that approximately 103 (50% of the 205 annual electric
vehicle models) electric vehicle models sold each year would have
updated or revised rescue sheets and ERGs. Because rescue sheets and
emergency response guides often cover several model years, the
percentage of models that would be needing new or updates to existing
or previously submitted rescue sheets and ERGs are likely to decrease
after the second year of the effective date.
Estimated Total Annual Burden Hours: 16,241 hours (2,506 hours for
emergency response information and 13,735 hours for risk mitigation
documentation).
For vehicle models that already have rescue sheets and ERGs that
conform to the proposed requirements, it is estimated to take 0.25 hour
to submit the required emergency response information to NHTSA's
website. The estimated burden hours for the 51 EV models to submit
their conformed rescue sheets and ERGs is 13 hours (0.25 hour/model x
51 models).
For each new electric vehicle model, it is anticipated that it will
take approximately 36 hours to complete the vehicle-specific rescue
sheet and emergency response guide following the required format and
layout provided in ISO-17840-1:2022, ISO-17840-2:2019, and ISO-17840-
3:2019. The estimated total annual burden hours for new rescue sheets
and emergency response guides is 1,849 hours (36.25 hours/model x 51
models).
It is anticipated that it will take approximately 6 hours to update
the rescue sheet and emergency response guide for a vehicle model. The
estimated total annual burden hours for updated rescue sheets and
emergency response guides is 644 hours (6.25 hours/model x 103 models).
The estimated total annual burden hours is 2,506 hours.
For each vehicle model, vehicle manufacturers will need an
estimated 67 hours to complete the three documentation requirements (17
hours to complete the documentation for low temperature operation
safety, 17 hours for the documentation about warning in the event of
operational failure of REESS vehicle controls, and 33 hours for the
documentation covering thermal runaway due to internal short in a
single cell of the REESS). After the proposed rule's effective date,
all 205 vehicle models are expected to compile the necessary
information to meet the three proposed documentation requirements. The
total estimated annual burden hours for the three documentation
requirements is an estimate of 13,735 hours (205 vehicle models x 67
hours).
Estimated Total Annual Burden Cost: $1,027,381 ($157,543 for
emergency response information and $869,838 for risk mitigation
documentation).
The preparation of information is anticipated to be done by a
technical writer. The U.S. Bureau of Labor Statistics (BLS) estimates
the mean hourly wage for technical writers in the motor vehicle
manufacturing industry as $44.71.\141\ The BLS estimates that private
industry workers' wages account for 70.6% of a worker's total
compensation.\142\ Therefore, NHTSA estimates the hourly labor costs to
be $63.33 ($44.71/hour/70.6%). The submission of information is
anticipated to be done by an administrative professional. The U.S. BLS
estimates the mean hourly wage for administrative professional in the
motor vehicle manufacturing industry is $29.36.\143\ Therefore, NHTSA
estimates the hourly labor costs for submission to be $41.59 ($29.36/
hour/70.6%).
---------------------------------------------------------------------------
\141\ See May 2022 National Industry-Specific Occupational
Employment and Wage Estimates, NAICS 336100--Motor Vehicle
Manufacturing, available at https://www.bls.gov/oes/current/naics4_336100.htm (accessed February 29, 2024).
\142\ See Table 1. Employer Costs for Employee Compensation by
ownership (Sept. 2023), available at Table 1. By ownership--2023 Q03
Results (bls.gov).
\143\ See May 2022 National Industry-Specific Occupational
Employment and Wage Estimates, NAICS 336100--Motor Vehicle
Manufacturing, available at https://www.bls.gov/oes/current/naics4_336100.htm (accessed February 29, 2024).
---------------------------------------------------------------------------
These estimates produce an annual cost burden to manufacturers of
$116,804 (51 models x ((36 hours x $63.33) + (0.25 hour x $41.59)) for
generating and submitting the emergency response information
documentation for new models, $40,209 (103 models x ((6 hours x $63.33)
+ (0.25 hour x $41.59)) for updating and submitting the documentation,
and $530 (51 models x (0.25 hour x $41.59)) for those EV models that
already conform to the proposed requirements for submission. The total
labor cost to prepare and submit the emergency response information
documentation to NHTSA's website is estimated to be $157,543 annually.
Because rescue sheets and emergency response guides often cover
several model years, the percentage of models that would be needing new
or updates to existing or previously submitted rescue sheets and ERGs
each year are likely to decrease in subsequent years. This would result
in a reduction in annual total burden hours and annual total burden
costs.
The preparation of the risk mitigation documentation is also
anticipated to be done by a technical writer. The total cost burden for
manufacturers for compiling and record keeping the three documentation
packets would be $869,838 (205 vehicle models x (67 hours x $63.33)).
The estimated total annual burden hours to manufacturers for the
proposed FMVSS No. 305a emergency response information and
documentation requirements would be 16,241 hours.
[[Page 26735]]
The estimated total annual cost burden to manufacturers for the
proposed FMVSS No. 305a emergency response information and
documentation requirements would be $1,027,381.
Public Comments Invited: You are asked to comment on any aspects of
this information collection, including (a) whether the proposed
collection of information is necessary for the proper performance of
the functions of the Department, including whether the information will
have practical utility; (b) the accuracy of the Department's estimate
of the burden of the proposed information collection; (c) ways to
enhance the quality, utility and clarity of the information to be
collected; and (d) ways to minimize the burden of the collection of
information on respondents, including the use of automated collection
techniques or other forms of information technology.
Please submit any comments, identified by the docket number in the
heading of this document, by the methods described in the ADDRESSES
section of this document to NHTSA and OMB. Although comments may be
submitted during the entire comment period, comments received within 30
days of publication are most useful.
National Technology Transfer and Advancement Act
Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law 104-113, as amended by Public Law 107-
107 (15 U.S.C. 272), directs the agency to evaluate and use voluntary
consensus standards in its regulatory activities unless doing so would
be inconsistent with applicable law or is otherwise impractical.
Voluntary consensus standards are technical standards (e.g., materials
specifications, test methods, sampling procedures, and business
practices) that are developed or adopted by voluntary consensus
standards bodies, such as the Society of Automotive Engineers (SAE).
The NTTAA directs us to provide Congress (through OMB) with
explanations when the agency decides not to use available and
potentially applicable voluntary consensus standards.
This proposal to adopt GTR No. 20 is consistent with the goals of
the NTTAA. This NPRM proposes to adopt a global consensus standard. The
GTR was developed by a global regulatory body and is designed to
increase global harmonization of differing vehicle standards. The GTR
leverages the expertise of governments in developing a vehicle standard
to increase electric vehicle safety, including the performance of the
REESS. NHTSA's consideration of GTR No. 20 accords with the principles
of NTTAA as NHTSA's consideration of an established, proven global
technical regulation has reduced the need for NHTSA to expend
significant agency resources on the same safety need addressed by GTR
No. 20.
Unfunded Mandates Reform Act
Section 202 of the Unfunded Mandates Reform Act of 1995 (UMRA),
Public Law 104-4, requires Federal agencies to prepare a written
assessment of the costs, benefits, and other effects of proposed or
final rules that include a Federal mandate likely to result in the
expenditure by State, local, or tribal governments, in the aggregate,
or by the private sector, of more than $100 million annually (adjusted
for inflation with base year of 1995). Adjusting this amount by the
implicit gross domestic product price deflator for the year 2022
results in $177 million (111.416/75.324 = 1.48). This NPRM would not
result in a cost of $177 million or more to either State, local, or
tribal governments, in the aggregate, or the private sector. Thus, this
NPRM is not subject to the requirements of sections 202 of the UMRA.
Executive Order 13609 (Promoting Regulatory Cooperation)
The policy statement in section 1 of Executive Order 13609
provides, in part: The regulatory approaches taken by foreign
governments may differ from those taken by U.S. regulatory agencies to
address similar issues. In some cases, the differences between the
regulatory approaches of U.S. agencies and those of their foreign
counterparts might not be necessary and might impair the ability of
American businesses to export and compete internationally. In meeting
shared challenges involving health, safety, labor, security,
environmental, and other issues, international regulatory cooperation
can identify approaches that are at least as protective as those that
are or would be adopted in the absence of such cooperation.
International regulatory cooperation can also reduce, eliminate, or
prevent unnecessary differences in regulatory requirements.
The agency participated in the development of GTR No. 20 to
harmonize the standards of electric vehicle. As a signatory member,
NHTSA is proposing to incorporate electrical safety requirements and
options specified in GTR No. 20 into FMVSS No. 305a.
Incorporation by Reference
Under regulations issued by the Office of the Federal Register (1
CFR 51.5(a)), an agency must summarize in the preamble of a proposed or
final rule the material it incorporates by reference and discuss the
ways the material is reasonably available to interested parties or how
the agency worked to make materials available to interested parties.
NHTSA proposes to incorporate by reference three documents into the
Code of Federal Regulations. The first document is ISO 17840-1:2022
(E), ``Road vehicles--Information for first and second responders--Part
1: Rescue sheet for passenger cars and light commercial vehicles.'' ISO
17840-1:2022(E) standardizes the content and layout of rescue sheets
for passenger cars and light commercial vehicles.
The second document is ISO 17840-2:2019(E), ``Road vehicles--
Information for first and second responders--Part 2: Rescue sheet for
buses, coaches and heavy commercial vehicles.'' ISO 17840-2:2019(E)
standardizes the rescue sheets for buses, coaches, and heavy commercial
vehicles.
The third document is ISO 17840-3:2019(E), ``Road vehicles--
Information for first and second responders--Part 3: Emergency response
guide template.'' ISO 17840-3:2019(E) establishes a template and
defines the general content for manufacturers' emergency response
guides for all vehicle types.
All three documents would be incorporated by reference solely to
specify the layout and format of the rescue sheets and emergency
response guides. The ISO material is available for review at NHTSA and
is available for purchase from ISO.\144\
---------------------------------------------------------------------------
\144\ ISO standards may be purchased from the ANSI webstore
https://webstore.ansi.org/.
---------------------------------------------------------------------------
Severability
The issue of severability of FMVSSs is addressed in 49 CFR 571.9.
It provides that if any FMVSS or its application to any person or
circumstance is held invalid, the remainder of the part and the
application of that standard to other persons or circumstances is
unaffected. Comments are requested on the severability of this proposed
FMVSS.
Regulation Identifier Number
The Department of Transportation assigns a regulation identifier
number (RIN) to each regulatory action listed in the Unified Agenda of
Federal Regulations. The Regulatory Information Service Center
publishes the Unified Agenda in April and October of each year. You may
use the RIN contained in
[[Page 26736]]
the heading at the beginning of this document to find this action in
the Unified Agenda.
Rulemaking Summary, 5 U.S.C. 553(b)(4)
As required by 5 U.S.C. 553(b)(4), a summary of this rule can be
found in the Abstract section of the Department's Unified Agenda entry
for this rulemaking at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM43.
Plain Language
Executive Order 12866 requires each agency to write all rules in
plain language. Application of the principles of plain language
includes consideration of the following questions:
Have we organized the material to suit the public's needs?
Are the requirements in the rule clearly stated?
Does the rule contain technical language or jargon that
isn't clear?
Would a different format (grouping and order of sections,
use of headings, paragraphing) make the rule easier to understand?
Would more (but shorter) sections be better?
Could we improve clarity by adding tables, lists, or
diagrams?
What else could we do to make the rule easier to
understand?
If you have any responses to these questions, please write to us
with your views.
IX. Public Participation
How long do I have to submit comments?
Please see DATES section at the beginning of this document.
How do I prepare and submit comments?
Your comments must be written in English.
To ensure that your comments are correctly filed in the
Docket, please include the Docket Number shown at the beginning of this
document in your comments.
Your comments must not be more than 15 pages long. (49 CFR
553.21). We established this limit to encourage you to write your
primary comments in a concise fashion. However, you may attach
necessary additional documents to your comments. There is no limit on
the length of the attachments.
If you are submitting comments electronically as a PDF
(Adobe) File, NHTSA asks that the documents be submitted using the
Optical Character Recognition (OCR) process, thus allowing NHTSA to
search and copy certain portions of your submissions. Comments may be
submitted to the docket electronically by logging onto the Docket
Management System website at https://www.regulations.gov. Follow the
online instructions for submitting comments.
You may also submit two copies of your comments, including
the attachments, to Docket Management at the address given above under
ADDRESSES.
Please note that pursuant to the Data Quality Act, in order for
substantive data to be relied upon and used by the agency, it must meet
the information quality standards set forth in the OMB and DOT Data
Quality Act guidelines. Accordingly, we encourage you to consult the
guidelines in preparing your comments. OMB's guidelines may be accessed
at https://www.whitehouse.gov/omb/fedreg/reproducible.html. DOT's
guidelines may be accessed at https://www.bts.gov/programs/statistical_policy_and_research/data_quality_guidelines.
How can I be sure that my comments were received?
If you wish Docket Management to notify you upon its receipt of
your comments, enclose a self-addressed, stamped postcard in the
envelope containing your comments. Upon receiving your comments, Docket
Management will return the postcard by mail.
How do I submit confidential business information?
You should submit a redacted ``public version'' of your comment
(including redacted versions of any additional documents or
attachments) to the docket using any of the methods identified under
ADDRESSES. This ``public version'' of your comment should contain only
the portions for which no claim of confidential treatment is made and
from which those portions for which confidential treatment is claimed
has been redacted. See below for further instructions on how to do
this.
You also need to submit a request for confidential treatment
directly to the Office of Chief Counsel. Requests for confidential
treatment are governed by 49 CFR part 512. Your request must set forth
the information specified in Part 512. This includes the materials for
which confidentiality is being requested (as explained in more detail
below); supporting information, pursuant to Part 512.8; and a
certificate, pursuant to Part 512.4(b) and Part 512, Appendix A.
You are required to submit to the Office of Chief Counsel one
unredacted ``confidential version'' of the information for which you
are seeking confidential treatment. Pursuant to Part 512.6, the words
``ENTIRE PAGE CONFIDENTIAL BUSINESS INFORMATION'' or ``CONFIDENTIAL
BUSINESS INFORMATION CONTAINED WITHIN BRACKETS'' (as applicable) must
appear at the top of each page containing information claimed to be
confidential. In the latter situation, where not all information on the
page is claimed to be confidential, identify each item of information
for which confidentiality is requested within brackets: ``[ ].''
You are also required to submit to the Office of Chief Counsel one
redacted ``public version'' of the information for which you are
seeking confidential treatment. Pursuant to Part 512.5(a)(2), the
redacted ``public version'' should include redactions of any
information for which you are seeking confidential treatment (i.e., the
only information that should be unredacted is information for which you
are not seeking confidential treatment).
NHTSA is currently treating electronic submission as an acceptable
method for submitting confidential business information to the agency
under Part 512. Please do not send a hardcopy of a request for
confidential treatment to NHTSA's headquarters. The request should be
sent to Dan Rabinovitz in NHTSA's Office of the Chief Counsel (NCC) at
[email protected]. You may either submit your request via email
or request a secure file transfer link. If you are submitting the
request via email, please also email a courtesy copy of the request to
K.Helena Sung in NCC at [email protected].
Will the agency consider late comments?
We will consider all comments that Docket Management receives
before the close of business on the comment closing date indicated
above under DATES. To the extent possible, we will also consider
comments that Docket Management receives after that date. If Docket
Management receives a comment too late for us to consider in developing
the final rule, we will consider that comment as an informal suggestion
for future rulemaking action.
How can I read the comments submitted by other people?
You may read the comments received by Docket Management at the
address given above under ADDRESSES. The hours of the Docket are
indicated above in the same location. You may also see the comments on
the internet. To read the comments on the internet, go to
[[Page 26737]]
https://www.regulations.gov. Follow the online instructions for
accessing the dockets.
Please note that, even after the comment closing date, we will
continue to file relevant information in the Docket as it becomes
available. Further, some people may submit late comments. Accordingly,
we recommend that you periodically check the Docket for new material.
X. Appendices to the Preamble
Appendix A. Table Comparing GTR No. 20, FMVSS No. 305, and FMVSS No.
305a
Table A below provides an overview of the requirements presently
in the GTR No. 20, FMVSS No. 305, and the proposed FMVSS No. 305a
for light vehicles (LVs) and heavy vehicles (HVs).
Table A--Overview of Safety Requirements in GTR No. 20, FMVSS No. 305, and Those Proposed in This NPRM
----------------------------------------------------------------------------------------------------------------
Requirement category Requirement GTR No. 20 FMVSS No. 305 FMVSS No. 305a
----------------------------------------------------------------------------------------------------------------
Electrical Safety under Normal Physical Barrier Yes for LV and HV Yes for LV....... Yes for LV and
Vehicle Operations. Protection Electrical HV.
Isolation Isolation
Monitoring (FCEVs)
Charging Safety
Driver Error
Mitigation.
Post-Crash Safety.............. REESS Retention Yes for LV....... Yes for LV....... Yes for LV and
Electrolyte Leakage heavy school
Electrical Safety. bus.
Fire Safety........... ................. No...............
Post-Crash Electrical Safety Low Voltage Electrical Yes for LV....... Yes for LV....... Yes for LV and
Compliance Options. Isolation Physical heavy school
Barrier Protection. bus.
Low Energy Yes for LV....... No............... Yes for LV and
(Capacitors). heavy school
bus.
Optional Post-crash Component Mechanical Crush Test Yes for LV....... No............... No.
Level REESS Tests. instead of crash test.
Mechanical Shock Test Only shock test
instead of crash test. for HV.
REESS Safety Performance during Overcharge Over- Yes for LV and HV No............... Yes for LV and
Normal Vehicle Operations. Discharge Over- HV.
Current Over-
Temperature External
Short-Circuit Low-
Temperature Thermal
Propagation Water
Exposure REESS
Venting.
Vibration Thermal Yes for HV and LV No............... No.
Shock & Cycling Fire
Resistance.
Warning Requirements........... Thermal Event Warning. Yes for LV and HV No............... Yes for LV and
HV.
Warning of Malfunction
of Vehicle Controls
for REESS Operations.
Low SOC............... ................. ................. No.
Emergency Response Information. Rescue Sheets......... No............... No...............
Emergency Response ................. ................. Yes for LV and
Guides (ERGs). HV.
----------------------------------------------------------------------------------------------------------------
Appendix B. Request for Comment on Phase 2 GTR No. 20 Approaches Under
Consideration by the IWG
1. Electrolyte Release and Venting From the REESS
NHTSA requests comment on the IWG's continuing work on venting.
Phase 2 of GTR No. 20 is considering more robust methods to verify
the occurrence and quantification of electrolyte release \145\ and/
or venting.\146\ Two possible approaches for detection of
electrolyte release are under consideration: (1) detection of solid
and liquid Li-ion, and (2) gas detection for the vapors released
from the liquid electrolyte and vented gases.
---------------------------------------------------------------------------
\145\ EVS21-E2TG-0200 [EC]. Detection of electrolyte leakage by
gas detection techniques. https://wiki.unece.org/display/trans/EVS+21st+session.
\146\ Gas emissions in thermal runaway propagation experiments,
https://wiki.unece.org/download/attachments/177242909/EVS25-E2TG-0400%20%5BEC%5DGas%20emissions%20in%20thermal%20runaway%20propagation%20experiments.pdf?api=v2.
---------------------------------------------------------------------------
Chemosensors \147\ are currently being studied to detect the
presence of Li-ion resulting from electrolyte release. However, no
commercially available chemosensors have been identified that could
be used for testing purposes to reliably detect electrolyte leakage.
---------------------------------------------------------------------------
\147\ Chemosensors indicate the presence of Li-ion through a
color and fluorescence change. Chemosensor means a molecule which is
able to simultaneously bind and signal the presence of other
species. F. Pina et al, J. Photochem. Photobiol. A, 126 (1999), 65-
69.
---------------------------------------------------------------------------
Common gas detection methods include gas chromatography,
fourier-transform infrared spectroscopy (FTIR), and different types
of gas sensors. Emitted gases under consideration include carbon
dioxide (CO2), carbon monoxide (CO), hydrogen
(H2), oxygen (O2), light C1-
C5 hydrocarbons, e.g., methane and ethane, and fluorine-
containing compounds such as hydrogen fluoride (HF) and fluoro-
organics such as e.g., ethyl-fluoride. However, practical, and cost-
effective methods of sampling the leakage/emissions/venting and
determining acceptable exposure levels for different gases are still
under development.
NHTSA seeks comment on:
How these detection methods (chemosensors and gas
detection methods) may best be utilized in a vehicle level test
procedure for both normal operating conditions and post-crash
scenarios.
How to best manage gases and particulates emitted from
the REESS for both normal operating conditions and post-crash
scenarios.
Which gases generated in and vented from Li-ion
batteries should be focused on for all types of REESS chemistries
and are anticipated to remain relevant as REESS
[[Page 26738]]
chemistry and technology changes in the future.
Practicable methods to verify the occurrence of
electrolyte release and venting and to quantify the vented gases and
vapors.
2. Single-Cell Thermal Runaway
The IWG is considering a test-based approach during Phase 2 of
GTR No. 20. GTR No. 20 would require that the thermal propagation
test procedure fulfill the following conditions:
Triggering of thermal runaway at a single-cell level
must be repeatable, reproducible, and practicable,
Judgment of thermal runaway through common sensors,
e.g., voltage and temperature, needs to be practical, repeatable,
and reproducible, and
Judgement of whether consequent thermal events involve
severe thermal propagation hazards, needs to be unequivocal and
evidence based.
The two main initiation methods under consideration in Phase 2
are a localized rapid external heating method and a nail penetration
method. The localized rapid external heating method is comprised of
a film heater which is attached to an initiation cell's surface. The
heater is turned on and set to reach its maximum power, and only
turned off after thermal runaway occurs. In the nail penetration
method, a steel nail 3 mm in diameter or more, with a circular cone
is inserted into the initiation cell at a speed of 0.1 ~ 10 mm/s,
which internally short-circuits the cell, inducing thermal runaway.
Current GTR No. 20 specifies three conditions in which thermal
runaway can be detected:
1. The measured voltage of the initiation cell drops,
2. The measured temperature exceeds the maximum operating
temperature defined by the manufacturer, and
3. The instantaneous rate of temperature change (dT/dt) >=1
[deg]C/s of the measured temperature.
Per GTR No. 20, thermal runaway can be judged when both (1) and
(3) are detected, or both (2) and (3) are detected.
For the test procedure development, the only operational mode
originally considered was the active driving possible mode. As
discussions continue in Phase 2, other operational modes such as
parking and externally charging are also under consideration.
However, the test methods and performance criteria are still under
development.
NHTSA conducted thermal runaway propagation tests on four
different electric vehicle models using both the localized rapid
external heating method \148\ and the nail penetration (NP)
method.\149\ The criteria for identifying whether thermal runaway
was initiated as described in ISO-6469-1:2019/DAM 1:2021(E) were
used. Six tests were conducted at the vehicle level (with REESS
installed in the vehicle) on four vehicle makes and models as shown
in Table B-1.
---------------------------------------------------------------------------
\148\ Thermal Runaway Initiation Method (TRIM) heater developed
by the National Research Council (NRC) Canada.
\149\ The testers used a generic nail similar to that specified
in the ISO-6469-1:2019/DAM 1 1:2021(E).
Table B-1--Thermal Runaway Propagation Tests Using Two Different Methods of Initiating Thermal Runaway on a
Single Cell
----------------------------------------------------------------------------------------------------------------
Thermal runaway initiation method
-----------------------------------------------------------
Vehicle make, model, and model year Localized external rapid
heater method Nail penetration method
----------------------------------------------------------------------------------------------------------------
2019 Chevrolet Bolt................................. X
2020 Nissan Leaf.................................... X
2020 Tesla Model 3.................................. X, X (Two tests)
2021 Chevrolet Bolt................................. X X
2021 Nissan Leaf.................................... X
2022 Kia Niro....................................... X X
----------------------------------------------------------------------------------------------------------------
Note--X represents a test was conducted.
Thermal runaway was initiated using the localized heating method
in tests with both the 2019 and 2021 Chevrolet Bolt vehicles, the
2020 Nissan Leaf, 2020 Tesla Model 3, and the 2022 Kia Niro. Two
tests using the localized heating method were conducted on the 2020
Tesla Model 3 because the first test did not result in a thermal
runaway. Tests were conducted on the 2021 Chevrolet Bolt, 2021
Nissan Leaf, and the 2022 Kia Nero using the nail penetration method
for initiating thermal runaway.
Significant information was needed from the manufacturers on
opening up the battery pack and on selecting the cell for initiating
thermal runaway using both methods. The selection of the cell for
initiating thermal runaway was not random and was based on which
cells were accessible; the cells were not necessarily those that are
more likely to cause thermal propagation if a thermal runaway was
initiated. Copious amounts of smoke were released within and outside
of the passenger cabin before flames were observed. Some of the gas
emissions include hydrogen (flammable) and carbon monoxide (toxic).
All vehicles tested have REESSs with pouch cells except for the
Tesla Model 3, whose REESS has cylindrical cells. In the first Tesla
Model 3, the initial heater was unsuccessful in transferring heat
into the target cell due to lack of back pressure on the heater. In
the second test, the target cell went into thermal runaway but
experienced a side wall rupture towards the outside of the battery
pack.\150\ The timing of the smoke emissions and the thermal
propagation was not the same for the two methods of initiating
thermal runaway in a single cell of the REESS. The results of the
tests and the timing of various events are shown in Table B-2 below.
---------------------------------------------------------------------------
\150\ Side wall rupture does not represent thermal runaway
events observed in the field.
Table B-2--Single-Cell Thermal Runaway and Propagation Test Results--Timing of Events
--------------------------------------------------------------------------------------------------------------------------------------------------------
External smoke Smoke in cabin External flame Warning observed Venting observed CO in ppm
Method Vehicle (min:sec) (min:sec) (min:sec) (min:sec) (min:sec) (min:sec)
--------------------------------------------------------------------------------------------------------------------------------------------------------
TRIM.......................... 2019 Chevrolet 00:15 00:38 22:29 No............... Yes............. N/A.
Bolt.
TRIM.......................... 2021 Chevrolet 00:17 01:10 08:17 Yes (00:51)...... Yes............. >100 ppm
Bolt. (02:20),
>1500 ppm
(03:30).
NP............................ 2021 Chevrolet 00:07 03:10 11:58 Yes (00:27)...... Yes............. >100 ppm
Bolt. (07:30),
>1200 ppm
(08:58).
TRIM.......................... 2020 Nissan Leaf. 00:25 04:45 31:09 Yes (00:45)...... Yes............. N/A.
NP............................ 2021 Nissan Leaf. 00:05 01:10 24:48 Yes (00:34)...... Yes............. >100 ppm
(10:10),
>800 ppm
(21:30).
TRIM.......................... 2020 Tesla Model N/A N/A N/A No............... No.............. N/A.
3.
TRIM.......................... 2021 Tesla Model 00:28 N/A N/A No............... Yes............. N/A.
3.
[[Page 26739]]
TRIM.......................... 2022 Kia Niro.... 01:01 03:57 177:03 No............... Yes............. 25 ppm (05:25).
NP............................ 2022 Kia Niro.... 07:16 14:40 59:31 No............... Yes............. >100 ppm
(14:20).
--------------------------------------------------------------------------------------------------------------------------------------------------------
For the localized rapid external heating method, the heating
element parameter may vary depending on the different battery
chemistries or cell type (e.g., large prismatic cells versus
cylindrical cells).\151\ More stable chemistries will require higher
heat inputs than less stable chemistries. Calorimetric testing may
need to be implemented to provide insights on what heating input
parameters would be representative to avoid penalizing more stable
cell chemistries, since they may require higher heat inputs to
induce thermal runaway. The nail penetration method may be
implemented in lieu of the localized rapid external heating method
for more stable chemistries. It remains unclear whether the two
initiation methods under consideration are equivalent in stringency.
NHTSA's research results indicate that the timing of thermal
propagation is different for the different thermal runaway
initiation methods for the same vehicle models. The rapid heating
and nail penetration thermal runaway initiation methods can be
applied to only some cells in the REESS or REESS subsystem; only the
cells that can be accessed and modified without impinging on
adjacent cells in the pack can be triggered in these tests.\152\
Additionally, the criteria for assessing whether thermal runaway has
occurred in a cell needs further development.
---------------------------------------------------------------------------
\151\ ISO 6469-1:2019/DAM1:2021(E), ``Electrically propelled
road vehicles--Safety specifications--Part 1: Rechargeable energy
storage system (RESS)--Draft Amendment 1.''
\152\ NHTSA's testing experience indicates that these testable
cells are generally located along the edges of a module. The result
of single-cell thermal runaway will vary with location based on heat
transfer to adjacent cells and other components.
---------------------------------------------------------------------------
Part of the performance criteria for a thermal runaway
propagation test under consideration is for some form of warning to
vehicle occupants and/or bystanders outside the vehicle in the event
of thermal propagation within and outside the REESS. However, NHTSA
considers warning to be a secondary mitigation strategy which would
not prevent the thermal propagation from occurring in the first
place. Thermal propagation resulting in EV fires are difficult to
extinguish and may cause significant damage to adjacent structures
and may pose a safety risk to people nearby, even when a warning is
provided. In comparison, in the agency's view, the proposed
documentation requirements provide a holistic risk mitigation of
thermal propagation events resulting from single-cell thermal
runaway due to an internal short-circuit within the cell. This risk
mitigation would include of a cell in an REESS significantly before
thermal runaway occurs to allow for appropriate action to be taken.
Vehicle manufacturers are currently incorporating such technologies
into the BMS to predict and evaluate the status of individual cells
and mitigate the occurrence of single cell thermal runaway (SCTR) in
the first place.
NHTSA seeks comment on the proposed reporting requirements to
mitigate the risk of SCTR due to an internal short-circuit in a
single cell of the REESS and the performance test under
consideration in GTR No. 20 Phase 2.
3. REESS Vibration Requirements
Currently, during Phase 2 development of GTR No. 20, there are
discussions for updating the vibration test to include vibration in
all three orthogonal axes and at higher amplitudes and frequency
range. NHTSA seeks comment on the safety need that would warrant an
update to a more stringent vibration test than that already in UN
38.3 Test T3.\153\ NHTSA seeks comment from vehicle manufacturers on
practices they have implemented to avoid reliability issues and
assure customer satisfaction in the field.
---------------------------------------------------------------------------
\153\ The vibration load spectrum in GTR No. 20 was derived from
UN 38.3.4.3 ``Recommendation on the Transport of Dangerous Goods,
Manual of Tests and Criteria.'' https://unece.org/fileadmin/DAM/trans/danger/publi/manual/Rev7/Manual_Rev7_E.pdf.
---------------------------------------------------------------------------
List of Subjects in 49 CFR Part 571
Imports, Incorporation by Reference, Motor vehicles, Motor vehicle
safety.
Proposed Regulatory Text
In consideration of the foregoing, NHTSA proposes to amend 49 CFR
part 571 as set forth below.
PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS
0
1. The authority citation for part 571 continues to read as follows:
Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166;
delegation of authority at 49 CFR 1.95.
0
2. Section 571.5 is amended by adding paragraphs (i)(5), (i)(6), and
(i)(7), to read as follows:
Sec. 571.5 Matter incorporated by reference.
* * * * *
(i) * * *
* * *
(5) ISO 17840-1:2022 (E), ``Road vehicles--Information for first
and second responders--Part 1: Rescue sheet for passenger cars and
light commercial vehicles,'' Second Edition, February 2022, into Sec.
571.305a.
(6) ISO 17840-2:2019 (E), ``Road vehicles--Information for first
and second responders--Part 2: Rescue sheet for buses, coaches and
heavy commercial vehicles,'' First edition, April 2019, into Sec.
571.305a.
(7) ISO 17840-3:2019 (E), '' Road vehicles--Information for first
and second responders--Part 3: Emergency response guide template,''
First Edition, April 2019, into Sec. 571.305a.
* * * * *
0
3. Section 571.305a is added to read as follows:
Sec. 571.305a Standard No. 305a; Electric-Powered Vehicles: Electric
Powertrain Integrity; Mandatory applicability begins on (this date will
be the compliance date of the final rule).
S1. Scope. This standard specifies requirements for protection from
harmful electric shock, fire, explosion, and gas venting during normal
vehicle operation and during and after a crash.
S2. Purpose. The purpose of this standard is to reduce deaths and
injuries during normal vehicle operations and during and after a crash
that occur because of electrolyte leakage, intrusion of electric energy
storage/conversion devices into the occupant compartment, electric
shock, fire, explosion, and gas venting, including deaths and injuries
due to driver error.
S3. Application. This standard applies to passenger cars,
multipurpose passenger vehicles, trucks, and buses that use electrical
propulsion components with working voltages greater than 60 volts
direct current (VDC) or 30 volts alternating current (VAC), and whose
speed attainable over a distance of 1.6 km on a paved level surface is
more than 40 km/h.
S4. Definitions.
Active driving possible mode means the vehicle mode when
application of pressure to the accelerator pedal (or activation of an
equivalent control) or release of the brake system causes the electric
power train to move the vehicle.
Automatic disconnect means a device that when triggered,
conductively separates a high voltage source from the electric power
train or the rest of the electric power train.
Breakout harness means connector wires that are connected for
testing purposes to the REESS on the traction side of the automatic
disconnect.
[[Page 26740]]
Capacitor means a device used to store electrical energy,
consisting of one or more pairs of conductors separated by an
insulator: x-capacitors are connected between electrical mains or
neutral and y-capacitors are connected between a main to ground.
Charge connector is a conductive device that, by insertion into a
vehicle charge inlet, establishes an electrical connection of the
vehicle to an external electric power supply for the purpose of
transferring energy.
Chassis dynamometer means a mechanical device that uses one or more
fixed roller assemblies to simulate different road conditions within a
controlled environment and is used for a wide variety of vehicle
testing.
Connector means a device providing mechanical connection and
disconnection of high voltage electrical conductors to a suitable
mating component, including its housing.
n C Rate means the constant current of the REESS, which takes 1/n
hours to charge or discharge the REESS between 0 and 100 percent state
of charge.
Direct contact is the contact of any person or persons with high
voltage live parts.
Electric energy storage device means a high voltage source that
stores energy for vehicle propulsion. This includes, but is not limited
to, a high voltage battery or battery pack, rechargeable energy storage
device, and capacitor module.
Electric energy storage/conversion device means a high voltage
source that stores or converts energy for vehicle propulsion. This
includes, but is not limited to, a high voltage battery or battery
pack, fuel cell stack, rechargeable energy storage device, and
capacitor module.
Electric energy storage/conversion system means an assembly of
electrical components that stores or converts electrical energy for
vehicle propulsion. This includes, but is not limited to, high voltage
batteries or battery packs, fuel cell stacks, rechargeable energy
storage systems, capacitor modules, inverters, interconnects, and
venting systems.
Electric power train means an assembly of electrically connected
components which includes, but is not limited to, electric energy
storage/conversion systems and propulsion systems.
Electrical chassis means conductive parts of the vehicle whose
electrical potential is taken as reference and which are:
(1) conductively linked together, and
(2) not high voltage sources during normal vehicle operation.
Electrical isolation of a high voltage source in the vehicle means
the electrical resistance between the high voltage source and any of
the vehicle's electrical chassis divided by the working voltage of the
high voltage source.
Electrical protection barrier is the part providing protection
against direct contact with high voltage live parts from any direction
of access.
Electrolyte leakage means the escape of liquid electrolyte from the
REESS.
Emergency response guide means a document containing in-depth
vehicle-specific information related to fire, submersion, leakage of
fluids, towing, and storage of vehicles for first and second
responders.
Exposed conductive part is the conductive part that can be touched
under the provisions of the IPXXB protection degree and that is not
normally energized, but that can become electrically energized under
isolation fault conditions. This includes parts under a cover if the
cover can be removed without using tools.
External Charging mode means the vehicle mode when the REESS is
charging with external electric power supply connected through the
charge connector to the vehicle charge inlet.
External electric power supply is a power supply external to the
vehicle that provides electric power to charge the electric energy
storage device in the vehicle through the charge connector.
First responder means a person with specialized training such as a
law enforcement officer, paramedic, emergency medical technician, and/
or firefighter.
Fuel cell system is a system containing the fuel cell stack(s), air
processing system, fuel flow control system, exhaust system, thermal
management system, and water management system.
High voltage live part means a live part of a high voltage source.
High voltage source means any electric component which is contained
in the electric power train or conductively connected to the electric
power train and has a working voltage greater than 30 VAC or 60 VDC.
Indirect contact is the contact of any person or persons with
exposed conductive parts.
Live part is a conductive part of the vehicle that is electrically
energized under normal vehicle operation.
Luggage compartment is the space in the vehicle for luggage
accommodation, separated from the passenger compartment by the front or
rear bulkhead and bounded by a roof, hood or trunk lid, floor, and side
walls, as well as by electrical protection barriers provided for
protecting the occupants from direct contact with high voltage live
parts.
Normal vehicle operation includes operating modes and conditions
that can reasonably be encountered during typical operation of the
vehicle, such as driving, parking, and standing in traffic, as well as
charging using chargers that are compatible with the specific charging
ports installed on the vehicle. It does not include conditions where
the vehicle is damaged, either by a crash or road debris, subjected to
fire or water submersion, or in a state where service and/or
maintenance is needed or being performed.
Parking mode is the vehicle mode in which the vehicle power is
turned off, the vehicle propulsion system and ancillary equipment such
as the radio are not operational, and the vehicle is stationary.
Passenger compartment is the space for occupant accommodation that
is bounded by the roof, floor, side walls, doors, outside glazing,
front bulkhead and rear bulkhead or rear gate, as well as electrical
protection barriers provided for protecting the occupants from direct
contact with high voltage live parts.
Propulsion system means an assembly of electric or electro-
mechanical components or circuits that propel the vehicle using the
energy that is supplied by a high voltage source. This includes, but is
not limited to, electric motors, inverters/converters, and electronic
controllers.
Protection degree IPXXB is protection from contact with high
voltage live parts. It is tested by probing electrical protection
barriers with the jointed test finger probe, IPXXB, in Figure 7b.
Protection degree IPXXD is protection from contact with high
voltage live parts. It is tested by probing electrical protection
barriers with the test wire probe, IPXXD, in Figure 7a.
Rechargeable Electrical Energy Storage System (REESS) means the
rechargeable electric energy storage system that provides electric
energy for electrical propulsion.
Rescue sheet means an abbreviated version of an emergency response
guide that gives quick information about a vehicle's construction,
intended for use by first and second responders at the scene of a
crash.
Rupture means an opening through the casing of the REESS that would
permit the IPXXB test probe to penetrate and contact live parts.
Second responder means a worker who supports first responders by
cleaning up a site, towing vehicles, and/
[[Page 26741]]
or supporting services after an event requiring first responders.
Service disconnect is the device for deactivation of an electrical
circuit when conducting checks and services of the vehicle electrical
propulsion system.
State of charge (SOC) means the available electrical charge in a
tested device expressed as a percentage of its rated capacity.
Thermal event means the condition when the temperature within the
REESS is significantly higher than the maximum operating temperature.
Thermal runaway means an uncontrolled increase of cell temperature
caused by exothermic reactions inside the cell.
Thermal propagation means the sequential occurrence of thermal
runaway within a REESS triggered by thermal runaway of a cell in the
REESS.
VAC means volts of alternating current (AC) expressed using the
root mean square value.
VDC means volts of direct current (DC).
Vehicle charge inlet is the device on the electric vehicle into
which the charge connector is inserted for the purpose of transferring
energy and exchanging information from an external electric power
supply.
Venting means the release of excessive internal pressure from cell
or battery in a manner intended by design to preclude rupture or
explosion.
Working voltage means the highest root mean square voltage of the
voltage source, which may occur across its terminals or between its
terminals and any conductive parts in open circuit conditions or under
normal operating conditions.
S5. General Requirements.
S5.1 Vehicles of GVWR of 4,536 kilograms (kg) or less (light
vehicles). Each vehicle with a GVWR of 4,536 kg or less shall meet the
requirements set forth in S6 (normal vehicle operation safety), S8
(post-crash safety), S11 (vehicle controls managing REESS safe
operations), S13.2 (thermal event in REESS warning), S14 (water
exposure safety), and S15 (emergency response information).
S5.2 Vehicles with a GVWR greater than 4,536 kg other than school
buses (heavy vehicles other than school buses). Each heavy vehicle with
a GVWR greater than 4,536 kg, other than school buses, shall meet the
requirements set forth in S6 (normal vehicle operation safety), S11
(vehicle controls managing REESS safe operations), S13.2 (thermal event
in REESS warning), S14 (water exposure safety), and S15 (emergency
response information).
S5.3 School buses with a GVWR greater than 4,536 kg. Each school
bus with a GVWR greater than 4,536 kg shall meet the requirements set
forth in S6 (normal vehicle operation safety), S8 (post-crash safety),
S11 (vehicle controls managing REESS safe operations), S13.2 (thermal
event in REESS warning), S14 (water exposure safety), and S15
(emergency response information).
S6. Normal vehicle operation safety. Each vehicle to which this
standard applies must meet the requirements in S6.1 to S6.6, when
tested according to the relevant provisions in S7.
S6.1 Protection against direct contact.
S6.1.1 Marking. The symbol shown in Figure 6 shall be present on or
near electric energy storage devices. The symbol in Figure 6 shall also
be visible on electrical protection barriers which, when removed,
expose live parts of high voltage sources. The symbol shall be yellow
and the bordering and the arrow shall be black.
S6.1.1.1 The marking is not required for electrical protection
barriers that cannot be physically accessed, opened, or removed without
the use of tools. Markings are not required for electrical connectors
or the vehicle charge inlet.
S6.1.2 High voltage cables. Cables for high voltage sources which
are not located within electrical protection barriers shall be
identified by having an outer covering with the color orange.
S6.1.3 Service disconnect. For a service disconnect which can be
opened, disassembled, or removed without tools, protection degree IPXXB
shall be provided when tested under procedures specified in S7.3.1
using the IPXXB test probe shown in Figures 7a and 7b.
S6.1.4 Protection degree of high voltage live parts.
(a) Protection degree IPXXD shall be provided for high voltage live
parts inside the passenger or luggage compartment when tested according
to the procedures specified in S7.3.1 using the IPXXD test probe shown
in Figure 7a.
(b) Protection degree IPXXB shall be provided for high voltage live
parts in areas other than the passenger or luggage compartment when
tested according to the procedures specified in S7.3.1 using the IPXXB
test probe shown in Figures 7a and 7b.
S6.1.5 Connectors. All connectors shall provide direct contact
protection by:
(a) Meeting the requirements specified in S6.1.4 when the connector
is connected to its corresponding mating component; and,
(b) If a connector can be separated from its mating component
without the use of a tool, meeting at least one of the following
conditions from (b)(1), (2), or (3) of this section:
(1) The connector meets the requirements of S6.1.4 when separated
from its mating component;
(2) The voltage of the live parts becomes less than or equal to 60
VDC or 30 VAC within one second after the connector is separated from
its mating component; or,
(3) The connector requires at least two distinct actions to
separate from its mating component and there are other components that
must be removed in order to separate the connector from its mating
component and these other components cannot be removed without the use
of tools.
S6.1.6 Vehicle charge inlet. Direct contact protection for a
vehicle charge inlet shall be provided by meeting the requirements
specified in S6.1.4 when the charge connector is connected to the
vehicle inlet and by meeting at least one of the requirements of
subparagraphs (a) or (b).
(a) The vehicle charge inlet meets the requirements of S6.1.4 when
the charge connector is not connected to it; or
(b) The voltage of the high voltage live parts becomes equal to or
less than 60 VDC or equal to or less than 30 VAC within 1 second after
the charge connector is separated from the vehicle charge inlet.
S6.2 Protection against indirect contact.
S6.2.1 The resistance between all exposed conductive parts of
electrical protection barriers and the electrical chassis shall be less
than 0.1 ohms when tested according to the procedures specified in
S7.3.2
S6.2.2 The resistance between any two simultaneously reachable
exposed conductive parts of the electrical protection barriers that are
less than 2.5 meters from each other shall be less than 0.2 ohms when
tested according to the procedures specified in S7.3.2.
S6.3 Electrical isolation.
S6.3.1 Electrical isolation of AC and DC high voltage sources. The
electrical isolation of a high voltage source, determined in accordance
with the procedure specified in S7.2 must be greater than or equal to
one of the following:
(a) 500 ohms/volt for an AC high voltage source;
(b) 100 ohms/volt for an AC high voltage source if it is
conductively connected to a DC high voltage source, but only if the AC
high voltage source meets the requirements for protection against
direct contact in S6.1.4 and the
[[Page 26742]]
protection from indirect contact in S6.2; or
(c) 100 ohms/volt for a DC high voltage source.
S6.3.2 Exclusion of high voltage sources from electrical isolation
requirements. A high voltage source that is conductively connected to
an electric component which is conductively connected to the electrical
chassis and has a working voltage less than or equal to 60 VDC, is not
required to meet the electrical isolation requirements in S6.3.1 if the
voltage between the high voltage source and the electrical chassis is
less than or equal to 30 VAC or 60 VDC.
S6.3.3 Electrical isolation of high voltage sources for charging
the electric energy storage device. For the vehicle charge inlet
intended to be conductively connected to the AC external electric power
supply, the electric isolation between the electrical chassis and the
high voltage sources that are conductively connected to the vehicle
charge inlet during charging of the electric energy storage device
shall be greater than or equal to 500 ohms/volt when the charge
connector is disconnected. The electrical isolation is measured at the
high voltage live parts of the vehicle charge inlet and determined in
accordance with the procedure specified in S7.2. During the
measurement, the electric energy storage device may be disconnected.
S6.4 Electrical isolation monitoring. DC high voltage sources of
vehicles with a fuel cell system shall be monitored by an electrical
isolation monitoring system that displays a warning for loss of
isolation when tested according to S7.4. The system must monitor its
own readiness and the visual warning display must be provided to the
driver. For a vehicle with autonomous driving systems and without
manually-operated driving controls, the visual warning must be provided
to all the front row occupants.
S6.5 Electric shock protection during charging. For motor vehicles
with an electric energy storage device that can be charged through a
conductive connection with a grounded external electric power supply, a
device to enable conductive connection of the electrical chassis to the
earth ground shall be provided. This device shall enable connection to
the earth ground before exterior voltage is applied to the vehicle and
retain the connection until after the exterior voltage is removed from
the vehicle.
S6.6 Mitigating driver error.
S6.6.1 Indicator of active driving possible mode. At least a
momentary indication shall be given to the driver each time the vehicle
is first placed in active driving possible mode after manual activation
of the propulsion system. This requirement does not apply under
conditions where an internal combustion engine directly or indirectly
provides the vehicle's propulsion power when the vehicle is first
placed in the active driving possible mode after manual activation of
the propulsion system.
S6.6.2 Indicator of active driving possible mode when leaving the
vehicle. When leaving the vehicle, the driver shall be informed by an
auditory or visual signal if the vehicle is still in the active driving
possible mode.
S6.6.3 Prevent drive-away. If the on-board electric energy storage
device can be externally charged, vehicle movement of more than 150 mm
by its own propulsion system shall not be possible as long as the
charge connector of the external electric power supply is physically
connected to the vehicle charge inlet in a manner that would permit
charging of the electric energy storage device.
S7. Electrical safety test procedures for normal vehicle operation
safety. The following provisions specify the test procedures associated
with the requirements of S6.
S7.1 Voltage measurements. For the purpose of determining the
voltage level of the high voltage source, voltage is measured as shown
in Figure 1 using a voltmeter that has an internal resistance of at
least 10 M[Omega]. All post-crash voltage measurements for determining
electrical isolation of high voltage sources specified in S8.2(a), the
voltage levels specified in S8.2(b), and the energy in capacitors
specified in S8.2(d) are made between 10 to 60 seconds after impact.
S7.1.1 For a high voltage source that has an automatic disconnect
that is physically contained within itself, the voltage measurement
after the test is made from the side of the automatic disconnect
connected to the electric power train or to the rest of the electric
power train if the high voltage source is a component contained in the
power train. For a high voltage source that has an automatic disconnect
that is not physically contained within itself, the voltage measurement
after the test is made from both the high voltage source side of the
automatic disconnect and from the side of the automatic disconnect
connected to the electric power train or to the rest of the electric
power train if the high voltage source is a component contained in the
power train.
S7.1.2 Voltage Vb is measured across the two terminals of the
voltage source. Before a vehicle crash test, Vb is equal to or greater
than the working voltage as specified by the vehicle manufacturer.
S7.1.3 Voltage V1 is measured between the negative side of the high
voltage source and the electrical chassis as shown in Figure 2. Voltage
V2 is measured between the positive side of the high voltage source and
the electrical chassis as shown in Figure 3.
S7.2 Test method for determining electrical isolation. Measure the
voltages V1, V2, and Vb as shown in Figure 1 in accordance with S7.1
S7.2.1 If V1 is greater than or equal to V2, insert a known
resistance (Ro) between the negative side of the high voltage source
and the electrical chassis. With the Ro installed, measure the voltage
(V1') as shown in Figure 4 between the negative side of the high
voltage source and the electrical chassis. Calculate the electrical
isolation resistance (Ri) according to the formula shown. Divide Ri (in
ohms) by the working voltage of the high voltage source (in volts) to
obtain the electrical isolation (in ohms/volt).
S7.2.2 If V2 is greater than V1, insert a known resistance (Ro)
between the positive side of the high voltage source and the electrical
chassis. With the Ro installed, measure the voltage (V2') as shown in
Figure 5 between the positive side of the high voltage source and the
electrical chassis. Calculate the electrical isolation resistance (Ri)
according to the formula shown. Divide Ri (in ohms) by the working
voltage of the high voltage source (in volts) to obtain the electrical
isolation (in ohms/volt).
S7.3 Test methods for evaluating physical barrier protection.
S7.3.1 Test method to evaluate protection from direct contact with
high voltage sources.
(a) Any parts surrounding the high voltage components are opened,
disassembled, or removed without the use of tools.
(b) The selected access probe is inserted into any gaps or openings
of the electrical protection barrier with a test force between 9 Newton
to 11 Newton with the IPXXB probe or 1 Newton to 2 Newton with the
IPXXD probe. If the probe partly or fully penetrates into the
electrical protection barrier, it is placed in every possible position
to evaluate contact with high voltage live parts. If partial or full
penetration into the electrical protection barrier occurs with the
IPXXB probe, the IPXXB probe shall be placed as follows: starting from
the straight position, both joints of the test finger are rotated
progressively through an angle of up to 90 degrees with respect to the
axis of the adjoining
[[Page 26743]]
section of the test finger and are placed in every possible position.
(c) A low voltage supply (of not less than 40 V and not more than
50 V) in series with a suitable lamp may be connected between the
access probe and any high voltage live parts inside the electrical
protection barrier to indicate whether high voltage live parts were
contacted.
(d) A mirror or fiberscope may be used to inspect whether the
access probe touches high voltage live parts inside the electrical
protection barrier.
(e) Protection degree IPXXD or IPXXB is verified when the following
conditions are met:
(1) The access probe does not touch high voltage live parts. The
IPXXB access probe may be manipulated as specified in S7.3.1(b) for
evaluating contact with high voltage live parts. The methods specified
in S7.3.1(c) or S7.3.1(d) may be used to aid the evaluation. If method
S7.3.1(c) is used for verifying protection degree IPXXB or IPXXD, the
lamp shall not light up.
(2) The stop face of the access probe does not fully penetrate into
the electrical protection barrier.
S7.3.2 Test method to evaluate protection against indirect contact
with high voltage sources. Any parts surrounding the high voltage
components are opened, disassembled, or removed without the use of
tools. At the option of the manufacturer, protection against indirect
contact with high voltage sources shall be determined using the test
method in subparagraph (a) or subparagraph (b).
(a) Test method using a resistance tester. The resistance tester is
connected to the measuring points (the electrical chassis and any
exposed conductive part of electrical protection barriers or any two
simultaneously reachable exposed conductive parts of electrical
protection barriers that are less than 2.5 meters from each other), and
the resistance is measured using a resistance tester that can supply
current levels of at least 0.2 Amperes with a resolution of 0.01 ohms
or less. The resistance between two exposed conductive parts of
electrical protection barriers that are less than 2.5 meters from each
other may be calculated using the separately measured resistances of
the relevant parts of the electric path.
(b) Test method using a DC power supply, voltmeter, and ammeter.
(1) Connect the DC power supply, voltmeter, and ammeter to the
measuring points (the electrical chassis and any exposed conductive
part or any two simultaneously reachable exposed conductive parts that
are less than 2.5 meters from each other) as shown in Figure 8.
(2) Adjust the voltage of the DC power supply so that the current
flow becomes more than 0.2 Amperes.
(3) Measure the current I and the voltage V shown in Figure 8.
(4) Calculate the resistance R according to the formula, R=V/I.
(5) The resistance between two simultaneously reachable exposed
conductive parts of electrical protection barriers that are less than
2.5 meters from each other may be calculated using the separately
measured resistances of the relevant parts of the electric path.
S7.3.3 Test method to determine voltage between exposed conductive
parts of electrical protection barriers and the electrical chassis and
between exposed conductive parts of electrical protection barriers.
(a) Any parts surrounding the high voltage components are opened,
disassembled, or removed without the use of tools.
(b) Connect the voltmeter to the measuring points (exposed
conductive part of an electrical protection barrier and the electrical
chassis or any two simultaneously reachable exposed conductive parts of
electrical protection barriers that are less than 2.5 meters from each
other).
(c) Measure the voltage.
(d) The voltage between two simultaneously reachable exposed
conductive parts of electrical protection barriers that are less than
2.5 meters from each other may be calculated using the separately
measured voltages between the relevant electrical protection barriers
and the electrical chassis.
S7.4 Test method for evaluating on-board electrical isolation
monitoring system.
Prior to any impact test, the requirements of S6.4 for the on-board
electrical isolation monitoring system shall be tested using the
following procedure.
(a) The electric energy storage device is at the state-of-charge
specified in S7.1.
(b) The switch or device that provides power from the electric
energy storage/conversion system to the propulsion system is in the
activated position or the ready-to-drive position.
(c) Determine the isolation resistance, Ri, of the high voltage
source with the electrical isolation monitoring system using the
procedure outlined in S7.2.
(d) Insert a resistor with resistance Ro equal to or greater than
1/(1/(95 times the working voltage of the high voltage source)--1/Ri)
and less than 1/(1/(100 times the working voltage of the high voltage
source)--1/Ri) between the positive terminal of the high voltage source
and the electrical chassis.
(e) The electrical isolation monitoring system indicator shall
provide a visual warning to the driver. For a vehicle with autonomous
driving systems and without manually-operated driving controls, the
visual warning must be provided to all the front row occupants.
S7.5 Test method for determining post-crash energy in capacitors.
(a) Prior to the crash tests, the vehicle manufacturer must
identify the capacitors, type of capacitors (x-capacitors and y-
capacitors) and their respective capacitance (Cx and Cy) in the
electric power train for which the low energy compliance option for
post-crash electrical safety in S8.2(d) is applied.
(b) Voltages Vb, V1, and V2 are measured across the capacitors in
accordance with S7.1.
(c) The energy in a x-capacitor is equal to 0.5 x Cx x Vb\2\
(d) The energy in a y-capacitor is equal to 0.5 x Cy x (V1\2\ +
V2\2\).
S8. Post-crash safety. Each vehicle with a GVWR of 4,536 kg or less
to which this standard applies, must meet the requirements in S8.1,
S8.2, S8.3, and S8.4 when tested according to S9 under the conditions
of S10. Each school bus with a GVWR greater than 4,536 kg to which this
standard applies, must meet the requirements in S8.1, S8.2, S8.3, and
S8.4 when tested according to S9.5 under the conditions of S10.
S8.1 Fire safety. Starting from the time of impact and continuing
until one hour after the completion of the sequence of tests specified
in S9 of this standard, there shall be no evidence of fire or explosion
in any part of the vehicle. The assessment of fire or explosion is
verified by visual inspection without disassembly of the REESS or
vehicle.
S8.2 Electrical safety. After each test specified in S9 of this
standard, each high voltage source in a vehicle must meet one of the
following electrical safety requirements: electrical isolation
requirements of subparagraph (a), the voltage level requirements of
subparagraph (b), or the physical barrier protection requirements of
subparagraph (c). High voltage capacitors in the electric power train
may also meet electrical safety requirements using the low-energy
requirements of subparagraph (d).
(a) The electrical isolation of the high voltage source, determined
in accordance with the procedure specified in S7.2, must be greater
than or equal to one of the following:
[[Page 26744]]
(1) 500 ohms/volt for an AC high voltage source; or
(2) 100 ohms/volt for an AC high voltage source if it is
conductively connected to a DC high voltage source, but only if the AC
high voltage source meets the physical barrier protection requirements
specified in S8.3(c)(1) and S8.3(c)(2); or
(3) 100 ohms/volt for a DC high voltage source.
(b) The voltages V1, V2, and Vb of the high voltage source,
measured according to the procedure specified in S7.1, must be less
than or equal to 30 VAC for AC components or 60 VDC for DC components.
(c) Protection against electric shock by direct and indirect
contact (physical barrier protection) shall be demonstrated by meeting
the following three conditions:
(1) The high voltage source (AC or DC) meets the protection degree
IPXXB when tested according to the procedure specified in S7.3.1 using
the IPXXB test probe shown in Figures 7a and 7b;
(2) The resistance between exposed conductive parts of the
electrical protection barrier of the high voltage source and the
electrical chassis is less than 0.1 ohms when tested according to the
procedures specified in S7.3.2. In addition, the resistance between an
exposed conductive part of the electrical protection barrier of the
high voltage source and any other simultaneously reachable exposed
conductive parts of electrical protection barriers within 2.5 meters of
it must be less than 0.2 ohms when tested using the test procedures
specified in S7.3.2; and
(3) The voltage between exposed conductive parts of the electrical
protection barrier of the high voltage source and the electrical
chassis is less than or equal to 30 VAC or 60 VDC as measured in
accordance with S7.3.3. In addition, the voltage between an exposed
conductive part of the electrical protection barrier of the high
voltage source and any other simultaneously reachable exposed
conductive parts of electrical protection barriers within 2.5 meters of
it must be less than or equal to 30 VAC or 60 VDC as measured in
accordance with S7.3.3.
(d) The total energy of unidirectional single impulse currents from
capacitors shall be less than 0.2 Joules when determined in accordance
with the procedure specified in S7.5.
S8.3 Electric energy storage/conversion device retention. During
and after each test specified in S9 of this standard:
(a) Electric energy storage/conversion devices shall remain
attached to the vehicle by at least one component anchorage, bracket,
or any structure that transfers loads from the device to the vehicle
structure, and
(b) Electric energy storage/conversion devices located outside the
occupant compartment shall not enter the occupant compartment.
S8.4 Electrolyte leakage from electric energy storage devices. Not
more than 5.0 liters of electrolyte shall leak from electric energy
storage devices, and no visible trace of electrolyte shall leak into
the passenger compartment. Leakage is measured from the time of the
impact until 30 minutes thereafter, and throughout any static rollover
after a barrier impact test, specified in S9 of this standard.
S9. Crash test specifications. A test vehicle with a GVWR less than
or equal to 4,536 kg, under the conditions of S10, is subject to any
one single barrier crash test of S9.1, S9.2, or S9.3, followed by the
static rollover test of S9.4. A school bus with a GVWR greater than
4,536 kg, under the conditions of S10, is subject to the contoured
barrier crash test of S9.5. A particular vehicle need not meet further
test requirements after having been subjected to a single barrier
crash/static rollover test sequence.
S9.1 Frontal barrier crash. The test vehicle, with test dummies in
accordance with S6.1 of 571.301 of this chapter, traveling
longitudinally forward at any speed up to and including 48 km/h,
impacts a fixed collision barrier that is perpendicular to the line of
travel of the vehicle, or at an angle up to 30 degrees in either
direction from the perpendicular to the line of travel of the vehicle.
S9.2 Rear moving barrier impact. The test vehicle, with test
dummies in accordance with S6.1 of 571.301 of this chapter, is impacted
from the rear by a barrier that conforms to S7.3(b) of 571.301 of this
chapter and that is moving at any speed between 79 and 81 km/h.
S9.3 Side moving deformable barrier impact. The test vehicle, with
the appropriate 49 CFR part 572 test dummies specified in 571.214 at
positions required for testing by S7.1.1, S7.2.1, or S7.2.2 of Standard
214, is impacted laterally on either side by a moving deformable
barrier moving at any speed between 52.0 km/h and 54.0 km/h.
S9. 4 Post-impact test static rollover. After each crash test
specified in S9.1, S9.2, and S9.3, without any alteration of the
vehicle, the vehicle is rotated on its longitudinal axis to each
successive increment of 90 degrees under the test conditions of S10.3.
S9.5 Moving contoured barrier crash. The test vehicle, under the
conditions of S10.1 and S10.2, is impacted at any point and at any
angle by the moving contoured barrier assembly, specified in S7.5 and
S7.6 in 571.301 of this chapter, traveling longitudinally forward at
any speed up to and including 48 km/h.
S10. Crash test conditions.
S10.1 State-of-charge. The electric energy storage device(s) shall
be at the state-of-charge specified in either subparagraph (a), (b), or
(c):
(a) At the maximum state-of-charge in accordance with the vehicle
manufacturer's recommended charging procedures, as stated in the
vehicle owner's manual or on a label that is permanently affixed to the
vehicle; or
(b) If the manufacturer has made no recommendation for charging
procedures in the owner's manual or on a label permanently affixed to
the vehicle, at a state-of-charge of not less than 95 percent of the
maximum capacity of the electric energy storage device(s); or
(c) If the electric energy storage device(s) is/are rechargeable
only by an energy source on the vehicle, at any state-of-charge within
the normal operating voltage defined by the vehicle manufacturer.
S10.2 Vehicle conditions. The switch or device that provides power
from the electric energy storage/conversion system to the propulsion
system is in the activated position or the ready-to-drive position.
Bypass any devices or systems that do not allow the propulsion system
to be energized at the time of impact when the vehicle ignition is on
and the vehicle is in neutral.
S10.2.1 The parking brake is disengaged and the vehicle drive
system is in the neutral position. In a test conducted under S9.3, the
parking brake is set.
S10.2.2 Tires are inflated to the manufacturer's specifications.
S10.2.3 The vehicle, including test devices and instrumentation, is
loaded as follows:
(a) A passenger car is loaded to its unloaded vehicle weight plus
its rated cargo and luggage capacity weight, secured in the luggage
compartment, plus the necessary test dummies as specified in S9,
restrained only by means that are installed in the vehicle for
protection at its seating position.
(b) A multipurpose passenger vehicle, truck, or bus, with a GVWR of
4,536 kg (10,000 lb) or less, is loaded to its unloaded vehicle weight
plus the necessary dummies, as specified in S9, plus 136 kg or its
rated GVWR, whichever is less, secured in the load carrying area and
distributed as nearly
[[Page 26745]]
as possible in proportion to its GVWR. For the purpose of this
standard, unloaded vehicle weight does not include the weight of work-
performing accessories. Each dummy is restrained only by means that are
installed in the vehicle for protection at its seating position.
S10.3 Static rollover test conditions. The vehicle is rotated about
its longitudinal axis, with the axis kept horizontal, to each
successive increment of 90[deg], 180[deg], and 270[deg] at a uniform
rate, with 90[deg] of rotation taking place in any time interval from 1
to 3 minutes. After reaching each 90[deg] increment the vehicle is held
in that position for 5 minutes.
S10.4 Rear moving barrier impact test conditions. The conditions of
S7.3(b) and S7.6 of 571.301 of this chapter apply to the conducting of
the rear moving deformable barrier impact test specified in S9.2.
S10.5 Side moving deformable barrier impact test conditions. The
conditions of S8.9, S8.10, and S8.11 of 571.214 of this chapter apply
to the conduct of the side moving deformable barrier impact test
specified in S9.3.
S11. Vehicle controls managing REESS safe operations. Each vehicle
to which the standard applies shall meet the requirements in S11.1,
S11.2, and S11.3, when tested according to S12.
S11.1 When tested in accordance with the overcharge test in S12.1,
the over-discharge test in S12.2, the overcurrent test in S12.3, the
high-temperature test in S12.4, and the short-circuit test in
accordance with S12.5, each vehicle shall meet the following:
(a) During the test, there shall be no evidence of electrolyte
leakage, rupture, venting, fire, or explosion of the REESS as verified
by visual inspection without disassembly of the vehicle.
(b) The isolation resistance of the high voltage sources measured
after the test shall not be less than 100 ohms/volt when determined in
accordance with S7.2.
S11.2 The vehicle manufacturer must make available to the agency,
upon request, documentation in accordance with S12.7 that demonstrates
whether the vehicle is equipped with controls for REESS operations at
or below the lower boundary REESS temperature threshold for safe REESS
operations specified by the manufacturer.
S11.3 The vehicle manufacturer must make available to the agency,
upon request, documentation in accordance with S12.8 that demonstrates
the activation of a visual warning, when the vehicle is in active
driving possible mode to indicate operational failure of the vehicle
controls that manage the safe operation of the REESS. The warning
system shall monitor its own readiness and the visual warning must be
provided to the driver. For a vehicle with autonomous driving systems
and without manually operated driving controls, the visual warning must
be provided to all the front row occupants.
S12. Test methods and documentation for evaluating vehicle controls
managing REESS safe operations.
S12.1 Overcharge test. The overcharge test is conducted at ambient
temperatures between 10 [deg]C and 30 [deg]C, with the vehicle REESS
initially set between 90 to 95 percent SOC. The following steps are
conducted to evaluate the vehicle's overcharge protection controls:
(a) A breakout harness is connected to the traction side of the
REESS. Manufacturer may specify an appropriate location(s) and
attachment point(s) to connect the breakout harness.
(b) Temperature probes are connected to the REESS outer casing to
monitor changes in REESS temperature. Temperature measurements may also
be obtained through communication with the REESS control module.
(c) The external charge/discharge equipment, with maximum voltage
and current set at least 10 percent higher than the REESS voltage and
current limits, is connected to the breakout harness.
(d) The vehicle switch or device that provides power to the vehicle
controls that manage REESS operations is set to the activated position.
(e) The REESS is charged with the external charge/discharge
equipment with the maximum charge current specified by the
manufacturer. If the manufacturer does not specify an appropriate
charge current, then a charge rate of \1/3\C is used.
(f) Charging is continued until the following occurs:
(1) The overcharge protection control terminates the charge
current;
(2) The REESS temperature is 10 [deg]C above the manufacturer
specified maximum operating temperature of the REESS; or
(3) 12 hours have passed since the start of charging the vehicle.
(g) After the charge current is terminated, if charge and discharge
is permitted by the vehicle controls, a standard cycle is performed in
accordance with S12.6.
(h) After the completion of the standard cycle, or if the standard
cycle was not performed, after charging is terminated, the vehicle is
observed for 1 hour for evidence of electrolyte leakage, rupture,
venting, fire, or explosion of the REESS.
(i) At the conclusion of the test, electrical isolation of the
REESS is determined in accordance with S7.2.
S12.2 Over-discharge test. The over-discharge test is conducted at
ambient temperatures between 10 [deg]C and 30 [deg]C, with the vehicle
REESS initially set between 10 and 15 percent SOC. For a vehicle with
on-board energy conversion systems such as an internal combustion
engine or a fuel cell, the fuel supply is set to the minimum level
where active driving possible mode is permitted. The following steps
are conducted to evaluate the vehicle's over-discharge protection
controls:
(a) A breakout harness is connected to the traction side of the
REESS. Manufacturer may specify an appropriate location(s) and
attachment point(s) to connect the breakout harness.
(b) Temperature probes are connected to the REESS outer casing to
monitor changes in REESS temperature. Temperature measurements may also
be obtained through communication with the REESS control module.
(c) The external charge/discharge equipment, with maximum voltage
and current set at least 10 percent higher than the REESS voltage and
current limits, is connected to the breakout harness.
(d) The vehicle switch or device that provides power from the REESS
to the electric power train is set to the activated position or the
active driving possible mode.
(e) The REESS is discharged with the external charge/discharge
equipment with the maximum discharge rate under normal operating
conditions specified by the manufacturer. If the manufacturer does not
specify an appropriate discharge rate, a power load of 1kW is used.
(f) Discharging is continued until the following occurs:
(1) The over-discharge protection control terminates the discharge
current;
(2) The temperature gradient of the REESS is less than 4 [deg]C
through 2 hours from the start of discharge; or
(3) the vehicle is discharged to 25 percent of its nominal voltage
level.
(g) After the discharge current is terminated, a standard cycle is
performed in accordance with S12.6, if charge and discharge is
permitted by the vehicle controls.
(h) After the completion of the standard cycle, or if the standard
cycle was not performed, after discharging is terminated, the vehicle
is observed for 1 hour for evidence of electrolyte leakage, rupture,
venting, fire, or explosion of the REESS.
[[Page 26746]]
(i) At the conclusion of the test, electrical isolation of the
REESS is determined in accordance with S7.2.
S12.3 Overcurrent test. The overcurrent test is only conducted on
vehicles that have the capability of charging by DC external
electricity supply. The test is conducted at ambient temperatures
between 10 [deg]C and 30 [deg]C, with the vehicle REESS initially set
between 40 to 50 percent SOC. The following steps are conducted to
evaluate the vehicle's over-current protection controls:
(a) A breakout harness is connected to the traction side of the
REESS. Manufacturer may specify an appropriate location(s) and
attachment point(s) to connect the breakout harness.
(b) Temperature probes are connected to the REESS outer casing to
monitor changes in REESS temperature. Temperature measurements may also
be obtained through communication with the REESS control module.
(c) The external charge/discharge equipment, with maximum voltage
and current set at least 10 percent higher than the REESS voltage and
current limits, is connected to the breakout harness.
(d) The vehicle switch or device that provides power to the vehicle
controls that manage REESS operations is set to the activated position.
(e) The REESS is charged with the external charge/discharge
equipment with the maximum charge current specified by the
manufacturer. If the manufacturer does not specify an appropriate
charge current, then a charge rate of \1/3\C is used.
(f) After charging is initiated, the overcurrent specified by the
manufacturer is supplied over the course of 5 seconds from the maximum
charge current level to the over-current level. If the vehicle
manufacturer does not supply an overcurrent level, a 10 Ampere over-
current is supplied over 5 seconds. If charging is not terminated, the
over-current supply is increased in steps of 10 Amperes.
(g) Charging at the over-current level is continued until the
following occurs:
(1) The over-current protection control terminates the charge
current; or
(2) The temperature gradient of the REESS is less than 4 [deg]C
through 2 hours from the first overcurrent input;
(h) After the charge current is terminated, if charge and discharge
is permitted by the vehicle controls, a standard cycle is performed in
accordance with S12.6.
(i) After the completion of the standard cycle or if the standard
cycle was not performed, after charging is terminated, the vehicle is
observed for 1 hour for evidence of electrolyte leakage, rupture,
venting, fire, or explosion of the REESS.
(j) At the conclusion of the test, electrical isolation of the
REESS is determined in accordance with S7.2.
S12.4 Over-temperature test. The overtemperature test is conducted
at ambient temperatures between 10 [deg]C and 30 [deg]C on a chassis-
dynamometer with the vehicle REESS initially set between 90 to 95
percent SOC. For a vehicle with on-board energy conversion systems such
as an internal combustion engine or a fuel cell, the fuel supply is set
to allow operation for about one hour of driving. The following steps
are conducted to evaluate the vehicle's high temperature protection
controls:
(a) The cooling system of the REESS is disabled using manufacturer
supplied information. For an REESS that will not operate if the cooling
system is disabled, the cooling operation is significantly reduced. If
manufacturer does not supply information to disable or significantly
reduce the cooling system, methods such as crimping the liquid cooling
hose, removing refrigerant fluid, or blocking cabin air intakes for air
cooled REESS are applied.
(b) Temperature probes are connected to the REESS outer casing to
monitor changes in REESS temperature. Temperature measurements may also
be obtained through communication with the REESS control module.
(c) The vehicle is installed on a chassis dynamometer and the
vehicle switch or device that provides power from the REESS to the
electric power train is set to the activated position or the active
driving possible mode.
(d) The vehicle is driven on the dynamometer using an appropriate
vehicle manufacturer supplied drive profile and charging information
for discharge and charge of the REESS to raise the REESS temperature to
its upper boundary safe operating temperature within one hour. If an
appropriate manufacturer supplied drive profile is not available, the
vehicle is repeatedly accelerated to 80 mph and then decelerated to 15
mph within 40 seconds. If the manufacturer does not supply a charge
profile, then a charge rate greater than \1/3\C current is used.
(e) The discharge/charge procedure on the chassis-dynamometer is
continued until the following occurs:
(1) The vehicle terminates the discharge/charge cycle;
(2) The temperature gradient of the REESS is less than 4 [deg]C
through 2 hours from the start of the discharge/charge cycle; or
(3) 3 hours have passed since the start of discharge/charge cycles.
(g) After the discharge and charge procedure is terminated, if
charge and discharge is permitted by the vehicle controls, a standard
cycle is performed in accordance with S12.6.
(h) After the completion of the standard cycle, or if the standard
cycle is not performed, after the discharge and charge procedure is
terminated, the vehicle is observed for 1 hour for evidence of
electrolyte leakage, rupture, venting, fire, or explosion of the REESS.
(i) At the conclusion of the test, electrical isolation of the
REESS is determined in accordance with S7.2.
S12.5 External Short circuit test. The short circuit test is
conducted at ambient conditions with the vehicle REESS initially set
between 90 to 95 percent SOC. The following steps are conducted to
evaluate the vehicle's overcharge protection controls:
(a) A breakout harness is connected to the REESS. Manufacturer may
specify an appropriate location(s) and attachment point(s) to connect
the breakout harness.
(b) Temperature probes are connected to the REESS outer casing to
monitor changes in REESS temperature. Temperature measurements may also
be obtained through communication with the REESS control module.
(c) The vehicle switch or device that provides power to the vehicle
controls that manage REESS operations is set to the activated position.
(d) The short circuit contactor (with the contactors in open
position) is connected to the breakout harnesses. The total resistance
of the equipment to create the external short circuit (short circuit
contactor and breakout harnesses) is verified to be between 2 to 5
milliohms.
(e) The short circuit contactor is closed to initiate the short-
circuit.
(f) The short circuit condition is continued until the following
occurs:
(1) Short circuit current is terminated; or
(2) The temperature gradient of the REESS is less than 4 [deg]C
through 2 hours from the start of initiating the short circuit
condition.
(g) After the short circuit current is terminated, if charge and
discharge is permitted by the vehicle controls, a standard cycle is
performed in accordance with S12.6.
(h) After the completion of the standard cycle, or if the standard
cycle was not performed, after short circuit current is terminated, the
vehicle is observed for 1 hour for evidence of electrolyte leakage,
rupture, venting, fire, or explosion of the REESS.
[[Page 26747]]
(i) At the conclusion of the test, electrical isolation of the
REESS is determined in accordance with S7.2.
S12.6 Standard cycle. The standard cycle is conducted at ambient
temperatures between 10 [deg]C and 30 [deg]C and starts with a standard
discharge followed by a standard charge. The discharge and charge
procedures would follow manufacturer supplied information. The charge
procedure is initiated 15 minutes after discharge is terminated.
(a) If the manufacturer does not provide a discharge procedure, the
vehicle is discharged with 1C current until discharge is terminated by
vehicle controls.
(b) If the manufacturer does not provide a charge procedure, the
vehicle is charged with \1/3\C current until terminated by vehicle
controls.
S12.7 Documentation for low temperature operation safety. At
NHTSA's request, each manufacturer shall submit documentation that
includes the following:
(a) The make, model, model year, and production dates of the
vehicles to which the submitted documentation applies.
(b) The lower temperature boundary for safe REESS operation in all
vehicle operating modes.
(c) A description and explanation of charge and discharge rates at
the lower temperature boundary for safe REESS operation.
(d) A description of the method used to detect REESS temperature.
(e) A system diagram with key components and subsystems involved in
maintaining safe REESS charging and discharging operation for
temperatures at or below the lower temperature boundary for safe REESS
operation.
(f) A description of how the vehicle controls, ancillary equipment,
and design features were validated and verified for maintaining safe
REESS operations at or below the lower temperature boundary for safe
REESS operation.
(g) Overall evaluation: A description of the final manufacturer
review/audit process and results of any final review or audit
evaluating the technical content and the completeness and verity of
S12.7(a) to S12.7(f).
S12.8 Documentation and visual warning in the event of operational
failure of vehicle controls.
(a) During the vehicle's active driving mode, the vehicle shall
provide a visual warning to the driver when there is a vehicle control
malfunction.
(b) At NHTSA's request, each manufacturer shall submit
documentation that includes the following:
(1) The make, model, model year, and production dates of the
vehicles to which the submitted documentation applies.
(2) A system diagram that identifies all the vehicle controls that
manage REESS operation. The diagram must identify what components are
used to generate a visual warning indicating malfunction of vehicle
controls to conduct one or more basic operations.
(3) A written explanation describing the basic operation of the
vehicle controls that manage REESS operation. The explanation must
identify the components of the vehicle control system, provide
description of their functions and capability to manage the REESS, and
provide a logic diagram and description of conditions that would lead
to triggering the telltale activation.
(4) Validation results from tests to confirm the display of a
visual warning in the presence of a malfunction of the vehicle controls
which manage safe operation of the REESS.
(5) Overall evaluation: A description of the final manufacturer
review/audit process and results of the final review or audit which
evaluated the technical content and the completeness and verity of
S12.8(b)(1) to S12.8(b)(4).
S13. REESS thermal propagation safety.
S13.1 Thermal runaway due to internal short in a single cell of the
REESS. The vehicle manufacturer shall make available to the agency,
upon request, documentation demonstrating how the vehicle and its REESS
are designed to mitigate the safety risks associated with thermal
propagation resulting from a single cell thermal runaway due to an
internal short within the cell. The documentation shall demonstrate
thermal propagation safety risk mitigation for the vehicle in external
charging mode, active driving possible mode, and parking mode. The
documentation shall include the following:
(a) The make, model, model year, and production dates of the
vehicles to which the submitted documentation applies.
(b) Part I: System analysis. This part of the documentation shall
identify the conditions which could lead to single-cell thermal runaway
due to an internal short-circuit in different vehicle operational modes
and allocate applicable functional units, components, subsystems to
each identified condition. This part shall include:
(1) A system diagram and a description of all relevant physical
systems and components of the REESS, including information about the
cell type and electrical configuration, cell chemistry, electrical
capacity, voltage, current limits during charging and discharging,
thermal limits of the components that are critical for thermal
propagation safety.
(2) A system diagram, operational description of sensors,
components, functional units relevant to single-cell thermal runaway
due to internal short-circuit and thermal propagation, and the
interrelationship between the identified sensors, components, and
functional units;
(3) A description of conditions under which a single-cell thermal
runaway and propagation event due to an internal short-circuit could
occur;
(4) A description of how the identified conditions were allocated
to each identified component, functional unit, and subsystem;
(5) A description of the process used to review the identified
conditions and their allocation to the identified sensors, components,
and functional units, for completeness and validity; and
(6) A description of the warning or notification system before the
thermal runaway occurred, including a description of the detection
technology and mitigation strategies, if any.
(c) Part II: Safety risk assessment and mitigation process. This
part of the documentation shall identify thermal propagation safety
risk mitigation strategies for identified conditions leading to single
cell thermal runaway in Part I and include:
(1) A description of the safety risks and safety risk mitigation
strategies, and how these were identified, and
(2) A description of how each risk mitigation strategy manages,
mitigates, or prevents the identified safety risks.
(3) Safety risk mitigation strategies identified should include
those that mitigate the risk of single cell thermal runaway due to an
internal short and mitigate the occurrence of thermal propagation due
to single-cell thermal runaway resulting from an internal short-circuit
within the cell.
(d) Part III: Verification and validation of risk mitigation
strategies. This part of the documentation pertains to verification
that the manufacturer identified safety risks and considered safety
risk mitigation strategies and include:
(1) A description of how each risk mitigation strategy was verified
and validated for effectiveness,
(2) A description of the verification and validation results for
each risk mitigation strategy, and
[[Page 26748]]
(3) A description of and results from the vehicle level assessment.
(e) Part IV: Overall evaluation of risk mitigation. This part of
the documentation summarizes the vehicle design and manufacturing
strategies and their validation to mitigate the safety risks associated
with thermal propagation due single cell thermal runaway resulting from
internal short within a cell. This part shall include a description of
the final manufacturer review/audit process and results of the final
review or audit evaluating the technical content and the completeness
and verity of S13.1(a) to S13.1(d).
S13.2 Warning in the case of thermal event in REESS. The vehicle
shall provide a warning to the driver of a thermal event in the REESS.
The warning shall activate within three minutes of activating a heater
within the REESS when tested in accordance with S13.3. The warning
shall consist of auditory and visual signals that remain active for at
least 5 minutes. The thermal event warning system must monitor its own
readiness and the warning must be provided to the driver.
S13.3 Test procedure for evaluating warning for thermal event in
REESS. The thermal event warning test is conducted at ambient
temperatures between 10 [deg]C and 30 [deg]C with the vehicle REESS
initially set between 90 to 95 percent SOC. The following steps are
conducted to evaluate the warning in the case of thermal event in the
REESS:
(a) If possible, the REESS is removed from the vehicle.
(b) The REESS casing is opened.
(c) A heater that achieves a peak temperature of 600 [deg]C within
30 seconds is attached to one or more cells in the REESS in a manner to
put at least one cell in the REESS into thermal runaway.
(d) The REESS casing is closed and the REESS is reinstalled into
the vehicle (if initially removed in (a)).
(e) Vehicle stops to prevent vehicle rollaway are installed.
(f) The vehicle is placed in active driving possible mode.
(g) The heater within the REESS is activated to achieve 600 [deg]C
within 30 seconds. The heater shall remain operational until thermal
runaway is initiated in at least one cell.
(h) The time for the activation of the warning to the front row
occupant (if any) from the time of activation of the heater is noted.
(i) The test is terminated after activation of the warning or after
four minutes of activating the heater in the REESS, whichever comes
first.
S14. Water exposure safety. Each vehicle to which the standard
applies shall maintain electrical isolation as specified in S6.3.1 and
S6.3.2 at these times: (a) just after exposure to water in each of the
two tests specified below and with the vehicle still wet; and (b) after
a minimum of 24 hours after completing each of the tests specified
below.
S14.1 Vehicle washing test. The vehicle is sprayed from any
direction with a stream of freshwater from a standard test nozzle shown
in Figure 9 that has a nozzle internal diameter of 6.3 millimeters,
delivery rate of 11.9 to 13.2 liters/minute, and water pressure at the
nozzle between 30 kPa to 35 kPa.
(a) During the washing, the distance from the nozzle to the vehicle
surface is 3.0 to 3.2 meters. The distance of the nozzle from the
vehicle surface may be reduced, if necessary, to ensure the surface is
wet when spraying upwards. The washing test duration per square meter
of the vehicle surface area is 60 to 75 seconds, with a minimum total
test duration of 3 minutes.
(b) The vehicle external surface, including the vehicle sides,
front, rear, top, and bottom is exposed to the water stream. Border
lines on the vehicle such glass seals, outline of opening parts (doors,
windows, vehicle inlet cover), outline of front grille, seals of
vehicle lamps are exposed to the water stream from any direction.
(c) At the conclusion of the normal washing test, with the vehicle
still wet, electrical isolation is determined in accordance with S7.2.
S14.2 Driving through standing water test. The vehicle is driven
through a wade pool of at least 10 centimeters but not more than 15
centimeters depth of freshwater for a distance of 500 meters at a
minimum speed of 12 mph (20 km/h) but not more than 15 mph (24 km/h).
(a) If the wade pool is less than 500 m in length, then the vehicle
shall be driven through it several times for a total distance of 500 m.
The total time, including the period outside of the wade pool, shall be
less than 5 minutes.
(b) At the conclusion of the standing water test, with the vehicle
still wet, electrical isolation is determined in accordance with S7.2.
S15. Rescue Sheets and Emergency Response Guides.
S15.1 Rescue Sheets. Prior to vehicle certification per 49 CFR part
567, vehicle manufacturers shall submit rescue sheets to NHTSA.
(a) For vehicles with a GVWR less than or equal to 4,536 kg to
which the standard applies, submitted rescue sheets shall follow the
layout and format in ISO-17840-1:2022(E).
(b) For vehicles with a GVWR greater than 4,536 kg to which the
standard applies, the submitted rescue sheets shall follow the layout
and format in ISO-17840-2:2019(E).
(c) The rescue sheets shall provide information for first
responders to extricate occupants.
S15.2 Emergency Response Guides. Prior to vehicle certification per
49 CFR part 567, vehicle manufacturers shall submit to NHTSA Emergency
Response Guides (ERGs) in accordance with the template layout and
format in ISO-17840-3:2019(E) for vehicles to which this standard
applies.
(a) The ERGs shall provide in-depth information linked and aligned
to the corresponding rescue sheet to support the quick and safe action
of first responders and second responders.
(b) The ERGs shall provide in-depth information related to electric
vehicle fire, submersion, leakage of fluids, towing, transportation,
and storage.
(c) The ERGs shall provide information to assist first responders
in extricating occupants.
Figures to FMVSS No. 305a
BILLING CODE 4910-59-P
[[Page 26749]]
[GRAPHIC] [TIFF OMITTED] TP15AP24.048
Figure 1. Voltage Measurements of the High Voltage Source
[GRAPHIC] [TIFF OMITTED] TP15AP24.049
Figure 2. Measurement for V1 Voltage Between the Negative Side of the
High Voltage Source and the Electrical Chassis
[[Page 26750]]
[GRAPHIC] [TIFF OMITTED] TP15AP24.050
Figure 3. Measurement for V2 Voltage Between the Positive Side of the
High Voltage Source and the Electrical Chassis
[GRAPHIC] [TIFF OMITTED] TP15AP24.051
Figure 4. Measurement for V1' Voltage Across Resistor Between Negative
Side of the High Voltage Source and Electrical Chassis
[[Page 26751]]
[GRAPHIC] [TIFF OMITTED] TP15AP24.052
Figure 5. Measurement for V2' Voltage Across Resistor Between Positive
Side of the High Voltage Source and Electrical Chassis
[GRAPHIC] [TIFF OMITTED] TP15AP24.053
Figure 6. Marking of High Voltage Sources
[[Page 26752]]
[GRAPHIC] [TIFF OMITTED] TP15AP24.054
Figure 7a. Access Probes for the Tests of Direct Contact Protection.
Access Probe IPXXB (Top) and Access Probe IPXXD (Bottom)
[[Page 26753]]
[GRAPHIC] [TIFF OMITTED] TP15AP24.055
Figure 7b. Jointed Test Finger IPXXB
[[Page 26754]]
[GRAPHIC] [TIFF OMITTED] TP15AP24.056
Figure 8. Connection To Determine Resistance Between Exposed Conductive
Parts of Electrical Protection Barrier and Electrical Chassis
[GRAPHIC] [TIFF OMITTED] TP15AP24.057
Figure 9. Standard Nozzle for IPX5 Water Exposure Test
Issued in Washington, DC, under authority delegated in 49 CFR
1.95 and 501.5.
Sophie Shulman,
Deputy Administrator.
[FR Doc. 2024-07646 Filed 4-12-24; 8:45 am]
BILLING CODE 4910-59-C
