104318 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

DEPARTMENT OF TRANSPORTATION 

National Highway Traffic Safety 

Administration 

49 CFR Parts 561 and 571 

[Docket No. NHTSA–2024–0091] 

RIN 2127–AM43 

Federal Motor Vehicle Safety 

Standards; FMVSS No. 305a ElectricPowered Vehicles: Electric Powertrain 

Integrity Global Technical Regulation 

No. 20 Incorporation by Reference 

AGENCY: National Highway Traffic 

Safety Administration (NHTSA), 

Department of Transportation (DOT). 

ACTION: Final rule. 

SUMMARY: Consistent with a Global 

Technical Regulation on electric vehicle 

safety, NHTSA is establishing 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 applies 

to light and heavy vehicles and includes 

performance requirements for the 

propulsion battery. NHTSA is also 

establishing a new regulation, part 561, 

‘‘Documentation for Electric-powered 

Vehicles,’’ that requires manufacturers 

to compile risk mitigation 

documentation and to submit 

standardized emergency response 

information to assist first and second 

responders handling electric vehicles. 

DATES: 

Effective date: This final rule is 

effective February 18, 2025. 

IBR date: The incorporation by 

reference of certain publications listed 

in the rule is approved by the Director 

of the Federal Register as of February 

18, 2025. 

Compliance dates: The compliance 

date is December 22, 2025, for the 

emergency response documentation 

requirements. For all other 

requirements, the compliance date is 

September 1, 2027, for vehicles with a 

gross vehicle weight rating of 4,536 

kilograms (kg) or less and September 1, 

2028, for vehicles with a gross vehicle 

weight rating over 4,536 kg. Smallvolume manufacturers, final-stage 

manufacturers, and alterers are provided 

an additional year to comply with the 

requirements beyond the dates 

identified above. Optional early 

compliance is permitted. 

Petitions for Reconsideration: 

Petitions for reconsideration of this final 

rule must be received no later than 

February 3, 2025. 

ADDRESSES: Petitions for reconsideration 

of this final rule must refer to the docket 

and notice number set forth above and 

be submitted to the Administrator, 

National Highway Traffic Safety 

Administration, 1200 New Jersey 

Avenue SE, West Building, Washington, 

DC 20590. All petitions received will be 

posted without change to http://

www.regulations.gov, including any 

personal information provided. 

Confidential Business Information: If 

you wish to submit any information 

under a claim of confidentiality, you 

should submit your complete 

submission, including the information 

you claim to be confidential business 

information, to the Chief Counsel, 

NHTSA, at the address given under FOR

FURTHER INFORMATION CONTACT. In 

addition, you should submit a copy, 

from which you have deleted the 

claimed confidential business 

information, to Docket Management at 

the address given above. When you send 

a submission containing information 

claimed to be confidential business 

information, you should include a cover 

letter setting forth the information 

specified in our confidential business 

information regulation (49 CFR part 

512). Please see further information in 

the Regulatory Notices and Analyses 

section of this preamble. 

Privacy Act: The petition will be 

placed in the docket. Anyone is able to 

search the electronic form of all 

submissions to any of our dockets by the 

name of the individual submitting the 

submission (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 (Volume 

65, Number 70; Pages 19477–78) or you 

may visit https://

www.transportation.gov/individuals/ 

privacy/privacy-act-system-recordsnotices. 

Docket: For access to the docket to 

read background documents or 

comments received, go to https://

www.regulations.gov at any time or to 

1200 New Jersey Avenue SE, West 

Building, Room W12–140, Washington, 

DC 20590, between 9 a.m. and 5 p.m., 

Monday through Friday, except Federal 

holidays. Telephone: (202) 366–9826. 

FOR FURTHER INFORMATION CONTACT: For 

technical issues, you may contact Ms. 

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 

c. Statutory Authority 

d. Overview of the Final Rule 

Requirements 

e. Changes From the NPRM to the Final 

Rule 

III. Summary of Comments 

IV. Response to Comments on Proposed 

Requirements 

a. Expanding Applicability of FMVSS No. 

305a to Heavy Vehicles 

1. Normal Vehicle Operations and 

Requirements for the REESS 

2. Post-Crash Safety for Heavy School 

Buses 

3. Post-Crash Safety for Other Heavy 

Vehicles 

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 Leakage 

c. Vehicle Controls for Safe REESS 

Operation 

1. Vehicle- and Component-Level Testing 

2. State of Charge (SOC) 

3. Breakout Harness Location 

4. Over-Temperature Test 

5. Overcurrent Protection 

6. Venting and Visual Inspection 

d. Mitigating Risk of Thermal Propagation 

Due to Internal Short Within a Single 

Cell in the REESS 

e. Thermal Event Warning 

f. Vehicle Control Malfunction Warning 

g. Protection Against Water Exposure 

h. Miscellaneous GTR No. 20 Provisions 

Not Proposed 

1. Vibration and Thermal Shock and 

Cycling 

2. Fire Resistance 

3. Low State of Charge 

i. Low-Speed Vehicles 

j. Emergency Response Information 

k. Documentation Requirements 

l. Compliance Dates 

V. Response to Comments on Issues Not 

Discussed in the NPRM 

a. Future Battery Chemistries 

b. Marking and Labeling 

c. Test Laboratories 

d. Other Electrical Specifications 

e. Static Rollover 

VI. Rulemaking Analyses and Notices 

I. Executive Summary 

NHTSA is issuing this final rule to 

achieve two goals. First, NHTSA is 

establishing FMVSS No. 305a, ‘‘Electricpowered Vehicles: Electric Powertrain 


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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104319 

1 ‘‘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. 

2 ‘‘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. 

3Stranded energy is the energy remaining inside 

the REESS after a crash or other incident. 

4 GTR No. 20, https://unece.org/fileadmin/DAM/ 

trans/main/wp29/wp29wgs/wp29gen/wp29registry/ 

ECE-TRANS-180a20e.pdf. 

5 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 the vehicle 

in drive mode, and charging. Final rule, 82 FR 

44950, September 27, 2017. 

Integrity,’’ to upgrade and replace 

existing FMVSS No. 305. The new 

FMVSS No. 305a has all the 

requirements of FMVSS No. 305 and 

expands its applicability to vehicles 

with a gross vehicle weight rating 

(GVWR) greater than 4,536 kilograms 

(kg) (10,000 pounds (lb)). FMVSS No. 

305a also adds requirements and test 

procedures covering new aspects of 

electric vehicle safety, such as 

performance requirements for the 

propulsion battery system, also referred 

to as the Rechargeable Electrical Energy 

Storage System (REESS). NHTSA is also 

establishing a new regulation, 49 CFR 

part 561 (part 561), ‘‘Documentation for 

Electric-powered Vehicles,’’ to require 

that manufacturers submit, at NHTSA’s 

request, documentation addressing 

safety risk mitigation under specified 

scenarios to demonstrate that they 

considered, assessed, and mitigated 

risks for safe operation of the vehicle. 

Manufacturers are also required to 

submit documentation to ensure both 

first 1 and second 2 responders have 

access to vehicle-specific information 

about extinguishing REESS fires and 

mitigating safety risks associated with 

stranded energy 3 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. 

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.’’ 4 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.5 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 final rule largely adopts these and 

other GTR No. 20 requirements. 

The notice of proposed rulemaking 

(NPRM) preceding this final rule was 

published on April 15, 2024. The 

comment period closed on June 14, 

2024. After carefully reviewing the 

comments, NHTSA is adopting the 

proposed requirements with some 

changes from the NPRM. Commenters to 

the NPRM commented on the 

applicability to heavy vehicles; vehiclelevel testing; technical details on 

documentation requirements; test 

procedures for evaluating fire risk 

mitigation; warning in the case of a 

thermal event in the battery pack; and 

water exposure safety. NHTSA 

addresses the comments in this final 

rule with minor changes to the 

regulatory text. These changes include 

edits to definitions and test procedures 

for clarity and accuracy, addition of a 

provision to exempt out-of-reach rooftop 

charging systems from direct contact 

protection requirements, and new 

regulation part 561 for documentation 

requirements and emergency response 

information requirements. 

High Level Summary of the Final Rule 

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, 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 the final FMVSS No. 305a, light 

vehicles will 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). They will also 

be subject to new requirements for the 

REESS. Heavy vehicles will 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 will not be subject to post-crash 

requirements. Heavy school buses 

(GVWRs greater than 4,536 kg (10,000 

lb)) will be subject to the requirements 

for electrical system safety during 

normal vehicle operations and to the 

requirements for the REESS, and will 

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 

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); REESS 

retention; electrolyte leakage; and fire 

safety. The requirements for REESS 

retention and electrolyte leakage are 

already in FMVSS No. 305, but the final 

rule adopts the NPRM proposal to 

enhance some provisions consistent 

with GTR No. 20. 

FMVSS No. 305a also includes new 

and comprehensive performance 

requirements and risk mitigation 

strategies for safety of the REESS. These 

REESS requirements will 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 requirements set a level of 

protection of the REESS against external 

fault inputs, ensure the REESS 

operations are within the manufacturerspecified functional range, and increase 

the likelihood of safe operation of the 

REESS and other electrical systems of 

the vehicle during and after water 

exposure during normal vehicle 

operations. 

The final rule 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 

demonstrates that they considered, 

assessed, and mitigated identified risks 

for safe operation of the vehicle. The 

final rule’s documentation requirements 

address: (a) safety risk mitigation 

associated with charging and 

discharging during low temperature; (b) 

providing a warning if there is a 

malfunction of vehicle controls that 

manage REESS safe operation; (c) 


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104320 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

6The NPRM proposed to include a thermal 

warning requirement and a corresponding test 

procedure. After consideration of comments, the 

final rule specifies an additional documentation 

requirement in part 561 for the REESS thermal 

event warning instead of a corresponding test 

procedure with the warning requirement. 

7 ‘‘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. 8 49 U.S.C. 322(a); 49 CFR 1.95. 

providing a warning if there is a thermal 

event in the REESS; 6 and (d) safety risk 

mitigation for thermal runaway and 

propagation due to an internal short 

circuit of a single cell. The GTR takes 

a documentation approach to these 

aspects of safety because of the rapidly 

evolving electric vehicle technologies 

and the variety of available REESS and 

electric vehicle designs. NHTSA agrees 

that there are currently no objective test 

procedures in these specified areas that 

are not design restrictive given the 

current state of knowledge. Thus, until 

test procedures and performance criteria 

can be developed for all vehicle 

powertrain architectures, 49 CFR part 

561 will require manufacturers to 

submit documentation to NHTSA, at 

NHTSA’s request, that identifies all 

known safety hazards, describes their 

risk mitigation strategies for the safety 

hazards, and, if applicable, describes 

how they provide a warning to address 

a safety hazard. The purpose of the 

documentation approach is two-fold. 

Given the variation of battery design 

and design specific risk mitigation 

systems, the documentation 

requirement will be a means of ensuring 

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 

ensure that manufacturers will identify 

and address the safety risks of the 

REESS until such time as objective 

performance standards can be 

developed that can be applied to all 

applicable REESS designs. 

As part of NHTSA’s battery 

initiative and in response to a 2020 

NTSB recommendation,7 the NPRM 

proposed to include in FMVSS No. 305a 

a requirement that vehicle 

manufacturers submit to NHTSA 

standardized emergency response 

guides (ERGs) and rescue sheets for each 

vehicle make, model, and model year. 

The uploaded ERGs and rescue sheets 

will be publicly available on NHTSA’s 

website for easy searchable access. ERGs 

and rescue sheets communicate vehiclespecific 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. The final rule adopts 

the proposed requirement to submit 

standardized emergency response 

information to a NHTSA website in part 

561. The standardized information will 

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 is issuing this final rule 

pursuant to and in accordance with its 

authority under the National Traffic and 

Motor Vehicle Safety Act (Safety Act). 

Under 49 United States Code (U.S.C.) 

Chapter 301, Motor Vehicle Safety (49 

U.S.C. 30101 et seq.), the Secretary of 

Transportation is responsible for 

prescribing motor vehicle safety 

standards that are practicable, meet the 

need for motor vehicle safety, and are 

stated in objective terms. The Safety Act 

also 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 authorized by 

delegation to issue regulations to carry 

out the agency’s duties of ensuring 

vehicle safety.8

NHTSA believes there are no notable 

costs associated with this final rule. 

This final rule 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 

finalized 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 part 561, they would just have to 

standardize the format and submit the 

information to NHTSA. 

II. Background 

a. Overview of FMVSS No. 305 

The purpose of FMVSS No. 305, 

‘‘Electric-powered vehicles: electrolyte 

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; 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 

the ‘‘in-use’’ testing (unlike ‘‘post-crash’’ 

testing) deals with performance criteria 

that will be assessed without first 

exposing the vehicle to a crash test. The 

standard’s post-crash test requirements 

address electrical isolation following 

frontal, rear, and side impacts of the 

vehicle, in addition to limiting 

electrolyte spillage from propulsion 

batteries. 

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 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 (‘‘1998 Agreement’’). 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 that 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. This process was initiated by 

the NPRM published on April 15, 2024. 


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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104321 

9The asterisk notes that the NPRM did not 

propose to adopt the GTR No. 20 requirement. 

10This requirement is intended for countries with 

type approval systems where a generic REESS can 

be approved separately 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. 

11 89 FR 26704 (Apr. 15, 2024). 

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.’’

2. GTR No. 20 

GTR No. 20 establishes performanceoriented requirements that reduce 

potential safety risks of electric vehicles 

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, for 

Phase 1 in the GTR development 

process, address issues relating to the 

safe operation of the REESS, and the 

mitigation of fire risk and other safety 

risks associated with the REESS. Phase 

2 of the GTR No. 20 development 

process, which is ongoing, will address 

issues involving long-term research and 

verification. 

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 regarding 

electric shock protection and applies 

these only to light vehicles. GTR No. 20 

also has safety requirements for the 

REESS beyond those in FMVSS No. 305. 

A summary of these additional 

requirements in GTR No. 20 for the 

REESS includes: 

Safe operation of REESS under the 

following exposures during normal 

vehicle operations: 

• REESS protection under external fault 

conditions and extreme operating 

temperatures: 

Æ External short circuit 

Æ Overcharge 

Æ Over-discharge 

Æ Overcurrent 

Æ High operating temperature 

Æ Low operating temperature 

• Management of REESS emitted gases 

• Water exposure during vehicle 

washing and driving through 10- 

centimeter (cm) deep water on 

roadway 

• Thermal shock and cycling (¥40 °C to 

60 °C)* 9

• Resistance to short duration external 

gasoline pool fire * 

• Vibration environment during normal 

vehicle operations * 

Warning systems for REESS safe 

operation in case of: 

• Low energy content in REESS * 

• REESS control operational failure 

• Thermal runaway propagation due to 

single cell short circuit in REESS 

• Thermal event in REESS 

• Installation (location) of REESS on the 

vehicle 10

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 April 2024 NPRM 11 proposed to 

complete the alignment of FMVSS No. 

305 with GTR No. 20 by proposing to 

establish FMVSS No. 305a, which 

adopts all the requirements in FMVSS 

No. 305 and extends the standard’s 

electrical safety requirements to heavy 

vehicles. The NPRM also proposed to 

adopt the above requirements under 

normal vehicle operations 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.’’ The NPRM 

proposed adding the post-crash test 

requirements in FMVSS No. 305 for 

light vehicles and adding a crash test for 

all school buses similar to that in 

FMVSS No. 301, ‘‘Fuel system 

integrity.’’ The NPRM also proposed a 

post-crash requirement for no observed 

fire or explosion in the vehicle for a 

duration of one hour after the crash test 

and a low energy post-crash option for 

capacitors in the electric power train to 

meet electrical safety requirements. 

c. Statutory Authority 

NHTSA is issuing this final rule 

pursuant to and in accordance with its 

authority under the National Traffic and 

Motor Vehicle Safety Act (Safety Act). 

Under 49 United States Code (U.S.C.) 

Chapter 301, Motor Vehicle Safety (49 

U.S.C. 30101 et seq.), the Secretary of 

Transportation is responsible for 

prescribing motor vehicle safety 

standards that are practicable, meet the 

need for motor vehicle safety, and are 

stated in objective terms (section 

30111(a)). ‘‘Motor vehicle safety’’ is 

defined in the Safety Act (section 

30102(a)(8)) as ‘‘the performance of a 

motor vehicle or motor vehicle 

equipment in a way that protects the 

public against unreasonable risk of 

accidents occurring because of the 

design, construction, or performance of 

a motor vehicle, and against 

unreasonable risk of death or injury in 

an accident, and includes 

nonoperational safety of a motor 

vehicle.’’ ‘‘Motor vehicle safety 

standard’’ means a minimum standard 

for motor vehicle or motor vehicle 

equipment performance (section 

30102(a)(9)). When prescribing such 

standards, the Secretary must consider 

all relevant available motor vehicle 

safety information (section 30111(b)(1)). 

The Secretary must also consider 

whether a proposed standard is 

reasonable, practicable, and appropriate 

for the particular type of motor vehicle 

or motor vehicle equipment for which it 

is prescribed (section 30111(b)(3)) and 

the extent to which the standard will 

further the statutory purpose of 

reducing traffic accidents and associated 

deaths and injuries (section 

30111(b)(4)). The responsibility for 

promulgation of FMVSSs is delegated to 

NHTSA (49 CFR 1.95). 

The Safety Act also 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 


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104322 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

12 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. 

13Current FMVSS No. 305 light vehicle postcrash test requirements (front, side, and rear 

crashes) are aligned with FMVSS No. 301’s light 

vehicle post-crash test requirements. 

14 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. 

15Section 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. 16https://www.nhtsa.gov/battery-safety-initiative. 

carry out the agency’s duties of ensuring 

vehicle safety.12

d. Overview of the Final Rule 

Requirements 

Consistent with GTR No. 20, the new 

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 FMVSS No. 305a: 

• Light vehicles are 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).13 They are also subject to new 

requirements for the REESS. 

• Heavy vehicles are 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 are 

not subject to post-crash requirements. 

This 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)) 14 are subject 

to the requirements for electrical system 

safety during normal vehicle operations 

and to the requirements for the REESS, 

and 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 

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); REESS 

retention; electrolyte leakage; and fire 

safety. The requirements for REESS 

retention and electrolyte leakage are in 

FMVSS No. 305, but FMVSS No. 305a 

enhances some provisions consistent 

with GTR No. 20. For example, 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, FMVSS No. 305a is 

prohibiting fire or explosion for a onehour post-test period. 

A substantial portion of FMVSS No. 

305a focuses on safety provisions for the 

propulsion battery, the REESS. FMVSS 

No. 305a includes comprehensive 

performance requirements for the 

REESS. These REESS requirements 

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 

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 

and after water exposure during normal 

vehicle operations. 

This final rule addresses some aspects 

of REESS safety through documentation 

measures, consistent with GTR No. 20, 

through a new regulation, part 561. 

‘‘Documentation measures’’ means a list 

of information provided by 

manufacturers, at NHTSA’s request, that 

demonstrates that they considered, 

assessed, and mitigated identified risks 

for safe operation of the vehicle. These 

documentation requirements address: 

(a) safety risk mitigation associated with 

charging and discharging during low 

temperature; (b) providing a warning if 

there is a malfunction of vehicle 

controls that manage REESS safe 

operation; (c) providing a warning if 

there is a thermal event in the REESS; 

and (d) safety risk mitigation for thermal 

runaway and propagation due to an 

internal short circuit of a single cell. 

The GTR takes a documentation 

approach to 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 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, 

manufacturers will be required to 

submit documentation to NHTSA, at 

NHTSA’s request, that identifies all 

known safety hazards, describes risk 

mitigation strategies for the safety 

hazards, and, if applicable, describes 

how they provide a warning to address 

a safety hazard.15 The purpose of the 

documentation approach is two-fold. 

Given the variation of battery design 

and design specific risk mitigation 

systems, the documentation 

requirement is a means of ensuring 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 

ensure that manufacturers will identify 

and address the safety risks of the 

REESS until such time as objective 

performance standards can be 

developed that can be applied to all 

applicable REESS designs. NHTSA will 

also acquire information from the 

submissions to learn about the safety of 

the REESSs and potentially develop the 

future performance standards for 

FMVSS No. 305a. The documentation 

requirements are based on the approach 

of GTR No. 20, but NHTSA focused the 

GTR’s documentation requirements to 

enable the agency to obtain more 

targeted information from 

manufacturers. 

As part of NHTSA’s battery 

initiative,16 this final rule also 

establishes, through regulation, 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 and second 

responders regarding the safe handling 

of the vehicle in emergencies and for 

towing and storing operations. The 

uploaded ERGs and rescue sheets will 

be publicly available on NHTSA’s 

website for easy searchable access. ERGs 

and rescue sheets communicate vehiclespecific information related to fire, 

submersion, and towing, as well as the 


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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 is requiring standardized 

formatting of the information. The ERG 

and rescue sheet requirements include 

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 will be 

available and understandable to first 

and second responders so they can 

easily refer to vehicle-specific rescue 

information enroute to, or at the scene 

of, a crash or fire event and respond to 

the emergency quickly and safely. 

e. Changes From the NPRM to the Final 

Rule 

In developing this final rule, NHTSA 

made some modifications to the 

proposed regulatory requirements in 

response to comments received and to 

improve clarity and accuracy of the 

regulatory text. In addition to 

typographical corrections, the final rule 

differs from the April 2024 NPRM in the 

following ways: 

1. Timing of voltage measurements for 

determining electrical isolation postcrash. The proposal required voltage 

measurements for assessment of postcrash electrical isolation to be made 

between 10 to 60 seconds from the time 

of impact. The final rule requires the 

voltage measurements for post-crash 

electrical isolation assessment to be 

made at least 10 seconds after impact. 

NHTSA determined that taking all the 

voltage measurements for determining 

electrical isolation would typically take 

more than 60 seconds and since 

electrical isolation value is not expected 

to change with time, only specifying a 

minimum time after impact for making 

the measurements is sufficient. 

2. Definition of State of Charge (SOC). 

The definition of SOC was updated to 

clarify that it is the available electric 

charge in a REESS expressed as a 

percentage of its normal operating 

capacity specified by the manufacturer 

and not as a percentage of the total 

charge (stored energy) in the REESS. 

3. Documentation requirements 

included in part 561. The NPRM 

proposed documentation requirements 

in FMVSS No. 305a for manufacturers to 

submit, upon request, documentation 

regarding vehicle and REESS designs to 

mitigate the risk of vehicle fire and 

explosion resulting from single cell 

thermal runaway in the REESS, loss or 

malfunction of controls managing safe 

operation of the REESS, and vehicle 

operations at low temperatures. The 

NPRM also proposed requiring 

manufacturers to submit emergency 

response information to a repository 

prior to the certification time of the 

vehicle. The final rule has moved these 

requirements to part 561 because 

documentation requirements without 

corresponding test procedures are better 

suited in a regulation. Additionally, the 

final rule requires emergency response 

information to be submitted to NHTSA’s 

repository before first sale or lease of the 

vehicle model upon the compliance 

date. 

4. Thermal event warning 

documentation requirement. The NPRM 

proposed a test procedure to evaluate 

the warning function resulting from a 

thermal event in the REESS. Due to 

practicability and safety concerns with 

the proposed test procedure, the final 

rule specifies an additional 

documentation requirement in part 561 

for the REESS thermal event warning 

instead of a corresponding test 

procedure with the warning 

requirement. 

5. Maximum time to conduct driving 

through standing water test (protection 

against water exposure). The NPRM 

proposed a maximum test duration of 5 

minutes for the driving through 

standing water test. Based on NHTSA’s 

recent testing, the final rule extends this 

time to 10 minutes because of the 

practicability concerns for conducting 

the test within 5 minutes for water pools 

shorter than 500 meters. 

7. Exclusion for rooftop charging 

systems. The final rule excludes those 

high voltage devices on heavy vehicles 

not energized except during charging of 

the REESS, that are installed out of 

reach on the vehicle rooftop, from direct 

contact protection requirements. 

NHTSA inadvertently excluded this 

carveout for the out of reach high 

voltage devices from the proposed direct 

contact protection requirements. 

8. Addition of loading specifications. 

The proposed crash test procedure for 

heavy school buses inadvertently 

omitted the loading specifications. 

Loading specifications matching FMVSS 

Nos. 301 and 303 have been added to 

the final regulatory text for 

completeness. 

9. Compliance dates. The final rule 

adopts the proposed 1-year lead time 

from the date of publication of the final 

rule to comply with the emergency 

response information requirements. The 

proposed 2-year lead time for complying 

with all other requirements for light 

vehicles is largely adopted with a slight 

date change to align with the beginning 

of the model year on or after the first 

September 1 that is at least two years 

after the publication of the final rule. In 

response to comments received, the 

final rule extends the heavy vehicles’ 

lead time to comply with the 

requirements other than the emergency 

response information requirements to 

the first September 1 that is at least 

three years after the publication of the 

final rule. 

III. Summary of Comments 

The NPRM preceding this final rule 

included requests for comment on 

several topics, including the post-crash 

requirements, the thermal event 

warning performance test, the water 

exposure tests, the exclusion of some 

GTR No. 20 requirements, and the 

documentation requirements. From 

April 15, 2024, to June 14, 2024, the 

agency received 38 comments on the 

NPRM, including one that appears to be 

an accidental duplicate submission. The 

comments were generally supportive of 

the proposed rule, particularly with 

regard to the collection of standardized 

emergency response information and 

harmonization with international 

regulations. Many commenters 

suggested modifications to the proposed 

requirements, including establishing 

documentation requirements in a 

separate regulation instead of the 

FMVSS. Of the 37 unique comments, 

the majority (26 comments) were 

submitted by vehicle and component 

manufacturers and industry 

associations. Comments were also 

submitted by standards testing 

laboratories (3 comments), a government 

agency (1 comment), and other 

stakeholders (7 comments). 

The vehicle and component 

manufacturers that provided comments 

were American Honda Motor Co. 

(‘‘Honda’’), Blue Bird Body Company 

(‘‘Blue Bird’’), Bugatti Rimac d.o.o. 

(‘‘Bugatti’’), Daimler Truck North 

America (‘‘DTNA’’), Eaton Corporation 

(‘‘Eaton’’), Ford Motor Company 

(‘‘Ford’’), Freudenberg Battery Power 

Systems (‘‘Freudenberg’’), Honeywell 

International (‘‘Honeywell’’), Hyundai 

America Technical Center (‘‘HATCI’’ or 

‘‘Hyundai’’), Lubrizol Corporation 

(‘‘Lubrizol’’), Lucid Motors (‘‘Lucid’’), 

Navistar, New Flyer of America 

(‘‘NFA’’), Nikola Corporation 

(‘‘Nikola’’), Nissan North America 

(‘‘Nissan’’), Prevost, Rivian Automotive 

(‘‘Rivian’’), Tesla, and Volkswagen 

Group of America (‘‘Volkswagen’’). 

The industry associations that 

provided comments were the Alliance 

for Automotive Innovation (‘‘Auto 

Innovators’’), Coalition for Safe 


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Autonomous Vehicles and 

Electrification (‘‘SAVE Coalition’’), 

Electric Drive Transportation 

Association (‘‘EDTA’’), MEMA Vehicle 

Suppliers Association (‘‘MEMA’’), 

National Electrical Manufacturers 

Association (‘‘NEMA’’), Truck and 

Engine Manufacturers Association 

(‘‘EMA’’), and Zero Emission 

Transportation Association (‘‘ZETA’’). 

Some manufacturers that submitted 

comments individually indicated that 

they belong to one of these industry 

associations and/or stated support for 

the comments submitted by an industry 

association. 

The standards testing laboratories and 

associations that provided comments 

were UL Solutions, the American 

Council of Independent Laboratories 

(‘‘ACIL’’), and the American Association 

for Laboratory Accreditation (‘‘A2LA’’). 

The National Transportation Safety 

Board (‘‘NTSB’’) submitted one 

comment, expressing strong support for 

the proposed rulemaking. 

The other stakeholders that provided 

comments were the Center for Auto 

Safety (‘‘CAS’’), Consumer Reports, 

Creaform/Ametek (‘‘Creaform’’), Electric 

Vehicle Rescue App (‘‘EV Rescue App,’’ 

two comments), Michael Lillo, and Kurt 

Vollmacher. 

With regard to heavy vehicles, the 

commenters generally expressed 

support for the proposed requirements 

for heavy school buses. Comments on 

applying additional requirements to 

other heavy vehicles were more varied, 

with some commenters in favor of 

additional test requirements at the 

component level or at the vehicle level, 

and others opposed. One commenter 

requested that NHTSA add an 

exemption from the direct contact 

protection requirements during normal 

vehicle operation for rooftop charging 

systems on heavy vehicles. 

With regard to post-crash safety, 

manufacturers expressed support for the 

inclusion of the low energy option for 

capacitors. Commenters also generally 

agreed with the proposed requirement 

that there be no evidence of fire or 

explosion for the duration of one hour 

after each crash test. Comments on the 

voltage measurement procedure were 

mixed, with some commenters in 

agreement and others requesting 

changes to the test specifications. Honda 

and Auto Innovators requested removal 

of the 60-second time limit for postcrash electrical isolation measurements, 

which would align the specification 

with GTR No. 20. For electrolyte 

leakage, commenters said that the 

updated terminology is appropriate, but 

the 5-liter maximum leakage 

requirement is no longer relevant with 

modern REESS chemistries. 

With regard to the proposed 

requirements for safe operation of the 

REESS, commenters commented about 

certain aspects of the proposed test 

procedures, particularly the state of 

charge, breakout harness location, and 

test termination specifications. Many 

comments from industry disagreed with 

the agency’s exclusion of componentlevel compliance test options. For the 

thermal event warning, some 

commenters also requested 

implementation of a documentation 

requirement instead of a test 

requirement. 

For the proposed documentation 

requirements, some commenters 

requested clarification of the 

requirements and implementation in a 

separate regulation. Most commenters 

expressed strong support for NHTSA’s 

proposed collection of standardized 

emergency response information, with a 

few vehicle manufacturers requesting a 

modification to the submission timeline. 

Some also requested extending the 

compliance date for the other proposed 

requirements beyond 2 years after 

publication of the final rule. 

IV. Response to Comments on Proposed 

Requirements 

a. Expanding Applicability of FMVSS 

No. 305a to Heavy Vehicles 

1. Normal Vehicle Operations and 

Requirements for the REESS 

Proposed Requirements 

Consistent with GTR No. 20, the 

NPRM proposed to expand the current 

applicability of FMVSS No. 305 to 

heavy vehicles. Under FMVSS No. 305a, 

heavy vehicles (including heavy school 

buses) would have to meet the same 

requirements as light vehicles for 

electrical system safety during normal 

vehicle operations and for the REESS. 

The fundamentals for protecting against 

an electrical shock are the same for light 

vehicles and heavy vehicles. A failure of 

a high voltage system may cause 

injurious electric shock to the human 

body. 

Comments Received 

Commenters generally expressed 

support for applying the expanded 

electrical system safety requirements 

during normal vehicle operations to 

heavy school buses. Comments on 

applying these requirements to other 

heavy vehicles were more varied, with 

some commenters in favor of additional 

test requirements at the component 

level or at the vehicle level, and others 

opposed. MEMA agreed with the 

inclusion of heavy-duty vehicles 

without crash testing. Auto Innovators 

commented that FMVSS No. 305a 

should not apply to heavy vehicles at 

this time and more research is needed. 

Auto Innovators noted that the proposed 

regulatory requirements that were not 

previously applicable to heavy vehicles 

have potential design implications that 

require thorough consideration by the 

agency. 

EMA disagreed specifically with 

application of the REESS overcurrent 

test to heavy vehicles, which were 

exempted in GTR No. 20. EMA said that 

NHTSA did not provide justification for 

applying the overcurrent test 

requirement to heavy vehicles. EMA 

also requested that NHTSA include an 

exemption from GTR No. 20 related to 

direct contact protection during normal 

vehicle operation. Specifically, EMA 

stated that the proposed requirement 

omitted an important exemption 

provision for some heavy vehicle 

applications. Under this provision, 

conductive connection devices not 

energized except during charging of the 

REESS that are located on the roof of the 

vehicle and out of reach of a person 

standing outside the vehicle are 

exempted from direct contact protection 

requirements. EMA explained that this 

exemption is necessary for rooftop 

pantograph charging systems used in 

some heavy vehicles like transit buses. 

Agency Response 

The agency is adopting most of the 

requirements for heavy vehicles as 

proposed in the NPRM, with one 

modification. Unlike the NPRM, the 

final rule excludes direct contact 

protection requirements from those high 

voltage devices on heavy vehicles not 

energized except during charging of the 

REESS, that are installed out of reach on 

the vehicle rooftop. NHTSA 

inadvertently excluded this carveout for 

high voltage rooftop charging devices on 

heavy vehicles from the direct contact 

protection provision in the proposed 

requirements for FMVSS No. 305a. GTR 

No. 20 excludes high voltage sources 

that are not energized except during 

charging of the REESS from direct 

contact protection requirements if they 

are located on the vehicle rooftop such 

that the wraparound distance from the 

instep of the vehicle, or the lowest step 

(if multiple steps are present) of the 

vehicle, to the high voltage source is at 

least 3 meters. NHTSA agrees that if the 

high voltage live parts are not energized 

except during charging of the REESS 

and are out of reach for a person 

standing outside of the vehicle, it is 

appropriate to exempt those parts from 

the IPXXB direct contact protection 


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17Electric Vehicle GTR No. 20 Test Development, 

Validation, and Assessment, DOT HS 812 092, 

April 2021, https://rosap.ntl.bts.gov/view/dot/ 

55584. 

18Lithium-ion Battery Safety Issues for Electric 

and Plug-in Hybrid Vehicles, DOT HS 812 418, 

October 2017, https://www.nhtsa.gov/sites/ 

nhtsa.gov/files/documents/12848-lithiumion

safetyhybrids_101217-v3-tag.pdf. 

requirement. NHTSA has included the 

relevant language in the regulatory text 

of the final rule. 

EMA also requested not applying the 

overcurrent test to heavy vehicles. The 

overcurrent test in GTR No. 20 is 

applicable to light vehicles that have the 

capability to be charged by an external 

DC supply. GTR No. 20 states that the 

overcurrent test for heavy vehicles will 

be considered in Phase 2, ‘‘as it is 

unclear how to apply on vehicles that 

have different charging technologies.’’ 

GTR No. 20 specifies two methods of 

conducting the overcurrent test. In the 

first method, the overcurrent is applied 

through the external DC supply 

equipment connected to the vehicle 

inlet while the vehicle is charging 

normally. In the second method, the 

charge current and the overcurrent are 

applied through a breakout harness 

connected just outside the REESS. The 

external DC supply equipment 

connected to the other end of the 

breakout harness supplies the normal 

charge as well as the overcurrent to the 

REESS. The overcurrent test procedure 

in FMVSS No. 305a uses the breakout 

harness method, so any challenges 

associated with testing via the charging 

inlet for different charging technologies 

are avoided. NHTSA evaluated the 

overcurrent test using the breakout 

harness and found it to be an easy test 

to conduct that is practical and feasible 

for different vehicle types.17

Auto Innovators recommended 

excluding heavy vehicles from FMVSS 

No. 305a electrical system safety during 

normal vehicle operations and REESS 

requirements at this time, citing the 

need for more research on the 

implications of these requirements on 

heavy vehicle designs. Auto Innovators 

did not provide additional information 

to support its statement. NHTSA 

believes the requirements for normal 

vehicle operations and the REESS in 

FMVSS No. 305a are basic safety 

measures that should be included in all 

electric vehicle designs.18 These basic 

safety measures ensure protection from 

electric shock and fire originating in the 

electric powertrain and specifically in 

the REESS. These measures include 

electrical isolation, direct and indirect 

contact protection, protection of the 

REESS from abuse and external inputs 

that could damage the REESS over time, 

and measures to ensure the REESS 

always operates within its safe operating 

boundaries. The agency believes that the 

requirements proposed in the NPRM for 

heavy vehicles, including the 

overcurrent test requirement, are 

relevant and appropriate for heavy 

vehicle safety and that the test 

procedures are practicable. 

2. Post-Crash Safety for Heavy School 

Buses 

Proposed Requirements 

In addition to the requirements for 

electrical system safety during normal 

vehicle operations and for the REESS, 

the NPRM also proposed requirements 

for post-crash safety of heavy electric 

school buses. The NPRM proposed use 

of a moving contoured barrier test, 

where a barrier traveling at any speed 

up to 48 km/h (30 mph) impacts the 

school bus at any point and angle. The 

crash test requirement aligns FMVSS 

No. 305a with the requirements for 

heavy school buses in FMVSS No. 301, 

‘‘Fuel system integrity,’’ and FMVSS 

No. 303, ‘‘Fuel system integrity of 

compressed natural gas vehicles.’’ The 

agency did not propose a provision in 

GTR No. 20 that allows the use of 

component-level mechanical integrity 

and mechanical shock tests instead of 

vehicle crash tests. NHTSA believes that 

post-crash safety is better evaluated at 

the system level in a crash test. 

Comments Received 

Commenters were generally in favor 

of the proposed crash test requirements 

for heavy school buses. Commenters 

NTSB, DTNA, Navistar, and EV Rescue 

App expressed full support for the 

expanded requirements for heavy school 

buses. In particular, NTSB agreed with 

expanding the post-crash requirements 

and making full use of the system-level 

requirements that exist for heavy school 

buses so the vehicles will be subject to 

the full intent and scope of FMVSS No. 

305a. Bus manufacturers DTNA 

(Thomas Built Buses) and Navistar (IC 

Bus) also agreed with the proposed 

crash test performance requirements, 

which are consistent with FMVSS No. 

301 and FMVSS No. 303. Navistar stated 

that the proposed requirements for 

heavy school buses were reasonable and 

would not add significant cost or weight 

to the vehicles. EMA noted that the 

loading requirements should be added 

to the crash test specifications in 

S10.2.3. Individual commenter Mr. Lillo 

also stated general support for enhanced 

EV school bus safety and suggested 

conducting time trials for bus 

evacuation. 

One manufacturer disagreed with the 

proposed requirements for heavy school 

buses. Blue Bird stated that including 

multiple post-crash requirements makes 

FMVSS No. 305a more burdensome 

than the corresponding requirements for 

non-electric school buses. Blue Bird also 

said that the proposed rule would 

require manufacturers to crash a school 

bus every time they make a change to 

the battery pack. Blue Bird requested 

component-level testing instead of fullvehicle testing. 

Agency Response 

After reviewing the comments, 

NHTSA is adopting the crash test and 

post-crash requirements for heavy 

school buses as proposed in the NPRM, 

with the addition of loading 

specifications. EMA noted that the 

proposed regulatory text in the NPRM 

did not state the school bus loading 

condition for the crash test. This final 

rule corrects this inadvertent omission; 

loading specifications matching FMVSS 

Nos. 301 and 303, as suggested by EMA, 

have been added to the regulatory text 

for completeness. With regard to 

potential fire emergencies, in addition 

to the requirements of this final rule, 

electric school buses are subject to 

FMVSS No. 217, ‘‘Bus emergency exits 

and window retention and release,’’ 

which specifies operating forces, 

opening dimensions, and markings for 

emergency exits on school buses to 

facilitate rapid evacuation, and FMVSS 

No. 302, ‘‘Flammability of interior 

materials,’’ which specifies burn 

resistance requirements. NHTSA will 

also continue to evaluate school bus 

safety, including school bus evacuation, 

and update applicable safety standards 

as technology changes over time. 

Most commenters, including bus 

manufacturers, agreed with the 

proposed requirements. The dissenting 

commenter expressed concerns over the 

testing burden. With regard to the crash 

test requirements for electric school 

buses, the dynamic moving contoured 

barrier test aligns FMVSS No. 305a with 

FMVSS Nos. 301 and 303, which 

address post-crash safety of heavy 

school buses using conventional fuel or 

compressed natural gas. The four postcrash requirements for FMVSS No. 305a 

are electric shock protection, REESS 

retention, electrolyte leakage, and fire 

safety. These requirements do not 

necessitate multiple crash tests and can 

be verified simultaneously. In other 

words, although there are four postcrash requirements, only one crash test 

is needed. There are also four 

compliance options for the electric 

shock protection requirement to provide 

flexibility. With regard to repeated fullVerDate Sep<11>2014 21:09 Dec 19, 2024 Jkt 265001 PO 00000 Frm 00009 Fmt 4701 Sfmt 4700 E:\FR\FM\20DER2.SGM 20DER2

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vehicle crash testing for component 

modifications, the FMVSS specifies the 

procedures that NHTSA uses to evaluate 

compliance. Manufacturers may use 

other reasonable methods to certify the 

compliance of their vehicles, such as 

simulations and component-level 

testing, which they may find 

appropriate when making minor 

changes. The vehicles must meet the 

FMVSS when tested by NHTSA 

according to the test procedures in the 

standard. For these reasons, the agency 

is not persuaded by Blue Bird’s 

comments on the test burden of 

conducting full-vehicle crash tests for 

school buses. NHTSA maintains that the 

requirements are reasonable and 

appropriate for school bus safety and is 

adopting all proposed requirements for 

heavy school buses from the NPRM. 

3. Post-Crash Safety for Other Heavy 

Vehicles 

Proposed Requirements 

The NPRM did not propose crash 

testing requirements for heavy vehicles 

other than heavy school buses because 

there is currently no available test that 

would be appropriate for these vehicles. 

The NPRM sought comment on 

applying a moving contoured barrier 

crash test to all heavy electric vehicles 

while acknowledging the cost and 

practicability constraints. The NPRM 

also sought comment on componentlevel tests that are representative of 

actual impact loads in heavy vehicle 

crashes and that can be applied to 

different weight classes of heavy 

vehicles. 

GTR No. 20 provides an option for 

evaluating post-crash safety of light 

vehicles using a mechanical integrity 

test (crush test) of the REESS, with a 

quasi-static load up to 100 kN. GTR No. 

20 also includes a mechanical shock test 

that evaluates the REESS mountings and 

fixtures by accelerating and decelerating 

the REESS installed on a sled system. 

However, as noted in the NPRM, the 

loads and accelerations specified in 

GTR No. 20 may be too low for heavy 

vehicles. In the absence of additional 

data to develop appropriate 

requirements, the NPRM did not 

propose component-level crash testing 

of heavy vehicle REESS. 

Comments Received 

Comments on the potential post-crash 

requirements for heavy vehicles other 

than school buses were varied, with 

some commenters suggesting vehiclelevel or component-level tests and 

others stating additional research is 

needed. NTSB commented that NHTSA 

should have proposed the REESS 

mechanical integrity and mechanical 

shock test requirements from GTR No. 

20 for heavy vehicles, calling the 

exclusion ‘‘unnecessary.’’ NTSB noted 

that the component-level tests constitute 

an established and applicable standard 

for heavy vehicle REESS that is not 

design-restrictive. Alternatively, NTSB 

stated, FMVSS No. 305a could at least 

include documentation requirements for 

post-crash safety of the heavy vehicle 

REESS. MEMA and Eaton also stated 

support for the inclusion of mechanical 

integrity and mechanical shock tests 

with additional isolation criteria. 

Heavy vehicle manufacturers, DTNA 

and Prevost, commented that additional 

research should be conducted before 

establishing test requirements for postcrash safety of heavy vehicle REESS. 

DTNA stated support for the concept of 

the mechanical integrity test in general, 

but said that further research is 

necessary to develop a repeatable, 

reproducible, and practical test method. 

Prevost said additional research is 

needed for mechanical shock testing 

because accelerations on the REESS are 

highly design dependent. While Auto 

Innovators disagreed with application of 

additional requirements to heavy 

vehicles in general, Auto Innovators 

said it did not have significant concerns 

about applying the mechanical shock 

test from GTR No. 20 to heavy vehicles 

and suggested refining the test 

procedure by defining the acceleration 

as a function of vehicle mass to provide 

a more granular method. 

Heavy vehicle manufacturer NFA 

agreed with NHTSA’s assessment that 

component-level tests are more 

appropriate than full scale crash tests 

for heavy vehicles due to practicability, 

as did Navistar and EMA. None of them 

provided data on crash loads for heavy 

vehicles; NFA expressly stated that it 

does not have sufficient data to 

determine test parameters at this time. 

NFA pointed to existing standards for 

mechanical shock testing, stating that it 

currently uses the mechanical shock 

requirements of UNECE R100, and 

noting industry standards for 

compressed natural gas (CNG) vehicles 

require that the CNG storage system can 

endure an inertial load of 8G, which is 

within the range of the component test 

procedure from GTR No. 20. 

Truck manufacturer Nikola stated that 

it designed and tested its vehicles based 

on the moving barrier tests currently in 

FMVSS Nos. 208, 214, and 305, and 

recommended that NHTSA likewise use 

the moving barrier for any heavy vehicle 

crash test requirements because it is 

more representative of a passenger 

vehicle. For mechanical shock testing, 

Nikola said that test facilities are not 

currently equipped with a test apparatus 

capable of testing Nikola’s entire REESS 

or subset. Regarding mechanical 

integrity testing, Nikola disagreed with 

establishing a requirement, as it is not 

required by GTR No. 20 and Nikola 

already requires its battery pack 

manufacturers to follow the UL 2580 

standard, which includes a crush test. 

Tesla commented that componentlevel testing is inadequate for 

mechanical integrity and mechanical 

shock testing, stating that the test will 

not be representative of the full vehicle, 

especially if the battery system must be 

removed from the vehicle for testing. 

Creaform, a 3D measurement and 

analysis company, also recommended 

vehicle-level post-crash requirements 

for heavy vehicles, saying that vehicle 

crashes can impose higher loads on an 

unprotected REESS than quasi-static 

crush tests, depending on the location of 

the REESS in the vehicle, and that 

adjusting the component-level 

mechanical integrity and mechanical 

shock test parameters would not cover 

the risks. Creaform said advanced 

numerical simulations can serve as a 

lower-cost alternative to vehicle crash 

testing. Battery manufacturer 

Freudenberg also disagreed with 

component-level mechanical integrity 

testing, stating it will place undue 

expectations on the battery enclosure. 

Freudenberg requested alignment of 

FMVSS No. 305a with the UNECE 

regulation, which exempts heavy 

vehicles from mechanical integrity test 

requirements. 

Agency Response 

In the absence of new data, the agency 

is not adopting post-crash requirements 

for heavy vehicles other than heavy 

school buses in FMVSS No. 305a. The 

agency did not propose post-crash 

requirements for heavy vehicles other 

than school buses in the NPRM because 

additional information is needed to 

develop requirements that are 

reasonable, practicable, and appropriate 

for the vehicles. While NTSB stated that 

the component-level tests in GTR No. 20 

are appropriate, the comment did not 

provide additional information. NTSB 

also suggested a documentation 

requirement for post-crash safety, which 

was not discussed in the NPRM and is 

therefore out of scope for this final rule. 

Comments from heavy vehicle 

manufacturers indicated that they 

currently use industry standards such as 

UL 2580, ‘‘Electric vehicle battery 

testing and certification,’’ and other 

safety regulations in designing their 

vehicles and procuring battery packs. 

The industry standards used by 

manufacturers are convenient tools to 


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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104327 

19ECE R.100, ‘‘Uniform provisions concerning 

the approval of vehicles with regard to specific 

requirements for the electric power train,’’ https:// 

unece.org/sites/default/files/2024-01/R0100r3e.pdf. 

20ECE R.94 Revision 4, ‘‘Concerning the 

Adoption of Harmonized Technical United Nations 

Regulations for Wheeled Vehicles, Equipment and 

Parts which can be Fitted and/or be Used on 

Wheeled Vehicles and the Conditions for 

Reciprocal Recognition of Approvals Granted on the 

Basis of these United Nations Regulations,’’ https:// 

unece.org/sites/default/files/2024-07/R094r4e.pdf. 

establish best practices in design and 

generally lack the objectivity needed for 

FMVSS. Further research will be needed 

to evaluate and modify such testing 

standards for inclusion in the FMVSS. 

Further investigation into heavy vehicle 

impacts and component-level test 

specifications would also address 

commenters’ concerns regarding 

accurate representation of crash forces. 

As none of the comments provided 

supporting data, the agency maintains 

that additional research is necessary to 

determine appropriate post-crash 

requirements and acceptability criteria 

for heavy vehicles other than heavy 

school buses for future consideration of 

FMVSS adoption. 

b. General Specifications Relating to 

Crash Testing 

The NPRM proposed several general 

provisions from GTR No. 20 that would 

apply to various testing and 

performance requirements. These 

provisions pertain to light vehicles and 

heavy school buses subject to the crash 

testing requirements of the proposed 

FMVSS No. 305a. 

1. Low Energy Option for Capacitors 

Proposed Requirements 

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. 

The NPRM proposed to include a postcrash low energy option for capacitors 

in the electric powertrain that is 

included in GTR No. 20. 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 option. 

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. NHTSA conducted 

an analysis of the potential hazard and 

concluded that the 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. 

Comments Received 

Comments on the low energy option 

for capacitors were positive, with 

manufacturers expressing support for 

the inclusion. Tesla agreed that there is 

no need to fully discharge all the 

capacitors, and Auto Innovators noted 

that the option is consistent with GTR 

No. 20 and other applicable 

international regulations. Auto 

Innovators suggested changing the ycapacitor calculation to match ECE 

100.03,19 noting that the proposed 

calculation ‘‘is inconsistent with ECE 

practice where the energy of a Y 

capacitor is the greater of 0.5Cy × V11∧2 

or 0.5Cy × V2∧2.’’ Auto Innovators also 

suggested a minor edit to the text of S8.2 

to clarify that the inclusion of the low 

energy specification for capacitors is an 

additional option for the post-crash 

electrical safety requirement. 

MEMA and Eaton commented that the 

low energy option for capacitors in the 

powertrain should include additional 

isolation requirements. MEMA said, 

‘‘criteria should include an isolation 

requirement from all parts of battery 

system to the external power output 

connectors of the battery pack as is 

currently included in FMVSS 305 S5.3, 

as well as avoiding a single point of 

failure as a standard and best-practice.’’ 

Eaton recommended the same criteria. 

MEMA and Eaton referred to these two 

additional requirements as 

‘‘acceptability criteria,’’ and requested 

their inclusion in multiple sections. 

Agency Response 

In response to the comments, the final 

rule follows the proposal in including a 

low energy option for capacitors for 

post-crash electrical safety. However, as 

detailed below, the final rule adopts the 

GTR No. 20 method of calculating 

energy in y-capacitors. In addition, the 

first paragraph of S8.2 has been edited 

for clarity and the typographical errors 

in S8.2(a)(2) have been corrected as 

suggested by commenters. 

Auto Innovators requested changing 

the y-capacitor energy calculation to 

that in ECE R.100.03. We note that ECE 

R.100.03 does not have the post-crash 

low energy optional method of meeting 

electric safety requirements because 

ECE R.100.03 does not address postcrash safety. The post-crash low energy 

option is available in ECE R.94,20 and 

the method of calculating capacitor 

energy post-crash is similar to that in 

GTR No. 20. The NPRM proposed 

calculating the energy stored in the two 

y-capacitors at once, assuming that each 

capacitance is the same, and requiring 

that the total energy not exceed 0.2 

Joules. However, GTR No. 20 calculates 

the energy in each y-capacitor 

separately, using the individual 

capacitance, and requires that the 

energy in each capacitor does not 

exceed 0.2 Joules. Because the GTR No. 

20 method uses the actual capacitance 

of each y-capacitor in the corresponding 

calculation, and therefore more 

accurately represents the stored energy 

in each, NHTSA is adopting the method 

from GTR No. 20 and requiring that the 

energy in each capacitor not exceed 0.2 

Joules. 

FMVSS No. 305a includes provisions 

for electrical isolation. As proposed, the 

post-crash electrical safety requirements 

in FMVSS No. 305a are the same as the 

current requirements in FMVSS No. 

305, except for the addition of a low 

energy option for capacitors to comply 

with electrical safety requirements. All 

high voltage sources, including the 

REESS, need to be either electrically 

isolated, contactors open resulting in 

low voltage, or have direct and indirect 

contact protection. The low energy 

option for capacitors does not 

circumvent the requirements for 

electrical protection, but rather allows 

for another verification method. 

The requirement to ensure no single 

point of failure (e.g., contact failure) was 

not discussed in the NPRM and is not 

in scope of this rulemaking. The FMVSS 

requirements are written in a manner to 

not be design restrictive, and therefore 

do not prescribe a particular connection 

to the battery due to the variation of 

battery designs. However, the 

requirements for the REESS that are 

included in FMVSS No. 305a for normal 

vehicle operations and post-crash 

scenarios verify that the system design 

provides a requisite level of safety. 

Comprehensive risk mitigation of 

potential hazards is further addressed 

by the documentation requirements. As 

discussed later in Section IV.n., 

‘‘Documentation Requirements,’’ 

manufacturers are required to 

demonstrate that they have considered 

and addressed identified safety risks for 

their vehicles. Designing separate 

connections to the battery and avoiding 

a single point of failure are examples of 

risk mitigation strategies that could be 

implemented by manufacturers along 


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104328 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

with other protective measures. 

Additional requirements for the postcrash low energy option for capacitors, 

beyond those test and documentation 

requirements discussed above, were not 

included in the NPRM and so are not in 

scope for this final rule. NHTSA will 

continue to study and discuss further 

requirements for battery safety, 

including additional requirements for 

post-crash low energy option for 

capacitors, during the ongoing efforts on 

Phase 2 updates to GTR No. 20. 

Harmonization with the GTR No. 20 

Phase 2 updates would be considered in 

future updates to the FMVSS No. 305a 

requirements. 

2. Assessing Fire or Explosion in 

Vehicle Post-Crash Test 

Proposed Requirements 

In accordance with GTR No. 20, 

NHTSA proposed 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. 

Comments Received 

Commenters generally agreed with the 

proposed requirement. MEMA, Auto 

Innovators, Lucid, and Nikola stated 

support, with Nikola saying that the 

provision should also apply to heavy 

vehicles if a crash test requirement is 

added. Tesla agreed with the proposal 

as well but requested additional 

guidance and an explicit evaluation 

procedure. In contrast to other industry 

members, SAVE Coalition disagreed 

with implementing the requirement at 

the vehicle level because FMVSS Nos. 

208, 214, 301, and 303 do not include 

the same requirement for other types of 

vehicles. SAVE Coalition said, ‘‘If 

NHTSA’s intent is to regulate fire risks 

from all vehicle systems, that 

requirement should be applied more 

generally in a regulation covering all 

vehicles regardless of powertrain. For 

the purposes of assessing electric 

vehicle safety, and to align with GTR 20 

and the stated intent in the preamble, 

this requirement should be clarified to 

be specific to REESS related fires.’’ 

Agency Response 

After considering the comments, 

NHTSA has decided to adopt the 

proposed post-crash requirement that 

there be no evidence of fire or 

explosion. For electric vehicles, thermal 

runaway and propagation poses a 

significant fire risk regardless of 

electrolyte leakage from the battery 

pack, so FMVSS No. 305a addresses fire 

safety assessment directly. The postcrash assessment does not require 

disassembly of the vehicle or 

components. Evidence of fire or 

explosion could include flames, smoke, 

scorch marks, or other indications. If 

such evidence were visible at any time 

within the one-hour inspection period 

following the crash test, the vehicle 

would fail to meet the safety 

requirement. The agency maintains that 

the requirement is appropriate as 

written. 

Regarding SAVE Coalition’s concern 

that only electric vehicles, not other 

vehicle types, are subject to post-crash 

fire assessment, NHTSA would like to 

explain the FMVSS safety requirements 

that were cited. FMVSS No. 208, 

‘‘Occupant crash protection,’’ and 

FMVSS No. 214, ‘‘Side impact 

protection,’’ apply to vehicles regardless 

of fuel type and address the physical 

forces and accelerations in a crash; 

electric and non-electric vehicles must 

meet the safety requirements in these 

FMVSSs. Fire resulting from spillage or 

leakage of combustible fuels is 

addressed in fuel specific FMVSSs, 

including FMVSS No. 301, ‘‘Fuel system 

integrity,’’ and FMVSS No. 303, ‘‘Fuel 

system integrity of compressed natural 

gas vehicles,’’ by limiting combustible 

fuel spillage or leakage. For electric 

vehicles, FMVSS No. 305a addresses 

fire safety assessment directly because 

limiting electrolyte leakage outside of 

the battery pack is insufficient to 

address the risk of fire from thermal 

runaway and propagation in the REESS. 

Further, it may be difficult to ascertain 

the origin of a fire observed at the 

vehicle level, and exempting fires that 

may originate in or involve other 

vehicle systems would not be beneficial 

to safety. For these reasons, the agency 

is adopting the proposed requirement. 

3. Assessing Post-Crash Voltage 

Measurements 

Proposed Requirements 

The NPRM proposed that the postcrash voltage measurements in FMVSS 

No. 305a would be made between 10 

seconds and 60 seconds after impact. 

Using the time of impact to define the 

measurement period avoids a source of 

ambiguity present in FMVSS No. 305 

and is consistent with the GTR No. 20 

test procedure. The voltage 

measurement and calculation methods 

in the NPRM are otherwise the same as 

those currently in FMVSS No. 305. 

Comments Received 

Comments on the voltage 

measurement procedure were mixed, 

with some commenters in agreement 

and others requesting changes to the test 

specifications. Manufacturers Nikola, 

Tesla, and Lucid agreed with the 

agency’s rationale and stated support for 

the proposed requirements. However, 

Honda said that the timing language is 

ambiguous and ‘‘could be 

misinterpreted to mean that the 

requirements must be met both at 10 

seconds and 60 seconds after the 

impact.’’ Honda also said that 60 

seconds is insufficient for isolation 

resistance measurements and requested 

full alignment with GTR No. 20, which 

does not include the upper time limit 

for electrical isolation. Auto Innovators 

provided a similar comment, noting that 

electrical isolation is stable and 

requesting removal of the 60-second 

limit for post-crash isolation 

measurements. 

Auto Innovators commented on the 

proposed calculation method as well, 

stating, ‘‘the NPRM assumes that 

V1+V2=Vbat, but this may not be 

strictly true,’’ due to multimeter 

resistance. Auto Innovators provided 

revised diagrams and formulas and 

suggested that FMVSS No. 305a provide 

an electrical isolation compliance 

option matching ECE 100.03. Bugatti 

also disagreed with the calculation 

method for the electrical isolation 

baseline measurement, saying that it 

does not address a potential zero-volt 

measurement across Ro that may occur 

if Ri is much higher. Bugatti noted that 

the proposed requirements do not allow 

the use of a megohmmeter as an 

alternative method to avoid the zerovolt issue. Bugatti requested 

clarification and recommended adding 

the megohmmeter measurement method 

allowed by ECE 100.03. As with the low 

energy option for capacitors, Eaton 

again suggested adding acceptability 

criteria for battery isolation. 

Agency Response 

The agency is adopting the proposed 

requirements with a minor revision for 

the timing of voltage measurements for 

assessing electrical isolation post-crash. 

The proposed requirements stated that 

the post-crash voltage measurements 

would be made ‘‘between 10 to 60 

seconds after impact.’’ The agency 

believes that this language is clear but 

agrees that the time specification should 

distinguish between compliance 

options. The post-crash electrical safety 

requirements include four compliance 

options: low voltage, electrical isolation, 

protective barrier, and low energy for 


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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104329 

21See Annex 5A on page 40 in ECE R.100.03 at 

https://unece.org/sites/default/files/2024-01/ 

R0100r3e.pdf. 

22Sodium ion aqueous batteries (SIAB), which 

are environmentally benign, provide a promising 

alternative for safe, cost-effective, and scalable 

energy storage, with high power density. However, 

current SIABs have limited output voltage and 

inadequate energy density for vehicle applications. 

23 GTR No. 20 also requires that no more than 7 

percent by volume of the REESS electrolyte shall 

leak into the passenger compartment. However, as 

noted in the NPRM, there is no practical way of 

measuring the quantity by volume of the electrolyte 

in the REESS to ensure compliance with such a 

requirement. 

capacitors. After further consideration, 

the agency agrees that the 60-second 

time limit is unnecessary for the 

electrical isolation measurement 

procedure because the values are static 

and that harmonization with the GTR 

No. 20 specification is appropriate. For 

these reasons, the post-crash test 

specification has been modified to state 

that the measurements for the electrical 

isolation compliance option are made at 

least 10 seconds after impact, with no 

upper time limit. 

With regard to possible zero-volt 

measurements in the electrical isolation 

baseline calculation, the agency does 

not believe there is an issue. Consistent 

with GTR No. 20, the minimum 

resistance of the voltmeter is specified, 

and a higher resistance R0 can be used 

if the voltage measurement is very low. 

The agency has not observed zero-volt 

measurements in testing using the 

specified procedures, which were 

evaluated for practicability and 

repeatability. The megohmmeter option 

from UNECE R100 is not incorporated 

because research has shown that the 

megohmmeter method may provide 

different results than the multimeter 

method. The agency believes inclusion 

of the megohmmeter option could lead 

to inconsistent results and would not be 

beneficial. 

Auto Innovators provided an alternate 

measurement method and calculations 

for electrical isolation resistance that 

takes into consideration the resistance 

of the multimeter used for voltage 

measurements. Auto Innovators noted 

that this alternate method is in ECE 

R.100.03 and requested harmonizing 

with ECE R.100.03. However, the test 

method and calculations in ECE 

R.100.03 21 are the same as those 

currently in FMVSS No. 305 and 

proposed in the NPRM for FMVSS No. 

305a. Regardless, the agency will 

continue evaluating the recommended 

alternate procedure to determine 

whether the results and ease of testing 

support its inclusion in FMVSS No. 

305a. The alternate method was not 

proposed in the NPRM and is therefore 

out of scope of this rulemaking. If the 

agency’s research supports use of the 

alternate measurement procedure and 

calculations, they may be added at a 

later date. At this time, NHTSA is 

adopting the method currently in 

FMVSS No. 305 and proposed in the 

NPRM for inclusion in FMVSS No. 

305a. 

The suggestion to add acceptability 

criteria for battery isolation to the postcrash requirements was discussed 

earlier in Section IV.b.1, ‘‘Low Energy 

Option for Capacitors.’’ 

4. Electrolyte Leakage 

Proposed Requirements 

The NPRM proposed to include a 

post-crash requirement limiting 

electrolyte leakage; this requirement is 

currently in FMVSS No. 305 as 

‘‘electrolyte spillage’’ and permits no 

more than 5 liters of electrolyte spilled 

or leaked. NHTSA sought comment on 

the necessity and relevance of such a 

requirement for current EVs, as well as 

recommendations regarding electrolyte 

leakage detection methods and 

differentiation from other liquids. 

Comments Received 

Commenters agreed that the updated 

terminology of ‘‘electrolyte leakage’’ is 

appropriate but stated that the 5-liter 

maximum leakage requirement is no 

longer relevant. Auto Innovators and 

Nikola both said that leakage outside of 

the battery pack should not occur with 

modern EVs and that 5 liters is a very 

large amount. Auto Innovators stated 

that there is no reliable method to detect 

or quantify leakage and recommended 

that the requirement be removed 

entirely. Tesla stated that physical 

characteristics can be used to determine 

whether electrolyte or coolant has 

leaked from the vehicle if differentiation 

is a concern. Nikola suggested that any 

electrolyte leakage outside of the battery 

pack should constitute a failure. Blue 

Bird noted that there are many different 

forms of electrolytes, including solids 

and gels, and leakage may not be 

observed. 

Agency Response 

This final rule adopts the updated 

‘‘electrolyte leakage’’ terminology and 

the current FMVSS No. 305 requirement 

for no more than 5 liters of electrolyte 

leakage post-crash. The cells of lithiumion batteries in current EVs have small 

quantities of electrolyte that could leak 

out of the battery casing rather than 

spill. The agency agrees with 

commenters that any electrolyte leakage 

in EVs using lithium-ion batteries 

would be significantly lower than the 

current 5-liter limit in FMVSS No. 305. 

However, there are other types of 

batteries with aqueous electrolyte that 

may be considered for vehicle 

applications in the future.22 At this 

time, it is unclear whether the 5-liter 

limit will remain appropriate for future 

batteries. Specifically for vehicles using 

a REESS with aqueous electrolyte, GTR 

No. 20 similarly includes a requirement 

limiting electrolyte leakage to no more 

than 5 liters within 60 minutes after the 

crash test.23 Because there is no further 

information available, the agency is 

adopting the post-crash electrolyte 

leakage limit of 5 liters that is consistent 

with the current requirements in 

FMVSS No. 305 and GTR No. 20. 

However, unlike GTR No. 20, the agency 

is not distinguishing between REESS 

with different types of electrolyte; the 

requirements in FMVSS No. 305a are 

established as battery chemistry-neutral 

and are applicable to all types of REESS. 

The agency will continue to review and 

update the requirements in FMVSS No. 

305a over time, as relevant information 

becomes available. 

While one commenter suggested a 

requirement for no electrolyte leakage 

outside of the battery pack, a post-crash 

requirement prohibiting any electrolyte 

leakage from the pack was not proposed 

in the NPRM and is out of scope for this 

final rule. A post-crash test requirement 

prohibiting any amount of leakage 

outside of the battery pack may also be 

challenging to verify. However, as in 

FMVSS No. 305, this final rule includes 

a requirement that no visible trace of 

electrolyte shall leak into the passenger 

compartment of the vehicle for occupant 

safety. This final rule also adopts visual 

inspection requirements in the tests 

evaluating safety during normal vehicle 

operations, including no evidence of 

electrolyte leakage or venting (without 

disassembly of the vehicle), as 

discussed in Section IV.c.6., below. 

c. Vehicle Controls for Safe REESS 

Operation 

Overview 

The NPRM proposed requirements 

and associated full-vehicle tests for 

vehicles to ensure they have controls 

managing safe REESS operation, 

specifically overcharge, over-discharge, 

overcurrent, over-temperature, and 

external short-circuit protection. These 

requirements are applicable to light 

vehicles and heavy vehicles, and are 

generally aligned with those in GTR No. 

20, with minor differences for ease of 

testing. The NPRM also proposed 

documentation requirements for lowtemperature protection, as in GTR No. 


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104330 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

24System-Level RESS Safety and Protection Test 

Procedure Development, Validation, and 

Assessment–Final Report,’’ DOT HS 812 782, 

https://rosap.ntl.bts.gov/view/dot/42551. 

25Test reports and laboratory test procedures are 

available in the docket NHTSA–2021–0029. https:// 

www.regulations.gov/docket/NHTSA-2021-0029/ 

document, Docket ID, NHTSA–2021–0029–0001, 

NHTSA–2021–0029–0002, and NHTSA–2021– 

0029–0003. 

26Safety Performance of Rechargeable Energy 

Storage Systems, DOT HS 812 717, 2019, https://

rosap.ntl.bts.gov/view/dot/40791. 

20, because no practical test procedure 

currently exists. 

Commenters addressed a variety of 

topics related to the requirements for 

safe REESS operation. The comments 

submitted by NTSB and Consumer 

Reports expressed appreciation and 

support for the requirements to ensure 

REESS safety and longevity. The 

comments from industry also expressed 

general agreement with the 

requirements for safe REESS operation 

but disagreed about certain aspects of 

the test procedures. Specifically, these 

comments addressed vehicle- and 

component-level testing, REESS state of 

charge, breakout harness location, overtemperature testing, overcurrent 

protection, and venting and visual 

inspection, as detailed below. Overall 

vehicle- and component-level testing is 

addressed below in section IV.c.1. 

Comments on specific testing provisions 

for vehicle controls are then addressed 

in sections IV.c.2 through c.6. 

1. Vehicle- and Component-Level 

Testing 

Proposed Requirements 

The NPRM proposed vehicle-level 

testing using a breakout harness 

connected to a battery tester/cycler to 

evaluate vehicle controls for safe REESS 

operation. The test procedures ensure 

the vehicle controls provide protection 

against overcharge, over-discharge, 

overcurrent, over-temperature, and 

external short-circuit fault conditions. 

Maintaining the REESS within the 

manufacturer-specified functional range 

minimizes the risk of fire and electrical 

shock. NHTSA proposed vehicle-level 

testing of the REESS because testing at 

the equipment level would not evaluate 

all relevant vehicle controls or any 

interaction or interference between 

vehicle controls. 

Comments Received 

Many comments from industry 

disagreed with the agency’s exclusion of 

component-level compliance test 

options, which are included in GTR No. 

20 and ECE R100.03. Auto Innovators, 

Bugatti, EMA, Ford, Honda, Hyundai, 

Lucid, NFA, Nissan, UL Solutions, and 

ZETA were among those that requested 

component-level testing. ZETA stated 

that manufacturers ‘‘could face hurdles 

in transitioning to vehicle-level testing, 

including changing logistics, higher 

costs, and lack of testing equipment 

availability.’’ Auto Innovators likewise 

said that vehicle-level testing would add 

significant cost without increasing 

robustness or stringency. 

Ford agreed with Auto Innovators, 

saying that it does not have large 

enough facilities, and noted that 

NHTSA did not provide data showing a 

need for full-vehicle testing. Honda 

stated that vehicle-level testing requires 

specialized parts, increases safety risks, 

and reduces control over test conditions 

compared to component-level testing. 

NFA said requiring full-vehicle testing 

would be burdensome and redundant, 

because the same pack would be tested 

multiple times. Hyundai said that the 

option to conduct testing at the 

component level would enable 

manufacturers to iterate on REESS 

design and safety systems more rapidly. 

Lucid said, ‘‘testing at the component 

level (REESS) provides the benefit of 

recreating the worst-case scenario, ideal 

for safety testing, due to its smaller 

thermal mass. Vehicle-level testing 

would also require larger thermal shock 

chambers than currently used at the 

REESS-level.’’ UL Solutions also 

suggested adding UL 2580 certification 

as another compliance option, while 

ZETA further requested that NHTSA 

allow manufacturers to specify their 

own boundary conditions for 

component-level testing because each 

vehicle model is different. 

A few commenters suggested that 

component-level testing should be 

allowed under certain conditions or for 

specific tests. Nissan suggested that 

NHTSA allow a component-level 

compliance option if the manufacturer 

can demonstrate that the test results 

reasonably reflect the safety 

performance of the complete REESS 

under the same conditions. UL 

Solutions similarly requested that the 

agency ‘‘allow independent testing of 

the battery if the battery can 

demonstrate compliance to the 

requirements without the benefit of the 

vehicle support systems.’’ Tesla agreed 

with most of the proposed test 

procedures but requested a componentlevel compliance option for the overtemperature test, as ‘‘it would be 

difficult to characterize real-world 

driving temperature profiles fully and 

accurately due to variable drive states.’’ 

Nikola stated that vehicle-level testing 

for overcharge, over-discharge, and 

over-temperature protection cannot be 

conducted on hybrid or fuel cell EVs, so 

those tests should be conducted at the 

component level. 

Agency Response 

After reviewing the comments, the 

agency is adopting the requirements as 

proposed because vehicle-level testing 

is supported by NHTSA’s research for 

its practicability and feasibility. 

NHTSA-funded research independently 

evaluated, refined, and validated the 

proposed vehicle-level test procedures 

for various types of electric vehicles 

(HEV, PHEV, and BEV).24 NHTSA 

conducted additional research to 

evaluate capabilities in compliance test 

laboratories and practicability of vehicle 

level tests.25 The test program 

demonstrated the ease of conducting 

tests at the 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. Evaluating 

REESS operation at the vehicle level is 

consistent with other FMVSSs and 

ensures the entire system is captured, 

including input from different 

subsystems and any interaction or 

interference between vehicle controls, 

and is most representative of real-world 

conditions. A vehicle level test also 

ensures that the boundary conditions 

are appropriate and would not be 

challenged in the event of a compliance 

test failure. NHTSA’s initial research for 

test procedure development for electric 

vehicles was done with the whole 

vehicle and not with individual 

components in the vehicle.26 The 

comments did not demonstrate that 

component-level testing of the REESS 

would provide the same comprehensive 

evaluation, nor that full-vehicle tests 

cannot be conducted on all applicable 

vehicles. 

In contrast to comments that vehiclelevel tests are burdensome, overly 

costly, and require additional safety 

measures, NHTSA’s testing program 

revealed the ease of conducting testing 

at the vehicle level multiple times on 

the same vehicle without significant 

cost. The overcharge, over-discharge, 

overcurrent, over-temperature, and 

external short-circuit test procedures in 

FMVSS No. 305a are non-destructive, 

are conducted at ambient temperatures, 

and can be conducted sequentially on 

the same vehicle, minimizing the time 

and cost of testing. The tests also 

include multiple end conditions for 

design flexibility. The agency maintains 

that the requirements are appropriate to 

replicate and confirm real-world vehicle 

operations and do not constitute an 

undue burden on manufacturers. 


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27As an example, see page 2–27 of a NCAP crash 

test report of the 2022 Chevrolet Bolt, which 

indicates that the voltage range corresponds to the 

‘‘usable energy’’ of the battery. https://nrd-static.

nhtsa.dot.gov/reports/vehdb/v10000/v14200/ 

v14218R001.pdf. 

28Electric Vehicle GTR No. 20 Test Development, 

Validation, and Assessment, DOT HS 812 092, 

April 2021, https://rosap.ntl.bts.gov/view/dot/ 

55584. 

We understand manufacturers may 

conduct testing for various scenarios 

beyond the requirements of FMVSS No. 

305a, and such testing may be 

conducted at the vehicle level and/or 

the component level. FMVSSs establish 

minimum safety requirements and the 

FMVSS test procedures provide notice 

to establish how the agency would 

verify compliance. However, this does 

not mean that manufacturers must 

conduct the exact test in the FMVSS to 

certify their vehicles. The Safety Act 

requires manufacturers to ensure their 

vehicles comply with all applicable 

FMVSSs and to certify compliance of 

their vehicles with all applicable 

FMVSSs, and the Safety Act specifies 

that manufacturers may not certify 

compliance if, in exercising reasonable 

care, the manufacturer has reason to 

know the certificate is false or 

misleading. A manufacturer may use 

component-level tests to certify its 

vehicles if they exercise reasonable care 

in doing so. In other words, a 

manufacturer must ensure that its 

vehicles will meet the requirements of 

FMVSS No. 305a when NHTSA tests the 

vehicles in accordance with the test 

procedures specified in the standard, 

but the manufacturer may use different 

test procedures to do so. 

2. State of Charge (SOC) 

Proposed Requirements 

Initial SOC ranges were specified for 

each of the proposed test procedures for 

vehicles to ensure they have controls 

managing safe REESS operations. Some 

of the SOC ranges differed from those in 

GTR No. 20 for practicability and ease 

of conducting the tests. For the 

overcharge, over-temperature, and 

external short-circuit tests, the REESS is 

initially at 90 to 95 percent SOC. For the 

over-discharge test, the REESS is 

initially at 10 to 15 percent SOC. For the 

over-current test, the REESS is initially 

at 40 to 45 percent SOC. 

Comments Received 

Several commenters stated that there 

should be more flexibility in the SOC 

ranges for the tests. Auto Innovators and 

Honda stated that the proposed values 

are too extreme and will likely have 

already activated the protections. Auto 

Innovators requested that NHTSA align 

the starting SOC values with those in 

GTR No. 20. Nissan suggested setting 

the starting SOC around the middle of 

the normal operating range for the 

overcharge and external short-circuit 

tests, as in UNECE Regulation No.100, 

because hybrid vehicles may fall outside 

the range of normal use if the REESS is 

initially set between 90 to 95 percent 

SOC. Bugatti commented similarly, 

‘‘Prescribing absolute values for SoC of 

the REESS, without consultation of 

manufacturer-specified SoC operational 

windows, may influence test results due 

to possible risk for the REESS to be out 

of its normal operating SoC range, even 

from the beginning of tests.’’ Bugatti 

recommended removing SOC values 

and taking a similar approach to UNECE 

Regulation No. 100, which references 

manufacturer-specified SOC. 

Agency Response 

After reviewing the comments, the 

agency is adopting the proposed 

requirements with a minor modification 

to the definition of SOC to clarify the 

requirements and address commenters’ 

concerns. The initial SOC specifications 

in the test procedures refer to the 

‘‘operating SOC,’’ or percent charge 

available under normal operation as it 

may be displayed to the user. In other 

words, the charge level for beginning 

each test is based on the normal 

functional range of the REESS defined 

by the manufacturer, not direct 

measurement of the battery capacity. 

This distinction was not sufficiently 

clear in the NPRM, leading to concerns 

about the validity of the test parameters. 

However, the specified parameters were 

tested and validated for different types 

of electric vehicles, including HEV and 

PHEV. These tests included vehicle 

crash tests of battery electric vehicles 27

and tests of vehicle controls that manage 

REESS operations and its health.28 The 

initial SOC ranges are intended to 

minimize the amount of time needed to 

conduct each test. Starting every test in 

the middle of the normal operating 

range rather than the upper or lower 

portion would lead to longer test times 

with no added benefit. In the event that 

the vehicle does not display the 

operating SOC, the charge level can be 

estimated using the information 

provided by the manufacturer. 

To improve clarity, NHTSA is 

changing the definition of ‘‘State of 

charge’’ to mean the available electrical 

charge in a REESS expressed as a 

percentage of the normal operating 

capacity specified by the vehicle 

manufacturer. 

3. Breakout Harness Location 

Proposed Requirements 

The NPRM proposed to conduct the 

REESS tests using a breakout harness 

connected to manufacturer-specified 

location(s) on the traction side of the 

REESS on the vehicle’s electric 

powertrain. The manufacturer is 

required to specify the location(s) for 

connecting the breakout harness and 

may also provide an appropriate 

breakout harness for testing the vehicle. 

If the manufacturer does not provide a 

breakout harness, NHTSA will use a 

generic breakout harness to connect to 

the traction side of the REESS. 

Comments Received 

Regarding the overcharge, overdischarge, and overcurrent test 

procedures, Honda stated that the term 

‘‘traction side’’ is too prescriptive and 

inconsistent with the proposed test 

procedure in S12.5, which did not 

include the same specification. Auto 

Innovators provided the same comment. 

Prevost requested clarification of the 

‘‘traction side’’ designation to make 

clear which systems and subsystems are 

considered to be part of the traction side 

of the REESS and which are not. An 

example to clarify is whether the 

charging inlet is part of the ‘‘traction 

side’’ of the REESS. Prevost further 

suggested making note of a designated 

location when it is not specified by the 

manufacturer. 

Agency Response 

This final rule adopts the proposed 

requirements for the breakout harness 

location(s) as described in the NPRM, 

with edits for clarity and consistency. 

The ‘‘traction side’’ of the REESS refers 

to the connection between the REESS 

and the transmission, so it does not 

include the charging inlet. The traction 

side of the REESS is specified to ensure 

that external charging and regenerative 

charging are both captured by the test. 

Regenerative charging can potentially 

lead to overcharge conditions even if the 

vehicle controls prevent overcharging 

from the charging inlet. The 

manufacturer is also required to state 

the connection location(s) because a 

single location would not work for all 

vehicles and because connecting the 

harness to the wrong points of the 

powertrain could be damaging and/or 

hazardous. For the test operators’ safety, 

ease of testing, and to prevent damage 

to the vehicle or test equipment, the 

manufacturer is required to recommend 

specific connection location(s). 

Although the NPRM clearly stated that 

the manufacturer is required to provide 

connection locations, the proposed 


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29NHTSA testing demonstrated that presoaking 

of the vehicle at elevated temperature does not raise 

the temperature of the REESS as significantly as by 

driving the vehicle under high acceleration and 

deceleration drive modes. See 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. 

30Nissan requested to meet with NHTSA to 

present information related to the proposed rule. 

An ex-parte memo has been submitted to the docket 

(https://www.regulations.gov/docket/NHTSA-2024- 

0012). 

regulatory text was inconsistent. The 

text in S12 has been edited to clarify the 

requirement. Additionally, because the 

manufacturer is required to provide 

connection locations, no default 

locations are necessary. Regarding the 

exclusion of ‘‘traction side’’ in S12.5, 

that test is intended to evaluate the 

response to an external short circuit, so 

the traction side specification does not 

apply. Another possible source of 

confusion could be due to the proposed 

text for S12.5 referencing ‘‘overcharge’’ 

instead of ‘‘external short-circuit;’’ the 

text has been corrected in the final rule. 

4. Over-Temperature Protection 

Proposed Requirements 

The NPRM proposed to include the 

over-temperature protection 

requirement and test procedure from 

GTR No. 20, with minor changes. 

NHTSA’s testing indicated that 

presoaking the vehicle was not 

necessary,29 so the NPRM proposed to 

remove presoaking from the procedure 

to reduce the test time and burden. The 

test procedure specifies that the test is 

conducted at ambient temperature, 

between 10°C and 30°C, with the 

cooling system disabled or minimized. 

The vehicle is driven on a chassis 

dynamometer using the manufacturerprovided drive profile, or with 

aggressive acceleration and deceleration 

if an appropriate drive profile is not 

provided. 

Comments Received 

Commenters generally agreed with the 

requirement but recommended changes 

to some aspects of the test procedure. 

MEMA stated agreement with the 

agency’s decision to remove presoaking, 

and Auto Innovators agreed with 

removing the requirement but said it 

should be permitted. Auto Innovators 

also stated that several provisions were 

overly prescriptive and unnecessary, 

specifically the directions to conduct 

the test on a chassis dynamometer and/ 

or in active driving mode, limit the 

ambient temperature to 30°C, and 

specify a one-hour time period. Honda 

also disagreed with the limits on the 

time period and ambient temperature, 

stating that there are situations where 

the battery temperature will not rise 

unless the ambient temperature rises. 

EMA also suggested modifying the 

standard cycle specification to allow a 

manufacturer supplied drive profile, as 

‘‘S12.4 (d) requires using an appropriate 

manufacturers supplied drive profile 

and (h) should follow the same drive 

profile or allow for the option to follow 

the same manufactured supplied drive 

profile.’’ In an ex-parte meeting,30

Nissan commented that it was unclear 

whether all three test termination 

conditions had to be fulfilled to 

terminate the charge/discharge cycle. 

Agency Response 

After reviewing the comments, the 

agency is adopting the proposed 

requirements with an additional 

clarification for the manufacturerprovided drive profile. The proposed 

rule defined an appropriate drive profile 

by stating that it should raise the 

temperature of the REESS above the safe 

operating temperature within one hour. 

The test procedure specifies that the 

cooling system is disabled or 

functionally minimized for testing, but 

this provision was not stated when 

defining an appropriate drive profile. 

The commenters did not specify if the 

REESS cooling system was minimized 

in their testing. However, the agency 

recognizes that some vehicles may not 

be operable with cooling reduced to a 

level that would allow the REESS to 

overheat under the specified test 

conditions. To address commenters’ 

concerns, if it is not possible to raise the 

temperature of the REESS without 

raising the ambient temperature of the 

vehicle above 30°C, the manufacturer 

may provide a drive profile that would 

trigger the over-temperature condition 

within one hour if the thermal 

management system were effectively 

disabled. 

For the performance test, the test 

termination conditions in FMVSS No. 

305a are identical to those in GTR No. 

20, where the vehicle may be charged 

and discharged for up to 3 hours. The 

test time is not limited to one hour and 

it is not required to trigger the overtemperature protection, to avoid 

penalizing effective thermal 

management. The test procedure also 

does not prohibit presoaking or 

otherwise specify the starting 

temperature of the vehicle. However, 

the test is conducted at ambient 

temperature to avoid the added cost of 

testing in a heat chamber. The use of a 

chassis dynamometer and active driving 

possible mode of the vehicle are 

specified to ensure that the vehicle is 

tested in the normal operating state. The 

termination conditions were accurately 

described in the preamble of the NPRM 

and are the same as those in GTR No. 

20. However, the agency agrees that the 

proposed regulatory text did not clearly 

indicate only one of the termination 

conditions needs to be fulfilled to 

terminate the discharge/charge cycle. 

The regulatory text specifying the test 

methods for evaluating vehicle controls 

managing REESS safe operations (S12) 

have all been modified to clarify the 

corresponding termination condition 

requirements in the final rule. 

Section S12.4(h) of the overtemperature test procedure specifies 

conducting a standard cycle, if allowed 

by the vehicle. A standard cycle, as 

defined in GTR No. 20 and FMVSS No. 

305a, consists of a standard discharge 

followed by a standard charge. The 

NPRM stated that the discharge and 

charge rates used for the standard cycle 

would be provided by the vehicle 

manufacturer. It also specified the 

alternative charge and discharge rates 

that would be used if the manufacturer 

did not provide them. The standard 

cycle is the same for each of the test 

procedures addressing safe operation of 

the REESS and is unrelated to other test 

specifications. The definition and use of 

the standard cycle are adopted as 

proposed. 

5. Overcurrent Protection 

Proposed Requirements 

The NPRM proposed to include the 

overcurrent protection and test for 

vehicles capable of charging by direct 

current (DC) external electricity supply, 

as in GTR No. 20. During the test, the 

REESS is charged using the battery 

tester/cycler in accordance with the 

manufacturer’s recommended charging 

procedure with the highest normal 

charge current specified by the 

manufacturer, or at a rate of C/3 current 

if none is provided. After charging is 

initiated, an over-current specified by 

the manufacturer is supplied, or the 

current is increased in 10-Ampere steps, 

until the vehicle over-current protection 

terminates charging or the temperature 

gradient of the REESS is within 4°C for 

a two-hour period. The standard cycle is 

then performed, if possible, and the test 

concludes with electrical isolation 

assessment and a one-hour observation 

period to assess evidence of electrolyte 

leakage, venting, fire, or rupture. 

Comments Received 

EDTA, MEMA, NEMA, and Eaton 

suggested expanding the overcurrent 

protection requirements to address 

battery isolation. NEMA said that the 


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31 If the contactor opens when the overcurrent is 

applied, the vehicle will not charge/discharge 

unless the controls are reset. 32https://www.nhtsa.gov/battery-safety-initiative. 

contactors can weld, leading to a system 

protection failure and a safety issue, and 

that GTR No. 20 does not offer adequate 

overcurrent protection in those cases. 

Eaton emphasized that contactor failure 

occurs frequently, as evidenced by 

recent vehicle recalls, and suggested 

NHTSA require manufacturers to 

demonstrate they can fully isolate the 

positive and negative poles of the 

battery following a vehicle crash or 

overcurrent event. EDTA, MEMA, and 

NEMA made similar comments, 

requesting battery isolation testing and 

documentation showing no single point 

of failure. 

Agency Response 

After reviewing the comments, the 

agency is adopting the proposed 

requirements. NHTSA agrees with 

commenters that contactor failure can 

lead to system protection failure and a 

safety issue. However, we do not see a 

need to explicitly require ‘‘fully 

isolat[ing] the positive and negative 

poles of the battery following a vehicle 

crash or overcurrent event,’’ as Eaton 

and other commenters suggested. The 

test procedures in the FMVSS are 

established to mitigate safety risks in a 

manner that is not design restrictive. In 

the adopted overcurrent test, the 

overcurrent is applied until either the 

protection controls terminate charging 

(contactors open), or a long time has 

passed without an appreciable change 

in REESS temperature. Additionally, 

after the overcurrent is applied, a 

standard cycle is performed, if 

possible,31 after which no electrolyte 

leakage, rupture, venting, fire, or 

explosion is permitted during a onehour observation period. At the 

conclusion of the observation period, 

the electrical isolation is determined in 

a similar manner as in FMVSS No. 305, 

using a voltmeter to measure the 

voltages. The agency believes that the 

termination criteria for the application 

of overcurrent and the subsequent 

evaluations ensure that the main 

contactors in the REESS are not fused 

due to the overcurrent and therefore 

mitigate the safety risk. These 

requirements are intended to enhance 

safety while allowing manufacturers 

design flexibility. 

NHTSA will continue to research and 

assess electric vehicle safety issues and 

the need for additional changes to the 

overcurrent requirements. NHTSA is 

also aware of vehicle fires originating at 

the vehicle charge inlet while the 

vehicle is being charged. Some of these 

fires have resulted from faulty 

connections between the charge 

connector and the vehicle. As part of 

NHTSA’s Battery Safety Initiative,32 the 

agency continues to evaluate these 

safety risks and potential future agency 

actions to mitigate these risks. 

6. Venting and Visual Inspection 

Proposed Requirements 

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 result in 

varying degrees of safety risks to the 

vehicle occupant. The NPRM proposed 

that each of the tests evaluating vehicle 

controls for safe REESS operation 

(overcharge, over-discharge, 

overcurrent, over-temperature, and 

external short-circuit test procedures) 

would end 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. NHTSA proposed that there 

be no evidence of electrolyte leakage, 

venting, or rupture that 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 agency acknowledged that 

research is needed to develop a 

repeatable, reproducible, and practical 

method to verify the occurrence of 

various vented gases and requested 

comment on the Informal Working 

Group’s continuing work in Phase 2 of 

the GTR. 

Comments Received 

As a whole, commenters agreed that 

venting detection methods are 

challenging to specify at this time and 

appropriate sensors are still under 

development. Auto Innovators stated 

that the proposed visual inspection 

requirement is unnecessary because 

visible venting is unlikely. On the other 

hand, DTNA agreed with the visual 

inspection requirement but requested 

adding a test procedure provision where 

venting inspection is captured visually 

and with written description of the 

findings. 

With regard to sensor research, Tesla 

stated agreement with the agency’s 

assessment that more research is 

needed, and Nikola said it doesn’t have 

enough to data to recommend the usage 

of such sensors for general application. 

For future test requirements, Rivian 

suggested that the detection method 

depend on whether the area of concern 

is the gas venting within the REESS or 

the risk of occupant/bystander exposure 

to vented gases. Rivian noted that gas 

detection outside of the REESS is more 

challenging than detection inside the 

REESS and recommended prioritizing 

carbon monoxide sensors. Auto 

Innovators suggested focusing on a 

limited number of critical gases, with an 

emphasis on release or venting that may 

impact occupants. 

Agency Response 

The agency is adopting the proposed 

requirements for no evidence of 

electrolyte leakage, rupture, venting, 

fire, or explosion as determined by 

visual inspection during a one-hour 

observation period for each of the 

vehicle controls for safe REESS 

operation tests. The commenters agreed 

that appropriate sensors and procedures 

for detection of vented gases are not 

currently available and that more 

research is needed. NHTSA is 

continuing to investigate gas detection 

methods and potential test procedures 

to address venting of hazardous gases 

such as carbon monoxide. This research 

will inform future rulemaking. At this 

time, the agency believes inclusion of 

the visual inspection requirement 

enhances safety protection to limit 

safety risk to vehicle occupants due to 

venting and should remain a minimum 

requirement until quantitative detection 

methods are fully developed. As with 

similar standards, the compliance test 

procedures will include recording of the 

visual inspection results, using detailed 

descriptions, video, and/or photographs 

as appropriate. 

d. Mitigating Risk of Thermal 

Propagation Due to Internal Short 

Within a Single Cell in the REESS 

Proposed Requirements 

The NPRM proposed documentation 

requirements for risk mitigation of 

thermal propagation events resulting 

from single-cell thermal runaway 

(SCTR) due to an internal short circuit 

within a cell in the REESS. NHTSA’s 

proposed documentation component 

structure is based on elements from GTR 

No. 20, ISO–6469–1: Amendment 1 


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33 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 REESSs, 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. 

34 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. 

35Lamb, 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. 

2022–11,33 and ISO–26262.34 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 external charging mode, 

active driving possible mode, and 

parking mode. The objective of the 

documentation requirements 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 manufacturers’ 

assessment and validation of risk 

mitigation strategies may involve a 

combination of physical testing and 

simulations at the component level and/ 

or full vehicle level. The requirements 

are not design restrictive and apply to 

REESSs of all types. 

Comments Received 

There were several comments on 

SCTR risk mitigation documentation, 

including multiple requests for 

clarification. Tesla, HATCI, and 

Honeywell stated support for the 

proposed documentation approach. 

However, HATCI disagreed with the 

addition of the two new operation 

modes, stating they are unlikely to add 

material safety benefits while 

unnecessarily increasing the test and 

documentation burden, whereas 

Honeywell said the addition 

acknowledges the need to identify 

distinct risks and mitigations for each 

operational mode. Nissan suggested that 

NHTSA add a detailed description of 

safety risks ‘‘such as fire, explosion, or 

smoke’’ to enhance clarity regarding the 

severity of these risks in S13.1. Lubrizol 

stated strong support for the 

requirements proposed in the NPRM 

and provided graphs demonstrating the 

performance of their fluids for 

immersed thermal management of the 

REESS. 

Auto Innovators questioned the 

necessity of the SCTR requirement given 

the inclusion of other thermal runaway 

and propagation requirements (e.g., the 

requirement for a thermal event 

warning), and asked the agency to 

provide additional research to support 

the inclusion of this requirement, 

though it also said that the proposed 

reporting requirements appear to be 

reasonable. Additionally, Auto 

Innovators said the requirement should 

not apply to Ni-MH batteries because 

the electrolyte generally used in Ni-MH 

batteries is not flammable; Auto 

Innovators noted that GTR No. 20 and 

industry standards limited the 

requirement to flammable electrolyte 

REESS and that internal short-circuits 

are less likely in Ni-MH batteries due to 

greater spacing of the electrodes. Auto 

Innovators further requested 

clarification on several aspects of the 

requirements, including risks, 

validation strategies, and terminology 

where the FMVSS deviates from GTR 

No. 20. Auto Innovators said the term 

‘‘vehicle power’’ in the definition of 

parking mode is ambiguous and could 

mean any voltage or just high voltage. 

Auto Innovators also said there should 

be processes for updates or corrections, 

the requirements should not be limiting, 

and providing confidential business 

information should not be required if 

the information is subject to public 

disclosure. 

Lucid and NFA also requested further 

clarification of the requirements. Lucid 

said, ‘‘As proposed, the requirements 

could lead to either over- or underreporting. Lucid stresses the importance 

of delineating the documentation 

requirement under Part IV, overall 

evaluation of risk mitigation, to avoid 

conflation with risk mitigation itself.’’ 

NFA likewise suggested that NHTSA 

define ‘‘the requisite detail level within 

the SCTR Risk Assessment and 

Mitigation documentation of the 

Proposal, with the expectation that it 

aligns with established best practices 

and industrial standards, such as ISO 

26262 or SAE J1739.’’ NFA also stated 

that the vehicle manufacturers will need 

information from the REESS 

manufacturer and NHTSA should 

follow the confidential document 

treatment procedure of 49 CFR part 512 

to protect proprietary information. 

Nikola agreed that it makes sense to not 

require a warning for SCTR and that a 

thermal runaway warning should be 

required. Nikola suggested a battery 

manufacturer requirement similar to the 

UL 2580 SCTR test, which forces a cell 

into thermal runaway. Similar to NFA, 

Nikola expressed concerns about 

obtaining proprietary information from 

battery manufacturers and suggested 

Confidential Business Information 

treatment per 49 CFR part 512. 

Agency Response 

For the final rule, the agency is 

adopting the proposed risk mitigation 

documentation requirements. However, 

instead of including the documentation 

requirements in FMVSS No. 305a as 

proposed, this final rule includes the 

risk mitigation documentation 

requirements in part 561. The purpose 

of these documentation requirements is 

to ensure that manufacturers have 

considered and addressed the risk of 

SCTR due to an internal short circuit, as 

the risk is highly dependent on REESS 

design and there is no one field-relevant 

performance test that can be applied to 

all REESS designs in a repeatable and 

reproducible manner. NHTSA-funded 

research examined various existing 

methods of initiating thermal runaway, 

including the heating element method, 

rapid heater method, nail penetration, 

and laser method, on batteries with a 

variety of chemistries, formats, and 

configurations.35 The agency’s 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 the battery chemistry, 

format, and configuration. Nikola 

referenced a private industry developed 

standard, UL 2580 ‘‘Standard for 

batteries for use in electric vehicles,’’ as 

a potential requirement for battery 

manufacturers. Among other 

requirements, UL 2580 specifies a test 

where a single cell is forced into 

thermal runaway, by any means 

recommended by the battery 

manufacturer, with a requirement for no 

evidence of fire or explosion for 1 hour 

after initiating thermal runaway. Such a 

test is not appropriate as a compliance 

test procedure because some thermal 

runaway initiation methods employed 

may require advanced equipment and 

knowledge of the REESS that is only 

available to the manufacturer. It is also 

difficult to establish objectivity and 

could be design restrictive. However, 

manufacturers may voluntarily use any 

or all of the tests in UL 2580 for 

validating risk mitigation strategies in 

their documentation submitted to the 

agency. For these reasons, the agency is 

not requiring a performance test for 

thermal runaway of a single cell. 

Regarding the need for SCTR risk 

mitigation requirements given the other 

requirements in the proposal, including 


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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104335 

36 ISO 26262, ‘‘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. 

https://webstore.ansi.org/industry/automotive/

electric/safety/functional-safety-iso-26262?psafe_

param=1&gad_source=1&gclid=Cj0KCQjw99

e4BhDiARIsAISE7P_bipjmLqkeh

MPUorfq0x2h6lAVWmd0GSbo7Z7qRtwAIRfd40YBMUaAuMuEALw_wcB. 

warning for a thermal event in the 

REESS, the agency believes a 

requirement to mitigate the risk of SCTR 

due to an internal short circuit is 

needed because: (1) there have been a 

number of electric vehicle fires in the 

field resulting from a short circuit 

within a cell in the REESS of vehicles 

in parking, charging, and driving modes, 

(2) none of the performance test 

requirements for the safe operation of 

the REESS (overcharge, over-discharge, 

overcurrent, external short-circuit tests) 

address SCTR and thermal propagation 

resulting from an internal short circuit, 

and (3) the thermal event warning is 

required when the vehicle is in the 

active driving possible mode to allow 

vehicle occupants to safely egress, but 

does not address prevention of vehicle 

fire. 

With regard to specific battery 

chemistries, the documentation 

requirements for SCTR are battery 

chemistry neutral. Safety risks need to 

be evaluated and mitigated for all types 

of vehicle REESS, regardless of 

chemistry, to minimize the possibility of 

hazardous conditions. Gas venting, 

explosion, or other hazards can occur 

even without flammable electrolyte. The 

documentation requirements include 

identification of safety risks and 

mitigation strategies. If a REESS uses 

non-flammable electrolyte and the 

REESS cells have large spacing between 

electrodes, those elements may be 

included as primary risk mitigation 

strategies in the required 

documentation. 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 to manage the health of the 

cells of an REESS and detect a possible 

thermal runaway condition before it 

occurs. Primary risk mitigation 

strategies reduce the risk of SCTR due 

to an internal short circuit and the 

occurrence of thermal propagation that 

may result from SCTR, while 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). 

The NPRM provided examples of 

mitigation strategies, but specific 

strategies are not mandated, allowing 

flexibility and practicability of various 

battery chemistry and battery systems 

without limiting only certain risk 

mitigation strategies known now. The 

risk reduction analysis requirement 

follows industry standard 

methodology.36

As previously stated, the 

requirements are based on those from 

GTR No. 20. NHTSA extended the 

requirements to include consideration 

of the external charging and parking 

modes to ensure safety under all normal 

vehicle operating conditions. The 

incremental amount of documentation 

from adding other operating modes is 

minimal. The operating modes were 

defined in the NPRM, with Parking 

mode defined as ‘‘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.’’ Per this definition, both the 

high-voltage and the low-voltage power 

are turned off. The regulatory text also 

describes the information to include in 

each section of the documentation for 

completeness, from system diagrams to 

validation of risk mitigation strategies. 

As proposed, the required 

documentation is to be submitted upon 

request. Documentation containing 

proprietary information can be 

submitted as Confidential Business 

Information (CBI) under 49 CFR part 

512 and will be handled accordingly. 

Documentation submission, regulations, 

and CBI are discussed further in Section 

k. 

e. Thermal Event Warning 

Proposed Requirements 

As part of a risk-mitigation approach 

addressing multiple aspects of electrical 

system safety, the NPRM proposed a 

performance requirement for a thermal 

event warning. The term ‘‘thermal 

event’’ 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 may 

occur due to moisture and dust 

accumulation that causes 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 when a thermal event 

within the REESS occurs while the 

vehicle is in active driving possible 

mode would reduce the likelihood of 

occupant exposure to hazardous smoke, 

fire, and/or explosion. NHTSA also 

proposed that the visual warnings be 

provided to all front row occupants for 

vehicles with automated driving 

systems without manually operated 

driving controls. 

Comments Received 

There were many comments on the 

proposed thermal event warning test. 

Comments from Consumer Reports, 

Lucid, and EMA stated support for the 

actual audio-visual warning. Consumer 

Reports also suggested that NHTSA 

work with manufacturers to ensure all 

warnings are sufficiently prominent and 

convey the severity of the event. SAVE 

Coalition agreed with the warning 

overall but noted that it was only 

directed to the driver of the vehicle. To 

include vehicles equipped with 

automated driving systems, SAVE 

Coalition suggested adding, ‘‘For a 

vehicle without manually operated 

driving controls, the warning must be 

provided to occupants in all outboard 

designated seating positions.’’ On the 

other hand, Auto Innovators said, ‘‘We 

recommend remove requirements for 

AVs without manual driving controls; 

NHTSA has not provided rationale for 

why any warning needs to be provided 

to the ‘front row occupant’; the 

occupant cannot take any action based 

on the visual warning.’’ Honeywell 

suggested adding an auditory warning 

requirement for active charging and 

parking modes to enable relocation of 

adjacent vehicles, evacuation of 

building occupants, and alerts to 

bystanders. ACIL likewise encouraged 

NHTSA to include requirements for a 

warning to vehicle occupants and/or 

bystanders outside the vehicle in the 

event of thermal propagation. 

Some commenters said that the NPRM 

discussion of ‘‘thermal runaway,’’ 

‘‘thermal propagation,’’ and ‘‘thermal 

event’’ was unclear. Nissan suggested 

that sections S13.2 and S13.3 for the 

thermal event warning should be 

distinct from S13, thermal propagation 

safety, to ensure clarity and precision in 

addressing thermal safety risks within 

the documentation. Nikola said, 

‘‘NHTSA is proposing to not have a 

warning for a thermal runaway but to 

require one for thermal event that is 

intended to inform occupants to egress 

the vehicle. The definitions of Thermal 

event and Thermal Runaway are being 


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104336 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

37See requirements in S9.2.2 of FMVSS No. 208 

with regard to the air bag suppression telltale. The 

telltale is required to be visible to the front outboard 

passengers. 

conflated.’’ NFA likewise stated that 

there appeared to be a discrepancy in 

NHTSA’s statements about the 

relevance of SCTR and thermal event 

warnings. 

Many comments disagreed with the 

parameters of the proposed test 

requirement. Auto Innovators said the 

NPRM did not provide references or 

otherwise explain the test parameters. 

They noted that battery modifications 

can be risky and suggested slower 

heating due to ‘‘concerns with the 

proposed test method of using a heater 

that abruptly achieves 600C within 30 

seconds [which] could result in unstable 

test conditions.’’ NFA said that the 

three-minute timeframe seems arbitrary 

and uncorrelated with occupant hazard 

exposure, and suggested using the SCTR 

thermal propagation criteria from ECE 

R100. Tesla, HATCI, Honeywell, ZETA, 

Lucid, Nikola, and Honda all expressed 

similar concerns over the timing and 

occurrence of actual thermal runaway 

and propagation with the proposed test 

procedure. Some suggested other 

initiation methods or a ramp of 180 

seconds as in GTR No. 20. Nissan said 

the temperature specification was too 

high. Honda recommended clarification 

that the temperature specification refers 

to the heater temperature, not the 

REESS temperature. Honda also 

requested clarification on allowable 

modifications to the REESS, including 

replacement of one or more cells with 

heater equipment preinstalled for 

accurate test results. Similarly, Bugatti 

requested ‘‘a clear definition of thermal 

runaway condition and confirmation 

whether instrumented cells will be 

allowed to recognize this event,’’ to 

ensure that manufacturers have 

flexibility to accommodate the test 

equipment if NHTSA does not allow 

other triggering methods. 

Several vehicle and component 

manufacturers said that the vehiclelevel test requirement is unnecessarily 

dangerous. MEMA said that the test 

would generate toxic smoke and other 

potentially unsafe conditions for test 

personnel, and contradicts other 

requirements to mitigate or stop thermal 

runaway. Ford said the heater test is 

‘‘unnecessarily destructive and 

burdensome in that it requires the 

initiation of a thermal runaway to 

confirm the illumination of a warning 

light,’’ and recommended verification 

using an electronic signal instead. 

Prevost also expressed safety concerns, 

noted additional difficulty in testing 

heavy vehicles, and suggested a 

subsystem test. EMA suggested a 

documentation requirement or 

component-level test, as the full-vehicle 

test could destroy the vehicle and 

introduce an unsafe situation. Many 

other commenters also recommended 

implementing the documentation 

requirement from GTR No. 20 due to 

issues with the proposed test 

requirement. 

Agency Response 

After consideration of the comments, 

the agency is not adopting the proposed 

performance test requirement for the 

thermal event warning but is 

implementing a corresponding 

documentation requirement in part 561 

instead. While the agency maintains the 

importance of the required thermal 

event warning, commenters raised 

concerns about the proposed test 

method and safety of testing. The 

agency agrees that additional research is 

needed to ensure that any performance 

test for the thermal event warning is 

well-defined, appropriate for all 

vehicles, and does not pose an undue 

risk to test personnel. In turn, the 

documentation requirements are 

adopted for the final rule. 

The documentation requirements for 

the audio-visual thermal event warning 

are similar to those in GTR No. 20. 

Manufacturers are required to provide 

documentation to the agency, upon 

request, with a detailed description of 

the system for triggering the warning. 

Specifically, the documentation 

requirements include 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, as well as a 

system diagram and written explanation 

describing the sensors and operation of 

the vehicle controls that manage the 

REESS in the event of a thermal event. 

The primary purpose of the adopted 

warning is to ensure occupants have 

sufficient time to exit the vehicle to 

minimize direct exposure to potential 

hazards. The warning is to be provided 

regardless of the cause of the thermal 

event. A thermal event in the REESS can 

lead to smoke, fire, and/or explosion, 

and a warning can reduce the likelihood 

of occupant exposure to these safety 

hazards. The audio-visual warning is 

provided to the driver, or to all front 

row occupants in the case of 

autonomous vehicles without manually 

operated controls, notifying of a thermal 

event in the REESS when the vehicle is 

in active driving possible mode. The 

agency believes this specification is 

appropriate to ensure the driver or the 

front row occupants in vehicles with 

automated driving systems without 

manually operated controls are alerted 

of the potential safety hazard to ensure 

the driver or occupants can stop and 

exit the vehicle. The front row provision 

for vehicles with automated driving 

systems is aligned with other FMVSSs 37

and may be revised over time. The 

primary purpose of the adopted warning 

is to ensure occupants have sufficient 

time to exit the vehicle to minimize 

direct exposure to potential hazards. 

Activation of a warning to bystanders 

outside the vehicle was not proposed in 

the NPRM and is not in scope for this 

final rule. Additionally, further research 

needs to be conducted to determine the 

type and efficacy of such a warning to 

people outside the vehicle. 

Some commenters said the discussion 

in the NPRM was unclear between the 

term of thermal event and SCTR and the 

corresponding warning requirements. 

Section 2 of the NPRM addressed 

thermal propagation from SCTR due to 

an internal short circuit within the cell; 

this is a specific hazard that can be 

minimized by risk evaluation and 

mitigation in design and manufacturing. 

Risk mitigation includes implementing 

strategies to prevent SCTR and to isolate 

a cell that is in thermal runaway to 

prevent thermal propagation. A warning 

specifically for SCTR is not required. 

However, any instance of thermal 

runaway and propagation that occurs, 

regardless of the cause, should trigger 

the thermal event warning for the 

vehicle occupants’ safety. To minimize 

confusion, the documentation 

requirements for the thermal event 

warning and for SCTR risk mitigation 

are adopted in separate sections of part 

561. 

f. Vehicle Control Malfunction Warning 

Proposed Requirements 

The NPRM proposed a documentation 

requirement for a driver warning in the 

event of a malfunction of vehicle 

controls that manages the safe operation 

of the REESS. The warning 

documentation requirement is similar to 

GTR No. 20, with two added provisions, 

and is an interim measure intended to 

ensure that manufacturers will identify, 

address, and validate the effectiveness 

of their visual warnings that help 

manage safe REESS operation. This 

approach is intended to evolve over 

time as battery technologies and 

NHTSA’s information about the REESS 

safety risk mitigation strategies evolve. 

Comments Received 

Comments on the vehicle control 

malfunction warning documentation 

requirement were positive. Nikola 


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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104337 

agreed with requiring a warning, stating 

that it already provides malfunction 

warnings to the driver and documents 

all the information in the monitoring 

and diagnostic documents required by 

the California Air Resources Board for 

powertrains. Tesla stated support for 

including the requirements in FMVSS 

No. 305a because they apply to all 

REESSs irrespective of crash conditions. 

HATCI and Auto Innovators also stated 

support for the proposed documentation 

requirements. Auto Innovators agreed 

that there is currently no practical test 

procedure and stated support for the 

documentation approach. 

Agency Response 

The agency is adopting the proposed 

requirements for a driver warning in the 

event of a malfunction of vehicle 

controls that manage the safe operation 

of the REESS. Commenters agreed that 

the warning and documentation 

requirement are appropriate and 

indicated that they may already 

maintain and produce such 

documentation as required by other 

regulations. For the final rule, the 

vehicle control malfunction warning 

requirements are adopted in FMVSS No. 

305a and part 561. 

g. Protection Against Water Exposure 

Proposed Requirements 

The NPRM proposed water exposure 

test requirements, 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. As in GTR No. 

20, the proposed test procedures specify 

the use of freshwater. The proposed 

physical test requirements comprised of 

two tests. The proposed washing test 

was similar to that in GTR No. 20, with 

the addition of exposing the vehicle 

underbody to the water stream to make 

the test more representative of vehicle 

washing. The proposed driving through 

standing water test was also similar to 

that in GTR No. 20, but with the 

maximum test duration reduced from 10 

minutes to 5 minutes. Electrical 

isolation was proposed to be determined 

at the conclusion of each test, and once 

again after 24 hours. 

The NPRM did not propose to allow 

the documentation or isolation loss 

warning compliance options from GTR 

No. 20 for the water exposure tests. The 

NPRM requested comment on the 

proposed test specifications, including 

water pressure for the washing test. The 

NPRM also requested comment on water 

salinity levels for the tests as well as 

potential test procedures for 

submersion. 

Comments Received 

There were a variety of comments on 

the water exposure requirements. Some 

commenters agreed with the proposed 

test procedures, while others requested 

additional compliance options or 

changes to the test specifications. For 

the washing test, Tesla stated support 

for the proposed test method and 

recommended keeping the freshwater 

specification from GTR No. 20. Auto 

Innovators suggested establishing a 

maximum test duration and changing 

the timing of the isolation checks to 12 

hours to reduce the time burden. Auto 

Innovators said the test parameters 

should not include salinity because it is 

unnecessary and because a large amount 

of water will be needed, and the 

reproducibility of salinity levels is 

challenging. Nissan also said that using 

saline in the proposed tests would not 

significantly impact the evaluation and 

is unnecessary. 

Hyundai requested clarification for 

the underbody spray distance and angle 

for the proposed test procedure to 

ensure the test is clear and repeatable. 

For water pressure, Eaton agreed with 

adopting IPX5 for normal driving 

conditions. NEMA also agreed that IPX5 

matches normal conditions but 

suggested using IPX7 to address 

submersion concerns. Nikola said, 

‘‘Increasing the pressure does seem 

prudent as it will be the standard 

practice to use a pressure washer to 

clean the vehicles,’’ and suggested IPX6. 

Eaton stated support for the inclusion 

of the driving through standing water 

test. Tesla also agreed with the proposed 

procedure and suggested keeping the 

long rectangular pool for ease of 

defining driving and test evaluation 

methodologies. As with the washing 

test, Auto Innovators said there should 

not be a salinity requirement and 

requested changing the timing of the 

isolation checks to 12 hours. Prevost 

and EMA opposed the driving through 

standing water test for heavy vehicles. 

Prevost said, ‘‘Since NHTSA suggests 

improving vehicle washing test by 

adding the underside of the vehicle to 

the scope of the test, the driving through 

standing water tests does not seem to 

add value to the safety of the vehicle, as 

the washing test with the underbody 

included will be a harsher requirement 

than driving through 10cm of water at 

20kph . . . Since facilities providing the 

infrastructures to perform the driving 

through standing water test will be 

scarce, this test would add significant 

costs while not improving vehicle 

safety.’’ EMA likewise stated that the 

washing test is more aggressive, test 

facilities for heavy vehicles do not 

currently exist, and NHTSA should 

remove the redundant and expensive 

driving through standing water test for 

heavy vehicles. 

Auto Innovators, Hyundai, Nissan, 

and NFA requested inclusion of 

compliance options from GTR No. 20. 

Hyundai recommended harmonizing 

with GTR No. 20 and UNECE R100, in 

which the electrical isolation loss 

warning system is allowed as a 

compliance option. Nissan similarly 

requested a compliance option to 

harmonize with the UNECE. Auto 

Innovators asked that NHTSA allow a 

component-level test compliance 

option, and transit bus manufacturer 

NFA specifically requested componentlevel water exposure safety tests instead 

of full vehicle tests for heavy buses and 

motor coaches. NFA asserted that 

spraying the battery pack directly would 

constitute a more rigorous test than the 

proposed full-vehicle tests and said it is 

open to component-level testing at the 

IPX6 level. 

With regard to submersion concerns, 

commenters generally agreed that 

further research is necessary, and some 

urged NHTSA to commit to a technical 

amendment. Auto Innovators said that 

more analysis is needed before 

determining whether additional test 

requirements should be implemented 

and recommended harmonizing with 

UNECE R100. EDTA recommended that 

NHTSA commit to a technical 

amendment and collaborate with 

stakeholders in collecting data to 

establish a test requirement addressing 

real-world flooding scenarios. MEMA, 

NEMA, and Eaton provided similar 

comments. Eaton also stated that 

rigorous test standards would enable the 

United States to maintain a position of 

technological leadership and prevent 

lower-quality imports from entering the 

market. NEMA said that testing 

documentation requirements should 

include water ingress and egress risks. 

Nikola said that submersion in saline 

should be compared to the salt spray 

test in UL2580. Tesla also recommended 

additional research on salinity. MEMA, 

NEMA, EDTA, and Eaton further 

recommended adding a leak check 

requirement for battery packs at the time 

of manufacture. MEMA and Eaton 

specified that the leak checks should 

include all sealing surfaces and be 

implemented as a documentation 

requirement; Eaton said the sealing 

surfaces between vent valves and the 

battery housing are often missed in 

current leak testing practices. 


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104338 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

38The testing is described in more detail in a 

separate document being placed in the docket for 

this rulemaking. 

39Overview of NHTSA EV Safety Activities, SAE 

Government Industry Meeting, January 2023, 

https://www.nhtsa.gov/sites/nhtsa.gov/files/2023- 

03/15874-NHTSA%20SAE%20GIM%202023_final_

032223-tag.pdf. 

Agency Response 

After consideration of the comments, 

the agency believes the proposed test 

procedures remains practicable and the 

requirements mitigate the risk of short 

circuit or loss of electrical isolation due 

to water ingress under normal operating 

scenarios such as driving through 

standing water on the road or vehicle 

washing. NHTSA is adopting the 

proposed requirements with minor 

changes, including an increase of the 

standing water test maximum duration 

from 5 minutes to 10 minutes due to 

recent NHTSA testing. For the vehicle 

washing test, the NPRM included a 

figure from GTR No. 20 to specify the 

dimensions of the water nozzle and 

stated that the ‘‘nozzle specifications are 

from IEC 60529 for IPX5 water jet 

nozzle.’’ However, the provided figure 

depicted the nozzle dimensions from 

IEC 60034, wherein one internal 

dimension of the nozzle deviates from 

IEC 60529 by 2 mm. As IEC 60034 is 

specific to rotating electrical machines, 

it is more appropriate to use the nozzle 

specifications from IEC 60529, which 

was the standard referenced in the text 

of the NPRM. For these reasons, this 

final rule contains a corrected figure 

specifying water nozzle dimensions 

consistent with IEC 60529. 

The NPRM proposed a maximum test 

duration of 5 minutes for the driving 

through standing water test instead of 

GTR No. 20’s 10 minutes but also sought 

comment on the maximum duration. 

NHTSA conducted the driving through 

standing water test in August 2024 

using a 30-meter length water pool with 

a 15-meter approach ramp on both ends 

of the pool.38 To accumulate 500 meters 

of driving through 10 cm of standing 

water, the vehicle needed to be driven 

17 times through the 30-meter water 

pool. Based on the testing, the agency 

determined that a test duration of 5 

minutes may not be sufficient when the 

test is conducted using a short water 

pool. Traversing the entry and exit 

ramps and turning around between each 

pass of the water pool adds to the total 

time necessary to complete the test. 

NHTSA estimates that 7.5 minutes is 

sufficient for a water pool length of 30 

meters. More time would be needed to 

complete the test using water pools 

shorter than 30 meters. The maximum 

test duration time for conducting the 

driving through standing water test is 10 

minutes in GTR No. 20, which NHTSA 

agrees is appropriate. Therefore, this 

final rule adopts a 10-minute time limit 

for the driving through standing water 

test. 

Some comments addressed other 

parameters of the vehicle washing test, 

specifically test time, spray angle, and 

spray distance. The maximum test time 

is not stated because the test procedure 

specifies ‘‘washing test duration per 

square meter of the vehicle surface area 

is 60 to 75 seconds.’’ The maximum test 

time depends on the surface area of the 

vehicle, which can be measured in 

square meters and multiplied by 75 

seconds per square meter to obtain the 

maximum test duration for the vehicle. 

The spray angle provision ensures that 

all directions are considered for water 

resistance and is consistent with the 

IPX5 standard and GTR No. 20. The test 

procedure states, ‘‘The vehicle is 

sprayed from any direction,’’ which 

means the vehicle must be able to meet 

the test requirements regardless of the 

angles used. With regard to the spray 

distance, the proposed requirement 

said, ‘‘the distance from the nozzle to 

the vehicle surface is 3.0 to 3.2 meters 

[and] may be reduced, if necessary, to 

ensure the surface is wet when spraying 

upwards.’’ The test procedure includes 

some adjustment to the nozzle distance 

because the water stream may not be 

capable of hitting a vehicle’s lower side 

and bottom (underbody) unless the 

nozzle is pointed upwards and 

positioned closer than 3.0 to 3.2 meters 

from these vehicle surface areas. These 

provisions are consistent with GTR No. 

20. Further, NHTSA believes the 

proposed testing parameters provide 

sufficient specification and flexibility 

for a repeatable test, thus, the agency is 

adopting the proposed specification. 

Regarding the time interval between 

isolation measurements, Auto 

Innovators did not provide any 

supporting data for the request to reduce 

the minimum wait time to 12 hours. The 

isolation measurements are conducted 

immediately after water exposure and 

after a minimum of 24 hours, which is 

identical to the GTR No. 20 and ECE 

R.100 specifications. The agency 

believes that the 24-hour wait time is 

appropriate and consistent with 

observed electric vehicle fires initiating 

a day or longer after water exposure/ 

submersion.39 In the absence of 

information demonstrating that 

reducing the time interval between 

isolation measurements would not 

significantly alter the test results, the 

agency is adopting the requirements as 

proposed. 

Some commenters supported the 

addition of a warning option. 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. Consequently, the 

agency is not adopting the loss of 

isolation warning compliance option 

because warning signals alone are not 

sufficient for addressing loss of 

electrical isolation concerns. 

Some commenters also requested 

component-level testing, particularly for 

heavy vehicles. The agency believes that 

component-level testing is not as 

representative of actual conditions as 

full-vehicle testing. Furthermore, the 

vehicle washing test does not pose an 

undue burden. 

The agency also disagrees with EMA 

and Prevost’s requests that heavy 

vehicles be excluded from the driving 

through standing water test. In support 

of their position, the two commenters 

said that test facilities do not 

accommodate heavy vehicles, it would 

be very expensive to conduct the test, 

and the test is redundant. The agency 

notes that FMVSSs establish minimum 

safety requirements and the FMVSS test 

procedures establish how the agency 

would verify compliance. The Safety 

Act requires manufacturers to ensure 

their vehicles comply with all 

applicable FMVSSs and to certify 

compliance of their vehicles with all 

applicable FMVSSs. The Safety Act 

specifies that manufacturers may not 

certify compliance if, in exercising 

reasonable care, the manufacturer has 

reason to know the certificate is false or 

misleading. A manufacturer may use 

component-level tests to certify its 

vehicles if they exercise reasonable care 

in doing so. Additionally, while NHTSA 

agrees that the driving through standing 

water test may not be as stringent as 

vehicle washing for certain heavy 

vehicle configurations with greater 

ground clearance and/or with the 

REESS located higher on the vehicle 

(e.g., on the roof), vehicle configuration 

is not prescribed by the FMVSS and is 

left to the discretion of the 

manufacturer. Both water exposure tests 

represent reasonable scenarios for 

normal vehicle operations and establish 

minimum levels of safety for water 

exposure of electric vehicles. With the 

flexibilities afforded to manufacturers to 

certify compliance, NHTSA disagrees 

that the cost burden may be excessive 

for heavy vehicles. Some vehicle 

manufacturers suggested use of the IPX6 


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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104339 

40A Teardown Study of Flood Damaged Electric 

Vehicles—EV Battery Safety, Part 2, SAE 

Government Industry Meeting, January 2024, 

https://www.nhtsa.gov/document/teardown-studyflood-damaged-electric-vehicles-ev-battery-safetypart-2. 

or IPX7 standard instead of IPX5. 

NHTSA agrees that other standards such 

as IPX6 or IPX7 may be appropriate for 

evaluating the water resistance of 

electric vehicles. However, the 

corresponding IPX6 or IPX7 test 

procedures were not proposed in the 

NPRM and are out of scope for this final 

rule. While the final rule adopts the 

proposed requirements corresponding to 

IPX5, manufacturers are not prohibited 

from additional test methods beyond the 

FMVSS specifications and may choose 

to use the IPX6 or IPX7 standard to 

evaluate the water resistance of their 

vehicles. 

The commenters agreed that saline 

should not be specified for the test 

procedures because it would not 

significantly affect the results and the 

salinity level would be difficult to 

maintain. The commenters also 

observed that the test procedures of 

using fresh water would harmonize with 

international standards. At this time, the 

agency agrees that generally, water 

exposure under normal vehicle 

operation occurs with freshwater; thus, 

keeping the freshwater specification is 

appropriate for these tests. 

With regard to the battery leak check 

requirements suggested by some 

commenters, such requirements were 

not proposed in the NPRM and are also 

out of scope for this final rule. Typical 

leak check procedures require access via 

one of the vent valves; a requirement to 

check all sealing surfaces would 

necessitate a different test method that 

does not use an opening in the pack. 

Additionally, research on flooddamaged vehicles has shown that water 

ingress occurs for a variety of reasons 

and does not necessarily lead to 

catastrophic failure.40

NHTSA recognizes that further 

research is needed on the field 

incidences of electric vehicle fires 

following water exposure, particularly 

saltwater exposure, in order to establish 

additional requirements. NHTSA is 

taking the first step by adopting the 

proposed water exposure requirements 

for normal vehicle operations and 

continues to research salinity, 

immersion, and test procedures to 

support the development of future 

safety requirements and inform 

potential updates to the FMVSS. 

h. Miscellaneous GTR No. 20 Provisions 

Not Proposed 

The NPRM did not propose to require 

some provisions from GTR No. 20 for 

vibration, thermal shock and cycling, 

fire resistance, and low state of charge 

(SOC) of the REESS during normal 

vehicle operations. The NPRM 

requested comment on these exclusions. 

j. Vibration and Thermal Shock and 

Cycling 

NPRM Discussion 

As stated in the NPRM, GTR No. 20 

contains a vibration requirement and 

test procedure that applies a generic 

vertical vibration profile to the tested 

vehicle. NHTSA believes that this test is 

not representative of real-world 

conditions. In addition, vehicle 

manufacturers routinely perform 

vibration testing to ensure customer 

satisfaction and reliability. At the 

component level, electric vehicle 

batteries are currently subject to 

vibration test requirements for 

transportation under the United States 

Hazardous Materials Regulations 

(HMR), along all three orthogonal axes 

and for frequencies up to 200 Hz. With 

these current tests, NHTSA does not 

believe that the GTR No. 20 vibration 

test would address an additional safety 

need. 

Similarly, 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 and includes a larger 

temperature range. NHTSA believes that 

incorporating the GTR No. 20 test would 

not address an additional safety need. 

Comments Received 

Comments from Auto Innovators and 

HATCI stated agreement with the 

agency’s rationale and exclusion of 

these requirements. Regarding the 

vibration and thermal shock and cycling 

requirements of GTR No. 20, HATCI 

agreed with NHTSA’s rationale for not 

including the tests given the more 

stringent U.S. regulations. Auto 

Innovators also agreed that introduction 

of new vibration profiles is unnecessary, 

as the test may not be representative of 

real-world conditions and industry uses 

other means to assess durability. For 

thermal shock and cycling, Auto 

Innovators said the test requirements in 

UN 38.3 T2 are sufficient. However, 

Nikola disagreed with the agency’s 

decision not to add the thermal shock 

and cycling test. Nikola said that the 

HMR requirements are insufficient 

because UN 38.3 does not require 

testing of the assembled battery pack, 

and that relying on the shipping 

requirements for the cells or modules is 

a low bar to set for safety. 

Agency Response 

After reviewing the comments, the 

agency is not adopting additional 

requirements for vibration and thermal 

shock and cycling. Commenters agreed 

with the agency’s rationale for 

excluding the vibration test 

requirements. Nikola said the thermal 

shock and cycling test requirements in 

GTR No. 20 should be included because 

testing of cells or modules is not 

equivalent to testing of the full battery 

pack; UN 38.3 does not require pack 

level testing if the cells and modules 

were tested. However, Nikola did not 

provide any data demonstrating that the 

existing requirements may be 

insufficient. For the final rule, the 

agency does not believe there is a safety 

need for additional thermal shock and 

cycling test requirements. In the absence 

of new supporting information, NHTSA 

maintains that UN 38.3 and the HMR 

appropriately address resistance to 

thermal shock and cycling for lithium 

cells and batteries. 

2. Fire Resistance 

NPRM Discussion 

The GTR No. 20 fire resistance 

requirement applies to REESSs with 

flammable electrolyte installed in a 

vehicle at a height less than 1.5 m above 

the ground and is based on a UN 

Regulation for liquid fueled vehicles 

with plastic tanks. During the test, the 

REESS is exposed to a flame directly for 

70 seconds and indirectly for 60 

seconds. As stated in the NPRM, vehicle 

testing by Transport Canada indicated 

that the short duration of the external 

fire test would not result in explosion. 

Consequently, during Phase 1 of the 

GTR No. 20 discussions, the United 

States and Canada noted that the short 

duration component level test would 

not address a safety need and 

recommended removing it from GTR 

No. 20. 

Comments Received 

As with the vibration and thermal 

shock and cycling tests, HATCI 

expressed agreement with NHTSA’s 

decision not to include the fire 

resistance test. Auto Innovators also 

agreed, stating that a test duration of 

under 10 minutes is insufficient to 

induce significant internal heating. 

Again, Nikola disagreed, stating that the 

vehicle testing by Transport Canada 


ddrumheller on DSK120RN23PROD with RULES2
104340 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

41See FMVSS No. 500, ‘‘Low speed vehicles,’’ 49 

CFR 500. 

does not support the exclusion because 

industry designed its vehicles to be able 

to withstand the test. As a result, Nikola 

said excluding the requirement from the 

FMVSS could lead to less safe EV 

designs. 

Agency Response 

After reviewing the comments, the 

agency is not adopting the short 

duration fire resistance test. One 

commenter said that manufacturers 

design for the test and the exclusion 

could reduce safety. However, the 

agency does not believe that excluding 

the test requirement will lead 

manufacturers to redesign U.S. vehicles 

or REESSs in a manner that reduces the 

resistance to flame from below. The 

comments did not provide any new and 

supporting data on fire exposure or 

design. In the absence of further 

information demonstrating a safety 

need, the agency is not adopting the fire 

resistance test requirement at this time. 

3. Low State of Charge (SOC) Telltale 

NPRM Discussion 

GTR No. 20 requires a telltale to the 

driver in the event of low REESS SOC. 

The NPRM did not propose the low SOC 

telltale because NHTSA believes this 

requirement is unnecessary because 

there is no corresponding low fuel 

warning requirement for conventional 

internal combustion engine vehicles. 

The NPRM requested comment on 

whether NHTSA should adopt the GTR 

No. 20’s low SOC telltale requirement, 

and if yes, what the telltale should look 

like. 

Comments Received 

All of the comments on the low SOC 

telltale requirement agreed with 

NHTSA’s proposal not to require a low 

SOC telltale. Nissan and Auto 

Innovators both stated that regulation is 

unnecessary because manufacturers 

already provide SOC information. 

HATCI likewise agreed with the stated 

rationale. Nikola also agreed with the 

exclusion, as ‘‘a requirement for low 

SOC would require standardizing when 

the light was to come on [and] it should 

be left up to the OEM.’’ 

Agency Response 

After reviewing the comments, the 

agency is not adding a low SOC telltale 

requirement. The agency believes that 

all electric-powered vehicles already 

provide low SOC telltales due to 

consumer demand. Regulation is 

unnecessary and excluding the low SOC 

telltale requirement is appropriate and 

consistent with not having a low fuel 

warning regulatory requirement for 

conventional internal combustion 

engine vehicles. 

j. Low-Speed Vehicles 

NPRM Discussion 

The NPRM requested comments on 

applying aspects of FMVSS No. 305a to 

electric low-speed vehicles that travel 

under 40 km/h (25 mph) (as defined in 

49 CFR 571.3).41 particularly for normal 

vehicle operations and safe operation of 

the REESS. The agency requested 

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. 

Comments Received 

A few commenters addressed the 

inclusion of low-speed electric vehicles 

(LSEVs). NTSB said that LSEVs should 

be included, as the risks and potential 

hazards are well established and 

because NHTSA’s proposed operational 

requirements involve appropriate safety 

planning and no performance measure 

or tests, and cited the collision of an 

autonomous electric shuttle that 

occurred in 2017. On the other hand, 

MEMA said the standard should not 

apply to LSEVs. Honeywell stated 

support specifically for application of 

the thermal event warning requirement, 

because low-speed vehicles often use 

the same battery cell types as cars and 

are likewise at risk for thermal events. 

Agency Response 

After reviewing the comments, the 

agency is not adopting additional 

requirements for LSEVs at this time. In 

general, low-speed vehicles such as golf 

carts are not subject to the same 

requirements as higher-speed motor 

vehicles. LSEVs are subject to FMVSS 

No. 500, ‘‘Low-speed vehicles,’’ which 

specifies required safety requirements 

for low-speed vehicles. While thermal 

events and other hazards are a concern 

for any rechargeable battery system, 

LSEVs generally have smaller batteries 

than higher-speed motor vehicles and 

are not subject to the same use 

conditions. The comments did not 

provide any supporting research on lowspeed vehicles demonstrating a safety 

need for additional requirements. The 

autonomous shuttle crash cited by 

NTSB occurred at a very low speed and 

did not exhibit any safety hazards from 

the REESS. NHTSA will continue to 

assess electric vehicle safety and the 

need to establish additional 

requirements for LSEVs in the future 

when additional data is available. 

j. Emergency Response Information 

Proposed Requirements 

The NPRM proposed to require 

manufacturers to submit standardized 

emergency response information for 

each vehicle model and model year to 

NHTSA’s website for public access. The 

emergency response information would 

include the rescue sheet and the 

emergency response guide (ERG). The 

rescue sheets must follow the layout 

and format in ISO–17840–1:2022I (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)). The 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 NPRM proposed that 

electronic versions of the rescue sheets 

and ERGs for all vehicles to which 

FMVSS No. 305a applies must be 

submitted prior to certification of the 

vehicle. 

Comments Received 

Many commenters expressed support 

for NHTSA’s collection of standardized 

emergency response information. 

Consumer Reports, DTNA, EMA, Lucid, 

Nikola, Tesla, Volkswagen, ZETA, CAS, 

and EV Rescue App were among the 

commenters that stated agreement with 

the proposed requirements. Firefighter 

and ISO project leader Kurt Vollmacher 

also expressed support for the use of 

ISO 17840 and for the establishment of 

a central database. Some commenters 

asked for clarification of the 

requirements, suggested additional 

provisions, or requested modification to 

the submission timeline. 

NTSB expressed strong support for all 

aspects of the proposed ERG and rescue 

sheet submission requirements, stating 

that NHTSA’s proposal is a better 

approach than incorporating the 

information as part of the New Car 

Assessment Program, as NTSB 

originally recommended. NTSB agreed 

with hosting the standardized 

documents on a NHTSA website and 

suggested that NHTSA work with NFPA 

to redirect users to the new source of 

information. NTSB also stated that it is 

important to include the legacy 

information from the NFPA website 

because responders interact with 

vehicles from previous model years. 

Lucid likewise said NHTSA should 

include the ERGs from the NFPA site. 

HATCI, Auto Innovators, and NFA 

expressed general support for the 

proposed requirements but requested 


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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104341 

42The website is expected to go online in 

February 2025. Instructions for manufacturers 

regarding login credentials and file uploads will be 

provided on the website at a later date. 

43https://www.nfpa.org/education-and-research/ 

emergency-response/emergency-responseguides#aq=%40culture%3D%22en

%22&cq=%40taglistingpage%3D

%3D(%22EV%20Guides%22)%20%20&number

OfResults=12&sortCriteria=%40title%20ascending. 

clarification. HATCI said, ‘‘it is unclear 

the method by which the Agency plans 

to have manufacturers submit these 

documents and how the Agency intends 

to process the submissions,’’ and 

inquired whether NHTSA’s proposal 

intends to replace the NFPA’s housing 

of information or if manufacturers will 

need to submit the ERGs to multiple 

locations. Auto Innovators likewise said 

NHTSA should provide clear 

information and guidance for uploading 

the information to the NHTSA website 

to ensure timeliness and accuracy, and 

should ‘‘clarify its interpretation of ISO 

17840 as the current standard on which 

all rescue sheets and ERGs should be 

based.’’ NFA asked ‘‘whether it would 

be permissible to consolidate the Rescue 

Sheet and ERG into a single document.’’ 

With regard to the submission 

timeline, Auto Innovators requested 

‘‘that NHTSA establish a process to 

ensure that ERGs are made available 

starting on the date when the subject 

vehicle is first introduced for sale in the 

United States . . . to protect final 

design information.’’ Volkswagen also 

requested submission just prior to 

market introduction, to allow the 

manufacturer to reserve its final design 

pictures or plans for press and social 

media release. Volkswagen said there 

would be no added risk to this timeline 

because the vehicle would not be 

available for sale or on public roads 

during this time. 

Other suggestions from Auto 

Innovators were for NHTSA to establish 

a website with a distinct URL for ease 

of access, increase first responder 

awareness of the new resource through 

safety marketing, and consider 

partnerships for mobile and desktop 

applications as seen with Euro NCAP. 

Lucid suggested an additional 

requirement for ERGs to provide highvoltage warnings and identify proper 

personal protective equipment for 

dealing with high-voltage systems. 

Nikola said NHTSA should have the 

standardized ERGs submitted to NFPA, 

because the first responder industry 

knows to go to the NFPA website for 

information. 

Agency Response 

After reviewing the comments, the 

agency is adopting the proposed 

emergency response information 

requirements in part 561. Comments 

were largely in favor of the 

requirements, including standardization 

and submission of the documentation. 

The required documents must be 

vehicle-specific and conform to the 

ISO–17840’s layout and format, which 

are incorporated by reference in part 

561. Adoption of the existing 

standardization means that vehicle 

manufacturers, as well as first and 

second responders, are already 

accustomed to the content and 

formatting of the ERGs and rescue 

sheets, and that the documents are 

consistent. The standardized colorcoded sections in a specific order will 

help first and second responders 

quickly identify pertinent vehiclespecific rescue information. Both the 

ERG and the rescue sheet are required, 

as the ERG provides relevant, in-depth 

information for a variety of potential 

incidents, while the rescue sheet is a 

shorter, simpler document for quick 

reference. The headings/contents of the 

rescue sheet and the ERG information 

from ISO are aligned with each other, 

i.e., the ERG information works as an 

extension of the related rescue sheet. 

Consequently, due to the varying 

emergent situations that could occur, 

the ERG and rescue sheet should be 

provided as separate documents for the 

relevant safety need, consistency, and 

ease of access without confusion. 

With regard to document submission 

and processing, the manufacturer will 

upload the emergency response 

documentation to the designated 

NHTSA website, https://

www.NHTSA.gov/ERG.42 The files will 

be publicly available and searchable by 

vehicle make, model, and model year, as 

provided at the time of upload. The 

documents should be submitted as PDF 

files per the guidelines provided on the 

website. NHTSA will not modify the 

contents of the documents submitted by 

the manufacturer. The manufacturer is 

responsible for submitting the correct 

ERG and rescue sheet files for each 

vehicle model and model year, 

including any subsequent updates or 

corrections that are needed. Secure user 

login will be provided for manufacturers 

to upload and manage documents. The 

ERGs and rescue sheets will be available 

to the public for viewing and to 

download without a login. 

Some commenters requested later 

submission of the emergency response 

documents to protect final design 

information prior to market introduction 

without affecting safety. NHTSA agrees 

that a later submission date than the 

proposed certification date is 

appropriate and has revised the timeline 

accordingly. This final rule requires 

manufacturers to submit the emergency 

response guides and rescue sheets prior 

to first sale or lease of the subject 

vehicle model in the United States. 

Commenters requested clarification 

on the legacy ERGs that are currently 

housed in the NFPA website 43 and 

whether manufacturers should be 

submitting ERGs to multiple locations. 

NHTSA is coordinating with NFPA on 

ERGs currently housed with NFPA to 

migrate these legacy documents to the 

NHTSA specific website. Manufacturers 

will only need to submit the ERGs and 

rescue sheets to the NHTSA specified 

website prior to first vehicle sale or 

lease on the specified compliance date. 

NHTSA will socialize the location of the 

NHTSA website to first and second 

responders. 

k. Documentation Requirements 

NPRM Discussion 

The NPRM requested comments on 

whether the proposed emergency 

response information requirements 

would be better placed in a general 

agency regulation than in FMVSS No. 

305a, given that the documentation 

specifications are more akin to a 

disclosure requirement (disclosing 

information to NHTSA and the public) 

than a performance test or a consumer 

safety information requirement. The 

NPRM also sought comments on 

whether the proposed risk mitigation 

documentation requirements would be 

better placed in a general agency 

regulation. The mechanisms for 

enforcing a failure to meet a 

documentation requirement could differ 

depending on whether the requirement 

is in an FMVSS or not. 

Comments Received 

Comments on the documentation 

provisions were mixed. For the 

emergency response information, NTSB 

said that the emergency responder 

information requirements are 

straightforward enough to be included 

in this proposed rulemaking and should 

not be delayed for a separate regulation. 

MEMA stated that it agrees with 

NHTSA’s proposed documentation 

provisions, with due regard for the 

protection of confidential business 

information that may be contained 

therein. Auto Innovators requested that 

NHTSA consider initiating rulemaking 

to add a Class Determination to 49 CFR 

part 512 for the technical 

documentation submissions to be 

presumptively confidential. 

Most manufacturers and manufacturer 

associations that commented on this 


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104342 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

44 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. 

45See, e.g., 49 U.S.C. 30165. 

46For example, prior to the final rule published 

on August 16, 2024 (89 FR 66629), NHTSA’s record 

retention period, under 49 CFR 576, for motor 

vehicles, child restraint systems, and tires 

concerning malfunctions that may be related to 

motor vehicle safety under the Safety Act was 5 

years. 

topic argued that the documentation 

should not be included in FMVSS No. 

305a. Auto Innovators asserted that the 

documentation requirements are not 

objective standards and that reporting 

requirements should not be subject to 

the same recall and remedy obligations 

for FMVSS compliance. They reasoned 

that documentation does not directly 

affect safety and may be subject to 

change over time. Comments from 

DTNA, HATCI, EMA, NFA, and Nikola 

were similar. DTNA said the 

documentation requirements should be 

moved because the documentation is 

not associated with the vehicle meeting 

the performance requirements or 

information necessary to carry out the 

test procedure. HATCI said, ‘‘Minor or 

subjective, yet remediable, inquiries or 

revision requests and other 

inconsequential errors could be 

inordinately difficult to resolve within 

the framework of an FMVSS.’’ 

Agency Response 

After reviewing the comments, the 

agency agrees that the documentation 

requirements are better suited to a 

separate regulation than inclusion in 

FMVSS No. 305a. NHTSA regulates 

motor vehicle safety under many grants 

of authority. For example, one such 

authority 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 Vehicle Safety 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.44 Documentation requirements 

would be authorized under these 

authorities. 

NHTSA is also 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. An 

exception to the recall requirement in 

section 30120(h) 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,45 but would not be subject to 

a recall notification and remedy 

provision described above. 

After consideration of the nature of 

the documentation specifications and 

corresponding enforcement 

mechanisms, this final rule establishes 

the technical documentation and 

emergency response documentation 

requirements in part 561, without 

additional delay. As proposed, 

submission of the emergency response 

information is required for all subject 

vehicles, while submission of the other 

documentation specified in part 561 is 

upon request. Requested documentation 

may be submitted as Confidential 

Business Information (CBI) under 49 

CFR part 512. NHTSA will follow 49 

CFR part 512 confidential submissions 

procedures. 

Aligned with NHTSA’s average record 

keeping requirements for regulations, 

the corresponding documentation 

requirements are required to be retained 

for five years.46

l. Compliance Dates 

Proposed Requirements 

The NPRM proposed a compliance 

date of two years after the publication 

of the final rule for the proposed 

requirements other than the emergency 

response information. The NPRM 

proposed a compliance date of one year 

after the final rule’s publication for the 

proposed emergency response 

information submission to NHTSA to 

assist first and second responders. The 

NPRM further proposed that smallvolume manufacturers, final-stage 

manufacturers, and alterers would be 

provided an additional year to comply 

with each of the requirements. Optional 

early compliance would be permitted. 

Comments Received 

MEMA agreed with the proposed 

compliance dates, while several other 

commenters requested additional time 

for the technical requirements. HATCI 

agreed with the compliance dates for the 

emergency response information but 

requested an additional year for the 

other requirements because some 

proposed provisions deviate from GTR 

No. 20 and heavy vehicle manufacturers 

will be newly subject to electric system 

integrity requirements. Auto Innovators 

also agreed with the one-year lead time 

for manufacturers to submit the required 

emergency response guides and rescue 

sheets but requested an additional two 

years beyond the proposed compliance 

date for the other requirements. In other 

words, they requested a lead time of 4 

years, because substantive design 

changes might be required. They 

supported allowing an additional year 

for small-volume manufacturers, finalstage manufacturers, and alterers. EMA 

requested a 5-year lead time for heavy 

vehicles because heavy duty vehicle 

manufacturers will need to perform 

validation testing and make the 

appropriate design and production 

changes. 

Bugatti requested a longer lead time 

for small-volume manufacturers because 

‘‘the proposed lead periods do not allow 

sufficient time for the necessary 

assessments and validation to be 

conducted properly for small volume 

manufacturers and including final-stage 

manufacturers.’’ Bugatti stated that the 

dates should be aligned with FMVSS 

No. 127, ‘‘Automatic Emergency Braking 

Systems for Light Vehicles,’’ which has 

compliance dates of September 2029 

and September 2030, so that multiple 

high impact regulations start 

simultaneously. For FMVSS No. 305a, 

these dates would result in lead times 

of approximately 5 years for large 

volume manufacturers and 6 years for 

small volume and final-stage 

manufacturers. 

Agency Response 

After reviewing the comments, the 

agency is adopting the proposed 

compliance date for the emergency 

response information requirements in 

part 561. The compliance date is one 

year after publication of this final rule 

for all applicable vehicles. 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. In 


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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104343 

47 49 CFR 571.8(b). 

the interest of public safety, 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. Commenters agreed 

with the proposed compliance date for 

submission of the emergency response 

information to support first and second 

responders. 

In response to the concern raised 

about proprietary information of new 

vehicle designs being made public 

before first sale or lease, the final rule 

submission timeline requires 

manufacturers to submit the emergency 

response guides and rescue sheets prior 

to first sale or lease of the subject 

vehicle model in the United States. In 

the first year that compliance with this 

requirement becomes mandatory, the 

compliance date may not coincide with 

the first sale or lease of a vehicle model 

for that year. In this case, the first sale 

or lease of the vehicle model on or after 

the mandatory compliance date is the 

time before which the emergency 

response information for the vehicle 

model must be submitted. 

This final rule modifies the proposed 

compliance date of two years after 

publication of the final rule for light 

vehicle requirements, other than the 

emergency response information, such 

that the compliance date starts on the 

first September 1 that is at least 2 years 

after the final rule publication date to 

correspond to when a vehicle model 

year typically begins, instead of the 

originally proposed two years after the 

final rule publication. 

HATCI requested an additional year 

and Auto Innovators requested an 

additional two years to meet the 

proposed requirements for light vehicles 

because some proposed provisions 

deviated from GTR No. 20. While the 

final rule generally adopts the proposed 

requirements, changes to the final rule 

largely align with GTR No. 20, such as 

the adoption of documentation for the 

thermal event warning requirement 

instead of a corresponding testing 

procedure and clarification of the 

definition of SOC. These final rule 

changes reduce the burden for 

additional lead time for compliance 

because of widespread voluntary 

compliance with GTR No. 20. Therefore, 

we believe a compliance date of the first 

September 1 that is at least 2 years after 

the publication of this final rule is 

sufficient for manufacturers of light 

vehicles to ensure compliance with the 

final rule. 

On the other hand, the agency is 

extending the compliance date for heavy 

vehicle requirements by an additional 

year from the originally proposed one 

year after the publication of the final 

rule. NHTSA recognizes that heavy 

vehicles are not subject to the current 

FMVSS No. 305, and additional lead 

time is needed because design changes 

may be needed for heavy vehicles. As 

noted earlier, the changes made in the 

final rule better align with GTR No. 20 

requirements. However, the final rule 

requires vehicle level testing that is 

optional in GTR No. 20 and requires 

overcurrent protection of the REESS for 

heavy vehicles that is not required in 

GTR No. 20. NHTSA acknowledges that 

heavy vehicle manufacturers may need 

time to assess fleet performance, review 

their risk management procedures, and 

document their mitigation strategies 

since they are newly subject to electric 

system integrity requirements. The 

agency believes a compliance date of the 

first September 1 that is at least 3 years 

after publication of the final rule is 

sufficient for applicable heavy vehicles 

to comply with FMVSS No. 305a. 

Under 49 U.S.C. 30111(d), 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 a reason for the finding. 

A phased-in compliance period of two 

to four years that also aligns with the 

normal vehicle design cycle (model 

year) is in the public interest because 

most vehicles will require upgrades of 

hardware or software to meet the 

requirements of this final rule. To 

require compliance with this standard 

outside of the normal development 

cycle would significantly increase the 

cost of the rule because vehicles cannot 

easily be made compliant with the 

requirements of this final rule outside of 

the normal vehicle design cycle. 

Note that as discussed in the 

Regulatory Flexibility Act section of this 

document, NHTSA is giving smallvolume manufacturers, final-stage 

manufacturers, and alterers an 

additional year to comply.47 Optional 

early compliance is permitted. 

Additionally, in the interest of public 

safety, the effective date of this final 

rule is 60 days after its publication to 

establish the new requirements in the 

Code of Federal Regulations and to 

allow for optional early compliance. 

V. Response to Comments on Issues Not 

Discussed in the NPRM 

a. Future Battery Chemistries 

Comments Received 

MEMA suggested limiting the 

application of FMVSS No. 305a to 

lithium battery vehicles, to better align 

with GTR No. 20 and avoid 

misconceptions regarding other future 

battery chemistries. Using 

Environmental Protection Agency 

(EPA)’s 40 CFR 86.1840–01 ‘‘Special test 

procedures’’ as an example, Rivian 

suggested that NHTSA incorporate a 

similar provision into the regulatory text 

to address new chemistries, allowing 

manufacturers to submit alternative test 

procedures for NHTSA’s review and 

advanced approval. 

Agency Response 

The agency believes that limiting the 

scope of FMVSS No. 305a to only 

lithium-ion batteries would not be 

beneficial to safety. There are safety 

risks with any type of propulsion 

system and any battery chemistry. 

While the FMVSS requirements are 

based on the current state of technology, 

they are intentionally chemistry neutral 

to allow for future developments. This 

neutral approach would not limit 

adoption of future battery chemistries 

and not be design restrictive. The 

emissions requirements cited by Rivian 

include additional provisions because 

vehicle manufacturers are required to 

obtain a certificate of conformity from 

the EPA. NHTSA’s authority and 

regulation requirements are different 

from EPA’s. NHTSA is authorized to 

issue FMVSSs that set performance 

requirements for new motor vehicles 

and items of motor vehicle equipment 

(see 49 U.S.C. Chapter 301). NHTSA 

does not provide approval of motor 

vehicles or motor vehicle equipment, 

and NHTSA does not determine 

compliance of a vehicle or item of motor 

vehicle equipment outside the context 

of an actual enforcement proceeding. 

Instead, manufacturers are required to 

self-certify that their products conform 

to all applicable safety standards that 

are in effect on the date of manufacture. 

FMVSS No. 305a does not specify or 

prohibit certain battery chemistries. 

Overall, NHTSA will continue to 

monitor the state of REESS technology 

and associated safety risks, and FMVSS 

requirements may be added or modified 

over time as REESS technology evolves. 

b. Marking and Labeling 

Comments Received 

The Center for Auto Safety suggested 

NHTSA to establish and require 


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distinctive marking in REESS-equipped 

vehicles to identify REESS-associated 

electrical shock hazards, electrical 

isolation points and mechanisms, and 

related design features by means of 

standardized, permanently affixed 

labels for reference by emergency 

personnel and consumers. Similarly, 

Consumer Reports suggested adding 

requirements for hazard warning labels 

aimed at consumers and maintenance 

technicians. 

Agency Response 

The NPRM did not propose additional 

requirements for specific, standardized 

markings or labeling of electric vehicles, 

and they are not in scope for this final 

rule. FMVSS No. 305, S5.4.1.1 currently 

requires high voltage cables to have an 

orange-colored outer covering and 

electric energy storage devices and 

electrical protection barriers to have a 

specific black and yellow high voltage 

marking. This final rule adopts these 

same high voltage identification 

requirements into FMVSS No. 305a, 

S6.1.1. In general, major maintenance 

and repair of electric vehicles is 

conducted by trained personnel at a 

manufacturer approved dealership; 

consumers are advised not to attempt 

modification or repair of high voltage 

systems. Emergency response personnel 

use vehicle documentation to help 

locate specific components, avoid 

electric shock hazards, and handle the 

vehicles safely. This final rule requires 

manufacturers to provide standardized 

ERGs and rescue sheets to NHTSA to 

create a centralized location for public 

access. In addition, some states already 

require specific license plates or other 

markings on the exterior of alternative 

fuel vehicles. NHTSA will continue to 

evaluate the type, location, and 

effectiveness of exterior markings that 

would further aid first and second 

responders and support general 

emergency mitigation. 

c. Test Laboratories 

Comment Received 

A2LA suggested adopting conformity 

assessment activities such as requiring 

manufacturers to use ISO/IEC 17025 

accredited testing laboratories. 

Agency Response 

As discussed above, NHTSA does not 

specify manufacturer development 

methods or test facility certifications. 

NHTSA does not provide approval of 

motor vehicles or motor vehicle 

equipment, and NHTSA does not 

determine compliance of a vehicle or 

item of motor vehicle equipment 

outside the context of an actual 

enforcement proceeding. Instead, 

manufacturers are required to selfcertify that their products conform to all 

applicable safety standards that are in 

effect on the date of manufacture. 

d. Other Electrical Specifications 

Comments Received 

EMA suggested adding definitions to 

S4 for ‘‘Tested-Device,’’ ‘‘Nominal 

voltage,’’ and ‘‘Suitable Lamp.’’ EMA 

also requested changing ‘‘working 

voltage’’ to ‘‘nominal voltage’’ in S7.1.2. 

For the loss of electrical isolation 

warning in S6.4, EMA suggested adding 

a 1-minute time limit for activation of 

the visual warning. EMA also requested 

removing the minimum voltage supply 

for the optional lamp in the physical 

barrier tests, as most vehicles have a 

standard voltage of 12 or 24 volts. EMA 

also said that S7.1 specified the 

voltmeter internal resistance be at least 

10 MW and that it should be changed 

to 10 MW, and that ‘‘chamber’’ should 

be corrected to ‘‘chamfer’’ in figure 7b. 

For high voltage sources excluded from 

electrical isolation requirements, MEMA 

recommended harmonization with 

UNECE R100 to clarify that the 60VDC 

threshold also applies to pulsating DC 

voltages less than 60VDC in cases where 

there is no change in polarity. 

Agency Response 

NHTSA appreciates the commenters’ 

review of the regulatory text and 

recommended updates. NHTSA’s 

response to each issue raised is as 

follows: 

1. Definition of Tested-Device: EMA 

requested allowing component-level 

testing and defining ‘‘Tested-Device.’ 

This final rule does not use the term 

‘‘Tested-Device,’’ because all tests are 

conducted at the full vehicle level and 

there are no component level tests in 

FMVSS No. 305a. The April 2024 NPRM 

used the definition for SOC that is in 

GTR No. 20, which refers to the charge 

of the ‘‘tested device.’’ However, in 

response to comments received, the 

SOC definition has been revised and 

now refers to the ‘‘REESS’’ instead of 

the ‘‘tested device.’’ 

2. Definition of Suitable Lamp: S7.3.1 

of FMVSS No. 305a describes the test 

procedure for evaluating protection 

from direct contact with high voltage 

sources. S7.3.1(c) specifies that a 

‘‘suitable lamp’’ in series with a low 

voltage supply of 40–50 volts may be 

connected between the access probe 

(IPXXB or IPXXD) and any high voltage 

live parts inside the electrical protection 

barrier to indicate whether high voltage 

live parts were contacted. EMA 

recommended defining ‘‘suitable lamp’’ 

to mean ‘‘a circuit tester with an input 

voltage range of 50 VDC minimum, that 

is one of the following types: an 

incandescent lamp, LED indicator, 

buzzer, or Voltmeter.’’ EMA stated that 

the specification for the voltage supply 

should be changed such that the 

vehicle’s own voltage of 12 or 24 volts 

could be used for the indicator lamp. 

The commenter’s definition does not 

specify an upper limit for the voltage 

and seemingly contradicts its request to 

allow use of the vehicle’s own power 

supply. The voltage range of 40–50 volts 

is specified in S7.3.1(c) to ensure 

sufficient current in the circuit that can 

be detected by the lamp, while also 

ensuring the current is not sufficiently 

high to pose a safety risk to testing 

personnel. The purpose of the lamp is 

merely to provide a quick visual 

indication of contact with high voltage 

sources. The agency believes that as 

long as a lamp compatible with the 

voltage supply of 40–50 volts is used, 

there is no need to specify the type of 

lamp. The regulatory text in FMVSS No. 

305a S7.3 was adopted from S9 in 

FMVSS No. 305, which has been 

effective since 2017, and is the same as 

that in GTR No. 20 and UNECE R100. 

The agency will further assess EMA’s 

recommendations regarding the test 

procedure for direct contact protection 

and will consider updates to the 

regulatory text later, if warranted. At 

this time, NHTSA is adopting the test 

procedure for direct contact protection 

currently in FMVSS No. 305 and 

proposed in the NPRM for inclusion in 

FMVSS No. 305a. 

3. Definition and Use of Nominal 

Voltage: EMA requested defining and 

using the term ‘‘nominal voltage,’’ 

instead of ‘‘working voltage,’’ for 

determining voltage in S7.1.2 of FMVSS 

No. 305a. EMA provided a definition of 

‘‘nominal voltage’’ to mean a value that 

represents the typical or midpoint of a 

battery’s maximum operating voltage 

and the minimum operating voltage 

over its charge and discharge cycle. 

NHTSA is not making this requested 

change in the final rule. The agency 

notes that the term ‘‘working voltage’’ 

and method of determining voltage are 

adopted from FMVSS No. 305 and have 

been effective since 2010. We believe 

the term ‘‘working voltage’’ is 

appropriate because it evaluates 

whether a component in the electric 

power train is a high voltage source 

when the vehicle is fully charged. 

Additionally, the singular instance of 

‘‘nominal voltage’’ in S12.2 of the 

NPRM regulatory text has been changed 

to ‘‘working voltage’’ for consistency. 

4. Time limit for activating warning 

alerting driver to loss of electrical 


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48 82 FR 44945 (Sept. 27, 2017). 

49See https://wiki.unece.org/download/ 

attachments/117508721/EVS21- 

K01%20%5BCLEPA%5DR100- 

3%2048V%20Issue.pptx?api=v2. 

50Section 5.3.4.1 of IEC TS 60479–2, ‘‘Effects of 

current on human beings and livestock—Part 2,’’ 

available at https://webstore.iec.ch/publication/ 

63392, states that for combination of DC and AC 

voltage sources where there is no change in 

polarity, half the peak voltage can be used for 

determining electric shock risk. Because the risk of 

electric shock for 30 VAC is the same as 60 VDC, 

pulsating DC voltages less than or equal to 60 VDC 

pose no additional risk and can also be excluded 

from the electrical isolation requirement. The direct 

and indirect contact protection requirements further 

mitigate the risk of electric shock. 

isolation: For the loss of electrical 

isolation warning in S6.4, EMA 

suggested adding a time limit: ‘‘The 

maximum time allowed to activate 

visual warning lamp shall be [less than] 

1 minute when tested per S7.4.’’ 

NHTSA did not include a time limit for 

the warning to activate when there is a 

loss in electrical isolation, which is 

consistent with other warning 

requirements in FMVSSs, e.g., the seat 

belt warning in FMVSS No. 208, 

‘‘Occupant crash protection.’’ Activation 

of the warning is assessed visually by 

test personnel when loss in electrical 

isolation is simulated in accordance 

with S7.4. 

5. Typographical Error in figure 7b: 

EMA requested changing the phrase, 

‘‘chamber all edges,’’ to ‘‘chamfer all 

edges,’’ in figure 7b. Jointed Test Finger 

IPXXB, of the regulatory text. This final 

rule corrects the typographical error in 

figure 7b. 

6. Voltmeter resistance in S7.1 of 

FMVSS No. 305a: EMA noted that the 

proposed S7.1 of FMVSS No. 305a 

specifies the voltmeter internal 

resistance be at least 10 MW and that it 

should be changed to 10 MW. The 

regulatory text in the April 2024 NPRM 

correctly specifies the voltmeter 

resistance in MW and so no change is 

made in the final rule regulatory text. 

7. Exclusion of certain high voltage 

sources from electrical isolation 

requirements: MEMA requested 

clarifying that the exclusion in S6.3.2 

also applies to pulsating DC voltages of 

less than 60 VDC in cases where there 

is no change in polarity. The September 

2017 final rule 48 updating FMVSS No. 

305 excluded 48 V systems that are 

connected to the electrical chassis from 

electrical isolation requirements. In 48 

V systems, the AC–DC inverter converts 

the DC current from the 48 V battery 

into AC for the 3-phase AC motor. The 

voltage between the electrical chassis 

and each of the phases of the AC electric 

motor is switched DC voltage (voltage 

between 0 and 48 volts). Because that 

voltage is less than 60 volts, it is 

considered low DC voltage under 

FMVSS No. 305. However, the voltage 

between two phases of the AC motor is 

AC, and may be slightly greater than 30 

VAC under certain circumstances, 

which can be considered a high voltage 

AC source under the standard. However, 

the physical barrier protection (both 

direct and indirect contact protection) 

around the AC motor, and around cables 

from the inverter to the motor, would 

mitigate human contact with these AC 

high voltage sources, and thereby 

mitigate the likelihood of electric shock. 

In the 21st meeting of the working group 

developing GTR No. 20 Phase 2, the 

European Association of Automotive 

Suppliers (CLEPA) provided a 

rationale 49 for also excluding pulsating 

DC high voltage sources with working 

voltage of 60 VDC or less where there 

is no change in polarity from electrical 

isolation requirements so as to 

accommodate 48 V air-cooled motor 

generators in the electric power train. 

NHTSA agrees with this rationale for 

this exclusion of pulsating DC high 

voltage sources with no change in 

polarity and with working voltage of 60 

VDC or less from the electrical isolation 

requirements of S6.3.1 of FMVSS No. 

305a.50 The regulatory text has been 

modified to provide this clarification. 

e. Static Rollover 

Comments Received 

Tesla requested that NHTSA 

reconsider the static rollover test 

requirement, given the current state of 

EV batteries compared to older lead-acid 

batteries. 

Agency Response 

The agency believes that there is merit 

in the static rollover test requirement, 

consistent with other FMVSS 

requirements. In addition, the agency is 

retaining requirements pertaining to 

electrolyte leakage for REESS with 

liquid electrolyte. 

VI. Rulemaking Analyses and Notices 

Executive Order 12866, Executive Order 

14094, Executive Order 13563, and DOT 

Order Regulatory Policies and 

Procedures 

NHTSA has considered the impact of 

this rulemaking action under Executive 

Orders 12866, 14094, and 13563, DOT 

Order 2100.6A and the Department of 

Transportation’s regulatory policies and 

procedures. The final rule is not 

considered to be significant under the 

Department of Transportation’s 

regulatory policies and procedures. 44 

FR 11034 (Feb. 26, 1979). This action 

was not reviewed by the Office of 

Management and Budget under E.O. 

12866. 

This final rule issues FMVSS No. 

305a and Part 561 to update and expand 

the requirements that are in FMVSS No. 

305. Most of GTR No. 20 has already 

been adopted into FMVSS No. 305; this 

final rule completes the process by 

expanding FMVSS No. 305’s 

applicability to heavy vehicles and by 

adopting the GTR’s requirements for the 

REESS. Because there is widespread 

conformance with the requirements that 

would apply to existing vehicles, we 

anticipate no costs or benefits associated 

with this rulemaking. 

This final rule also requires 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. Under Part 561, 

manufacturers will submit ERGs and 

rescue sheets to NHTSA instead. We 

anticipate no additional costs by the 

manufacturers. 

Regulatory Flexibility Act 

The Regulatory Flexibility Act of 1980 

(5 U.S.C. 601 et seq.) (‘‘the Act’’) 

requires agencies to evaluate the 

potential effects of their proposed and 

final rules on small businesses, small 

organizations, and small Government 

jurisdictions. The Small Business 

Administration’s regulations at 13 CFR 

part 121 define a small business, in part, 

as a business entity ‘‘which operates 

primarily within the United States.’’ (13 

CFR 121.105(a)). 

The Act requires agencies to prepare 

and make available an initial and final 

regulatory flexibility analysis (RFA) 

describing the impact of proposed and 

final rules on small entities. An RFA is 

not required if the head of the agency 

certifies that the proposed or final rule 

will not have a significant impact on a 

substantial number of small entities. 

The head of the agency has made such 

a certification with regard to this final 

rule. 

The factual basis for the certification 

(5 U.S.C. 605(b)) is set forth below. 

Although the agency is not required to 

issue an initial regulatory flexibility 

analysis, this section discusses many of 


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51Final-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. 

52Alterers 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. 

53See 49 CFR 571.8(b). 

the issues that an initial regulatory 

flexibility analysis would address. 

Section 603(b) of the Act specifies the 

content of an RFA. Each RFA must 

contain: 

1. A description of the reasons why 

action by the agency is being 

considered; 

2. A succinct statement of the 

objectives of, and legal basis for, a final 

rule; 

3. A description of and, where 

feasible, an estimate of the number of 

small entities to which the final rule 

will apply; 

4. A description of the projected 

reporting, recording keeping and other 

compliance requirements of a final rule, 

including an estimate of the classes of 

small entities that will be subject to the 

requirement and the type of professional 

skills necessary for preparation of the 

report or record; 

5. An identification, to the extent 

practicable, of all relevant Federal rules 

which may duplicate, overlap or 

conflict with the final rule; 

6. Each final regulatory flexibility 

analysis shall also contain a description 

of any significant alternatives to the 

final rule which accomplish the stated 

objectives of applicable statutes and 

which minimize any significant 

economic impact of the final rule on 

small entities. 

A description of the reason why 

action by the agency is being considered 

and the objectives of, and legal basis for, 

the final rule are discussed at length 

earlier in this document. 

This final rule will directly affect 

manufacturers subject to FMVSS No. 

305a and Part 561. The Small Business 

Administration’s size standard 

regulation at 13 CFR part 121, ‘‘Small 

business size regulations,’’ prescribes 

small business size standards by North 

American Industry Classification 

System (NAICS) codes. NAICS code 

336211, Motor Vehicle Body 

Manufacturing, prescribes a small 

business size standard of 1,000 or fewer 

employees. NAICS code 336390, Other 

Motor Vehicle Parts Manufacturing, 

prescribes a small business size 

standard of 1,000 or fewer employees. 

Most motor vehicle manufacturers 

would not qualify as a small business. 

NHTSA is aware of 3 small 

manufacturers of light and heavy 

electric vehicles. NHTSA believes that 

this rule will not have a significant 

economic impact on these 

manufacturers for the following reasons. 

First, small manufacturers of light 

electric vehicles 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 requirements 

for the REESS are manageable because 

the overcharge, over-discharge, overcurrent, 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, warning for 

a thermal event, 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 

voluntary 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 final rule allows one 

additional year for small volume 

manufacturers, final-stage 

manufacturers, and alterers to comply. 

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 will be developed by vehicle 

designers and suppliers and integrated 

into the fleets of larger vehicle 

manufacturers first, before small 

manufacturers. This final rule provides 

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 final rule applies 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.51 According to the U.S. 

Census, there are 570 small businesses 

in body manufacturing for light, 

medium, and heavy-duty classes. 

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.52 Furthermore, 

even if the final-stage manufacturer or 

alterer must make the certification 

independently, as explained above this 

certification responsibility is 

manageable. The 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 rule 

further accommodates final-stage 

manufacturers and alterers by providing 

them an additional year before 

compliance is required.53 For the 

reasons above, NHTSA does not believe 

that the economic impacts on small 

entities will be significant. 

With regard to the 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 those 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 

rule accommodates 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 


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does not believe that the economic 

impacts of this rule on small entities 

will be significant. 

National Environmental Policy Act 

NHTSA has analyzed this rule for the 

purposes of the National Environmental 

Policy Act. In accordance with 49 CFR 

1.81, 42 U.S.C. 4336, and DOT NEPA 

Order 5610.1C, NHTSA has determined 

that this rule is categorically excluded 

pursuant to 23 CFR 771.118(c)(4) 

(planning and administrative activities, 

such as promulgation of rules, that do 

not involve or lead directly to 

construction). This rulemaking, which 

establishes Federal Motor Vehicle Safety 

Standard (FMVSS) No. 305a, ‘‘Electricpowered vehicles: Electrolyte spillage 

and electrical shock protection,’’ to 

update and replace FMVSS No.305 and 

to include performance requirements for 

propulsion batteries for light and heavy 

vehicles, and which establishes a new 

regulation, Part 561, ‘‘Documentation 

for Electric-powered Vehicles,’’ that 

requires manufactures to compile risk 

mitigation documentation and submit 

standardized emergency response 

information to assist first and second 

responders handling electric vehicles, is 

not anticipated to result in any 

environmental impacts, and there are no 

extraordinary circumstances present in 

connection with this rulemaking. 

Executive Order 13132 (Federalism) 

NHTSA has examined this 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 rule does not have 

sufficient federalism implications to 

warrant consultation with State and 

local officials or the preparation of a 

federalism summary impact statement. 

The rule 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]ompliance 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. 

NHTSA rules can also preempt State 

law if complying with the FMVSS 

would render the motor vehicle 

manufacturers liable under State tort 

law. 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 

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 rule and finds this 

rule, like many NHTSA rules, would 

prescribe only a minimum safety 

standard. As such, NHTSA does not 

intend that this rule preempt state tort 

law that would effectively impose a 

higher standard on motor vehicle 

manufacturers than that established by 

this rule. Establishment of a higher 

standard by means of State tort law 

would not conflict with the standards in 

this final rule. 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) 

adequately defines key terms; and (6) 

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. 

Executive Order 13045 (Protection of 

Children From Environmental Health 

and Safety Risk) 

Executive Order 13045 (62 FR 19885, 

April 23, 1997) applies to any rule that: 

(1) is determined to be ‘‘economically 

significant’’ as defined under E.O. 

12866, and (2) concerns an 

environmental, health, or safety risk that 

NHTSA has reason to believe may have 

a disproportionate effect on children. If 

the regulatory action meets both criteria, 

we must evaluate the environmental 

health or safety effects of the planned 

rule on children and explain why the 

planned regulation is preferable to other 

potentially effective and reasonably 

feasible alternatives considered by us. 

This final rule is not subject to the 

Executive order because it is not 

economically significant as defined in 

E.O. 12866. 

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 http://

www.dot.gov/privacy.html. 

Congressional Review Act 

The Congressional Review Act, 5 

U.S.C. 801 et. seq., as added by the 

Small Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 


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54 89 FR 26704. 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. NHTSA will 

submit a report containing this rule and 

other required information to the U.S. 

Senate, the U.S. House of 

Representatives, and the Comptroller 

General of the United States prior to 

publication of the rule in the Federal 

Register. This rule does not meet the 

criteria in 5 U.S.C. 804(2) to be 

considered a major rule. The rule will 

be effective sixty days after the date of 

publication in the Federal Register. 

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 new 

information collection described below 

has been forwarded to OMB for review 

and comment. 

The final rule has two types of new 

collection of information that are part of 

the Part 561 requirements: (1) Electric 

Vehicles: Rescue Sheets and Emergency 

Response Guides and (2) Electric 

Vehicles: REESS Thermal Propagation 

Safety Risk Analysis and Mitigation 

Documentation. NHTSA sought 

comment on the new information 

collection requirements in the NPRM 

published on April 15, 2024.54 There 

were no PRA-specific comments 

provided. NHTSA’s response to the 

comments and the final rule’s 

information collection requirements are 

discussed in sections IV.j–l above. As 

discussed, NHTSA is largely adopting 

the proposal with some changes. In 

accordance with the requirements of the 

PRA, NHTSA is resubmitting the ICR for 

this final rule. In the final rule, the 

emergency response information and 

four documentation requirements are 

added to the general regulation Part 561 

rather than in the proposed FMVSS No. 

305a, given that the documentation 

specifications are more akin to a 

disclosure requirement than a 

performance test. The estimated total 

burden of this collection is modified to 

account for the final rule’s addition of 

the audio-visual warning for a thermal 

event in the REESS to be part of the 

documentation requirements that was 

not initially proposed in the NPRM. For 

each vehicle model, vehicle 

manufacturers will need an estimated 

84 hours to complete the four 

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, 17 hours for the 

documentation for thermal event 

warning, and 33 hours for the 

documentation covering thermal 

runaway due to internal short in a single 

cell of the REESS). After this rule’s 

effective date, all 205 vehicle models are 

expected to compile the necessary 

information to meet the four 

documentation requirements. The total 

estimated annual burden hours for the 

four documentation requirements is 

17,220 hours (205 vehicle models x 84 

hours). The previous total estimated 

burden hours for the three 

documentation requirements in the 

NPRM was 13,735 hours (205 vehicle 

models × 67 hours). 

The estimated total annual burden 

hours for the emergency response 

information was slightly decreased to 

approximately 2,335 hours from the 

original estimation of 2,506 burden 

hours. Because rescue sheets and 

emergency response guides often cover 

several model years, the percentage of 

models that would need new or updates 

to existing or previously submitted 

rescue sheets and ERGs is likely to 

decrease after the second year of the 

effective date. With additional 

documentation requirements from the 

final rule, the total estimated annual 

burden hours for the two new types of 

information collection is estimated to be 

19,565 burden hours. 

In the NPRM, NHTSA originally 

included labor costs under the burden 

cost calculation. NHTSA now estimates 

that there will be no costs to 

respondents other than the labor costs 

from the corresponding burden hours of 

compiling the information. Therefore, 

the total annual burden cost has now 

been corrected to be $0. 

The OMB control numbers for 

NHTSA regulations are displayed at 49 

CFR part 509. When OMB approves this 

ICR, the agency will announce that 

approval in the Federal Register and, as 

appropriate, display the OMB control 

number on the applicable collection 

instruments and publish a technical 

amendment to 49 CFR part 509 to 

display the OMB control number for the 

approved information collection 

activities contained in this final rule. 

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 final rule is consistent with the 

goals of the NTTAA. This rule adopts 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. 

In addition, the following voluntary 

consensus standards have been used in 

developing this final rule: 

• ISO–6469–1: Amendment 1 2022– 

11. 

• ISO–26262:2018. 

• 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. 

• 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 201. 

• ISO 17840–3:2019(E), ‘‘Road 

vehicles—Information for first and 

second responders—Part 3: Emergency 

response guide template,’’ First Edition, 

April 2019. 


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55 ISO standards may be purchased from the ANSI 

webstore https://webstore.ansi.org/. 

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 rule will not result in a 

cost of $177 million or more to State, 

local, or Tribal governments, in the 

aggregate, or the private sector. Thus, 

this rule 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 

vehicles. As a signatory member, 

NHTSA is incorporating electrical safety 

requirements and options specified in 

GTR No. 20 with modifications into 

FMVSS No. 305a and Part 561. 

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. 

In this final rule, NHTSA incorporates 

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 are 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.55

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. 

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 

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/eAgenda

ViewRule?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. 

Submission of Confidential Information 

You should submit a redacted ‘‘public 

version’’ of your comment (including 

redacted versions of any additional 

documents or attachments). 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 information includes the 

materials for which confidentiality is 

being requested (as explained in more 

detail below); supporting information, 

pursuant to § 512.8; and a certificate, 

pursuant to § 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 

§ 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 


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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 § 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 the Office of the Chief 

Counsel 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 

at Helena.Sung@dot.gov. 

List of Subjects 

49 CFR Part 561 

Imports, Incorporation by reference, 

Motor vehicles, Motor vehicle safety. 

49 CFR Part 571 

Imports, Motor vehicles, Motor 

vehicle safety. 

In consideration of the foregoing, 

NHTSA amends 49 CFR chapter V as set 

forth below. 

■ 1. Add part 561 to read as follows: 

PART 561—DOCUMENTATION FOR 

ELECTRIC–POWERED VEHICLES. 

Sec. 

561.1 Scope. 

561.2 Purpose. 

561.3 Application. 

561.4 Matter incorporated by reference. 

561.5 Definitions. 

561.6 Rescue sheets and emergency 

response guides. 

561.7 Documentation for low temperature 

operation safety. 

561.8 Documentation of a visual warning 

for malfunction of vehicle controls that 

manage REESS operation. 

561.9 Documentation of an audio-visual 

warning for a thermal event in the 

REESS. 

561.10 Documentation for single cell 

thermal runaway and propagation safety 

risk mitigation. 

561.11 Record retention. 

Authority: 49 U.S.C. 322, 30111, 30115, 

30117, and 30166; delegation of authority at 

49 CFR 1.95. 

§ 561.1 Scope. 

This part specifies requirements for 

the submission of standardized 

emergency response guides (ERGs) and 

rescue sheets for electric-powered 

vehicles. It also specifies requirements 

for other documentation, to be 

submitted to NHTSA upon request, 

addressing low temperature operation 

safety, warning in the event of 

malfunction of vehicle controls 

managing Rechargeable Electrical 

Energy Storage System (REESS) 

operations, warning in the case of a 

thermal event in the REESS, and safety 

risk mitigation for thermal runaway and 

propagation. 

§ 561.2 Purpose. 

The purpose of this part is to ensure 

emergency response information is 

readily available for first and second 

responders regarding the safe handling 

of electric-powered vehicles and to 

ensure vehicle occupants are alerted to 

potentially hazardous conditions. The 

other documentation requirements are 

to ensure vehicle manufacturers identify 

and address safety risks associated with 

the electric propulsion system in 

addition to the requirements of part 571 

of this chapter. 

§ 561.3 Application. 

This part 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. 

(a) Rescue sheets and emergency 

response guides requirements. Vehicles 

manufactured on or after December 22, 

2025, are subject to § 561.6. 

(b) Documentation requirements. (1) 

Vehicles with a gross vehicle weight 

rating of 4,536 kilograms (kg) or less 

manufactured on or after September 1, 

2027, are subject to §§ 561.7 through 

561.10. 

(2) Vehicles with a gross vehicle 

weight rating over 4,536 kilograms (kg) 

manufactured on or after September 1, 

2028, are subject to §§ 561.7 through 

561.10. 

(3) The requirements §§ 561.7 through 

561.10 do not apply to small-volume 

manufacturers, final-stage 

manufacturers, and alterers of vehicles 

with a gross vehicle weight rating under 

4,536 kilograms (kg) until one year after 

the date specified in paragraph (b)(1) of 

this section. 

(4) The requirements §§ 561.7 through 

561.10 do not apply to small-volume 

manufacturers, final-stage 

manufacturers, and alterers of vehicles 

with a gross vehicle weight rating over 

4,536 kilograms (kg) until one year after 

the date specified in paragraph (b)(2) of 

this section. 

§ 561.4 Matter incorporated by reference. 

The material listed in this section is 

incorporated by reference into this 

section with the approval of the Director 

of the Federal Register in accordance 

with 5 U.S.C. 522(a) and 1 CFR part 51. 

All approved incorporation by reference 

(IBR) material is available for inspection 

at the National Highway Traffic Safety 

Administration (NHTSA) or at the 

National Archives and Records 

Administration (NARA). Contact 

NHTSA at: 1200 New Jersey Avenue SE, 

Washington, DC 20590; (202) 366–2588; 

www.nhtsa.gov/about-nhtsa/electronicreading-room. For information on the 

availability of this material at NARA, 

visit www.archives.gov/contact. The 

material may be obtained from the 

following paragraphs of this section. 

(a) International Organization for 

Standardization (ISO), 1, ch. de la VoieCreuse, CP 56, CH–1211 Geneva 20, 

Switzerland; phone: + 41 22 749 01 11; 

fax: + 41 22 733 34 30; website: 

www.iso.org. 

(1) 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 § 561.6. 

(2) 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 § 561.6. 

(3) ISO 17840–3:2019(E), Road 

vehicles—Information for first and 

second responders—Part 3: Emergency 

response guide template, First Edition, 

April 2019, into § 561.6. 

(b) [Reserved] 

§ 561.5 Definitions. 

(a) Statutory definitions. All terms 

defined in section 30102 of the National 

Traffic and Motor Vehicle Safety Act (49 

U.S.C. chapter 301, et seq.) are used in 

their statutory meaning. 

(b) Motor vehicle safety standard 

definitions. All terms defined in 49 CFR 

part 571 are used as defined therein. 

(c) Other definitions— 

Emergency response guide means a 

document containing in-depth vehiclespecific information related to fire, 


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submersion, leakage of fluids, towing, 

and storage of vehicles for first and 

second responders. 

First responder means a person with 

specialized training such as a law 

enforcement officer, paramedic, 

emergency medical technician, and/or 

firefighter. 

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. 

Second responder means a worker 

who supports first responders by 

cleaning up a site, towing vehicles, and/ 

or supporting services after an event 

requiring first responders. 

§ 561.6 Rescue sheets and emergency 

response guides. 

(a) Rescue sheets. Prior to first vehicle 

sale or lease, vehicle manufacturers 

shall submit rescue sheets to NHTSA. 

(1) For vehicles with a GVWR less 

than or equal to 4,536 kg to which the 

requirement applies, submitted rescue 

sheets shall follow the layout and 

format in ISO–17840–1:2022(E) 

(incorporated by reference; see § 561.4). 

(2) 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) (incorporated by 

reference; see § 561.4). 

(3) The rescue sheets shall provide 

information for first responders to 

extricate occupants. 

(b) Emergency response guides 

(ERGs). Prior to first vehicle sale or 

lease, vehicle manufacturers shall 

submit emergency response guides to 

NHTSA in accordance with the template 

layout and format in ISO–17840– 

3:2019(E) (incorporated by reference; 

see § 561.4). vehicles to which this 

requirement applies. 

(1) 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. 

(2) The ERGs shall provide in-depth 

information related to electric vehicle 

fire, submersion, leakage of fluids, 

towing, transportation, and storage. 

(3) The ERGs shall provide 

information to assist first responders in 

extricating occupants. 

§ 561.7 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 

manufacturer specified 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 manufacturer specified 

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 manufacturer 

specified 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 

paragraphs (a) through (f) of this section. 

§ 561.8 Documentation of a visual warning 

for malfunction of vehicle controls that 

manage REESS operation. 

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) 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 REESS 

operations. 

(c) 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. 

(d) 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. 

(e) 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 paragraphs (a) through (d) of this 

section. 

§ 561.9 Documentation of an audio-visual 

warning for a thermal event in the REESS. 

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) A system diagram of the thermal 

event warning system. 

(c) A written explanation describing 

the basic operation of the thermal event 

warning system. The explanation must 

identify the components of the thermal 

event warning system, provide 

descriptions of their functions and 

capability, and provide a logic diagram 

and description of conditions that 

would lead to triggering the warning 

activation. 

(d) Validation results from tests to 

confirm the activation of an audiovisual warning in the case of a thermal 

event in the REESS. 

(e) 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 paragraphs (a) through (d) of this 

section. 

§ 561.10 Documentation for single cell 

thermal runaway and propagation safety 

risk mitigation. 

The vehicle manufacturer shall make 

available to NHTSA, 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) Vehicle information. This part of 

the documentation shall identify 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 


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operational modes and allocate 

applicable functional units, 

components, and 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, and 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 among 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 occurs, 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 

shall 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 

(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 to 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 paragraphs (a) through (d) 

of this section. 

§ 561.11 Record retention. 

Each applicable manufacturer shall 

maintain the information specified in 

§§ 561.7 through 561.10 for the 

documentation requirements for a 

period of five years from the date of 

manufacture. 

PART 571—FEDERAL MOTOR 

VEHICLE SAFETY STANDARDS 

■ 2. 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. 

■ 3. Section 571.305 is amended by 

revising the section heading and S3 to 

read as follows: 

§ 571.305 Standard No. 305; electricpowered vehicles: electrolyte spillage and 

electrical shock protection; applicable 

unless a vehicle is certified to § 571.305a. 

* * * * * 

S3. Application. This standard 

applies to passenger cars, and to 

multipurpose passenger vehicles, 

trucks, and buses with a gross vehicle 

weight rating (GVWR) of 4,536 

kilograms (kg) or less, 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, that are manufactured before 

September 1, 2027. 

* * * * * 

■ 4. Section 571.305a is added to read 

as follows: 

§ 571.305a Standard No. 305a; electricpowered vehicles: Electric powertrain 

integrity; mandatory applicability begins on 

September 1, 2027. 

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. (a) 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. 

(b) Mandatory applicability begins 

September 1, 2027, for vehicles with a 

gross vehicle weight rating of 4,536 

kilograms (kg) or less and September 1, 

2028, for vehicles with a gross vehicle 

weight rating over 4,536 kg. Smallvolume manufacturers, final-stage 

manufacturers, and alterers are provided 

an additional year to comply with the 

requirements beyond the dates 

identified in this paragraph (b). 

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. 

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. 


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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. 

Exposed conductive part is a 

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. 

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 to this 

standard. 

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 to this 

standard. 

Rechargeable Electrical Energy 

Storage System (REESS) means the 

rechargeable electric energy storage 

system that provides electric energy for 

electrical propulsion. 

Rupture means an opening through 

the casing of the REESS that would 

permit the IPXXB test probe to penetrate 

and contact live parts. 

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 REESS 

expressed as a percentage of the normal 

operating capacity specified by the 

vehicle manufacturer. 

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. 


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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 (warning in the case of 

thermal event in REESS), and S14 

(water exposure safety) of this standard. 

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 (warning in the case of 

thermal event in REESS), and S14 

(water exposure safety) of this standard. 

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 

(warning in the case of thermal event in 

REESS), and S14 (water exposure safety) 

of this standard. 

S6. Normal vehicle operation safety. 

Each vehicle to which this standard 

applies must meet the requirements in 

S6.1 to S6.6 of this standard, when 

tested according to the relevant 

provisions in S7 of this standard. 

S6.1 Protection against direct 

contact. 

S6.1.1 Marking. The symbol shown 

in figure 6 to this standard 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 of this 

standard using the IPXXB test probe 

shown in figures 7a and 7b to this 

standard. 

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 of this standard using the IPXXD 

test probe shown in figure 7a to this 

standard. 

(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 of this standard using the IPXXB 

test probe shown in figures 7a and 7b to 

this standard. High voltage live parts 

that are not energized except during 

charging of the REESS are excluded 

from protection degree IPXXB if they are 

located on the vehicle roof such that the 

wrap around distance from the instep of 

the vehicle, or the lowest step (if 

multiple steps are present) of the 

vehicle, to the high voltage source is at 

least 3 meters. 

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 S6.1.5(b)(1), 

(2), or (3): 

(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 S6.1.6(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 of this standard. 

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 of 

this standard. 

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 of this 

standard, 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 

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, including a pulsating DC 

voltage source without a change in 

polarity, 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 


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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 of this 

standard. 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 of this standard. The system must 

monitor its own readiness and the 

visual warning display must be 

provided to the driver. For a vehicle 

with automated 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 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 of this standard. 

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 to this 

standard 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) of 

this standard are made at least 10 

seconds after impact. All post-crash 

voltage measurements for determining 

the voltage levels specified in S8.2(b) of 

this standard and the energy in 

capacitors specified in S8.2(d) of this 

standard 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 to this standard. 

Voltage V2 is measured between the 

positive side of the high voltage source 

and the electrical chassis as shown in 

figure 3 to this standard. 

S7.2 Test method for determining 

electrical isolation. Measure the voltages 

V1, V2, and Vb as shown in figure 1 to 

this standard 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 to this 

standard 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 to this standard 

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 

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. 


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(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 

S7.3.2(a) or (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 to this standard. 

(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 to this 

standard. 

(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 of this standard 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 

automated 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 Cy1 and 

Cy2) in the electric power train for 

which the low energy compliance 

option for post-crash electrical safety in 

S8.2(d) of this standard is applied. 

(b) Voltages Vb, V1, and V2 are 

measured across the capacitors in 

accordance with S7.1. 

(c) The total energy in a x-capacitor is 

equal to 0.5 × Cx × Vb2. 

(d) The total energy in the y-capacitor 

Cy1 is equal to 0.5 × Cy1 × V12 and the 

total energy in the y-capacitor Cy2 is 

equal to 0.5 × Cy2 × 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 of this 

standard under the conditions of S10 of 

this standard. 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 of 

this standard 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 S8.2(a), the voltage 

level requirements of S8.2 (b), or the 

physical barrier protection requirements 

of S8.2(c); or the high voltage capacitors 

in the electric power train must meet 

the low-energy requirements of S8.2(d). 

(a) The electrical isolation of the high 

voltage source, determined in 

accordance with the procedure specified 

in S7.2 of this standard, must be greater 

than or equal to one of the following: 

(1) 500 ohms/volt for an AC high 

voltage source; 

(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 S8.2(c)(1) and 

(2); or 

(3) 100 ohms/volt for a DC high 

voltage source. 


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(b) The voltages V1, V2, and Vb of the 

high voltage source, measured according 

to the procedure specified in S7.1 of this 

standard, 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 of this standard 

using the IPXXB test probe shown in 

figures 7a and 7b to this standard; 

(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 of 

this standard. 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 of 

this standard; 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 of 

this standard. 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 

of this standard. 

(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 of this 

standard. 

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 

of this standard, 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, 

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, is 

impacted from the rear by a barrier that 

conforms to S7.3(b) of § 571.301 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 

(§ 571.214), 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 of this standard. 

S9.5 Moving contoured barrier 

crash. The test vehicle, under the 

conditions of S10.1 and S10.2 of this 

standard, 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, 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 

S10.1(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 of this standard, 

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 of this standard, 

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 

of this standard, plus 136 kg or its rated 

GVWR, whichever is less, secured in the 

load carrying area and distributed as 

nearly 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 


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vehicle for protection at its seating 

position. 

(c) A school bus with a GVWR greater 

than 4,536 kg is loaded to its unloaded 

vehicle weight, plus 54 kg of unsecured 

mass at each designated 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 apply to 

the conducting of the rear moving 

deformable barrier impact test specified 

in S9.2 of this standard. 

S10.5 Side moving deformable 

barrier impact test conditions. The 

conditions of S8.9, S8.10, and S8.11 of 

§ 571.214 apply to the conduct of the 

side moving deformable barrier impact 

test specified in S9.3 of this standard. 

S11. Vehicle controls managing 

REESS safe operations. Each vehicle to 

which the standard applies shall meet 

the requirements in S11.1, when tested 

according to S12 of this standard and 

the requirements in S11.2. 

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 short 

circuit test in accordance with S12.5 of 

this standard, 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 of this standard. 

S11.2 In the event of operational 

failure of the vehicle controls that 

manage safe operation of the REESS, the 

vehicle must provide a visual warning 

while in active driving possible mode. 

The warning system shall monitor its 

own readiness and the visual warning 

must be provided to the driver. For a 

vehicle with automated driving systems 

and without manually operated driving 

controls, the visual warning must be 

provided to all the front row occupants. 

S12. Test methods 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. The 

manufacturer must 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 one of 

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 are 

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 of 

this standard. 

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. The 

manufacturer must 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 one 

of 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 working voltage level. 

(g) After the discharge current is 

terminated, a standard cycle is 

performed in accordance with S12.6, if 

charge and discharge are 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. 

(i) At the conclusion of the test, 

electrical isolation of the REESS is 

determined in accordance with S7.2 of 

this standard. 

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 


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evaluate the vehicle’s over-current 

protection controls: 

(a) A breakout harness is connected to 

the traction side of the REESS. The 

manufacturer must 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 one of 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 are 

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 of 

this standard. 

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 one of 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 

(3) Three (3) hours have passed since 

the start of discharge/charge cycles. 

(f) After the discharge and charge 

procedure is terminated, if charge and 

discharge are permitted by the vehicle 

controls, a standard cycle is performed 

in accordance with S12.6. 

(g) 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. 

(h) At the conclusion of the test, 

electrical isolation of the REESS is 

determined in accordance with S7.2 of 

this standard. 

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 

external short circuit protection 

controls: 

(a) A breakout harness is connected to 

the REESS. The manufacturer must 

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 one of 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 are 

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. 

(i) At the conclusion of the test, 

electrical isolation of the REESS is 

determined in accordance with S7.2 of 

this standard. 

S12.6 Standard cycle. The standard 

cycle is conducted at ambient 

temperatures between 10 °C and 30 °C 

and starts with a standard discharge 


ddrumheller on DSK120RN23PROD with RULES2
104360 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

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. 

S13. Warning in the case of thermal 

event in REESS. The vehicle shall 

provide a warning to the driver in the 

case of a thermal event in the REESS 

when the vehicle is in active driving 

possible mode. The thermal event 

warning system must monitor its own 

readiness. The warning shall activate 

within three minutes of the onset of the 

thermal event. The warning shall 

consist of auditory and visual signals 

that remain active for at least 5 minutes. 

For a vehicle with automated driving 

systems and without manually operated 

driving controls, the visual warning 

must be provided to all the front row 

occupants. 

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 of this 

standard 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 in 

S14.1 and S14.2. 

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 

to this standard 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, and 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 of this standard. 

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 10 

minutes. 

(b) At the conclusion of the standing 

water test, with the vehicle still wet, 

electrical isolation is determined in 

accordance with S7.2 of this standard. 

Figures to FMVSS No. 305a 

Figure 1. Voltage Measurements of the 

High Voltage Source 


ddrumheller on DSK120RN23PROD with RULES2ER20DE24.000</GPH>

Electrical Chassis 

Energy Conversion System 

+ 

I 

I 

I 

·-----------------------· 

Electrical Chassis 

Propulsion 

System 

t 

V1 

V2 

Vb 

Energy Storage System 

r-----------------7 

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·------------------· 
Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104361 

Figure 2. Measurement for V1 Voltage 

Between the Negative Side of the High 

Voltage Source and the Electrical 

Chassis 

Figure 3. Measurement for V2 Voltage 

Between the Positive Side of the High 

Voltage Source and the Electrical 

Chassis 


ddrumheller on DSK120RN23PROD with RULES2ER20DE24.001</GPH> ER20DE24.002</GPH>

Electrical Chassis 

Energy Conversion System 

,---------------------

+ 

Electrical Chassis 

Electrical Chassis 

Energy Conversion 

System 

,---------------------

+ 

Electrical Chassis 

Propulsion 

System 

t 

V1 

Propulsion 

System 

t 

V2 

l 

Energy Storage System 

,----------------

Energy Storage 

System 

.----------------
104362 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

Figure 4. Measurement for V1’ Voltage 

Across Resistor Between Negative Side 

of the High Voltage Source and 

Electrical Chassis 


ddrumheller on DSK120RN23PROD with RULES2ER20DE24.003</GPH> ER20DE24.004</GPH>

Electrical Chassis 

Energy Conversion System 

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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104363 

Figure 5. Measurement for V2’ Voltage 

Across Resistor Between Positive Side 

of the High Voltage Source and 

Electrical Chassis 

Figure 6. Marking of High Voltage 

Sources 

Figure 7a. Access Probes for the Tests 

of Direct Contact Protection. Access 

Probe IPXXB (Top) and Access Probe 

IPXXD (Bottom) 


ddrumheller on DSK120RN23PROD with RULES2ER20DE24.005</GPH> ER20DE24.006</GPH>

IPXXB 

IPXXD 

SeeFlg-7b - for full 

demenslons 

Access probe (Dimensions in mm) 

Jointed test finger 

Stop face 

--(050x20) 

Jointed test finger 

(Metal) 

msulattng material ---ao---

Test wire 1.0 mm diameter, 100 mm long 

Sphere 35.:1:.0.2 

Approx.100 

Handle 

(Insulating malerlal) 

Stop face 

(Insulating material) 

(01+o.OS) 

twfre 

) Edgesfree 

from burrs 
104364 Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 

Figure 7b. Jointed Test Finger IPXXB 


ddrumheller on DSK120RN23PROD with RULES2ER20DE24.007</GPH>

Access probe 

(Dimensions in mm) 

IPXXB Jointed test finger 

Joints 

Rli0.05 

cylindrical 

Section ♦ A-A 

$ 

SectionB-B 

Insulating 

material 

075 

050 

Material: metal, except where otherwise specified 

Linear dimensions in millimeters 

Tolerances on dimensions without specific tolerance: 

on angles, 0/10 degrees 

on linear dimensions: 

up to 25 mm: 0/-0.05 mm 

over 25 mm: z0.2 mm 

I 

.... 

Both joints shall permit movement in the same plane and the same direction through 

an angle of 90° with a 0° to + 10° tolerance. 
Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations 104365 

Figure 8. Connection To Determine 

Resistance Between Exposed 

Conductive Parts of Electrical 

Protection Barrier and Electrical 

Chassis 

Figure 9. Standard Nozzle for IPX5 

Water Exposure Test 

Issued in Washington, DC, under authority 

delegated in 49 CFR 1.95 and 501. 

Adam Raviv, 

Chief Counsel. 

[FR Doc. 2024–28707 Filed 12–19–24; 8:45 am] 

BILLING CODE 4910–59–P 


ddrumheller on DSK120RN23PROD with RULES2ER20DE24.008</GPH> ER20DE24.009</GPH>

Connection to Exposed Conductive Parts 

D.C. 

I 

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Power 

Supply 

V 

Connection to Electrical Chassis 

4 8 

Dimensions in millimetres 

Dis6.3mm 

13 5 

Exposed Conductive 

Parts 

~ Electrical Chassis