ISO 6469-1 - Battery Design

Electrically Propelled Road Vehicles — Safety Specifications — Part 1: Rechargeable Energy Storage System (RESS)

ISO 6469-1 is an international standard published by the International Organization for Standardization (ISO) that defines safety specifications for the rechargeable energy storage system (RESS) in electrically propelled road vehicles, with the primary objective of protecting persons — vehicle occupants, service personnel, and bystanders — from hazards arising from the RESS. The standard addresses protection against electric shock, protection from fire and explosion, and protection against mechanical hazards attributable to the RESS. Amendment 1 (2022) added requirements for thermal propagation management, aligning with advances in the field since the 2019 edition.

Published by: International Organization for Standardization (ISO)

Current edition: ISO 6469-1:2019 with Amendment 1:2022

Replaces: ISO 6469-1:2009 (1st edition)

Series context: Part of ISO 6469 series — Part 2 covers operational safety requirements, Part 3 covers electrical safety, Part 4 covers post-crash electrical safety

Vehicles in scope: M and N category road vehicles (passenger cars and commercial vehicles); does not cover L-category (motorcycles, scooters)

Scope

ISO 6469-1 applies to the rechargeable energy storage system (RESS) of electrically propelled road vehicles, covering:

Battery electric vehicles (BEVs): primary energy source for propulsion
Plug-in hybrid electric vehicles (PHEVs): large RESS providing electric-only range
Hybrid electric vehicles (HEVs): smaller RESS providing power assist and energy recovery
Fuel cell vehicles (FCVs): buffer RESS for energy recovery and power assistance

Exclusions: Cells and modules below RESS level, battery performance testing (addressed by ISO 12405-4 and IEC 62660 series), and EV charging systems (addressed by IEC 61851 series) are not within scope.

Key Safety Requirements

Protection Against Electric Shock

Protection against direct contact: RESS enclosures must achieve IP6K (dust-tight) and IP9K (high-pressure water) protection at internal high-voltage parts when closed; minimum IP4KX when open during service procedures
Protection against indirect contact: protective earth bonding of RESS metallic enclosure to vehicle chassis; isolation monitoring to detect and alert on insulation faults
Electrical isolation of RESS from vehicle chassis: defined minimum isolation resistance requirements in both normal operation and fault condition; isolation monitoring system response time requirements
High-voltage interlock loop (HVIL): HVIL circuit must prevent reconnection of RESS high-voltage circuit unless all protective covers are properly installed

Protection Against Thermal Hazards — Fire and Explosion

No fire or explosion under normal operating conditions: RESS design and BMS must prevent cell temperature from exceeding defined limits during charging and discharging
Venting provisions: RESS enclosures used with venting cells must prevent concentration of flammable gases above explosive limits within the vehicle cabin or enclosed spaces
Thermal runaway management (Amendment 1:2022): the Amendment adds explicit requirements for the RESS to provide an early warning signal to the vehicle occupants in the event of thermal runaway in any cell; the warning must be provided before fire or explosion occurs at the RESS boundary, giving occupants time to evacuate

Protection Against Mechanical Hazards

Structural integrity under vehicle loads: RESS must withstand static and dynamic loads during normal operation without electrical isolation failure or fire/explosion
Crash protection: RESS must be designed and positioned such that in a defined crash event (per relevant UN regulations or FMVSS) there is no fire, explosion, or severe electrical isolation failure
Protection during service: defined procedures and requirements for safe service-disconnect; manual service disconnect (MSD) required for voltages above 60 V DC

BMS Requirements

Overvoltage protection: BMS must disconnect or prevent charge if any cell exceeds maximum allowable voltage
Undervoltage protection: BMS must prevent discharge below minimum allowable cell voltage
Temperature monitoring: continuous cell temperature monitoring with defined alert and protection thresholds
State of Charge (SoC) management: BMS must maintain SoC within allowable window; accurate SoC estimation required for safe operation

Regional and Regulatory Adoption

European Union: ISO 6469-1 is referenced in EU vehicle type-approval for EVs (Regulation 2018/858/EU); Member States may also reference it in EV-specific technical provisions
UN: closely related to UN GTR 20 (Global Technical Regulation on EV Safety); both share core person-protection objectives
Japan: national JASO/JARI standards for EV safety align with ISO 6469-1
China: GB/T 38031 is the primary mandatory EV battery safety standard in China; ISO 6469-1 is referenced for international programmes

Related Standards

ISO 12405-4 — Performance testing of Li-ion traction battery packs and systems (the performance counterpart; ISO 6469-1 covers safety for persons)
IEC 62619 — Industrial Li battery safety; ISO 6469-1 addresses person-safety requirements in the vehicle context
GB/T 38031 — China mandatory EV battery safety standard; includes thermal propagation requirements similar to ISO 6469-1 Amendment 1
ISO 6469-2:2022 — Electrically propelled road vehicles — Safety specifications — Part 2: Operational safety
ISO 6469-3:2021 — Electrically propelled road vehicles — Safety specifications — Part 3: Electrical safety
UN GTR 20 — Global Technical Regulation on the Safety of Electric Vehicles

Disclaimer: This is not a definitive guide, just an indication and it is important that you always go back to the source for legislation.

References

See also: FMVSS 305a, UN Regulation 100