ISO 6469-4 - Battery Design

Electrically propelled road vehicles — Safety specifications — Part 4: Post crash electrical safety

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ISO 6469-4:2015 (reconfirmed 2022) specifies the electrical safety requirements that apply to a battery electric vehicle (BEV) or hybrid electric vehicle (HEV) after a crash event. Its primary concern is protecting vehicle occupants and first responders from electric shock, electric arc, and thermal hazards arising from high-voltage system damage caused by the collision. The standard sets maximum permissible touch voltage levels on exposed conductive parts, limits on energy that can appear at accessible points, and requirements for post-crash electrical isolation between the high-voltage bus and the chassis. ISO 6469-4 is part of the broader ISO 6469 series that covers the complete electrical safety envelope of electric road vehicles, and it is referenced by type approval regulations globally — including UNECE Regulation 100 (ECE R100) for battery electric vehicles.

Published by: International Organization for Standardization (ISO)

Current edition: ISO 6469-4:2015 (reconfirmed 2022)

Scope

ISO 6469-4 applies to BEVs and HEVs with high-voltage systems. Post-crash safety requirements include:

Touch voltage protection: Maximum permissible DC and AC touch voltage on accessible conductive parts after a crash (60 V DC / 25 V AC for internal and 30 V DC / 25 V AC for external)
Energy limitation: Maximum stored charge and energy on accessible parts to limit the severity of electric shock
Isolation resistance: Minimum post-crash isolation resistance between HV bus and exposed conductive parts (100 Ω/V)
HV circuit protection: Requirements for automatic disconnection devices (service disconnects, contactors) to isolate the HV bus in a crash event
Test procedures: Electrical safety measurements to be taken after front, rear, and side barrier crash tests

Relationship to other standards

ISO 6469-4 is Part 4 of the ISO 6469 series. ISO 6469-1 covers rechargeable energy storage systems (REESS); ISO 6469-2 covers vehicle operational safety; ISO 6469-3 covers protection against electric shock during normal operation. UNECE Regulation 100 (ECE R100) mandates compliance with post-crash electrical safety requirements equivalent to ISO 6469-4 for type approval in markets using the UN regulatory framework. IEC 62196, ISO 17409, and IEC 61851 govern the charging interface; ISO 6469-4 governs what happens after a crash. For cybersecurity of electric vehicles, UN Regulation 155 and ISO/SAE 21434 are the complementary standards.

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