volker_squareVolker Rothe is “Technical Lead Engineer Regulatory” at Adam Opel AG. He is responsible for the development and implementation of regulations and standards for electric vehicles. He is the chairperson of the ISO working group on EV safety and a member of various working groups on electric mobility in ISO and IEC. Full bio

 

Electric vehicles fulfil the same high safety requirements as conventional vehicles. In addition, electric vehicle safety standards consider requirements for protection against electric shock, protection against short circuit impact and specific requirements for the safety of propulsion batteries or more general the Rechargeable Energy Storage System – RESS.

Vehicle safety standards should be performance-based and avoid design restrictions to allow technical progress. They are developed based on broad international participation of experts from interested stakeholders. Vehicle safety standards support the development of useful harmonised vehicle safety regulations.

The standard series ISO 6469 “Electrically propelled road vehicles – Safety specifications” contains the following parts:

  • Part 1: On-board Rechargeable Energy Storage System – RESS
  • Part 2: Vehicle operational safety means and protection against failures
  • Part 3: Protection of persons against electric shock
  • Part 4: Post-crash electrical safety

This part 4 specifies electrical safety requirements for vehicle post-crash conditions. It applies to vehicle electric circuits with maximum working voltages according to voltage class B (30-1000 VAC or 60-1500 VDC). The electrical safety requirements apply to applicable vehicles in accordance with the existing crash test procedures of each country or region. The standard does not specify any crash test procedure.

For electric shock protection, at least one of the “Four Criteria” shall be met:

  • Absence of High Voltage (above 30 VAC or 60 VDC)
  • Low Electrical Energy (0.2 Joules)
  • Physical Protection: Protection against direct contact (IPXXB) and protection against indirect contact (potential equalization < 0.1 Ω)
  • Isolation resistance of at least 100 Ω/volt for DC buses and 500 Ω/volt for AC buses

In addition, protection regarding potential over-currents shall be provided.

Electrolyte leakage is not allowed to spill into the passenger compartment and limited to 5 l outside the passenger compartment.

The UN regulations for specific crash tests No. 12 (steering mechanism), No. 94 (frontal collision) and No. 95 (lateral collision) contain requirements for electric shock protection and electrolyte leakage analogical to ISO 6469-4.
In addition, the following requirements on RESS retention are specified:

  • RESS located inside the passenger compartment shall remain in the location in which they are installed and RESS components shall remain inside RESS boundaries.
  • No part of any RESS that is located outside the passenger compartment shall enter the passenger compartment during the test procedures.

The new draft Global Technical Regulation (GTR) on Electric Vehicle Safety in principle contains the same requirements on electric shock protection and electrolyte leakage as the above-mentioned UN regulations. Independent from specific vehicle crash tests it allows to demonstrate compliance on RESS level through specified tests on mechanical impact and mechanical integrity.

In the case of non-aqueous electrolyte RESS, there shall be no liquid electrolyte leakage from the RESS into the passenger compartment or luggage compartment and no liquid electrolyte leakage to outside the vehicle.

To address the fire hazard, one hour after the crash test there shall be no fire of the REESS.

As a result of intensive discussions in standards development organisations and regulatory groups, there is a general consistency of EV post-crash requirements in ISO standards and international regulations.

By Volker Rothe, Adam Opel AG, Product Regulations

Leave a Comment