Electric vehicle [EV] and hybrid electric vehicle [HEV] battery packs, typically lithium-ion [Li-ion] or nickel-metal hydride [NiMH], are not much like the small lead-acid batteries that are found in petroleum-driven vehicles today. Even the biggest lead-acid battery systems only rate to 48 Volts, and those are on tractor trailers. For the most part, the standard 12 V battery won’t cause a whole lot of problems in an accident.
The Li-ion and NiMH battery packs in EVs and HEVs are typically rated over 300 V, and in operation this voltage can be boosted as high as 650 V. In order to keep safe, the high voltage wiring in EVs and HEVs is insulated and wrapped in bright orange coverings, with bright orange plugs and warning labels everywhere. Special care is required when working on these high voltage systems, including special discharge and lockout instructions and insulating rubber gloves.
In the case of an accident though, first responders need to be aware of the risks that come up when an EV or HEV is involved. This isn’t really new, as HEVs have been on the road for the last fifteen years or so, but as more EVs and HEVs get on the road, the more first responders may come into contact with them. Tow truck drivers, EMTs, Police, and Fire personnel all have to be aware of the dangers and how to mitigate them.
Todd Mackintosh, chairman of a Society of Automotive Engineers [SAE] committee, mentions, “As electric vehicles enter the marketplace in greater numbers, it’s an appropriate time to recognize best practices that facilitate a safe response when these vehicles are in an accident.”
Currently, there is no single law covering locking out the high voltage batteries in case of an emergency. Some EVs and HEVs automatically lock out in an accident, and others might require pulling a plug. Mackintosh suggests universal automatic lockouts as well as well-publicized procedures for locking out high voltage systems manually. Many automakers, including Toyota, General Motors, and Nissan, have been getting the message out to first responders to keep them safe.