When electric vehicles crash, one of the biggest dangers, aside from the impact itself, is the possibility of electric shock from high-voltage components. But two explosive technology developments can help improve EV crash safety.
They're similar in function but slightly different in design. In an accident, each can automatically deactivate the high-energy power circuit from the battery in less than a millisecond.
One, by Bosch Group, is called a pyrofuse.
The other, by Autoliv, is described as a "pyrotechnical safety switch."
At impact, when airbags fire, a microchip in the electronic control unit triggers a small charge within the devices. In the Bosch pyrofuse, a section of high-voltage cable is severed. In the Autoliv switch, a copper bus bar is broken.
New versions of electric vehicles have 400- to 800-volt batteries, enabling quicker charging, more efficient regenerative braking and ranges of 300 miles or more. But when these vehicles have accidents, first responders generally must move cautiously because of the safety issues specific to big battery power.
If the power is still on and the vehicle is energized, there are dangers from unexpected vehicle movement or electric shock and fire from crushed batteries or severed high-voltage cables.
Traditionally, electric vehicles have had either manual under-hood shut-off switches or shut-down cable loops that must be cut in order to properly de-energize the vehicle. Only then can emergency personnel attempt to remove injured passengers.
But those scenarios — identifying the vehicle while referencing an illustrated field guide to find brand- or model-specific manual switches or shut-down loops — delay treatment of injured occupants and put unwary good Samaritans at significant risk of injury.
If it seems slightly counterintuitive to use even a miniature explosive to improve safety, this is not an entirely new idea. Indeed, technically, the airbag is a pyrotechnic device, and many makers, including GM and Mercedes, have even used pyrotechnically activated pop-up roll bars on their convertibles.