Bosch's New System Help to Keep Electric Cars Safer After an Accident

Auto supplier Bosch's new system disconnects the battery pack by blowing apart sections of wiring immediately following an accident to help make rescue and escape shock-free.

·"Explosions that save lives" is how automotive supplier Bosch describes a new component that can quickly disconnect the battery pack in an electric vehicle in case of an accident.

·The pyrofuse technology cuts off electrical current to other parts of the vehicle so first responders or vehicle occupants won't get an electric shock.

·This system, which serves a similar function to an inertia switch that stops the fuel flow in a gas-powered vehicle, is triggered by Bosch's microchip that's already widely used to deploy airbags.

Whether you're talking about gallons of combustible fuel or explosive airbag inflators, potentially dangerous items are commonplace in cars. Bosch is taking this old idea to electric vehicles with a new technology designed to make batteries safer in a crash. And it includes a component with a cool name: pyrofuse.

That sounds . . . explosive, and it is. According to Bosch, this is how you keep an electric or hybrid vehicle's batteries safe. The Bosch-developed system uses tiny, controlled explosive charges on an EV's battery to isolate the power supply if there's a collision. When the car's sensors detect a crash, the pyrofuse (technically known as a pyrotechnical safety switch system) will use its miniature explosive charges to physically blow apart sections of wiring between the high-voltage battery unit and the rest of the vehicle with up to four small wedges. These wedges sever the wires and thus cut off the current flow, making it safe for vehicle occupants or first responders to touch the car's metal without the risk of an electric shock caused by a short from accident damage.

Pyrofuse serves the same function as the inertia switch in a gas-powered vehicle, which shuts off fuel flow following an accident, although Bosch's EV application isn't reversible like hitting the simple reset button on an inertia switch. This new system obviously doesn't do anything to dissipate the energy stored in the battery pack, and if the pack itself is breached there's still a very real threat of a fire.

The Bosch semiconductor chips used in this technology are smaller than a fingernail and are what Bosch calls application-specific integrated circuits (ASIC). Each ASIC has millions of transistors and will respond "within a fraction of a second," according to a statement by Jens Fabrowsky, member of the executive management of Bosch's Automotive Electronics division.

The ASIC used in the pyrofuse system is called CG912, and Bosch has been using a version of it in airbags for years. The battery-safety version of the CG912 was introduced at Electronica 2018, a trade show for electronics, last November. Bosch says the airbag version of the CG912 "has been proven in the field a million times over."

Bosch isn't saying which automakers are using these safety pyrofuses in their cars, which partially minimizes the value to first responders knowing which EVs might be more dangerous than others when approaching a crash scene.