What Is A Pyrotechnic Battery Disconnect

While all electric vehicles still represent a relatively small segment of new vehicle sales, the percentage is growing by leaps and bounds each year. In 2021, EVs represented just 3.2% of new vehicle sales in the United States, a number which ballooned to 5.8% in 2022 — that's a 65% increase in market share, according to Kelly Blue Book. With the growing popularity of EVs, manufacturers are incorporating some unique safety features, one of which being the pyrotechnic battery disconnect.

"Pyrotechnic" is a scary word that you wouldn't normally want to use when discussing automobiles or batteries, but it's actually a vital safety aspect for EV drivers. In a crash, EV batteries and wiring can be damaged, which potentially exposes the vehicle's occupants and emergency responders to extremely high electrical voltage. A "pyrotechnic battery disconnect" like the one developed by Joyson Safety Systems can cut that dangerous power in less than 1 millisecond if a short circuit occurs because of a crash, or any other reason.

The way the device works is that it detects excess voltage or current running through the electrical propulsion system and quickly interrupts the flow, sort of like a conventional fuse. As an extra precaution, the battery disconnect can also be triggered by a vehicle's onboard electronics if a crash is detected, even if that crash doesn't cause damage to the battery or wiring. At the same time, the gadget safely suppresses a plasma arc that can result from abruptly cutting voltages in excess of 460 volts DC inside a specially insulated combustion chamber.

Besides protecting drivers, passengers, and first responders, the disconnect can also save money on repair costs to a vehicle that was involved in a crash by isolating increasingly complicated electronics from short circuits and surges. Outside of being involved in a crash, the pyrotechnic device also provides a margin of safety in the unlikely event that a malfunction occurs while charging an EV, minimizing the risk of fire or damage to the vehicle's sensitive electronics. 

In a nutshell, while a pyrotechnic battery disconnect sounds intimidating, the device quickly disconnects an EV's electrical system in the event of a crash or malfunction while managing the arc that results from a sudden disconnect. Widespread adoption of this device should be a step forward toward reinforcing the safety of electric vehicle ownership.