How-to: Disconnect 12v battery

[BigBob]

I've always wondered why today's cars don't come with a master disconnect switch under the hood, one which would allow simple power cycle of all onboard electronics. "Turn it off and back on again" has been the oldest trick in the IT book for decades now.

There’s also a fire safety issue I would guess too.
I know one of the first things the fire brigade do at a car accident is disconnect the 12v battery. I guess it’s more of an ICE thing with electric/petrol not mixing well, but even so. Seems crazy you can’t isolate it for a host of reasons I can’t think of at the moment.

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[whitex]

There’s also a fire safety issue I would guess too.
I know one of the first things the fire brigade do at a car accident is disconnect the 12v battery. I guess it’s more of an ICE thing with electric/petrol not mixing well, but even so. Seems crazy you can’t isolate it for a host of reasons I can’t think of at the moment.

BEVs typically have a "fireman's loop" which the fire department cuts to prevent the 800V from energizing (or to de-energize it if still energized). That is the very first thing any first responder should be doing to avoid getting electrocuted. That does not however cut off 12V in many EVs.