Scenario: There is a parked car in a garage, that's been unused for a month and has the negative side of the battery disconnected. Car is from 2001.

Could the battery explode? Or could the car cause a fire in some other way?

Are both scenarios unlikely?

  • 2
    Very unlikely, unless someone goes in with a petrol bomb and matches.
    – Solar Mike
    Nov 18 '20 at 9:11
  • @SolarMike thanks! I know exploding car batteries aren't uncommon and short circuits can cause fire... but given the car had been unused and battery was partly disconnected, I've assumed it is unlikely that a car in this scenario could start a fire?
    – Noobie1357
    Nov 18 '20 at 9:16

Well... cars (and car batteries) are made to not spontaniously catch fire.

Unless if you have electrical issues, but even that is not likely to cause a fire, especially since you have the battery disconnected.

If you want to be extra sure, you can remove the fuel from the fuel tank, but that's probably overkill.

  • Thanks! If the battery is still in the car, but just the negative side disconnected, is it still possible for something to short circuit/spark and thus cause a fire? The car was just sitting there for a month so I want to assume its extremely unlikely something like that could happen.
    – Noobie1357
    Nov 18 '20 at 10:50
  • To be extra safe, you could take out the entire battery, but I think you can safely assume nothing like is ever going to happen.
    – user60481
    Nov 18 '20 at 11:13
  • If there is nothing touching the negative terminal post, then nothing can happen.
    – John Canon
    Nov 28 '20 at 3:42

In 35 years, I've never heard of a battery exploding by itself. A battery with the negative removed will not spark.

I've seen a few cars burn, but it was always due to leaking gasoline. If you can smell gasoline/petrol, it is definitely a fire hazard. If not, there is no concern.

  • Many years ago my brother managed to do it ( not a car guy). He had been cranking ( no start) and recharging the battery . He was disconnecting or reconnecting the battery and a side of the battery blew out. Hydrogen had apparently collected in the battery and expolded with a spark. Nov 19 '20 at 14:47
  • Thanks very much for sharing that experience. After I posted the answer, I did remember the potential for hydrogen buildup. I decided not to change my post b/c I didn't feel it's enough of a threat to start a fire. Nevertheless, a battery can obviously be a danger!
    – Carguy
    Nov 21 '20 at 18:47

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