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I'm not doing anything related to physics, but I'm just curious: What really happen when I short circuit an alkaline battery? Some article on the internet says that fire/explosion can happen when you short circuit the battery. How can this happen? I saw another article that said that there is an "internal" resistance of the battery that prevents very high current from flowing, so I think this become the safety tool, so current or temperature won't be a problem.

But why can they still produce fire or explosion? And why the manufacture of the battery (like for example some of AA alkaline) doesn't provide info about maximum C-rating or maximum current to be drawn (so where can I find it?). Usually only voltage and capacity (mAh) is printed. Is that kind of info is not important, so it's ignored. Sometime the mAh is not even printed on AA batteries. I can only see it on LiPo or NiMH batteries.

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I've just sacrificed an AA manganese alkaline battery to the cause of physics.

When I first shorted the battery it produced a current of about 9.5 amps, which I thought was actually pretty impressive. However over the course of 30 seconds the current dropped to around 5 amps. The battery got pretty warm, though I don't think it would have set fire to anything and it didn't explode. The power generated was around 7.5 watts, so it isn't huge, though the power is concentrated in a fairly small area.

I'd be careful about doing this to a bigger battery. Larger batteries will have a lower internal resistance, and given how much current an AA battery produces I can well believe you could heat a bigger battery to the point where it becomes dangerous.

I'vd be very very careful about trying this with batteries that have a particularly low internal resistance like lead-acid or nickel-cadmium batteries!

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  • $\begingroup$ Hi John, thanx for doing that experiment, that's very kind of you. I was afraid doing that coz i don't want the batt to burst into my face lol. So the alkaline AA 1.5V battery won't actually explode :-), i won't try it with bigger battery (or my rc car -lippo battery) for sure. $\endgroup$
    – andio
    Commented Jun 22, 2012 at 8:46
  • $\begingroup$ I checked the battery manufacturers web site first, and that assured me that an AA battery was very unlikely to explode. Still, I stood well back while I was doing it :-) $\endgroup$
    – John Rennie
    Commented Jun 22, 2012 at 9:05
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    $\begingroup$ I've set stuff on fire by accidentally shorting a D cell NiCd. Yikes! $\endgroup$
    – dmckee --- ex-moderator kitten
    Commented Mar 21, 2013 at 3:27
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    $\begingroup$ @dmckee: I'm part of a robotics team of my institute (for ASME SDC 2013). Now, we use Lithium polymer batteries. Short these, and they explode. No intermediate fire stage, just boom. And we have some rather large LiPo batteries in the lab which we use regularly. I've seen a large lead acid battery catch fire, but I've never been (mis)fortunate enough to see a LiPo exploding :S $\endgroup$
    – Manishearth
    Commented Mar 21, 2013 at 12:47
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    $\begingroup$ I did a similar test with a Zinc-Carbon battery: physics.stackexchange.com/questions/76220/… What I did not monitored was the flow of current, because I was afraid it could blow my meter. @JohnRennie How did you measured that 9.5 amps? Did you use a normal multimeter? Thanks. $\endgroup$
    – Dakatine
    Commented Sep 5, 2013 at 10:52

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