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Today I have by accident thrown a AAA battery into a bucket of water. I fished it out of the water immediately (within 20 seconds or so) and nothing notable had happened and the battery is still full according to a battery test device. As the water should have short circuited the battery I would have expected that something should have happened, at least that the battery should have been emptied rather quickly.

Is my expectation wrong, is there something that I didn't think of or was the time the battery spent in water was just too short to substantially drain it?

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Partially answered by the accepted answer of – DumpsterDoofus Mar 14 '14 at 22:33
up vote 9 down vote accepted

The resistance of water, even with ions and minerals and such, is still fairly high. So, a tiny current flowed through the water, but not very much.

Additionally, the heating effect that often destroys them when short circuited would also be nullified by the cooling water.

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As I mentioned in a comment, the electrical conductivity of tap water is pretty low, so while current definitely did flow while underwater, it was only a small amount, hardly enough to drain the battery.

You can actually measure the current using an ammeter if you have access to one.

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Nice hint with the ammeter. I will try that just for fun! – Benedikt Bauer Mar 14 '14 at 22:41

Water, unless tainted by ionic matter, is a pretty lousy conductor. The main source of ions is its own dissociation $2\,\text{H}_2\,\text{O} \leftrightharpoons \text{H}_3\,\text{O}^+ + \text{O}\,\text{H}^-$, whose equilibrium constant is $10^{-14}$ (hence pH 7), so you can work out how many ions were there. Maybe other stuff was there - tiny amounts of salt, ions from denatured cells formerly belonging to a few dead bugs here and there. But compared to the kind of conductance you get from a wire, negligible current flows. It's pretty certain that negligible current was drawn from your battery.

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protected by Qmechanic Oct 4 '15 at 14:56

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