Sign up ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free.

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?

share|cite|improve this question
Partially answered by the accepted answer of – DumpsterDoofus Mar 14 '14 at 22:33

3 Answers 3

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.

share|cite|improve this answer

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.

share|cite|improve this answer
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.

share|cite|improve this answer

protected by Qmechanic Oct 4 at 14:56

Thank you for your interest in this question. Because it has attracted low-quality answers, posting an answer now requires 10 reputation on this site.

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.