I was shorting a Duracell AAA battery in a SAFE area with proper precautions. After 2 minutes I disconnected the circuit and measured the voltage, it dropped from 2.8V to 2.6V and the battery was hot. When I reconnected the circuit for another 2 minutes the voltage didn't decrease and the battery wasn't hot. I tried a few more times (after waiting 30 minutes) and the same pattern occurred: the battery drained a bit, but after some time it seemed as if the current stopped during a short. I used the battery to power up a led, it still works.
So I'm wondering if there are internal short circuit protections. If so what are they and can I get a few references?
Best Answer
Alkaline batteries have an internal resistance. There isn't a current limiter as such, that's just the physical properties of alkaline chemistry and the limits of the relatively-small AAA battery.
The thermal vs. voltage effects you see relate to the the ionic properties of the battery, as it recovers from a high discharge. Multiple high discharges will deplete the battery faster than a continuous, moderate discharge.
More info here: http://data.energizer.com/pdfs/alkaline_appman.pdf
(Don't try that with a Li-ion, please.)