Battery power output...............?

Question

This is something I've never thought of before, but does a battery have a maximum instantaneous current that it can provide? i.e. a maximum number of amps per second (or whatever time period) regardless of its mAh rating? If so, how can I calculate this?

Answer 1

The rating depends greatly on how you use it. If you take a lot of power out for a very short time you will be OK. But if you continue to take a large amount of power the battery will get hot and could pop.

Answer 2

Yes. maximum current is determined by the internal resistance of the battery. If you know it's value, you can calculate the max current. If the Ri = 0.2 ohm in a 12 volt battery, then the max current is I = 12/0.2 = 60 amps.  Ri will change depending on the state of charge of the battery, and the battery's age.

manufacturers are reluctant to supply this number, but it can be measured, not calculated.

Just measure the voltage out of a battery with no load, Vo

measure it again (VL) with a heavy load, say 1 amp, I.

Then Ri = (Vo-VL)/I

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