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capacitor based battery replacement Answered

I was wandering how big does a normal capacitor have to be to replace a AAA battery?


Hack A Day used to have an article on a 9v supercap battery replacement, it was even sized properly. The article is still there with a picture of the finished product, but the link to the how-to is dead.

I'm very drunk right now, so check my work, but a AAA is 1.5 volts about 900 mah for a total of 4800 Joules. Energy of a capacitor is 1/2CV2. So solving for c you need a capacitor of 4300 Farads. Whoa, somebody check that.

Sounds about right. Supercaps aren't really anywhere close to batteries in capacity yet, though they have certain other advantages...

I'm assuming that size and weight is no object I'm thinking of is a set up that that produces as much juice and lasts as long as a AAA battery

Again, it depends on the use, but if you want an equivalent to a AAA battery but rechargeable, maybe try a rechargeable AAA? What device are you wanting to run?

there is no device i want to run I'm just curious as to how big a capacitor (or capacitors) would have to be to equal a AAA battery in electrical performance. i don't want a rechargeable battery cause those wear out and stop holding a charge eventually. as far as I've read capacitors work the same every time for a lot longer (usually until catastrophic failure ends it life).

In electrical performance, you can definitely get enough voltage, I'll do some testing though to see if you an use it just as long.