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Farads relation to Watts or Amps? Answered

is there any relation between farads, watts, and amps? can the energy stored in farads be translated into watts or amps?


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4 years ago

I have been chasing this dragon for awhile and it just isn't as simple with supercaps. When it comes to capacitors don't think of supercaps even as capacitors. Think of them as linear batteries. Batteries are chemical and in the case of an automotive battery it outputs amp hours over 11.9 to 13.5volts. A supercap outputs its amp seconds over 0-Max voltage linearly. So in the case of a 350 farad supercap 0-350 farads over 0-2.5/2.7 volts. There is not a drop in output till you are completely discharged.

The point is, Supercaps are a measure of Joules per Second, batteries are Joules per Hour. Convert batteries to joules per hour and the capacitor to joules per hour and you can compare.

That isn't the whole story though. For example a 58 Farad 16.2v supercap bank can start a case at 0 cel, but if you cranked for 1 second longer you are below 8v and the bendix closes.

If you want the best way to learn, I found an App for the iPhone called Electronics toolbox. It not only has calculators, but the formulas you need. It gets messy in the conversion. I have not found an android equilivent and yes I use both equally, and support both equally.

Farads Convert to Joules/Time
Joules/Time convert to Joules/Hour
Joules/hour convert to Amps/hour

Depending on how it's done it can be seconds, minutes, hours..... Most amp rating on battery are over hour and Farads are in seconds.