# Capacitor Battery Recharging



## CPLTECH (Sep 14, 2007)

A capacitor can be placed across the battery (parallel) as a filter (to reduce the pulsating DC), but I doubt there is any charging benefit. If you do, observe cap polarity.

However, it appears you want to put the capacitor in series for charging. Won’t work in that scenario, since capacitors will pass AC but block DC voltage and you are charging the batteries with DC.

It could be that the charger you saw did not use a step-down transformer, but instead used a cap to limit the current, hence the voltage desired to recharge a battery pack. The mfd rating of the cap determines the max current provided. Works better than a resistor since there is negligible heat. 

Most of us use a charger that gives a high current (often manually adjustable) until the batts hit a certain voltage, then automatically drops down to top them off. Some install a timer to shut it all down after so many hours if not around. But for many, this is our baby & we JUST have the inner fatherly sense when it’s time to go out and unplug.


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## michaeljayclark (Apr 3, 2008)

hhhmmmm what about the 1 and 2 farad capacitors that they use in stereo systems to help the amplifiers from draining the battery to quickly.. thats DC


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## CPLTECH (Sep 14, 2007)

michaeljayclark said:


> hhhmmmm what about the 1 and 2 farad capacitors that they use in stereo systems to help the amplifiers from draining the battery to quickly.. thats DC


I have to assume that it is put across the battery, not in series. In that way it can briefly provide some of the needed electrons when the battery can't. The example of unplugging a radio... the sound drifts away. Or the tube-type guitar amp decays when the plug removed. The capacitor stores electrons until depletion (does not make them like a battery's chemical action).


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