Thread: Joule Ringer!
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Old 12-30-2010, 10:46 PM
gyula gyula is offline
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Join Date: Apr 2007
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Inner resistance of supercaps

Originally Posted by Jbignes5 View Post
The more you parallel the less resistance as you say. It makes perfect sense. The problem is why use super caps when the normal electrolytic caps work so well. Cost wise it makes better sense to use the normal caps.
Hi Jbigness5,

I underlined in your text I want to answer. there are several types of supercaps manufactured for different purposes. Memory backup types has an inherent high inner resistance because the current draw demanded by modern memory chips is in the order of a few microAmper (say 3-10uA) or lower, hence the inner voltage drop of the supercap across their 50-100 OHm resistance is negligible. See such memory backup type data sheets in Page 43, at the bottom, for instance

But other types have an inner resistance of under 0.1 Ohm or less like in case of a good rechargable battery and several hundred Amper may flow when you short the pins of a charged up supercap with a heavy wire piece.

So make sure what purpose a supercap is manufactured for and choose accordingly.

rgds, Gyula
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