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I am looking into using a capacitor to buffer voltage drops for a 12V solar power system. Since it seems I need a pretty big Farad number to give at least half a second of buffer time for my load, I noticed that there are plenty of large capacitors for sale for use in automobile stereos. It seems like a good way to buy an inexpensive, well-packaged cap.

Example: 1.5 Farad capacitor w 20 Volt Working Voltage/24 Volt Surge

My question is, would using something like this be any different than using a "parts" capacitor from one of the big electronics sites? Would there be any special considerations or things to look out for? Another possible advantage is that some of the more expensive ones offer things like polarity reversal protection, which would be nice because of the high Farad value.

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    \$\begingroup\$ You'd need to check the ESL and ESR. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Jul 21, 2016 at 4:40
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    \$\begingroup\$ Why would the 'high farad value' make any difference to the desirablility of polarity reversal protection? Just don't connect polarised caps backwards, that's what the rest of the world does. Protection only needed in cars, because mecahnics apparently often connect batteries backwards, and car electronics is protected against that. - If a capacitor does what you want. Most people would opt for a battery for minutes or hours rather than seconds of carry-over. \$\endgroup\$
    – Neil_UK
    Jul 21, 2016 at 6:09
  • \$\begingroup\$ A supercapacitor or array of them might be more appropriate. They are a fraction of the size and ESL/ESR should be a non-issue, unlike electrolytics. They also don't leak. \$\endgroup\$
    – jbarlow
    Jul 21, 2016 at 7:16
  • \$\begingroup\$ You may find the self discharge rate of the audio cap too high, whereas a super cap may hold charge much longer. \$\endgroup\$
    – scorpdaddy
    Jul 21, 2016 at 14:21
  • \$\begingroup\$ Interesting point about the battery, hadn't thought about using a small one as a buffer \$\endgroup\$
    – Josh Diehl
    Jul 23, 2016 at 23:22

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