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20dcv capacitor blowing fuses

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=128979
Printed Date: June 04, 2024 at 6:39 AM


Topic: 20dcv capacitor blowing fuses

Posted By: c3d
Subject: 20dcv capacitor blowing fuses
Date Posted: October 26, 2011 at 5:44 PM

Im installing a capacitor in my 2002 audi s4. Ive had a sub and amp working for over a year. I just picked up a capacitor to help out a little. but when I installed it, it keeps blowing fuses!

Current setup:
8 gauge wire from batter (with 60 amp inline fuse) to trunk connects to positive of capacitor
4 gauge wire from positive of capacitor to positive of amp
8 gauge wire from amp negative to capacitor negative
4 gauge wire from capacitor negative to ground in trunk (that ive been using for over a year)

Yet every time i reconnect the negative on the battery, the fuse blows. Anyone have any ideas?

**edit: also remember, as the title says, the capacitor says 20dcv. Which im beginning to think may not be suitable for my car?

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1987 Nissan 300ZX N/A
1994 Audi 90 Quattro CS



Replies:

Posted By: oldspark
Date Posted: October 26, 2011 at 9:14 PM
Yes - read its instructions....

It should tell you to pre-charge it - ie, through a resistor, else a headlight or bulb etc.

An uncharged capacitor is like a dead-short when connected across a voltage.
As it charges, its current drops.
Your cap's initial charge current is more than what your fuses tolerate.


The 20VDC is merely a "voltage withstand" rating - ie, it will handle up to 20V.


Strange to see the different wire gauges used...
At least match the amp inputs - ie, amp- to 4G.
Usually fatter gauges are used for the longer runs to minimise resistance, however sometimes the shorter runs are fatter since they are cheaper. Both assume the smallest gauge is rated for the required current.


& FYI - in general, AGM batteries are more effective than caps (ie, an AGM battery is usually placed next to the amp rather than a cap).




Posted By: i am an idiot
Date Posted: October 26, 2011 at 9:27 PM
I am betting you have a faulty capacitor.  The "Charging Instructions"  for a capacitor is only so you do not arc the pretty terminal on your capacitor or your battery. 




Posted By: z03mz03m
Date Posted: October 26, 2011 at 9:29 PM
Do yourself a favor and return the cap and get a small battery instead. I just installed a 2F cap on my system because I had it...it was a waste of my time just like I have read on here over and over again. my amps are a total of 1000W RMS and class D ICE, the most efficient amplifiers on the market.

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Dodge Magnum in progress:
Pioneer DEH-80PRS - PPI Amps - Dayton Subwoofer(s) - Exodus Anarchy's - Vifa Tweeters - Kinetik Battery




Posted By: oldspark
Date Posted: October 27, 2011 at 4:05 AM
i am an idiot wrote:

...is only so you do not arc the pretty terminal on your capacitor or your battery.
IOW, high current.

I like welding caps to beams. Welding requires quite a few Amps.





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