Leaky capacitors

Thread Starter

Razor Concepts

Joined Oct 7, 2008
Is it safe to use these capacitors? They appear to be leaking around the negative side, I used some wet wipes to clean it off and now they look like this:



Joined Jul 17, 2007
No, they are no good.

I just pulled a Nichicon 470uF 25v electrolytic out of one of my parts drawers that looks very much like those; it is leaking as well. It will go in the trash bin. No sense in trying to use something that you know right up front is bad.

There were discussions awhile back about some Asian manufacturers who used too strong of an electrolyte solution. This initially gave the parts higher specifications for a given size, but the strong electrolyte solution quickly ate away the caps from the inside out, leading to premature failures. Leaking electrolyte = a cap that if it isn't dead already, will very soon be dead.

High quality electrolytic capacitors can last for many years, but if they have not been in service for awhile, they should be re-formed before applying full power. The process of re-forming is to slowly apply voltage via a current-limited source until the capacitor is charged to it's rated voltage, and the leakage rate is acceptable.
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