A good find Russell. I was trying to explain this to some students last wee=
k, but could tell they were sceptical.

Joe

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of=
 RussellMc
Sent: 01 May 2013 00:47
To: Microcontroller discussion list - Public.
Subject: Re: [EE] verifying working voltage of electrolytic capacitors

> Bought some large electrolytic capacitors online, they are likely fakes.
> I'd like to figure out if the voltage rating is anywhere near correct=20
> before I use them.

This informative paper on electrolytic capacitor manufacture gives some ins=
ight into what may be useful. Not analytical/numeric.
The attached graph is from there.

       http://jianghai-europe.com/wp-content/uploads/3-Jianghai-Europe-E-Ca=
p-Voltage-Proof-AAL-2012-10-30.pdf

Using a large series resistor and progressively ramping (or stepping) volta=
ge up from say 80% rated voltage to 110% rated voltage over several days ma=
y improve your outcomes.

Doing that and then doing an increasing voltage sweep and observing current=
 should give a fair idea where the "knee" is.
Doing it with several of them shows if they are consistent.


      Russell


--=20
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