electrolytic capacitors shelf life 1

[MacGyver15147]

I have found that electrolytic capacitors only have a shelf life around a year. By not being used they degrade and read out of spec.

I purchased a large assortment of caps and found many are reading low when tested. I have herd of reconditioning but finding conflicting info on how best to do this.

I would like to make a simple bread board style reconditioning device that I could just plug in dozens at a time to keep them fresh.

So what would be the best voltage to do this at as a percentage of the cap rating, What kind of current limiting is recommended, and a time length to do this?

 

[VEBill]

"Come up with nothing relevant."

What's wrong with the first two hits, from Illinois Capacitor and Panasonic? You need beyond what the manufacturers recommend?

 

[MacGyver15147]

Again back to conflicting info. one source says it best to use 1/2 rated voltage the other says use full voltage rating. Other sources later on say never use full voltage which makes sense that if you push something straight to the rated breaking point it may break. Other sources are saying voltage does not mater. So like doing this with a D cell battery should work as good as a precision adjustable DC power supply for any cap. There is also conflicting times I have seen everything from 30 seconds to overnight.

 

[VEBill]

It's almost certainly a speed vs risk trade off. So the optimum depends on the circumstances and your judgment. In your case, take the most conservative advice.

 

[MacGyver15147]

I just hate using my better judgment with nothing solid to back it up. From what I have researched and compiled would be to use a power source at 1/4 the cap rating with a 1K ohm resistor on the positive side for 10 min. then up the voltage to 50% the caps rating for 20 min.

 

[IRstuff]

"nothing solid to back it up"

You've got at least 3 sources from what you've just said, so you have lots of solid backing. As an engineer, it's up to you to adjudicate situations like this.

TTFN
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[MacGyver15147]

Read the posts IRstuff. That's At least 3 conflicting sources. Conflicting sources = Nothing solid

 

[MacGyver15147]

So as a licensed A&P mechanic I am trained to have at least 3 reference that can verify that what I am doing is correct and confirmed by all the sources before ever touching an aircraft to a F.A.A inspector at any time. IRstuff as you list your profession as "aerospace" do you read and follow those procedures?

 

[IRstuff]

They are not conflicting in the sense that if you pick the most conservative approach, it does not conflict with the most aggressive approach.

As for "aerospace," that includes defense, which is not subject to FAA regulation. Nevertheless, rather than waste time looking for "solid" sources, I can apply engineering analysis, test, and/or judgement to justify my decisions to my customers.

TTFN
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[GregLocock]

If I try and work out the torsional properties of a thin walled section there are at least three approaches documented, in textbooks, that I could use. Each will give different results.

Since the general aim of reconditioning capacitors has a rather indeterminate meaning, three reliable sources have come up with different, but roughly equivalent, recommendations.

You choose which one seems to apply, or a mixture to give the most conservative.

Cheers

Greg Locock


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[mcgyvr]

Just buy new ones.. Hardly worth the time.
Some people just take "cheap" too far.