Author Topic: electrolytic capacitor truth or myth?  (Read 1597 times)

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Offline classicsamus87

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electrolytic capacitor truth or myth?
« on: January 02, 2021, 04:09:01 pm »
What do manufacturers say about electrolytic capacitors going unused for a long time? a person told me to use all my electrolytic capacitors that have electrolytic capacitors at least once a month for at least 30 minutes otherwise the electrolytic capacitors depolarize and lose capacitance, is this information true? is there a correct interval or not to energize the electrolytic capacitors and preserve them?
 

Offline JohnnyMalaria

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Re: electrolytic capacitor truth or myth?
« Reply #1 on: January 02, 2021, 05:19:34 pm »
I've used all kinds of electronic equipment over many decades that often have gone unused for years. With one exception, I've never had a failure because of bad polarized capacitor.

As for what manufacturers say, see page 18 of this https://www.nichicon.co.jp/english/products/pdf/aluminum.pdf
« Last Edit: January 02, 2021, 05:25:44 pm by JohnnyMalaria »
 

Offline Gyro

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Re: electrolytic capacitor truth or myth?
« Reply #2 on: January 02, 2021, 05:42:24 pm »
What do manufacturers say about electrolytic capacitors going unused for a long time? a person told me to use all my electrolytic capacitors that have electrolytic capacitors at least once a month for at least 30 minutes otherwise the electrolytic capacitors depolarize and lose capacitance, is this information true? is there a correct interval or not to energize the electrolytic capacitors and preserve them?

This guy is like a repeating record, you're being spammed.  ::)

https://www.eevblog.com/forum/chat/old-electronic-devices-electrolytic-capacitors/
Chris

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Offline classicsamus87

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Re: electrolytic capacitor truth or myth?
« Reply #3 on: January 02, 2021, 05:59:23 pm »
What do manufacturers say about electrolytic capacitors going unused for a long time? a person told me to use all my electrolytic capacitors that have electrolytic capacitors at least once a month for at least 30 minutes otherwise the electrolytic capacitors depolarize and lose capacitance, is this information true? is there a correct interval or not to energize the electrolytic capacitors and preserve them?

This guy is like a repeating record, you're being spammed.  ::)

https://www.eevblog.com/forum/chat/old-electronic-devices-electrolytic-capacitors/
I didn't understand why they gave me information that I need to use electrolytics every month. I have electronics with old and new electrolytic capacitors.
 

Offline JohnnyMalaria

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Re: electrolytic capacitor truth or myth?
« Reply #4 on: January 02, 2021, 06:01:39 pm »
What do manufacturers say about electrolytic capacitors going unused for a long time? a person told me to use all my electrolytic capacitors that have electrolytic capacitors at least once a month for at least 30 minutes otherwise the electrolytic capacitors depolarize and lose capacitance, is this information true? is there a correct interval or not to energize the electrolytic capacitors and preserve them?

This guy is like a repeating record, you're being spammed.  ::)

https://www.eevblog.com/forum/chat/old-electronic-devices-electrolytic-capacitors/
I suspected such. I was going to suggest I just plug my old electronics in backwards so I can back-flush those pesky capacitors. :)
 

Offline classicsamus87

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Re: electrolytic capacitor truth or myth?
« Reply #5 on: January 02, 2021, 06:13:55 pm »
what other manufacturers provide this information? from what i read in the nichico document the electrolytic capacitors can remain up to two years without being used energized and they will not have any reduction of useful life because of this and do not depolarize
 


Offline cdev

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Re: electrolytic capacitor truth or myth?
« Reply #7 on: January 02, 2021, 06:52:26 pm »
Not long ago I posted a question on this and a lot of people provided information on it including a bunch of things I had never even heard before about electrolytic capacitors.

It depends on a lot of factors!

When there is an alternative, under some conditions, old caps shouldn't be used unless care is taken to reform them.  Even reformed, they shouldn't be used off the shelf if they are really old. If they are, they should test out as good, and still be derated, if its possible. But its complicated.

Its not likely to be necessary with fairly new equipment that's been sitting for just a few years.

There have been lots in other threads.

https://www.eevblog.com/forum/beginners/electrolytic-reform-school-how-long-a-period-of-inactivity-to-be-necessary

https://www.eevblog.com/forum/chat/reforming-aluminum-electrolytic-capacitors

Also there's a bunch of info in this thread.

https://www.eevblog.com/forum/projects/electronics-repair-cookbook-save-time-and-money-by-fixing-electronics-yourself

There were links posted that I found interesting.

Good stuff to know. Here are some of the links..

https://www.cde.com/resources/catalogs/AEappGUIDE.pdf
https://library.e.abb.com/public/9f1befcd62ce445ec1257466003c02e2/3BFE64050629.pdf

https://web.archive.org/web/20050204082149/http://www.lowesr.com/QT_LowESR.pdf

Also, I just saw a recommendation to check out  MIL-HDBK-1131

But if there is a new replacement available, and there is any doubt.

read this:

Quote
Quote from: tggzzz on 2020-12-07, 00:05:01

The first Tek 485 that I resurrected had a PSU cap that needed "reforming". Once reformed it stayed good(ish) for 12 hours, and then needed reforming again. I replaced all the "similar" caps. For that and other reasons, I'm not a fan of reforming caps.

The symptom was that it would take 60s to spring into life. If switched off and on it would spring to life as expected - unless it had been switched off for >12 hours. Only being able to attempt two transient debugging sessions per day was slow.

Now, when next "reforming" your capacitor, what makes you confident something equivalent won't happen?

« Last Edit: January 02, 2021, 07:24:11 pm by cdev »
"What the large print giveth, the small print taketh away."
 

Offline classicsamus87

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Re: electrolytic capacitor truth or myth?
« Reply #8 on: January 02, 2021, 07:31:27 pm »
What is the maximum time interval without using electronic devices without harming electrolytic capacitors and their useful life? don't manufacturers talk about this period?
 

Offline cdev

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Re: electrolytic capacitor truth or myth?
« Reply #9 on: January 02, 2021, 08:45:44 pm »
They do, they publish extensive notes on how to be safe rather than sorry. (as in the links above)  Also all sorts of factors figure in. There is no hard and fast rule. If there is any doubt, I would reform even "new" capacitors and check the leakage. Sometimes reputable vendors sell capacitors made some time ago.

What is the maximum time interval without using electronic devices without harming electrolytic capacitors and their useful life? don't manufacturers talk about this period?
« Last Edit: January 02, 2021, 08:48:18 pm by cdev »
"What the large print giveth, the small print taketh away."
 

Offline opampsmoker

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Re: electrolytic capacitor truth or myth?
« Reply #10 on: January 03, 2021, 02:53:07 am »
In theory, an electolytic cap thats been left without voltage on it for months will have a high leakage current for a short time just after it is powered up again.
Its not at all clear how much leakage current this would be, but i've never been able to find evidence of it being enough to overheat and kill the capacitor.

With el caps, the big evil is operating them, even for  very short periods, above their  case rated temperature.....if this is done, then that el cap is a gonna, and will soon die completely. Also, operating them at their case rated temperature for their rated hours, as you know, means they  are basically dead. Often for 'lytics, you  get eg 5000 hours at 110degC (which also means 10000hrs at 100degc, 20000hrs at 90degc, etc etc).
There's 8736 hrs in a year.
 

Offline tiago1986

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Re: electrolytic capacitor truth or myth?
« Reply #11 on: May 15, 2021, 10:12:55 am »
For electrolytic capacitors from 1990 already used and mounted on a circuit, do you have any tips or rules for maximum time allowed without use?
 

Offline BMK

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Re: electrolytic capacitor truth or myth?
« Reply #12 on: May 15, 2021, 10:47:14 am »
Myth or not, I have for the past 14 years had a 4 day per year gig at a major med-device company. The job is to check condition of 80 15-30KW VFDs in 40 bits of gear, each with a redundant standby/duty arrangement. Additionally they have another 40, wired up and built in control cabinets in storage ready to use in case of plant room disaster. Every year as per their procedure, these are powered up by a Variac, ran for 10 minutes, then put back in stores. Never have I seen a failure.  But every year I get the PO, and every year I go!
 
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Offline tiago1986

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Re: electrolytic capacitor truth or myth?
« Reply #13 on: May 15, 2021, 01:51:33 pm »
if the electrolytic capacitors remain unused for many years what happens to their chemistry?
 

Offline schmitt trigger

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Re: electrolytic capacitor truth or myth?
« Reply #14 on: May 15, 2021, 02:36:28 pm »
Again, there is no simple, one size fits all answer.

Modern electrolytes are a complex chemical soup, which are closely guarded intellectual property.

We have all heard the story several years ago of the stolen electrolyte formula, which was copied with errors and caused major recalls
 

Offline cdev

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Re: electrolytic capacitor truth or myth?
« Reply #15 on: May 18, 2021, 02:15:17 am »
I have a procedure like @BMK that I now follow when I have old electronics to keep them from exploding when power is first applied, its basically just running it for a short time off a variac when I turn it on for the first time in a while. then gradually raising the voltage to normal. I also use an incandescent light bulb in series.


I think its better to do it a little longer. You can monitor the leakage current and you'll see it go up when you turn up the voltage and then gradually go down in little jumps. Seeing that gives me a little feeling of reassurance that all is well.


« Last Edit: May 18, 2021, 02:27:51 am by cdev »
"What the large print giveth, the small print taketh away."
 

Offline tiago1986

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Re: electrolytic capacitor truth or myth?
« Reply #16 on: May 22, 2021, 07:25:22 pm »
using the devices every month is the correct one for electrolytic capacitors because of the variation of capacitor manufacturers?
 

Offline Gyro

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Re: electrolytic capacitor truth or myth?
« Reply #17 on: May 22, 2021, 07:38:10 pm »
using the devices every month is the correct one for electrolytic capacitors because of the variation of capacitor manufacturers?

Anyone else detecting a certain similarity to the OP?
Chris

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