When to toss unused old electrolytic capacitors

I'm tidying up my home lab and getting back into it after a lapse of several years. I have unused electrolytic capacitors going back anywhere from 10 to 30 years, stored in air conditioning.

I understand that electrolytics can't be sold as new if they are more than 2 or 3 years old.

At what age do they become unreliable and unsuitable for breadboarding and repair? I understand repair is the more critical of the two because we want reliability going forward.

If a capacitor has been re-formed by charging through a resistor, and then tests OK on an ESR meter, does it still have a long life ahead of it? Or should I toss it anyhow (without even making this test) if it's old? How old?

 

[mpm]

On Tuesday, October 1, 2019 at 6:12:41 PM UTC-4, m...@uga.edu wrote:

My "plan" is to warehouse them for another 6 months and just repurpose them as fuses.

 

[Phil Allison]

m...@uga.edu wrote:

--------------------

I'm tidying up my home lab and getting back into it after a lapse of several years. I have unused electrolytic capacitors going back anywhere from 10 to 30 years, stored in air conditioning.

I understand that electrolytics can't be sold as new if they are more than 2 or 3 years old.

** Seen ones go very bad in less than that if not used, but likely a manufacturing fault in those cases.

Siemens brand 40,000uF @ 100V turned into a 10V cap after two years in storage - and could not be reformed in any sensible time.

At what age do they become unreliable and unsuitable for breadboarding and repair? I understand repair is the more critical of the two because we want reliability going forward.

** There is no particular age, but large physical size examples seem to be long survivors - 30 years is not unusual.

If a capacitor has been re-formed by charging through a resistor, and then tests OK on an ESR meter, does it still have a long life ahead of it?

** The answer is a very definite maybe...




.... Phil

 

[whit3rd]

On Tuesday, October 1, 2019 at 3:12:41 PM UTC-7, m...@uga.edu wrote:

I'm tidying up my home lab and getting back into it after a lapse of several years. I have unused electrolytic capacitors going back anywhere from 10 to 30 years, stored in air conditioning.

I understand that electrolytics can't be sold as new if they are more than 2 or 3 years old.

Yeah, but the manufacturers just recommend 'conditioning' before use.
It's not great if you want to feed an assembly line, but for a 'got it in stock'
event to occur and make you happy, it helps to keep the stock around.

I've recovered shelf-worn capacitors with a milliameter, current limit resistor,
and variable voltage source. Watch the leakage on the meter, and maybe
blow some hot air at the capacitor. When/if the leakage goes to zero, if the
capacitance reads good, you're golden. Success is more likely than a dead
capacitor, and it's a lot quicker than e-maiing in an order (or driving across town).

 

[Michael Kellett]

On 02/10/2019 07:08, whit3rd wrote:

On Tuesday, October 1, 2019 at 3:12:41 PM UTC-7, m...@uga.edu wrote:
I'm tidying up my home lab and getting back into it after a lapse of several years. I have unused electrolytic capacitors going back anywhere from 10 to 30 years, stored in air conditioning.

I understand that electrolytics can't be sold as new if they are more than 2 or 3 years old.

Yeah, but the manufacturers just recommend 'conditioning' before use.
It's not great if you want to feed an assembly line, but for a 'got it in stock'
event to occur and make you happy, it helps to keep the stock around.

I've recovered shelf-worn capacitors with a milliameter, current limit resistor,
and variable voltage source. Watch the leakage on the meter, and maybe
blow some hot air at the capacitor. When/if the leakage goes to zero, if the
capacitance reads good, you're golden. Success is more likely than a dead
capacitor, and it's a lot quicker than e-maiing in an order (or driving across town).

I recently tested a range of capacitors for leakage current under bias
and over temperature -there is a write up of the results on E14:

https://www.element14.com/community/community/design-challenges/polymer-capacitors/blog/2019/06/26/capacitor-leakage-current-over-temperature

One of the types I tested was a couple of ancient but unused 10uF 16V
specimens (probably Sprague) that are about 25 years old (I bought them
at an auction 19 years ago), They seem OK. (leakage current about 30nA
10V bias, 80C, less than 1nA at -20C).

I might use them in a quick test on the bench but I certainly wouldn't
inflict them on a customer.

MK


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[Jan Panteltje]

On a sunny day (Wed, 2 Oct 2019 10:06:25 +0100) it happened Michael Kellett
<mk@mkesc.co.uk> wrote in <Q-KdnQ1t1OwO9QnAnZ2dnUU78YHNnZ2d@giganews.com>:

I recently tested a range of capacitors for leakage current under bias
and over temperature -there is a write up of the results on E14:

https://www.element14.com/community/community/design-challenges/polymer-capacitors/blog/2019/06/26/capacitor-leakage-current-over
-temperature

One of the types I tested was a couple of ancient but unused 10uF 16V
specimens (probably Sprague) that are about 25 years old (I bought them
at an auction 19 years ago), They seem OK. (leakage current about 30nA
10V bias, 80C, less than 1nA at -20C).

I might use them in a quick test on the bench but I certainly wouldn't
inflict them on a customer.

MK

Not sure it is relevant,
I have electrolytic caps (Philips) from about 50 years old (from the seventies).
Those are still fine.
My test is: just scope the ripple if in a supply circuit.

Elcos are the parts that most often fail in my experience.
Funny, just yesterday a security camera failed (at 5 o'clock at night), turns out
its wallwart died, and a 1000uF 16V cap was sort of looking puffed up.
Replaced it with 2 470uF 16V from some other scrap board, now works fine to this moment.
Reason is probably high temperatures that cause the Schottky diodes to leak more,
causing a large AC component in the filter caps...
I measure outside housing of that wallwart to be around 50 degrees C,
inside must be a lot higher...
Problem with fixing wallwarts is those are all glued, they saved on screws, a law should be made to force
them to use screws so you can open those and repair those.
There is some political push here now in the Netherlands towards making things 'repairable'.
Using screws would be a good start.
Almost every wallwart that delivers some power here and is on 24/7 (about 8 or 10 I think)
has now had its electrolytic filter capacitors changed,

 

[Piotr Wyderski]

Jan Panteltje wrote:

> Elcos are the parts that most often fail in my experience.

Unquestionably true, but OTOH: if a 1000uF/16V electrolytic were
replaced with 300 pieces of 1206 10uF/50V caps (3000uF nominally,
but one needs to include the C(V) loss, which is huge for many parts),
would the resulting capacitor battery be more reliable? One MLCC would
for sure be better, but for hundreds of them the probability of failure
is merciless -- one shorted, the entire unit is dead. The electrolytics
often have a limited level of self-healing, which MLCCs lack.

Best regards, Piotr

 

On Wednesday, 2 October 2019 11:31:00 UTC+1, Jan Panteltje wrote:

On a sunny day (Wed, 2 Oct 2019 10:06:25 +0100) it happened Michael Kellett
mk@mkesc.co.uk> wrote in <Q-KdnQ1t1OwO9QnAnZ2dnUU78YHNnZ2d@giganews.com>:

I recently tested a range of capacitors for leakage current under bias
and over temperature -there is a write up of the results on E14:

https://www.element14.com/community/community/design-challenges/polymer-capacitors/blog/2019/06/26/capacitor-leakage-current-over
-temperature

One of the types I tested was a couple of ancient but unused 10uF 16V
specimens (probably Sprague) that are about 25 years old (I bought them
at an auction 19 years ago), They seem OK. (leakage current about 30nA
10V bias, 80C, less than 1nA at -20C).

I might use them in a quick test on the bench but I certainly wouldn't
inflict them on a customer.

MK

Not sure it is relevant,
I have electrolytic caps (Philips) from about 50 years old (from the seventies).
Those are still fine.
My test is: just scope the ripple if in a supply circuit.

Elcos are the parts that most often fail in my experience.
Funny, just yesterday a security camera failed (at 5 o'clock at night), turns out
its wallwart died, and a 1000uF 16V cap was sort of looking puffed up.
Replaced it with 2 470uF 16V from some other scrap board, now works fine to this moment.
Reason is probably high temperatures that cause the Schottky diodes to leak more,
causing a large AC component in the filter caps...
I measure outside housing of that wallwart to be around 50 degrees C,
inside must be a lot higher...
Problem with fixing wallwarts is those are all glued, they saved on screws, a law should be made to force
them to use screws so you can open those and repair those.
There is some political push here now in the Netherlands towards making things 'repairable'.
Using screws would be a good start.
Almost every wallwart that delivers some power here and is on 24/7 (about 8 or 10 I think)
has now had its electrolytic filter capacitors changed,

Drilling holes in the case can drop the temp a lot. Assorted caveats apply of course.

If you do have a no-better replacement ready, a hammer sometimes opens ultrasonic welds.

Re caps... all depends on use. Last time I checked them the majority of my few 1930s lytics were still ok.


NT

 

[George Herold]

On Tuesday, October 1, 2019 at 6:55:08 PM UTC-4, Phil Allison wrote:

m...@uga.edu wrote:

--------------------

I'm tidying up my home lab and getting back into it after a lapse of several years. I have unused electrolytic capacitors going back anywhere from 10 to 30 years, stored in air conditioning.

I understand that electrolytics can't be sold as new if they are more than 2 or 3 years old.


** Seen ones go very bad in less than that if not used, but likely a manufacturing fault in those cases.

Siemens brand 40,000uF @ 100V turned into a 10V cap after two years in storage - and could not be reformed in any sensible time.


At what age do they become unreliable and unsuitable for breadboarding and repair? I understand repair is the more critical of the two because we want reliability going forward.


** There is no particular age, but large physical size examples seem to be long survivors - 30 years is not unusual.


If a capacitor has been re-formed by charging through a resistor, and then tests OK on an ESR meter, does it still have a long life ahead of it?


** The answer is a very definite maybe...




... Phil

Huh I've got several ~5-10 year old Al electro's in my parts drawers. These
are just used for prototyping, is there some easy test to check if they are
still good? They seem to work OK, but lots of times I wouldn't notice
the difference between 1 and 100 uF.

(Oh never mind... not 'my' parts box anymore, someone else's problem :^)

George H.

 

[Jan Panteltje]

On a sunny day (Wed, 2 Oct 2019 04:54:54 -0700 (PDT)) it happened
tabbypurr@gmail.com wrote in
<87e690f7-df73-46af-b70a-af752ee60a00@googlegroups.com>:

On Wednesday, 2 October 2019 11:31:00 UTC+1, Jan Panteltje wrote:
On a sunny day (Wed, 2 Oct 2019 10:06:25 +0100) it happened Michael Kellett
mk@mkesc.co.uk> wrote in <Q-KdnQ1t1OwO9QnAnZ2dnUU78YHNnZ2d@giganews.com>:
Problem with fixing wallwarts is those are all glued, they saved on screws, a law should be made to force
them to use screws so you can open those and repair those.
There is some political push here now in the Netherlands towards making things 'repairable'.
Using screws would be a good start.
Almost every wallwart that delivers some power here and is on 24/7 (about 8 or 10 I think)
has now had its electrolytic filter capacitors changed,

Drilling holes in the case can drop the temp a lot. Assorted caveats apply of course.

Yes, interesting idea


>If you do have a no-better replacement ready, a hammer sometimes opens ultrasonic welds.

In this case I used a vice to hold the bottom part, and the biggest pliers I have to wiggle the top part lose.
Case opened that way without damage.
Cable ties now keep it closed (and easy to remove).

Re caps... all depends on use. Last time I checked them the majority of my few 1930s lytics were still ok.


NT

 

[Jan Panteltje]

On a sunny day (Wed, 2 Oct 2019 13:47:53 +0200) it happened Piotr Wyderski
<peter.pan@neverland.mil> wrote in <qn22p8$1gp5$1@gioia.aioe.org>:

Jan Panteltje wrote:

Elcos are the parts that most often fail in my experience.

Unquestionably true, but OTOH: if a 1000uF/16V electrolytic were
replaced with 300 pieces of 1206 10uF/50V caps (3000uF nominally,
but one needs to include the C(V) loss, which is huge for many parts),
would the resulting capacitor battery be more reliable? One MLCC would
for sure be better, but for hundreds of them the probability of failure
is merciless -- one shorted, the entire unit is dead. The electrolytics
often have a limited level of self-healing, which MLCCs lack.

Best regards, Piotr

A hypothetical question indeed,
I would not want to do that in practice,
I bought some Nichicon LF 16V 470UF low ESR High ripple current aluminum
solid capacitors on ebay for my drone systems,
those so far work OK, several in parallel, what was it? 10A ripple at 100 kHz
and 7.5 V or something like that:
http://panteltje.com/pub/h501s_drone_remote_power_drone_side_IMG_6278.JPG
uses air cooling from the propellers for the rectifiers and caps.

Used to keep it flying indefinitely via a thin coax and a few hundred volts transformed down (in that ring-core).
http://panteltje.com/pub/h501s_drone_remote_power_flight_test_1_IMG_6274.JPG
one turn secondary hehe

 

[Cursitor Doom]

On Wed, 02 Oct 2019 10:30:52 +0000, Jan Panteltje wrote:

Not sure it is relevant,
I have electrolytic caps (Philips) from about 50 years old (from the
seventies).
Those are still fine.

My experience too. My test is using a proprietory ESR meter and I have
found provided the caps concerned come from quality manufacturers,
they're usually fine, whether they've been in service for years and years
on end or not.
Sometimes I do find the odd duff electro in a 40-50yr old piece of
equipment, but it's really not *that* common.
So to answer the OP's question, I would *never* throw an old electro out
*unless* it tested faulty.



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[Clifford Heath]

On 3/10/19 12:07 am, Jan Panteltje wrote:

On a sunny day (Wed, 2 Oct 2019 04:54:54 -0700 (PDT)) it happened
tabbypurr@gmail.com wrote in
87e690f7-df73-46af-b70a-af752ee60a00@googlegroups.com>:
On Wednesday, 2 October 2019 11:31:00 UTC+1, Jan Panteltje wrote:
There is some political push here now in the Netherlands towards making things 'repairable'.
Using screws would be a good start.
Almost every wallwart that delivers some power here and is on 24/7 (about 8 or 10 I think)
has now had its electrolytic filter capacitors changed,
If you do have a no-better replacement ready, a hammer sometimes opens ultrasonic welds.

In this case I used a vice to hold the bottom part, and the biggest pliers I have to wiggle the top part lose.
Case opened that way without damage.
Cable ties now keep it closed (and easy to remove).

These cases are molded with an outer and an inner part with overlapping
lips. A series of sharp raps delivered to the inner side adjacent to the
weld via a flat screwdriver blade breaks the weld but leaves the lip
intact. Go right around and the case falls open, but can easily be glued
shut again.

Clifford Heath.