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Electrolytic capacitors are kinda like lead-acid batteries in that they are polarized through manufacturing processes. A voltage is applied in the factory to an

Electrolytic capacitors are kinda like lead-acid batteries in that they are polarized through manufacturing processes. A voltage is applied in the factory to anodize the anode with a thin oxide layer. For fun, I think it would be possible to buy a quality low voltage cap and reverse the polarity of it in-situ which would remove the anodization from the new cathode and deposit a new layer on the new anode (former cathode) hopefully without over-pressurizing it to bursting, albeit with much less anticipated lifespan. PSA: Electrolytic capacitors have a rough lifespan of 10 years. Any much older than that need to be checked out-of-circuit for ESR and then capacitance. Also, tantalums (historically) suck(ed). [0] Quality audio equipment from the 80's like a/d/s/ car amps used only ceramic caps and other over-engineered passives, and have the potential (pun intended) to basically last forever. 0. https://www.eevblog.com/forum/projects/whenwhy-(not)-to-use-tantalum-capacitors-pros-cons-alternatives/msg359601/#msg359601 https://www.eevblog.com/forum/projects/whenwhy-(not)-to-use-...

kevindamm 2y ago
Or much shorter, around two years, if it was part of the Capacitor Plague. https://en.wikipedia.org/wiki/Capacitor_plague#Premature_failure https://en.wikipedia.org/wiki/Capacitor_plague#Premature_fai... The normal lifespan of a non-solid electrolytic capacitor of consumer quality, typically rated at 2000 h/85 °C and operating at 40 °C, is roughly 6 years. It can be more than 10 years for a 1000 h/105 °C capacitor operating at 40 °C. Electrolytic capacitors that operate at a lower temperature can have a considerably longer lifespan. ... The life of an electrolytic capacitor with defective electrolyte can be as little as two years.
- Workaccount2 2y ago
  This is also why so many LED bulbs are shit, lots of heat in a small space full of electrolytic caps.
  - magic_smoke_ee 2y ago
    Intentional planned consumption/obsolescence by design. This class of problem is where under-regulation and lack of standards benefits only sellers and cheats buyers. PS: Also, Amazon should be required to test all of the electronic, safety, and food products on its site such that they can prove safety and standards conformance.
    - Filligree 2y ago
      That, and customers insisting on preexisting form factors. Fitting the electronics and LEDs into the space of a traditional lightbulb comes with compromises, such as not having proper heat dissipation on either.
      - BlueTemplar 2y ago
        Yeah, you would think they would be two separate devices by now...
    - Workaccount2 2y ago
      I am assuming you are an ee (like myself)...I have never designed a product with a built in expiration, nor have I ever seen any app notes or write ups on the engineering of it - something engineers love to do. What I have seen done is cheaping out on parts in order to get the price as low as possible, because customers shop primarily on price. Not to lash out, but it kind of hits a nerve for me, because people think we design products to purposely fail. Hell no, we try really hard to do the opposite, but everyone just loves to buy the cheapest shit. The $25 LED bulb that will last for eternity will rot on the shelf next to the $3 bulb that will probably be dead in 6 months. And one more "they build these things to fail" complaint will be posted online.
      - belval 2y ago
        To be fair this is hardly limited to EE and is the issue with the race to the bottom in all product categories. Make long-lasting high-quality 100$ pants? People prefer spending 10$ on Shein. Additionally, the issue is that as a consumer, it's not easy to differentiate between quality markup and greedy markup. I don't see the cap manufacturer on the box so the 25$ light bulb might last 10 years or it might last 6 months just like the 3$ one. At least with the 3$ one I can come back and buy another...
  - JJMcJ 2y ago
    Recently read that if you are going to be using an LED bulb in an enclosed space, buy bulbs designed for the high temperature, otherwise you WILL get premature failures in bulbs that will last for years in ordinary lamps. https://duckduckgo.com/?t=lm&q=led+bulbs+enclosed+fixture+rated&ia=web https://duckduckgo.com/?t=lm&q=led+bulbs+enclosed+fixture+ra...
    - bmicraft 2y ago
      Alternatively, there are now much more efficient bulbs available. If they're passing A under the new EU Energy Label (from 2021) they'll barely be warm to the touch.
outworlder 2y ago
> Any much older than that need to be checked out-of-circuit for ESR and then capacitance And that's a very time consuming and somewhat risky operation on an old machine you want to keep running. Some old PCBs are quite fragile. I wish there was a way to test capacitors without removing them.
- mgsouth 2y ago
  You can test ESR in-circuit, with caveats. Here's a good thread from EEVblog [1]. [1] https://www.eevblog.com/forum/beginners/is-there-any-way-to-test-capacitors-while-on-the-circuit-board/ https://www.eevblog.com/forum/beginners/is-there-any-way-to-...
anon_cow1111 2y ago
Here's a question for EE nerds that happen to be reading this (maybe in the future). What if I have a stash of big electrolytics that have been out of service for 10+ years? I know that I need to reform them over a few days, but can they even run at spec after so long out of operation? We're talking BIG stuff, 400v, 200+J each
- buescher 2y ago
  For hobby or laboratory purposes, it’s worth a try. Some probably will come back completely. But if you wanted to use them in production, and be able to blame me when it didn’t work, I’d say no.

kevindamm 2y ago

Or much shorter, around two years, if it was part of the Capacitor Plague. https://en.wikipedia.org/wiki/Capacitor_plague#Premature_failure https://en.wikipedia.org/wiki/Capacitor_plague#Premature_fai... The normal lifespan of a non-solid electrolytic capacitor of consumer quality, typically rated at 2000 h/85 °C and operating at 40 °C, is roughly 6 years. It can be more than 10 years for a 1000 h/105 °C capacitor operating at 40 °C. Electrolytic capacitors that operate at a lower temperature can have a considerably longer lifespan. ... The life of an electrolytic capacitor with defective electrolyte can be as little as two years.

Workaccount2 2y ago
This is also why so many LED bulbs are shit, lots of heat in a small space full of electrolytic caps.
- magic_smoke_ee 2y ago
  Intentional planned consumption/obsolescence by design. This class of problem is where under-regulation and lack of standards benefits only sellers and cheats buyers. PS: Also, Amazon should be required to test all of the electronic, safety, and food products on its site such that they can prove safety and standards conformance.
  - Filligree 2y ago
    That, and customers insisting on preexisting form factors. Fitting the electronics and LEDs into the space of a traditional lightbulb comes with compromises, such as not having proper heat dissipation on either.
    - BlueTemplar 2y ago
      Yeah, you would think they would be two separate devices by now...
  - Workaccount2 2y ago
    I am assuming you are an ee (like myself)...I have never designed a product with a built in expiration, nor have I ever seen any app notes or write ups on the engineering of it - something engineers love to do. What I have seen done is cheaping out on parts in order to get the price as low as possible, because customers shop primarily on price. Not to lash out, but it kind of hits a nerve for me, because people think we design products to purposely fail. Hell no, we try really hard to do the opposite, but everyone just loves to buy the cheapest shit. The $25 LED bulb that will last for eternity will rot on the shelf next to the $3 bulb that will probably be dead in 6 months. And one more "they build these things to fail" complaint will be posted online.
    - belval 2y ago
      To be fair this is hardly limited to EE and is the issue with the race to the bottom in all product categories. Make long-lasting high-quality 100$ pants? People prefer spending 10$ on Shein. Additionally, the issue is that as a consumer, it's not easy to differentiate between quality markup and greedy markup. I don't see the cap manufacturer on the box so the 25$ light bulb might last 10 years or it might last 6 months just like the 3$ one. At least with the 3$ one I can come back and buy another...
- JJMcJ 2y ago
  Recently read that if you are going to be using an LED bulb in an enclosed space, buy bulbs designed for the high temperature, otherwise you WILL get premature failures in bulbs that will last for years in ordinary lamps. https://duckduckgo.com/?t=lm&q=led+bulbs+enclosed+fixture+rated&ia=web https://duckduckgo.com/?t=lm&q=led+bulbs+enclosed+fixture+ra...
  - bmicraft 2y ago
    Alternatively, there are now much more efficient bulbs available. If they're passing A under the new EU Energy Label (from 2021) they'll barely be warm to the touch.

outworlder 2y ago

> Any much older than that need to be checked out-of-circuit for ESR and then capacitance And that's a very time consuming and somewhat risky operation on an old machine you want to keep running. Some old PCBs are quite fragile. I wish there was a way to test capacitors without removing them.

mgsouth 2y ago
You can test ESR in-circuit, with caveats. Here's a good thread from EEVblog [1]. [1] https://www.eevblog.com/forum/beginners/is-there-any-way-to-test-capacitors-while-on-the-circuit-board/ https://www.eevblog.com/forum/beginners/is-there-any-way-to-...

anon_cow1111 2y ago

Here's a question for EE nerds that happen to be reading this (maybe in the future). What if I have a stash of big electrolytics that have been out of service for 10+ years? I know that I need to reform them over a few days, but can they even run at spec after so long out of operation? We're talking BIG stuff, 400v, 200+J each

buescher 2y ago
For hobby or laboratory purposes, it’s worth a try. Some probably will come back completely. But if you wanted to use them in production, and be able to blame me when it didn’t work, I’d say no.