Doubts about electrolytic capacitor - Page 1
Forum section: electronics / beginners

author: johnrodrigues
author_rank: Newbie
timestamp: August 14, 2020, 05:53:47 pm
content: Electrolytic capacitor kept unused for many months or year suffers depolarization, short circuit and loss of capacitance?I have a technical friend in electronics and he instructed me to use my old electronic devices once a month for 30 minutes because if I do not follow this guidance, electrolytic capacitors can depolarize, short circuit and lose capacitanceis this information true or false?

author: JohanH
author_rank: Frequent Contributor
timestamp: August 14, 2020, 06:15:58 pm
content: There is some truth to it. Electrolytic capacitors age in two ways.The oxidation layer inside might deplete if not used for a long time. This could cause the capacitor to arc through its insulation and cause a short circuit (inside the capacitor). With individual capacitors, this can be remedied by bringing up voltage slowly and let the capacitor reform the oxide layer during several hours at full voltage (and without load). So this cannot really be done inside a device, unless you connect the device to a variac and slowly start the device that way (and not all devices could be treated in this way). So to avoid this, use the device now and then.Then there is the fact that electrolytic capacitors do age also in use, due to heat and simply aging materials. They might gradually lose their capacitance. A really old electrolytic capacitor will eventually dry out and there is no way to save it, because the electrolytic is simply missing. It can only be replaced at that point.But depolarization? I think that is a battery thing...

author: jpanhalt
author_rank: Super Contributor
timestamp: August 14, 2020, 06:31:22 pm
content: Now that you have gotten the same answer from at least 3 different forums, it is time to ask your "friend" for some documentation?Why do you still have a question?

author: WattsThat
author_rank: Frequent Contributor
timestamp: August 14, 2020, 06:36:28 pm
content: It’s simply amazing how this urban legend nonsense grows legs and comes to lifeFrom a pure technical viewpoint, yes, electrolytic capacitors change when left unpowered for extended periods of time. Yes, there are cases where it matters and needs to be addressed, for example:https://library.e.abb.com/public/43b21606a20648d79c6c1029f2fc5f48/EN_Capacitor_reforming_instructions_G_A4.pdfBut, consider that these are extremely high values of capacitors used in very high current industrial devices that push the components to their absolute maximum ratings 24/7. Even with that usage, there is no need to reform until one year or more of unpowered storage.From a practical standpoint, especially with modern consumer electronics, your friends recommendation is just over-hyped school girl gossip. Forget it and move on with your life, there are far more important things to learn.IMO, it rates up there with the audiophools and their cable burn-in devices.

author: JohanH
author_rank: Frequent Contributor
timestamp: August 14, 2020, 06:48:49 pm
content: I agree that this is a topic that easily could drift into audiophoolery. In really old gear electrolytic capacitors should be changed anyway. At least finally when something breaks down. There is nothing you can do against aging.

author: johnrodrigues
author_rank: Newbie
timestamp: August 14, 2020, 07:07:00 pm
content: My friend told me to use the electronic devices once a month for 30 minutes to preserve the electrolytic capacitors by avoiding short circuit and depolarization, the manufacturers of electrolytic capacitors also say to use once a month for 30 minutes to keep the electrolytes good?

author: JohanH
author_rank: Frequent Contributor
timestamp: August 14, 2020, 07:11:57 pm
content: No, they don't.

author: Gyro
author_rank: Super Contributor
timestamp: August 14, 2020, 07:21:23 pm
content: Quote from: johnrodrigues on August 14, 2020, 07:07:00 pmLooking at it logically -do youdoes your friend really think electronics distributors spend their time applying power to their entire electrolyitic capacitor stock once a month?

author: JohanH
author_rank: Frequent Contributor
timestamp: August 14, 2020, 07:43:55 pm
content: Quote from: Gyro on August 14, 2020, 07:21:23 pmBut think about the job possibilities as capacitor reformer!(Sorry, couldn't resist, but the topic actually became quite funny when put this way)

author: Manul
author_rank: Super Contributor
timestamp: August 14, 2020, 08:29:19 pm
content: In my opinion this information is false (orginal question). If capacitors are not dry (loose electrolyte) and are otherwise in good shape, but were just sitting long without voltage - they just temporary loose little bit of their oxide layer. It manifests itself as a temporary increase in leakage current, but for a very short time. They reform really quickly after voltage is applied. I have never practically seen a case where temporary leakage would be so big (or long) as to cause problems. Except possiblly some really high energy circuits, or precise analog circuits were allowed leakage margin is small.So generally speaking you just power your device and use it when you need it. Most of oxide imperfections will be gone after just a second of beeing powered and all will be as good as it was.Personally I powered electronics which has been sitting 20-30 years without beeing used and all was ok.

author: james_s
author_rank: Super Contributor
timestamp: August 14, 2020, 09:58:29 pm
content: I have dozens of rarely used devices, some sit for a year or more without being powered up and I have not had any trouble with the capacitors. Things that I HAVE had to replace capacitors in are those that are powered on all the time.

author: rsjsouza
author_rank: Super Contributor
timestamp: August 15, 2020, 12:54:41 am
content: Quote from: jpanhalt on August 14, 2020, 06:31:22 pmNot to mention the ban on AAC trying to stir the same pot.Quote from: james_s on August 14, 2020, 09:58:29 pmYes, although I noticed that, if capacitors were heavily used for a period of time under higher stress (plugpacks, for example)tand then left alone for a long period, they tend to do much more damage (understandable due to the higher chance of a failed seal on their housing)

author: srb1954
author_rank: Super Contributor
timestamp: August 15, 2020, 01:03:22 am
content: My experience is that electrolytic capacitors actually gain a little bit of capacitance if they are left on the shelf for many years. I assume that this is due to the oxide dielectric layer gradually becoming thinner when there is no bias voltage applied.The leakage current also increases considerably due to this thinner oxide layer but this generally reduces fairly quickly to acceptable levels when normal bias is applied to the capacitor again and the oxide layer is reformed.

author: weirdnerd
author_rank: Newbie
timestamp: August 15, 2020, 03:34:06 am
content: True reform would take place as a conversion of them to solid state capacitors. In my experience, capacitors die if they are used continuously but lithium ion batteries swell and explode when they are left alone as devices. Capacitors of what devices is the OP talking about. It does sound like audiophoolery. I was talking about this exact topic, I thought they were solid state and old hifi DACs and TV sets still sound good so I wasn't sure if they died, but apparently they are just chemicals stuck in a small container.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 15, 2020, 09:08:35 am
content: Quote from: jukk on August 14, 2020, 07:43:55 pmRepent!Sinful capacitors!

author: TimFox
author_rank: Super Contributor
timestamp: August 15, 2020, 01:26:33 pm
content: As Mathias 'Paddy' Bauler stated in 1939, ''Chicago ain`t ready for reform.''

author: MK14
author_rank: Super Contributor
timestamp: August 15, 2020, 03:21:05 pm
content: Quote from: johnrodrigues on August 14, 2020, 07:07:00 pmBefore you post in this thread, bare in mind, the same/similar text, appears a number of times, on other forums, followed by Aliexpress (protection bag) stuff. I.e. I think they are a spammer.Two examples (google is your friend, for possibly more):https://www.electro-tech-online.com/search/51343/https://forum.allaboutcircuits.com/threads/doubts-electrolytic-capacitor.172041/#post-1540750Also, they seem to just parrot the same text, over and over. In the same thread. I.e. It is NOT a real question. Some kind of Aliexpress spam thing, for later.

author: rstofer
author_rank: Super Contributor
timestamp: August 15, 2020, 03:23:23 pm
content: OP:The consensus is (and it is correct) that this is a non-issue except in some strange situations like huge electrolytics in gigantic UPS systems where reforming is a real thing if the unit has been out of service for a while (for large values of 'while').But why not just run everything like your friend suggests? It can't hurt anything except the electric bill and that will be modest if even noticeable.I won't do it, nobody around here will do it, but there is nothing preventing you from doing it.

author: perieanuo
author_rank: Frequent Contributor
timestamp: August 17, 2020, 04:34:18 pm
content: hi!well, when I was poor I repaired all sort of stuff, including tv's.I still do it for friends, some neighbour had his tv set died in quarantine time.so, lot of people told me their set died after it was switched off for holidays or something alike.found dried electrolytic capacitors, replaced them, all okso yes, your friend is not wrong.in fact, datasheet from major factories specify that, even after keeping them in temperature/humidity controlled storage area, the electrolytic capacitors needs to be polarised to recreate the oxide layer.you see the resemblance, other 'genies' here don't.so I can confirm from practice that electrolytics live longer (or they don't blow the pwm controller away) if you keep them UNDER VOLTAGE.any philosophy around the subject is non-professional.they are just like our muscles, if you don't use them they get weak sort of speaking.that's what panasonic and others are saying, I just repeat.best regards,pierre

author: Simon
author_rank: Unknown
timestamp: August 17, 2020, 05:15:52 pm
content: How old are the TV's? TV's are often designed to last just out of warranty and many consumer goods do not treat capacitors properly like putting them near hot parts.

author: JoeyG
author_rank: Regular Contributor
timestamp: November 08, 2020, 01:13:05 pm
content: This manufacturer says storage warranted for 2~3 years under certain conditionshttp://www.chemi-con.co.jp/e/catalog/pdf/al-e/al-all-e1001u-2020.pdfSearch for the word "years" in the PDF

author: dietert1
author_rank: Super Contributor
timestamp: November 08, 2020, 03:18:58 pm
content: There may be a difference in this respect between normal alu electrolytical capacitors and tantalum capacitors, that are known to develop short when unused for long time. Recently i fixed a ONKYO A-8690 amplifier from the 90s that had apparently been in stock for years. That series had a design error in the DAC section (cheap ceramic resonator instead of true crystal).I exchanged about 15 electrolytes and found that most of them had reduced their capacitance by about 30 % and doubled their ESR. One small cap had developed an ESR of 95 Ohms. One of the larger caps had dry salt under it (lost electrolyte).Then there were some special green ones with less than 30 % of their nominal capacitance. They were being used at low voltages like 10 or 20 mV even when the amplifier was powered on. There were pairs of anti serial caps to simulate bipolar caps. I replaced that with MLCC caps.Regards, Dieter

author: rsjsouza
author_rank: Super Contributor
timestamp: November 09, 2020, 01:30:18 am
content: Quote from: JoeyG on November 08, 2020, 01:13:05 pmThat is certainly what is claimed, but don't forget the manufacturers need to be liable for any faults - most certainly their capacitors last a lot longer on the shelf for this.I have some bandolier strips of 100 capacitors bought new eight or nine years ago and always stored in a 10% RH in temperatures up to 35°C. My sampling tests did not reveal any out of spec. Not to mention equipment I have unpowered for a number of years that is still working just fine.

author: jmelson
author_rank: Super Contributor
timestamp: November 09, 2020, 02:48:31 am
content: Quote from: johnrodrigues on August 14, 2020, 05:53:47 pmAluminum electrolytics have a very slow degradation of the dielectric, which recovers quickly when powered on. The above might be true of REALLY old equipment, like 1950's vintage. A gradual power up with a Variac can restore them safely.Certain types of Tantalum electrolytics have a degradation mechanism where if they are powered off for a few years, and then suddenly turned on at full voltgae can cause the dielectric to fail shorted, sometimes spectacularly.That one is true, I have seen it happen.I have a ton of old gear with aluminum electrolytics and have just about never had problems with them.Jon

author: The Electrician
author_rank: Frequent Contributor
timestamp: November 09, 2020, 05:32:34 am
content: Quote from: dietert1 on November 08, 2020, 03:18:58 pmHow can you say how much the capacitors' ESR and capacitance has changed with measurements made now, unless you measured them when the amp was built in the 90's for reference?

author: dietert1
author_rank: Super Contributor
timestamp: November 09, 2020, 10:42:28 am
content: Yes, instead of "most of them" i should have written "on average". And nowadays new electrolytical capacitors may have lower tolerances in comparison to 30 years ago.That ONKYO amplifier has many more electrolytics, but after replacing some i thought i can keep most of them and look only at those in the audio signal path.Regards, Dieter