Question electrolytic capacitor

[Station X]

Thread reopened.

[GMB]

This modern document from Vishay is worth reading. It has very detailed information on their aluminium electrolytics including lifetime and storage data - which also explains why these parameters vary so widely due to the exact conditions.

https://www.vishay.com/docs/28356/alucapsintrobcc.pdf

[cloudff7]

Any reliable concrete studies to indicate storage time of electronics with electrolytic capacitors without the risk of having failures due to disuse? i have snes, ps2 slim and crt tv consoles and they were manufactured in the early 90's and early 2000's and the temperature in my city ranges from 33-35C

[Al (astral highway)]

Originally Posted by cloudff7

about electrolytic capacitors in electronic circuits manufactured in the early 90's and early 2000's what is the recommended period of time without use allowed...

Hello, I see that you keep asking variations of the same question, just with a few words changed round! Your determination is remarkable.

There isn't a body of research or information inside one person, of any discipline, that will have be predictive for the survival rates of your capacitors. There aren't better answers than the ones that have already been stated.

It's a probability question. Mnufacturers might know that 1 in 10,000 of these will fail in 10,000 hours at 70C. (I just made that up to illustrate that this wouldn't define whether yours was one of those with a 'fail' destiny written on it - don't take it as being grounded in any reality).

So stats aren't actually deterministic for their time to failure or the one that will fail. You can only define that in the past, once they have actually gone leaky or failed altogether.

Nothing is going to blow up violently. If a cap fails eventually, you can fix it.

Try to relax about it, it'll be fine.

[cloudff7]

if the electronic device kept for many years the electrolytic capacitors will have failures due to disuse? equipment manufactured in the early 90's and early 2000's

[Al (astral highway)]

Originally Posted by cloudff7

if the electronic device kept for many years the electrolytic capacitors will have failures due to disuse? equipment manufactured in the early 90's and early 2000's

Same old question! Are you actually a bot?

[Radio Wrangler]

OK, there has been work done on electronic components including many different types of capacitors in stored equipment. This is very important to the military. They need to have some confidence that when they need to pull some piece of equipment from stores that it will work as intended.

The basic reliability statistics is in a document called MIL-HDBK-217. There will be a suffix letter after that 217 part showing which revision you have.

The first thing is that this data principally covers parts in use and under stress. There are curves and other information for estimating mean lifetimes under lowered stress, and setting these to your conditions will give you the estimated mean lifetime of the parts in storage.

The second thing is that this data often came from premium quality parts from manufacturers operating certified quality control plans. The capacitors and other parts in your consumer devices were bought simply in consideration of their price.

The third thing is that this data is statistical in nature. It will give a reasonable guide to what the failure rate and life expectancies will be averaged across a very large number of parts, but over the number you have in your individual devices, the uncertainty will be too large to be helpful.

Additionally, the date range you mention covers a period when through industrial espionage some capacitor manufacturers in China were using electrolyte recipes stolen from Japanese capacitor firms engaged in research into higher performance electrolytes. It seems that what they got was not the final recipe, it lacked some additives needed to fix a degradation problem. The result has been a lot of consumer goods failing due to corrosion effects inside electrolytic capacitors.

Do your devices contain any of these parts?

Maybe.

No-one has a list of all the brand names they appeared with, and there may be no marlings which make it clear. No-one has a list of all the end products affected.

So you want to know how often you should power up stored devices to keep their electrolytics formed?

No one knows for sure. What testing has been done comes from capacitor manufacturer's testing done when their products were newly introduced. lifetime estimates are just estimates. and based on accelerated lifetime tests.

So, you want to know if you should replace all your electrolytic capacitors?

It's likely that if your devices still work today, they must have missed the big corrosion problem. So you may as well leave them alone.

If you do decide to change the capacitors, then you run into the problem of avoiding fake ones. If you hit the auction sites and other places offering capacitors at the very lowest prices, it is likely that some of the ones you get will be fakes. Even if you think you are paying for premium parts. These fake parts are found in a fair number of repair jobs. The seem to have very poor reliability and very poor manufacturing standards.

How do you avoid fakes?

The best way is to buy only directly from a distributor approved by the capacitor maker and to stick to renowned brands. This will be expensive, and as these will be large-scale distributors, you will run into minimum order quantities more suited to commercial users than individuals.

Some data does exist about estimated life testing done by capacitor manufacturers. They show it only to trusted customers in companies which have signed legally binding non-disclosure agreements. I was involved in choosing capacitors needed to have a high probability of surviving for a specified minimum period at high altitude for unusually long periods of time. Temperatures were going to vary over a wide range. What they went into was the subject of more non disclosure agreements. We wound up with some parts which ought to do the job with reasonable confidence, and which have worked as required so far.

So there is some information , but you may not be able to access it, and it is likely only collected for capacitors too expensive to be in your equipment.

Lots of theory and parts outside the price budget of your equipment... so what most people do is to live with it and fix things when they discover there have been failures. In industry, most important equipment is powered up at least once a year for re-calibration and this serves to allow electrolytics to re-form, so a lot of knowledge comes from this. Information from warranty repairs used to be collected when most manufacturing was in the west and in Japan. But it seems many companies don't bother. A lot of consumer goods seem not to be repaired. One which fails during warranty gets replaced with a new one, making the consumer very happy. One which fails outside warranty can't be repaired because often ther is no repair service, no spare parts, no repair people. Most goods are now treated as disposable.

I'm sorry, but this is all the information available. Asking the same question repeatedly will not change this.

The military data will refer to a different quality grade of components than you will find in consumer goods.

The data from the manufacturer's own product testing is treated as commercially sensitive. They do not want it getting into their competitor's hands where it could be used against them. Anyone you come across who has or has had access to this commercial data will be covered by binding agreement not to disclose it.

David

[Ed_Dinning]

Hi Folks, when I was running design teams for SMPS, we were given XL sheets by our major suppliers that equated lifetimes with ambient temp, ripple current (in RMS), frequency and shape of cap. This allowed use to have a high level of confidence in cap lifetime as well as making an economic choice of cap (typically aiming for 5+ years).
Note that an often neglected parameter is the L/D ratio of the can for better cooling.

We also actually measured the RMS current in the cap under worst case conditions to be certain.

The US MIL standard are a great help in this work, but unfortunately these days manufacture's data , like some devices, cannot be relied on !

Ed