Question Advice on storing aluminum electrolytic capacitors ?

[cloudff7ps1]

What recommendations on how to prevent deformation of the dielectric layers in aluminum electrolytic capacitors from stored electronic devices that were manufactured in the early 90s and early 2000s and store in my home at a temperature of 33-36C, humidity 57-67% and energized devices at 220v AC 60hz?

 

[Misgar]

Over decades, some degradation in electrolytics is inevitable and storage temperatures over 30C are not ideal. Some people subject old electrolytics to a gradual "reforming" process, instead of simply switching the unit on.
https://www.qsl.net/g3oou/reform.html

This often requires a thorough understanding of power supply operation and the danger of removing covers on mains PSUs, so it is not advisable unless you are a trained electronics engineer, technician or HAM radio enthusiast.

On a 30-year old item of equipment, I regard all power electrolytics as suspect and potential (small) time bombs. I've had electrolytics explode in equipment that has been running in standby mode for many years and then switched on.

When all else fails, I recommend replacing all electrolytics with brand new components. This is best done before powering on the unit containing ancient capacitors. A short circuit capacitor could kill associated semiconductor devices.

 

[BFG-9000]

Well nandobadam, you can't really prevent that but it shouldn't be a problem in itself.

See, electrolytic capacitors built until the 1970s could corrode and fail with a dead short or explosion which could damage circuits if just abruptly powered on again after long storage. So if stored unpowered for many years, they should be gradually preconditioned by gradually raising the voltage to reform the oxide layer slowly. The problem is many circuits are actually damaged if you did this in-circuit, leading to the suggestion to remove them to do so--and if you went to the trouble to remove them anyway, well may as well replace them with more modern equivalents.

Supposedly after that, the components used were high enough purity that this just didn't happen anymore, and the oxide layer will reform properly just by switching it on--it may not operate properly the first time it is switched on after long storage, but shouldn't damage anything. But there's liquid inside which can dry out over many years through the rubber seal on the bottom with two holes in it, and if it did that then the circuit wouldn't work until the capacitors were replaced, but again--very little likelihood of damage from just switching it on with dried capacitors.

In your case the early 90s capacitors should be OK, but 1999-2007 was the capacitor plague when apparently some engineer stole an incomplete copy of the secret electrolyte formula from Rubycon of Japan. All electrolytic capacitors from China or Taiwan during this period are extremely suspect and should be tested before operation, while Made in USA or Japan should be OK if they haven't dried out.

 

[Ralston18]

@cloudff7ps1

Reading your post my first thought was "don't".

After reading the next two posts per @Misgar and @BFG-9000 my second thought was "don't."

So "don't" store them.

Ensure that they can be properly disposed of and get rid of them.

Don't put your home, your family, and you at risk with old electronics. Stored or otherwise.

Just my thoughts on the matter.

 

[USAFRet]

This is in relation to buying some piece of hardware, and storing it on the shelf for a few decades?
And then, hoping it will magically 'just work'?

HDD, DVD, tape drive, PC, monitor...?

Don't.

 

[cloudff7ps1]

Well nandobadam, you can't really prevent that but it shouldn't be a problem in itself.

See, electrolytic capacitors built until the 1970s could corrode and fail with a dead short or explosion which could damage circuits if just abruptly powered on again after long storage. So if stored unpowered for many years, they should be gradually preconditioned by gradually raising the voltage to reform the oxide layer slowly. The problem is many circuits are actually damaged if you did this in-circuit, leading to the suggestion to remove them to do so--and if you went to the trouble to remove them anyway, well may as well replace them with more modern equivalents.

Supposedly after that, the components used were high enough purity that this just didn't happen anymore, and the oxide layer will reform properly just by switching it on--it may not operate properly the first time it is switched on after long storage, but shouldn't damage anything. But there's liquid inside which can dry out over many years through the rubber seal on the bottom with two holes in it, and if it did that then the circuit wouldn't work until the capacitors were replaced, but again--very little likelihood of damage from just switching it on with dried capacitors.

In your case the early 90s capacitors should be OK, but 1999-2007 was the capacitor plague when apparently some engineer stole an incomplete copy of the secret electrolyte formula from Rubycon of Japan. All electrolytic capacitors from China or Taiwan during this period are extremely suspect and should be tested before operation, while Made in USA or Japan should be OK if they haven't dried out.

Some people had told me to turn on my devices constantly to prevent failures in the aluminum electrolytic capacitors, they were wrong because my electronic devices are from the early 90s and early 2000s and some more modern? My temperature, humidity and age conditions of the devices have already been mentioned above.

 

[USAFRet]

Some people had told me to turn on my devices constantly to prevent failures in the aluminum electrolytic capacitors, they were wrong because my electronic devices are from the early 90s and early 2000s and some more modern? My temperature, humidity and age conditions of the devices have already been mentioned above.

Why do you think those people were 'wrong'?

 

[BFG-9000]

Electrolytic capacitors in electronics are the least reliable non-moving part and follow the Arrhenius equation so for every 10°C rise in temperature their expected life is halved, and every 10°C drop means life is doubled. You could thus look up the datasheet for your capacitors where they will be rated for so many hours at 85°C or 105°C, and work out for yourself roughly how long they should last at 35°C.

You'd only need to power on your devices once per year to avoid depolarization and the oxides on the capacitors ever having to reform, and the datasheet on some caps may even state 2 years is OK. The problem if you leave them powered-on all of the time is then they tend to be hotter and that reduces their lifespan.

But as stated, reforming a modern capacitor isn't an issue, and the primary reason they fail is because the electrolyte dries up. Even the bad capacitors from the plague failed because they generated internal gas pressure and vented... leading them to rapidly dry up because the seal was compromised.

If you plan to keep your electronics for many decades, then it is reasonable to expect to have to replace capacitors as they fail. The problem is some electronics like CRTs may have hundreds of capacitors inside making this rather uneconomical and too labor-intensive if more modern replacements like LCDs are available. So you could just keep your vintage broken junk around until they become rare and valuable enough that repair makes sense.

When I have to replace capacitors, I usually first try substituting solid or polymer caps as they often will work and not being wet have both a much longer lifespan and higher temperature tolerance. But that may not always work, as some circuits might be tuned for a very specific ESR that's either difficult to replicate with solids or even unknown as the cheapest no-name caps may not even have a datasheet at all + you don't have a good example to test so it's trial-and-error.

Things could be worse--tantalum caps fail by catching on fire.

 

[cloudff7ps1]

Electrolytic capacitors in electronics are the least reliable non-moving part and follow the Arrhenius equation so for every 10°C rise in temperature their expected life is halved, and every 10°C drop means life is doubled. You could thus look up the datasheet for your capacitors where they will be rated for so many hours at 85°C or 105°C, and work out for yourself roughly how long they should last at 35°C.

You'd only need to power on your devices once per year to avoid depolarization and the oxides on the capacitors ever having to reform, and the datasheet on some caps may even state 2 years is OK. The problem if you leave them powered-on all of the time is then they tend to be hotter and that reduces their lifespan.

But as stated, reforming a modern capacitor isn't an issue, and the primary reason they fail is because the electrolyte dries up. Even the bad capacitors from the plague failed because they generated internal gas pressure and vented... leading them to rapidly dry up because the seal was compromised.

If you plan to keep your electronics for many decades, then it is reasonable to expect to have to replace capacitors as they fail. The problem is some electronics like CRTs may have hundreds of capacitors inside making this rather uneconomical and too labor-intensive if more modern replacements like LCDs are available. So you could just keep your vintage broken junk around until they become rare and valuable enough that repair makes sense.

When I have to replace capacitors, I usually first try substituting solid or polymer caps as they often will work and not being wet have both a much longer lifespan and higher temperature tolerance. But that may not always work, as some circuits might be tuned for a very specific ESR that's either difficult to replicate with solids or even unknown as the cheapest no-name caps may not even have a datasheet at all + you don't have a good example to test so it's trial-and-error.

Things could be worse--tantalum caps fail by catching on fire.

I currently turn on my electronic devices manufactured in the 90s and 2000s once a year for 1 hour (60 minutes), is this correct for my conditions of humidity 57-67%, temperature 33-36C and age of the devices? Someone once recommended that I turn them on twice a year for 24 hours
Is there a study or article or PDF recommending the interval to turn on these devices in cases similar to mine with humidity and high temperature?