aluminium capacitor tolerances over temperature/time

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umesh49

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Hi,
I am using Panasonic made aluminum capacitor and looking for the information for capacitor tolerance over temperature and aging.
Any one have any idea how to consider it for 22uF, 20% capacitor? Any help would be highly appreciated.

Regards,
Umesh
 


You can ask the Panasonic company for such data. I am afraid they woul not like to publish it. Elecrolytic capacitors are notoriously known for poor dependence over temperature and time. It is recommended where appopriate to use larger values and higher voltage rating.
Tantalum capacitors promise to be better but still I had exploding ones rated for 30V on a 12 v dc bus.
Over time, many electrolytics die or lose capacitance. If you can, use paper or ceramic capacitors or connect such ones in parallel.

There may be some data in MIL standard on reliabilty but I failed to find any.
 

Depends a bit on which model you look at, but roughly you double projected life-time for every 10C you drop the cap in temperature. So if your cap is rated 2000h@105C, it may crap out after 4000h@95C, 8000h@85C and so on...
 

As Ice tea mentions, temperature is a key factor.

But it is not only external temperature...self-heating is also a factor, depending on the amount and frequency of the ripple current.
In those instances it is usually better to have two (or more) capacitors in parallel instead of single large one. For instance, the combined total ripple current of 3 X 1000 uF is usually larger than that of a 3300 uF (assuming the same voltage and capacitor series).

As an example: a Nichicon 63 volt, 3300 uF VK series, has a max ripple of 2700 mA, whereas 3 X 1000 uF, 63 volt has a 1300 X 3 = 4200 mA max ripple rating.
 

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