Re: gEDA-user: electrolytic capacitors

[Steve Underwood <steveu@xxxxxxxxxxx>]

gene wrote:
> What does it mean when manufactures specify 'Endurance @ temp' or 'life 
> time @ temp'?  For example, one company claims:
> Endurance : 105 C 1000 h to 5000h
> Then they further state that after testing at 105C with maximum ripple 
> current applied, that when the part is cooled to 20C, it will then meet 
> original specs.
>
> Do that mean, that whatever degradation occurs at elevated temperature 
> and ripple current, that they go back to normal once cooled?  I'm just 
> looking for validation that my understanding is correct.
>   
Most electrolytics are liquid types. Some are solid. The solid ones last 
an extremely long time, with very little variation in performance. The 
liquid ones dry out, as they are not hermetically sealed. Their 
lifetimes are dependent on the drying out rate. The hotter you run them, 
the faster they dry out. These time vs temperature specs are simply a 
measure of how fast that drying occurs. Run them hot for just a few 
weeks, and they are toast.

Regards,
Steve



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