[time-nuts] Replacing electrolytics - any disadvantages of high temp ones?

Dr. David Kirkby david.kirkby at onetel.net
Mon Jun 20 23:40:09 UTC 2011

On 06/20/11 10:44 PM, Poul-Henning Kamp wrote:
> In message<4DFFBAF4.4070004 at onetel.net>, "Dr. David Kirkby" writes:
>> 1) Higher temperature devices (like 105 deg C) will be more relieable than low
>> temperature ones like the standard 85 deg C cap. I'm sure at high temperatures,
> You should check both temperature and lifetime rating of the capactors.

I have, but I would assume one rated at 6000 hours at 125 deg C would be at 
least as good as one rated at 7000 hours at 105 deg C.

> There are many capacitors on the market these days with 5000h or
> even 2000h rated life.
> That is 7 or 3 months respectively.

Even 1000 hours I've seen. But these are of course at the maximum temperature, 
which few would use them at. Otherwise failure rates would be a lot higher than 
they are.

I've not seen any electrolytics rated more than 10,000 hours (14 months), but 
they last a lot longer if the temperature is lower.

My PC is already more than 14 months old, and has been on 24/7. Hopefully it is 
not dying on me.

> And yes, it should be criminal to manufacture and sell those.

Well, I think the MTBF will be a lot more than that in practical use, as few 
would design equipment to run at 85 deg C, which is the lowest maximum 
temperature rating I've seen on any cap.

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