> "Life is defined to be expired when the capacitance is reduced to 30% of
> the nominal value" and:
> "Supercap life = (life in hours at To)  * [ 2 ** ( ( To - T) / a) ]"
>
> where
> To = operating temp
> T = test temperature
> a = some coefficient in the range of 6-7

OR

> All components double their life for every 10 deg C temperature reduction.

I'm not a supercap expert BUT -

Version two is THE standard rule of thumb for electrolytics in general and
is as close as you are generally going to get. It is far less likely to
apply strictly to other types of components.

Rule 1 MAY apply to components made by the manufacturer who proposes it but
it's probably empirically derived and there's no reason to think that it
would apply with precision to anyone else's caps and only some reason to
think it would apply with any degree of precision to NEC caps over many
decades of temperature. ie at 20C for a 105C cap odds are that the rule of
thumb could be quite wrong.

I'd guess that in any crucial application that you need to err on the side
of caution (as always).

It's worth noting that the quoted and calculate lifetimes apply to
electrolytics with full rated voltage applied. Aluminium electrolytics die
far quicker at extended temperatures when no voltage is applied (which may
be the opposite to what is expected intuitively). I have no idea how this
applies to super caps.


        RM

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