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From: john larkin <JL@gct.com>
Newsgroups: sci.electronics.design
Subject: Re: heating a cap
Date: Sat, 05 Oct 2024 08:09:21 -0700
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On Sat, 5 Oct 2024 13:20:51 +0100, Clive Arthur
<clive@nowaytoday.co.uk> wrote:

>On 04/10/2024 00:36, john larkin wrote:
>> I got a small (under 1" long) aluminum electro cap, 220 uF 63v, and
>> cranked up the voltage. It started drawing a bunch of current at 105
>> volts, got hot, and folded back to 80 mA at 87v.
>> 
>> It got too hot to touch in a couple of minutes, after roughly 500
>> joules. Freeze spray let it go back up to 100 volts or so.
>> 
>> None of that seemed to damage it, so an electrolytic cap sort of has a
>> built-in MOV.
>> 
>
>If you need a high temperature cap, these work and they're not horribly 
>expensive...
>
>https://www.mouser.co.uk/datasheet/2/40/THJ-3165556.pdf

I reall want to absorb joules when a power supply is back-driven by a
load, like decelerating a motor for instance. So I want caps with a
lot of mass, or MOVs that can get very hot before they die.

The environment won't be very hot, but the cap (or MOV) will.