If I have a 100V rated capacitor, can I expose it to a 200V source as long as I cut off the source before the the capacitor is fully charged? For example remove the 200V source when the capacitor itself reaches 80V of charge.
Does it perhaps make a difference on chemistry/material as well? I was thinking of doing this with the electrolytic can type.
Capacitors are rated for the voltage across their terminals.
Be aware that in many cases it is desirable for reliability to derate capacitors so that they never get close to their max rating. Also the ratings may also be lower if the temperature is higher.
Why are you using a 200V supply if you are only going to charge the capacitor to 80V? You will be waking more than 50% of the energy.
charge pump (using a switched capacitor to supply a high-voltage, low-current load) or a switch-mode power supply (using a switched inductor)... either way, it's tricky enough that it's worth looking into these before trying to roll your own.
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