# Are capacitor voltage ratings for max charge or exposed source?

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.

• It can be done, but it's kinda tricky. 1.) Assuming you've got a hot 200 volt source and your box is connected to it and its output is sitting at at 0 volts, how long can you wait for the box's output to rise to 80 volts? 2.) How much current will your 80 volt load require? 3.) How much output ripple can you stand? – EM Fields Oct 11 '15 at 4:31

• That idea sounds like either a 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. – MarkU Oct 11 '15 at 4:03