# Capacitor Question

Discussion in 'Datasheets, Manuals and Component Identification' started by Supercap2F, Apr 10, 2014.

1. ### Supercap2F

550
150
Mar 22, 2014
Hi Everyone!

This is most likely a dumb question but I can’t find a answer in any books on electronics. So here it is: Can a capacitor charge to a higher voltage than what is apply to it? Like if I was to hook up a capacitor to 9VDC and if it had a 30V max voltage would it charge higher than 9VDC?

Thanks for you time

Dan

2. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,480
2,828
Jan 21, 2010

However you can charge up two capacitors to 9V from your battery, then place the capacitors in series with each other and you have 18 volts (briefly)

There are circuits called "switched capacitor voltage doublers" that do this very fast so you can charge another capacitor to twice the voltage of the power source.

And there are other ways too. But without resorting to some fairly clever means (all of which require switching power on and off at some level) a capacitor will only charge to the same voltage as the power source.

3. ### Supercap2F

550
150
Mar 22, 2014
Well that cleared some stuff up.

Thanks for the help Steve

Dan

5,165
1,087
Dec 18, 2013
If you apply nine volts to a capacitor rated at 30 volts you will only get nine volts. From your post it seem you think it might charge to 30 volts. The capacitor has a max voltage of 30 volts. Also the cap value is at its rated voltage. So a 100uf cap rated at 100V will read different at 10 volts.