Capacitor not keeping its charge? Please help

[MO_GUY]

When I charged my friends capacitor the voltage wouldn't stay up? Should the capacitor be hooked into the amp's power also or what? I had a ground wire and the power wire that comes from the battery.....I hooked the power wire to the + of the cap and put the resistor on the - of the cap and touched the ground to the other end of the resistor, it went up to 12.5 volts then as soon as i stopped touching the resistor with the ground wire the voltage dropped.......why is not holding the charge?

 

[Nate1]

You have to ground it! Leave the ground touching the resistor (you may want to do a parallel+series combo of a few to dissapate heat better), and let the cap charge up.
Then permantly attach the ground without the resistor, and let be.
You want as short as possible a length of right guage power wire from the + terminal of the cap to the amp.

 

[MO_GUY]

i have to take the resistor off sooner or later.....it says to charge it before touching the ground to the - on the cap.....will the voltage stop dropping when i put ground to the -?

 

[Nate1]

Yeah. The resistor is to fill the cap with charge. Voltage is only potential difference. If you dont have a ground, you cant measure voltage. Once the cap is charged up with juice, think of it as a 10,000amp battery. You dont want it sucking all that at once, hence you use the resistor. After a few seconds (30?) with the resistor, take it off and forget it. Just connect the ground and marvel at your solid voltage.

 

[MO_GUY]

well we hooked up the light bulb til it wasnt lighting up and the voltage read 12.5 like the instructions said.....then took it off and the voltage went down.......so now i just hook it up like it should be and it should be charged?

 

[Nate1]

Yes it should be. If not, sue
The worst that can happen is you will touch the terminal and a big zap of current will leap through a few strands of copper and they will vaporize, and spark, and you will pull your hand back and yell 'HOLY S**T'.
Seriously, you'll be fine.

 

[MO_GUY]

cool! thanks nate!