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View Full Version : Charging a Capacitor?



jnolte
07-06-2006, 06:00 PM
Any one know how?

I have a 1 farad cap that i was using, it was charged by the previous owner, this past week i uninstalled my system and reinstalled it with some diffrent components, hooked it up and the cap turns on but dosent have any numbers on the Digital display like before. I was playing the music for awhile and a led started blinking red and i quickly shut off the car.

I think the cap needs to be charged or something since there is no voltage numbers being displayed on the cap.

anyone know how to charge a cap, correctly?

c55m8o
07-06-2006, 06:49 PM
1 Farad. Big!
Otherwise, ? I'm befuddled. I thought any Cap runs in parallel to the power supply, and all you have to do is apply power and charging is 'automatic'. Obviously here there's some electronics in the way that needs to be triggered to allow the voltage to be applied to the Cap and charge built. I'm eager to hear the answer from someone.

jnolte
07-06-2006, 06:51 PM
you need to charge the cap first with a 1 watt resistor.

1 farad is too small i should be using a 2 farad perhaps this is an excuse to upgrade!

c55m8o
07-06-2006, 06:56 PM
Great thing about caps are to get to the second Farad you just need to buy and add another 1 Farad in parallel instead of getting rid of the first 1 Farad and buying a 2 Farad.

Renn 208
07-06-2006, 08:17 PM
Not to distract too much from jnolte's question, but can someone explain to me at what point does a person need 2 farads of capacitance? Why is it better than say, putting in a higher output alternator?

jnolte
07-06-2006, 08:44 PM
Originally posted by Renn 208
Not to distract too much from jnolte's question, but can someone explain to me at what point does a person need 2 farads of capacitance? Why is it better than say, putting in a higher output alternator?


putting in a higher output alternator is better but generally more expensive. Its also hard to find for mercedes. 2 farads generally covers for 2000 watts or less of power

1995c280
07-07-2006, 02:45 AM
jnolte, put the resistor in series with the power wire. connect a power wire from the battery. then you have your fuse like when you wire the system. then connect the resistor to that. you can hold it with your hand. it won't get that hott. then hold wire to the other side of the resistor straight to the power of the cap. then. also connect ground to the cap. hold it like this until the cap reaches at least 12V. then hook up the cap to the system like you would normally wire it. radio shack has resistors or go to any audio store and get a resistor with a bulb built in (like $3). with those you just hold the wires until the light goes out, then its fully charged. if your using 4 gauge wire for your system you can hold that to the resistor. hope this helps out!

Jason

rman
07-07-2006, 06:07 AM
capacitance is very...um....touchy

a cap is actually just a bandaid to help bridge the gap that you are losing from lacking alternators or batteries. The better choice would be to upgrade the alt.

You can see mralternator.com and see if he has any, or send yours in (or a spare) to have it rewired somewhere.

Also, many people say that a cap is good for 1000w. But is that RMS or MAX?!? I have heard that really you should have one for every 500w, again is that RMS or MAX.

the best way (if anyone is super anal about it) is to check your voltage drop (with a multimeter) during hardcore bass notes. then add a cap and test again, repeating until the car sustains voltage. Should be in the 14ish range. (with engine on).

Anyone here ever try a batcap? i've read reviews on them (and they are good) but never met anyone who's actually tried it

Renn 208
07-07-2006, 09:43 AM
okay, I think I understand a little better now...thanks for the info!

NISMOPOWERED
07-08-2006, 03:26 PM
In general a battery or alt are not as fast as the amps would like. A cap has the ability to supply the power in the spikes to match the music. They can discharge and recharge alot faster.

therock2689
07-11-2006, 07:49 PM
Like said above, a cap and discharge much fast then a battery and supply mroe power the an alt in the same time. Now, a cap can only put out for so long since its a quick discharge. A battery can "create" power, if you will, from a chemical process, while a cap can only store power. An upgrades alt will help alot, with an external volt. regulator. Problem with most alts is that it is on a internal volt. regulator, and when electrocal parts get hope, and impedence goes up, causeing the voltage to go dn.
as far as charging a cap, i know my Rockford came with one and most caps do come with one, it can either be put on the electrodes(post) just clamped on there or can be conected with wires attached to it. They probly will get you one if you ask for it, i dont know for sure. but you can build one like explaned above from radio shack. What i do though, is a grab either my power inverter or my computer power supply and charge it there and then hook it up, with the charge card.
Good luck though with all you ventures.
Srry for any spelling mistakes, i suck as english