Compacitor?

Drowsy09

I have a few questions about compacitors.


What exactly do they do?

Will I need one for a C500.1, C400.4, and a Optima Yellow battery?

PolkThug

If you have a good alternator, you don't really need a capacitor.

sept298901

To find out if your car can take ur amps, find the total RMS of your amp. Take the total RMS and divide by 12 volts, and then to roughly factor in the efficiency of the amp multiply by 1.2 if its a class D, or 1.4 if its AB. This will give u do this to all your amps, and add them up, this will be to current draw for your amps, add this to ur car's hot rating and use this to find an alternator that will work for you. if ur current alternator is on the edge then get a capacitor to help out dimming lights, but its really a good thing to have about a 10 amp buffer so ur system, as well as all other accessories in your car can function properly.

hope this helps

madmax

Capacitors store energy, kinda like a battery but short term. The reason you use one is because it can deliver its energy very quickly, quicker than a battery. Imagine a bass drum hit. The cap is charged up and delivers a pretty massive current supply when called for. This somewhat discharges the cap but by the time the next high current surge is needed it is charged back up using energy from the battery when it is not being taxed so much. I used a drum beat in the example but it takes much less time for the cap to re-charge. Its almost instantanious. If you have only a battery you may still get the same effect (or not) depending on what capacitance the amp supply is, the condition of the battery, the amount of energy you are trying to pull out in a given time etc.
madmax

Aimen RG

if ur current alternator is on the edge then get a capacitor to help out dimming lights

dont think so, once the cap provides current to amp, at that moment, the lights wont dim as cap is providing current. but after that, the cap will want itself to recharge to full power again, and recharging is quiete fast, which in turn can cause light dimming,

Jstas

Capacitors are for voltage stiffening and a certain amount of line conditioning and that's it. They are not meant as a band-aid to fix dimming lights nor ore they a fix for a poorly designed stereo or insufficient charging system resources. If you use them for anything other than providing a tad bit of overhead for musical peaks then you are wasting your time and money. Capacitors really only have value in a competition level system where the voltage drops can actually be measured and make a difference.

As far as how to gauge your amperage demands, do not use RMS power ratings. Those are for constant playback and it totally ignores the peak values which many amps will reach when reproducing musical peaks at extreme volumes. If you don't take the peak value into account, you will over-draw your charging system and send all of your equipment into clipping at the same time. Then you destroy stuff.

A much better way is to find the fused ratings on your amps. Your amps will not be able to draw more than that amount of current without popping that fuse. Add ALL the fuse ratings together then look at how much amperage they will draw and compare it to your alternator rating. If you are going to draw more than 50% of what your alternator is putting out, you are going to be pushing the limits of your charging system. Also, take into account things like power seats, window defrosters, electric mirrors, heated mirrors, fog lights, navigation systems and other electrically powered accessories. Those draw current too. So does your drivetrain computer, your anti-lock brakes, your lights (interior and exterior), your engine management computer, if you have an electric cooling fan...the list goes on.

Essentially, if you have a 120 amp alternator and you have all kinds of power doodads and such, probably 60-70 amps of that 120 amps will be sucked up to power everything in the car. If your peak value of all your amps adds up to 65 amps, you have now accounted for all of your alternator capacity and you leave no headroom at all. You can fudge it a bit and get away with it because your amps will not draw peak values in normal listening conditions and your won't always be moving seats and mirrors and such either. So you will be able to get away with it but the more stuff you have to power, the less overall power you have in reserve and you still have to charge the battery too.