Max Alternator Output

radensb

Actually, it is showing the capacitor in parallel with the amplifier, which is correct. But I agree the diagram is not drawn very intuitively.

Capacitors are only of use in certain situations.

1. The car alternator has to already be up to the task to power the system.
2. The type of music that is played.

Typically, audio amps are rated for peak power, which is rarely ever reached. Most of the time, you are running RMS (root means squared) power, so keep that in mind.

The caps can help lower the instantaneous power demands of the amplifier from the cars power system during high current bursts (heavy bass bump) because it can supply the needed current faster than the battery can. (a cap is just a battery at heart and looks like an open circuit component once charged thus it doesn't draw anymore current but can supply it when needed) It IS still a load on the cars power system while it is being charged. If you have music that is playing heavy beats that are hitting back to back, over and over again, you will never give the cap time to charge, and thus render it useless (and additionally an extra strain on the power system).

The charge time for a 3 farad cap is not trivial. Lets assume that the resistance in the wire from the 12 volt battery to the 3 Farad cap is 0.5 Ohms. That means it will take 1.5 seconds to charge! If your resistance is 1 Ohm, the charge time increases to 3 seconds.

The point of a cap is not to supplement the power responsibility from the alternator. Rather, it is there to help regulate current spikes and voltage drops caused by the inherent rapid power demands that audio amplifiers introduce.