Originally Posted by xsdbs
The TAU rate of a cap is where issues can come into play. A cap will charge and discharge rapidly causing transient spikes to the alternator. What does this do? It causes the alternator charging circuitry to spike high and low quickly, the alternator may not be able to keep up with these spikes. It will also cause most alternators to have excessive heat due to added resistance. These items we usually lead to decreased life of the alternator.
What's the best bet then? Well in the systems that I used to build, I would incorporate a high output alternator and also an extra battery close to the amp rack. The battery is actually an extremely large cap and provides more consistent filtered power without the spikes.
Yes, a alternator upgrade to handle the extra power consumption of the amps that was not in the design of your truck.
A battery at the location of the amps to eliminate the spikes from the amps may work if your alternator is not upgraded. Don't use the capacitor.
Run your wiring kit to the extra battery (+) then connect your amps to that extra battery. Make sure you use a sealed battery and a fuse after each battery.
Hope your alternator can keep-up with the power draw.