Alternator/battery and capacitor huge different is their discharge rate.

Those current surge/voltage drop can only compensated with capacitor (instantaneous,extremely short time), even if your alternator got 1000A also useless, it just can't compensate fast enough compare to capacitor.

Try to think about that, every PSU circuit they are main filter/supply caps, what the purpose? Same as what i said above.

I'm R&D engineer in electrical field, i'm talking neither based on my book nor my cock, but from my research and result from expensive testing equipment.

Still add or not is up to you, becos most of the electrical equipment such as amp and player adi got such same function cap inside, just that usually the value is too small to store enough charges. If your car alternator is bad in nature, add or DIY cap aka VS will help a little bit.

This post has been edited by coolkwc: Jan 24 2011, 06:12 PM