2 part q: amp battery/alt question

[goodbabbu]

This is a 2 part question...
1. What is the purpose of a battery when you are running an amplifier(s)? If the amplifier draws all the current from the alternator, then why do ppl suggest to get a good battery?
2. I am getting a mono amp that might draw about 100-120 amps alone! So, the only thing i can do is put a big alternator? How can a capacitor help in anyway?

thanks for the input!
G

[leapin]

Well first off the alternator is only there to charge the battery. Everything draws from the battery. The alternator "trickle charges" it kinda when ever it is needed. People say get a good battery because it is less work for the alternator. A junk battery will not hold well and then the alternator will be working overtime. A capacitor in theory is a device to hold a charge as well and basicaly smoothen out the draw the battery sees. So when the bass hits and the amp needs juice it can pull a reserve from the capaicitor and not from the battery as much.