Extra batteries do have their place, however. Think of the altenator as your job, and a battery as your piggy bank. Your daily expenses get paid by your job, and you've got some left to throw in the ole piggy. But when you miss a couple days, but still want the AudioThunder 100000 you've been dreaming of, you bust open said piggy, and spend baby, spend.

Same thing in car audio. Your alternator puts out current, say, 100 amps. On a regular day, music at normal level, maybe your amp uses 25 of that, and the rest of the car another 25 (just numbers here). The remaining 50 can go in your battery, for later. Now, a good tune comes on, you crank the stereo, and start driving faster (the two just go together). Now, your amp is pulling 75 amps, and your car 50. Since your alternator can only provide 100 amps, the other 25 have to come from your battery. Obviously, if you did this too long, your car would be stopped and silent.

The extra battery acts just like an extra piggy bank. The alternator will fill any demands, and then take the rest of the day off. That can mean filling one battery, or seven batteries. Obviously, more piggies is good for those spending sprees.

Now, think of your stereo as your girl. If she's cool, and just goes along with things, and doesn't mind QSL Thursday's as her night out, that's great. Your job will be good enough, and you can get by with one or two piggy banks. But, if she's one of those Paris wannabes who just has to have the latest designer shit, and only eats at places you can't pronounce, you'll eventually need a better job, or another job. See where this is going...piggy banks only work if you can refill them quicker than you empty them. Batteries only work if you have enough alternator to refill them before your stereo sucks them dry. If your stereo is high maintenance, you'll soon need either a bigger or a second alternator. Just like the hot chick, everyone wants a bigger, badder stereo, but you can't score the hottie working at BK. Or, you can date the more realistic chick, who's content only going out big time once or twice a week.

So, if you've got a modest to large stereo, and you can live with modest volume most of the time, but still want to jack it up once in a while, your stock alternator and battery, plus maybe one more, will do it. But, if you have to be cranking it all the time, and / or you just need bunches of watts, you'll need a bigger, better (or second) alternator.

Also, contrary to popular belief, if you're pulling big power, more batteries and bigger alternators generally wont keep your lights from dimming on bass notes, nor will they keep you at 14.4, or even 13.8 volts. Nothing happens that instantaniously. When your amp suddenly wants 150 amps, even your 250 amp alternator takes time to get there. Sure, your batteries try to pitch in, but they don't react intantly, either. In whatever amount of time this takes, there will be a voltage drop, and your lights will dim.

If I were you, I'd give up on trying to get 14.4 at the amps. The amount of time and money that would take is just not worth it. Like I said above, even all the way down at 12v, you only lose about 1 db. Since you'll probably be up around 13.5, the loss will be even less. If you just have to have 1000 watts RMS in your setup, find an amp that will do it at 12.5-13v, instead of 14.4.

Toby