[Ricochet]

Most autoshops will test your alternator for free. I would take your car to one and test that before replacing the battery, or anything else. If your alternator's hosed, I'd recommend buying one from a junkyard as they are cheaper there (opposed to buying a new one for $300-$400). If your alternator is fine, maybe your battery just needs replaced. You should replace your battery every 3-4 years anyways. Those are easy to do, just unplug the old one and swap in the new. You could also buy a capacitor (I'd recommend a 1 or 1.5 farad) for your subs to lessen the power draw. I have a .5 farad cap for a 500 watt amp and it hardly did anything, that's why I recommend a higher one for your relatively larger power problems.