You can, but what happenes when that battery runs out of juice? I dont know exactly how to do it since ive never needed to, but you can get a battery and put it in the trunk and put an isolator on it so that when your car is off your amp and stereo only run off of that battery, leaving the one under the hood untouched for starting.
ill advised. when the battery depletes, which it will in a matter of minutes running a sub with nothing to recharge it, the voltage rails will sag, the amp will clip, and you'll fry the subs.
just get a big enough alternator, and put a dedicated battery on an isolator. that will be the best solution.
Ok cool, I was just wondering... my lights dim when the bass hits and don't really know what path to take to resolve the issue. I guess the big 3 upgrade first then a new HO alternator next...