Re: How long can I listen before the battery dies?
More than likely it wasn't caused by the amplifier, even it it was at 300watts. 1000 watts or so is a whole another story.
You said "it needed jumped", so I'm assuming you had the car jumper-stated and it then started? Was the car cranking/turning over when you tried to start it? If so, you most likely have a dead battery; like sungwei said, typically every 5 years. Unless you have the wrong battery for your vehicle, then it can go bad in as little as a year; I've even heard 3 months. It could also be bad cables, starter relay, or even the starter itself, but usually if its the starter there's no sound. Speaking of this being a car audio board, your cables are connected securely right? Loose battery cables can cause starting problems, and even degrade engine power.
Calling us NO GOOD; you are the social enemy, us people change day to day...