Last night on my way home from meeting a few friends at tim hortons I was just cruising when my radio started flickering on and off, then suddenly I had no power at all and the motor completely shut off. After opeining the hood and using my cell phone as a flash light I removed the subwoofer connection from the battery terminal and hooked the terminal back up and realized the bolt was stripped so the connection wasn't very good, but even so shouldn't the car still run off the alternator if its already running? What would cause it not to?