I was told that you can only charge it with the special charger if it drops below a certain level. My friend Brian Coleman just accidentally ran his down by inadvertently leaving something turned on. When he hooked the Optima charger up to it, it didn't wake up the battery. He called antigravity and they said just jump it and run it and it will be fine. So I don't really know what the real answer is to that question. I forgot my fan and water pump on one time when I was wondering around the pits. I came back 20 to 30 minutes later and tried to start the car. The battery wasn't stone dead or shut off. It cranked over about a half a turn, but that was it, it didn't start. I put a jumper pack on it and fired it right up. It charged up from the alternator.