This battery is rated at 12 amp hrs. @6volts. That means you can draw one amp for 12hrs or 12 amps at 1 hr---ROUGHLY. In theory, you could daisy chain 2 of them in series to get the 12 volts you need, but in practice, you risk an overheat situation with the case rupturing--or worse. I tried that once and lucky, it was in my garage----acid all over the wall. I don't want to think of that in a car. PE has good 12v batteries. Also consider a "marine deep cycle" battery. They are designed to discharge almost all the way between charges.