How long have you run your carpc off battery?
Just curious. How long have you guys run your carpc's off the battery alone with the engine off? Were you using a DC-DC PSU, or a inverter? Approximately how much power were you drawing and how big is your battery?
I have a 52 amp hour stock battery and I am paranoid about my carpc draining it. I think I might get a second deep cycle battery which my carpc will run off, and I will use a relay to completely isolate that second battery from the main electrical system when the car is off. This way, I wont have to worry about my carpc draining my main battery and preventing me from starting my car (eg. if my computer hangs on shutdown).