On an OBDII system can you power up the car enough to unlock the door through the accessory port using a battery "jumping" device that has a cigarette lighter power out? Or must you connect it through the OBDII port? I'm thinking of giving my daughters one of these for Christmas for this purpose. I am aware that you cannot actually jump the car with one. Just wanting everyone to be a little safer by having it in the glovebox for the dead battery/door lock eventuality. Trying to save a window too.