down if i let it sit for more than a couple of weeks. i really did not know what was doing it until i unhooked the anti theft module. i unhooked it because i have a bad lock switch or something, every time i unlocked my car the damn alarm would go off. after i disabled the anti theft, my car sits weeks at a time and i never have a dead battery. this may not be your issue, but it is something to look into.