I doubt that you would be keen to leave the car without alarm protection if disconnected. If the alarm was activated whilst the battery was connected then it will of course keep going until you return !! Either sort out your battery drain or do as suggested,buy a jump start pack. I have read about the sat nav unit in the boot draining on some models causing grief if not allowed to shut down properly , but never having this system on my car , i dont know a great deal about it ...
