As above the clock can draw small current..also some after market Alarms.....but only small draws on Battery...main item to kill a battery over night is a leaking Alternator Diode....best way to check unplug the Alternator... you should have then just ..2 / 3 ma amps or less re type of Alarm...with a duff Alternator..up to 7 amps....OAP Pete