Rover 75

[Rudge]

Why does my battery go flat overnight, Rover Dealer cannot find anything wrong no indication on the dash board that there is a fault. Battery seems to be OK

[woolleysheep]

try disconnecting the battery and leaving it disconnected over night. reconnect next morning, if the battery is still charged it would indicate the battery is ok, if not the battery is losing its charge when not connected the battery is at fault.

[stanleyman]

Check that the boot light and any others are going off when the lids are closed. However, this should not be enough to drain a battery overnight. Batteries are cheap enough so try a new one.

[spaced]

one problem, which we have had with a car on our fleet, is that the brake pedal was slightly low and loose, so when the car was left over night the pedal would slightly drop meaning that the brake lights would come on, thus draining the battery

[wacky racer]

You didn't say how old the battery is. If it is more than four or five years old it would go flat overight if you left an interior light on for example. If the battery is quite new (and is charging properly during the day) it should be doing nothing more than keeping the clock going overnight. If you have access to an ammeter you could measure if there is any significant current flow from the battery when everything else is turned off. An old Astra of a colleague was discharging back through the alternator/regulator due to a bad connection.