I've got a Rover 214Si which loses a lot of charge overnight, particularly if it's a cold night. I've got three batteries which all hold full charge when they're off the car, but all three lose charge when they're fitted. The car starts instantly when I use one of the spare batteries with jump leads. Once it starts it's ok for the rest of the day.
The alternator's been tested and it's delivering what it should be. It is newish, after all.
The only electrical device running overnight is the immobiliser, but the battery loses charge as if the lights had been left on all the time.
I'm just wondering if anybody's had the same problem and found a cure.
Cheers,
KeithC