Can anyone advise if the close proximity of the keys to the car when it is parked could make any difference to the battery drain? I have heard that if the keys are stored close enough to the car, then the canbus (?) system doesn't shut down fully - hence more drain. My keys are usually stored indoors, but the cupboard is probably less than five feet from the fuse box of the car.
Also, I wonder could that also trigger my repeated fault mode on the Ctek charger?
I'll experiment further with key position and Ctek reconnected.