Originally Posted by HP Autowerks
I don't think it is an issue with a defective battery from Braille, but more of a electrical draw issue. There are way too many electronic consumers on the E9X cars, especially with comfort access, that particular system might be staying awake at all times, drawing maybe 80-100 milliamps, which can run the Braille batter down in a few hours. a 40-50 milliamps is the typical draw on the late model BMW's that won't cause any problems.
In addtion, if the car is only drive a few miles a day, that is not enough to keep the battery charged. We have seen cars driven on city street coming in for service that only have a charge level of 70%
It comes down to a simple question. Either the battery is suitable for the M3 or not. I suppose you might be able to qualify that and say it is OK for non CA and not OK for CA but that is really pushing it.
Are you sure CA takes that much power, ~1 watt? The system should be
an RFID system that consumes truly 0 power until it has to reply. If it will drain the Braille in a few hours it would certainly drain the OEM battery in a few days, which it doesn't.