I tried charging my R9T battery using a cheap battery tender with a adaptor plug into the aux socket, it wouldn't work, I tried turn on the ignition and off, it worked for 5 min then off, then I found this charger on the website TecMate OptiMate 4 Dual Program Battery Charger for BMW CANbus - RevZilla.
It seems that the charger must be compatible with the can bus system, is this the right charger? Do I have to buy one from the dealer? Any one has a good suggestion, thanks
It seems that the charger must be compatible with the can bus system, is this the right charger? Do I have to buy one from the dealer? Any one has a good suggestion, thanks