Ups...I also got that announcement last week. It was about -20C degrees outside and I put auxiliary heater on with remote.

After 30 min I noticed that it wasn't on ( ) and the car was asking date and time with high battery discharge text.

Anyway it has only happened once...this far.

 

I had the same problem also. My dealer told me that the driver door comfort access sensor is constantly searching for a key. That drains the battery out.

 

Well, they swapped ot the comfort access sensor and it's still happening....back to the dealer soon.