I charge my M3 RWD using a 240V 24A Nema 10-30. When the traction battery cell temps are below 54F and above 44F, it charges at 7 to 8 MPH instead of the normal 22 to 23 MPH. I have not charged with cell temps below 45F this year but from last year temps around 40F no miles were added initially while the traction battery was warming. As soon as the cell temp reaches 54F, the traction battery heating stops and the charge rate reaches 22 to 23 MPH. Since I was getting 8MPH and the remaining power was used for heating, I assumed no heating would be needed if I set the amperage setting to 5A; however, all of the power was sent to the stator for traction battery heating with a MPH charge level of 0. Logic told me that at 50F cell temps no battery heating would be required at the 5 Amp setting so I was surprised by the 0 MPH.