stopcrazypp
Well-Known Member
That's the situation I exactly suspected. The rep thought the range would "return" except he failed to factor in the fact that the guy already drove 11 miles to reach that charger and charged for an hour on a J1772 charger so the pack should have already warmed up. A simple way to tell is to look at the available regen (not sure if it shows up while the car is stationary though).Just got an e-mail from the author. It sounds like the author understood from a Tesla engineer that miles would be added back as he drove (which is somewhat accurate when the pack warms up) but he did in fact leave with about 40 miles of rated range for the 65 mile trip to Milford hoping that he would capture back the range from the cold pack. He was charging for an hour on a J1772 charger so the pack was already warm.
As I calculated before, the actual range lost overnight was 44 miles (~15kWh or 18% of the battery), which indicates a draw of about 1.36kW overnight or around the same as a space heater. So it could have been the BMS frantically trying to keep up the temperature and like David says, the flat pack with large surface area probably makes matters worse than the Roadster in terms of pack insulation.
Besides from an automatic warning to plug the car in during cold temperatures, there can also be a cold temperature parking mode (also a long term parking mode for airport, but that's off topic). You tell the car how long you will be parked and how far you need to travel and the BMS can optimize the heating cycle (the bare minimum usage would be to allow the pack to cold soak and keeping the pack at -10C/14F, the minimum operating temperature of 18650s). Right now the car can't tell so it probably assumes you will use the car shortly and thus tries to keep the battery temp much higher (which is not optimal in this situation).