There is still so much confusion about battery heating and cooling...
- If you activate pre-heating, the battery will also heat if the BMS determines that it's required (the temperature is low enough). There is no way to specifically command battery heating to begin unless you have an S or X with Ludicrous mode and you activate Max Battery Power.
- Battery cooling will happen automatically any time the BMS determines that it's required (the temperature is too high). There is no way to specifically command battery cooling unless you turn on Track Mode in a Model 3 Performance.
Model S & X have a bespoke battery heater - a resistive heater unit that is dedicated to the battery coolant loop. It can cycle on and off but not output variable power.
Model 3 uses the motor itself to generate heat for the battery. The inverter sends an inefficient wave form to the motor that generates up to 4 kW (13,600 BTU) worth of heat and sends that to the battery pack via the coolant loop. The Model 3's BMS
can vary the amount of heat that it generates. You can see how much heat is being produced on the power bar below the speedometer - it will show some power being used even though you're stopped.
The heating process is what it is and there is no way to speed it up or pre-condition it beyond what the BMS wants to do.