This estimator calculates how cabin-heating energy changes the charging time needed after a cold-weather EV trip, with a heat pump represented by its coefficient of performance (COP). It compares the heat-pump load with a simple resistance-heating baseline.
The result is useful for trip and charging-stop planning. It uses average heating demand and charging power, so it does not reproduce a vehicle-specific thermal system or charging curve.
1. Enter driving energy
Use battery energy for propulsion and other loads excluding cabin heat.
2. Estimate cabin heat demand
Enter the thermal energy needed during the trip.
3. Set heat-pump COP
COP is heat delivered divided by electricity consumed; it is normally at least 1.
4. Add charging assumptions
Enter average delivered power and charging loss.
5. Compare charging times
The breakdown shows heat-pump and resistance-heating scenarios.
The resistance-heating comparison assumes COP = 1.
The headline is the time required to replace the modeled trip energy when the cabin heat is supplied by the heat pump.
Actual COP changes with ambient temperature, system design, defrost operation, and operating point.
Given: 45 kWh driving energy, 6 kWh of cabin heat, COP 2.5, 80 kW average charging power, and 10% loss.
Calculation: Heat-pump electricity = 6 / 2.5 = 2.4 kWh. Grid energy = (45 + 2.4) / 0.90 = 52.67 kWh. Time = 52.67 / 80 = 0.658 hours.
Result: About 39.5 minutes, saving roughly 3.0 minutes compared with resistance heating.
Coefficient of performance is heat delivered divided by electrical energy used. A COP of 2.5 delivers 2.5 kWh of heat per 1 kWh of electricity.
Yes. Heat-pump performance may decline, and supplemental resistance heat or defrost can reduce the effective COP.
Include it in driving energy or cabin heat demand if it is part of the trip energy you want to replace.
Maximum power may occur only briefly. Average power better represents the full charging session.
Only when heating is needed and the heat pump uses less electricity than the alternative heating method.