Auxiliary Energy Consumption
Auxiliary energy consumption is the electrical energy used by vehicle systems other than the traction power needed to move the wheels.
What counts as an auxiliary load
Examples include cabin heating and cooling, battery thermal management, pumps, fans, lights, infotainment, computers, sensors, heated windows, seats, and steering or braking support systems. The exact boundary depends on the measurement method, so published auxiliary values may not include the same equipment.
Auxiliary power is especially important for EV range because it comes from the same stored energy used for propulsion. A nearly constant 2 kW heating load consumes 2 kWh in one hour whether the vehicle travels quickly, slowly, or waits in traffic. Its energy cost per kilometre is therefore larger on a slow or short trip than on a faster trip of the same duration relationship.
Loads can change sharply with weather and vehicle state. Heating a cold cabin or battery may require high power initially and less after the target temperature is reached. Preconditioning while connected to a charger can shift some of that energy away from the driving portion, but the result depends on the vehicle, charger, temperature, and departure timing.
For how auxiliaries combine with road load to determine consumption and range, see Understanding EV Range.