Estimate what an electric vehicle charge costs, either from battery capacity and percentage added, or from trip miles and consumption, with an editable charging efficiency.
Charge amount mode
Trip mode, and cost per mile
Trip mode uses miles and consumption; cost per mile uses the consumption figure in both modes.
Estimate only. Home and public charging prices differ, and charging losses are covered by the efficiency field.
In charge amount mode, energy added to the battery is the battery capacity multiplied by the percentage charged. In trip mode, energy used is the miles multiplied by the consumption in kWh per 100 miles, divided by 100. The electricity actually drawn from the supply is higher than the energy stored, because charging is not perfectly efficient: the estimate divides by the charging efficiency (90% by default, roughly a 10% loss) and prices the drawn energy. Cost per mile uses the consumption figure and the same efficiency adjustment. All results are estimates: home electricity is usually priced well below public fast charging, time-of-use tariffs change the price by the hour, and consumption varies with speed, weather and terrain.
Why is charging efficiency included? Not all the electricity drawn from the supply ends up stored in the battery; some is lost as heat in the charger and battery. At 90% efficiency, storing 45 kWh means drawing 50 kWh, and the bill is for the 50 kWh drawn.
Why do home and public charging costs differ so much? Home charging uses a residential electricity tariff, often the cheapest rate available, while public chargers add equipment, network and service costs on top of the electricity. The same charge can cost several times more at a public fast charger.
How is cost per mile worked out? Cost per mile is the electricity price multiplied by the consumption per mile. At 30 kWh per 100 miles, consumption is 0.30 kWh per mile, adjusted by the charging efficiency, then multiplied by the price per kWh.