Calculate the cost of electricity and charging for an EV
Enter kilometers, consumption at the battery, charging loss and price per kWh. See both the energy for the driving and the larger amount of energy drawn from the grid.
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Worked example
- Distance driven: 100 mi
- Consumption: 30 kWh/100 mi
- Charging loss: 10 %
- Price per kWh: 0.38 USD/kWh
Result
Energy at the battery
30 kWh
Energy from the grid
33.3333 kWh
Cost
12.67 USD
Working
- E_battery = mi × consumption / 100
100 mi × 30 kWh/100 mi / 100 = 30 kWh - E_grid = E_battery / (1 − loss/100)
30 kWh / (1 − 10/100) = 33.3333 kWh - cost = E_grid × price
33.3333 kWh × 0.38 USD/kWh = 12.67 USD
Consumption at the battery and electricity from the grid
The car's consumption is entered in kWh/100 km and must be measured at the battery. The energy needed for the driving is found by multiplying the kilometers by the consumption per 100 km and dividing by 100.
The charging loss is the share of the electricity from the grid that does not reach the battery. If a consumption figure has already been measured from the grid including charging loss, it does not fit the assumption of the field. Use values that describe the same calculation, so the loss is not counted twice.
The formula for charging loss and cost
The energy from the grid is calculated with E_grid = E_battery / (1 − loss/100). The cost is then found by multiplying the energy from the grid by the price per kWh. It is therefore not enough simply to add the loss percentage to the energy of the battery.
Use your own price and a known charging loss. If a figure is missing, it is unknown, and it cannot be replaced by the example's value as an assumption about your car. The calculation gives the electricity cost for the kilometers entered.
Example with 100 km and 10% charging loss
The consumption is 18 kWh per 100 km. For 100 km, 100 × 18 / 100 = 18 kWh is needed at the battery. With a 10% loss, the share that reaches the battery is 1 − 10 / 100 = 0.9. From the grid, 18 / 0.9 = 20 kWh is needed. With the example price of 2.50 per kWh, the cost is 20 × 2.50 = 50.