The cost of charging an electric vehicle varies depending on the battery size of the vehicle. Working out the cost is simple math’s. all you need to know is the size of the battery in kw and how much you pay for a kWh of electricity from your energy provider. Example: If the battery was completely empty. vehicle battery size, 50kW. Energy cost 0.14p per kWh 50 x 0.14 = £7.00 to charge the battery from empty.