Kilowatt-hour (kWh)

A kilowatt-hour is a quantity of energy: one kilowatt of power flowing for one hour. For an EV, the battery's kWh figure plays the role a fuel tank's gallons play in a gasoline car.

Typical EV packs range from about 40 kWh in small commuters to over 100 kWh in long-range models. Divide range by capacity to judge efficiency: a car covering 300 miles on 75 kWh uses energy better than one needing 100 kWh for the same trip.