A method for supplementing and calculating energy consumed by a vehicle. A system enables electrically operated vehicles to be provided with electrical energy within a limited time slot, and payment for the energy. A vehicle comprising a receiving area for a first energy accumulator, and is characterized in that e) the first energy accumulator is removed from the vehicle, f) a second energy accumulator having a preset level is introduced into the vehicle, g) the difference between the amount of energy in the first accumulator and in the second accumulator is determined, and h) a value indicating the difference is transmitted to a data acquisition device.