Charging device (1, 1a, 1b) for charging the traction battery of an electric vehicle from an energy source suitable for charging the traction battery, the charging device (1, 1a, 1b) having at least one terminal for connection to the charging port of the electric vehicle and at least one terminal for connection to the energy source suitable for charging the traction battery, wherein a) the charging device (1, 1a, 1b) is designed as a portable charging device (1, 1a, 1b) that can be carried in the electric vehicle, b) wherein the charging device (1, 1a, 1b) is set up to detect a vehicle identifier that clearly identifies the connected electric vehicle, c) the charging device (1, 1a, 1b) being set up to detect the amount of energy charged from the energy source into the electric vehicle during a charging process or a parameter characterizing the amount of energy and to store it in a storage device (13, 40, 41), which can be a storage device of the charging device (1, 1a, 1b) and/or a remote storage device (40, 41), with an assignment to the vehicle identifier of the electric vehicle, characterized in that d) the charging device (1, 1a, 1b) is set up to detect an energy source identifier which uniquely identifies the connected energy source, e) wherein the charging device (1, 1a, 1b) is set up to store the detected charged energy quantity or the parameter characterizing the energy quantity with an assignment to the energy source identification of the energy source in the storage device (13, 40, 41), f) wherein the charging device (1, 1a, 1b) is set up to store the detected charged energy quantity or the parameter characterizing the energy quantity with an assignment to a charging device identifier uniquely identifying the charging device (1, 1a, 1b) in the storage device (13, 40, 41), g) it being possible to create an energy consumption list for each individual electric vehicle or for respective groups of electric vehicles from the energy consumption data stored in the storage device (13, 40, 41). a) the charging device (1, 1a, 1b) is designed as a portable charging device (1, 1a, 1b) that can be carried in the electric vehicle, b) wherein the charging device (1, 1a, 1b) is set up to detect a vehicle identifier that clearly identifies the connected electric vehicle, c) the charging device (1, 1a, 1b) being set up to detect the amount of energy charged from the energy source into the electric vehicle during a charging process or a parameter characterizing the amount of energy and to store it in a storage device (13, 40, 41), which can be a storage device of the charging device (1, 1a, 1b) and/or a remote storage device (40, 41), with an assignment to the vehicle identifier of the electric vehicle, characterized in that d) the charging device (1, 1a, 1b) is set up to detect an energy source identifier which uniquely identifies the connected energy source, e) wherein the charging device (1, 1a, 1b) is set up to store the detected charged energy quantity or the parameter characterizing the energy quantity with an assignment to the energy source identification of the energy source in the storage device (13, 40, 41), f) wherein the charging device (1, 1a, 1b) is set up to store the detected charged energy quantity or the parameter characterizing the energy quantity with an assignment to a charging device identifier uniquely identifying the charging device (1, 1a, 1b) in the storage device (13, 40, 41), g) it being possible to create an energy consumption list for each individual electric vehicle or for respective groups of electric vehicles from the energy consumption data stored in the storage device (13, 40, 41).