The invention relates to an electrically-driven container straddle carrier, terminal tractor or equivalent free-travel device which runs on rubber tyres and handles containers. The device (1, 2, 3) is provided with a repeatedly-chargeable electric power storage and an automatic charging system connected to the power storage which is arranged to couple to an external source of electric power for a part of the work cycle of the device (1, 2, 3) handling containers for charging the electric power storage without disturbing the normal work cycle of the device. When the device is a transport straddle carrier (1) which operates in a cargo terminal between a crane (4) and a container interchange area (5), the automatic charging system comprises a power supply station (7) arranged in the terminal area advantageously into connection with the container interchange area (5), provided with a power supply head, whereby the container straddle carrier (1) is provided with a charging head (12) connected to the power storage and coupling to the power supply station (7).