The invention relates to an energy supply (11) for supplying an energy consumer with electrical energy. The energy supply (11) comprises a mounting device (20) as well as a battery (29), a charger device (30) and a load connection (33). The energy supply (11) also comprises an energy connection for connecting an energy source, and an energy converter (31) for converting the energy received at the energy connection into a form of electrical energy which is suitable for charging the battery (29). The energy which is stored in the battery (29) can then be made available at the load connection (33) for supplying one or more energy consumers which are connected thereto. The mounting device (20) is provided here with connecting devices (23, 24) which are compatible with those attachment devices with which corresponding transportation containers can usually be connected to a transportation vehicle. It is therefore possible to arrange such an energy supply (11) for transporting a transportation container between the latter and the appropriate transportation vehicle, wherein for example the kinetic energy of the moved transportation vehicle can be utilised for the charging of the battery (29) in that e.g. the rotation of the wheel axle of the vehicle is converted into electrical energy with a hydraulic generator.