An electric energy storage and supply system comprising a tank capable of accommodating a plurality of battery units where each battery unit comprises an electric energy reservoir having positive and negative voltage supply terminals, three or more electric contact pads on an outer surface of the battery unit, and a dynamically configurable connection unit for electrically connecting each of said positive and negative voltage supply terminals to any one or more of said electric contact pads, wherein electric energy can be drawn from the electric energy reservoir via selectively different combinations of electric contact pads. The system further comprises at least two inwardly facing tank contact pads provided on the inside of the tank for contacting electric contact pads of neighbouring battery units and for delivering electrical energy from the system towards an external load, a tank loader for loading battery units into the tank such that electrical contact pads of adjacent battery units are or have a high probability of being in contact and the orientation and location of individual battery units within the tank is unknown a priori, and a tank unloader for unloading battery units from the tank.