The issue of carrying electrical energy to remote countryside locations remained. It was not until 1905, at the Liège Exhibition, that Henri Tudor and the engineer Maurice Braun were able to display a possible solution, designed as a replacement for the traditional portable engine. The cart, which they called an ""Energy-Car"", was compact and carefully designed. It consisted of an internal combustion engine, a generator, a lead-acid battery and the instruments required to control its operation. It was not a self-propelling vehicle. The device was first built in the Rosport factory, and subsequently at the Braun workshop in Brussels.