In this paper, the authors propose an approach to the problem of the energy management in ECCE laboratory hybrid vehicle project. ECCE is a series hybrid vehicle, which currently has three sources of energy: two diesel motors each coupled with an alternator and a battery module of rated voltage DC 540V. This contribution is focused on the energy coupling between batteries and two supercapacitors modules. The authors present a strategy for coupling these power sources with the batteries in order to find the best compromise between sizes of the on-board devices, dynamics of the supply and efficiency of the energy storage. The target is to provide 200kW power during 20s from the supercapacitors modules.