Energy management of multi-sources vehicles is a complex task. The higher the number of sources becomes, the higher the complexity is. In this study, a decomposed energy management strategy is used for a vehicle fed by three energy sources: a fuel-cell, a battery and Supercapacitors (SCs). The decomposition allows simplifying the synthesis of the Energy Management Strategy. A comparison with a fuel cell (alone) vehicle is performed by simulation. By imposing a constant current to the fuel-cell, the developed strategy enables to improve the fuel cell lifetime. Moreover, the fuel consumption is reduced in comparison with the fuel-cell (alone) vehicle.