Energy management strategies are mandatory for hybrid energy storage systems in applications for electric and hybrid vehicles. Optimization-based real-time strategies are of interest since they are straightforward to optimize performance criteria. The available methods are often the combinations of adaptive mechanisms with solutions deduced by optimal control techniques such as Pontryagin's minimum principle (PMP). This paper proposes an approach to develop a real-time strategy for battery/supercapacitor systems based on PMP and Energetic Macroscopic Representation without any need of adaptive mechanism for the co-state variable. Its performances are validated by simulation.