This paper describes both models and control algorithms, which can be used for simulation of the electric power train used for heavy vehicles. By making use of Saber software, simulation model is set-up including detailed models of: (i) battery, (ii) internal combustion engine, (iii) electrical generators (iv) and AC/DC converters. Simulation on a dual hybrid generator has been performed in order to study the behaviour of the components of the electrical energy system. The main work is focused on the comportment of the battery. Energy strategy management depends on the availability of energy sources and their components. Such a simulator could helps to make decision in case of failure and to study fault tolerant behaviour.