Nowadays the popularity of the Electric Vehicles (EV) has increased more than ever. The "green" trend and the oil dependent automotive industry's strong will to find alternative energy resources are taking a big part in bringing the EV projects to life. Most of the carmakers devote significant budgets for developing this technology which had been partially industrialized at the end of 19th century. However, there are still some difficulties to industrialize the EVs due to the unsatisfactory level of battery technology. Therefore, most of the studies concerning EVs arc focused on the battery. In this paper, the Renault Fluence ZE's li-ion battery computer -based modeling and specifically the cell balancing development study has been presented.