Comparative Analysis of Passive and Active Cell Balancing of Li Ion Batteries

In this paper a comparative analysis of active and passive cell balancing of Li ion batteries are presented. Li ion batteries are widely used in mobile phones, laptops, electric tools, electric car, telecommunication, aerospace, street lamp standby power, navigation lights, small household electrical appliances etc. Overcharging or over-discharging of a battery may reduce its lifespan. A proper Battery Management System is needed for the energy storage cells if they connected in series. Thereby the reliability and performance of the cells in the battery pack can be improved. Balancing, management and protection are the three main parts of the Battery Management System (BMS). Balancing is the most important out of the three parts. Continuous charging and discharging in battery systems cause cell imbalance. Battery life can be extended by proper cell balancing. Modeling of SoC Charge controller of Li ion battery with Nominal battery voltage 7.2V and rated capacity is 5.4 Ah is considered as test case which has been compared with passive and active cell balancing in MATLAB/Simulink with four cells in the battery pack . From the analysis, it is observed that the active cell balancing approach has more advantages than passive balancing approach in lithium-ion batteries.