Design of Passive Cell Balancing for 48V Lithium Batteries for EV/Drones Applications

Battery is one of the most crucial parts of electric vehicles(EVs) as an energy source. Electric Vehicles (EVs) powered by lithium batteries have become a viable alternative option due to growing worries about global warming, greenhouse gas emissions, and the depletion of fossil fuels. In this study, passive cell balancing is achieved with optimum resistance value for the 48 V Lithium–ion Battery Pack (BP). While balancing the battery pack, the cell lower cut-off voltage and maximum peak discharge current value are considered. If the battery cell voltage is very low it will affect the battery lifetime, to avoid this, the minimum cell voltage will be maintained and the discharge current value should be also within the operating limits. The passive cell balancing algorithm was simulated for a 48V lithium-ion battery pack using Matlab software. The balancing time is varying from 68 seconds to 80 seconds depending on the initial SoC of the cells ranging from 95% to 30% respectively. The optimum resistance value is also obtained to balance the cells varying from 65ohms to 70 ohms.