Experimental analysis of electric vehicle's Li-ion battery with constant pulse and constant voltage charging method

Li-ion batteries are one of the most prominent rechargeable batteries. They are extensively used in most of the electric vehicles to the portable electronic devices. This is due to high energy density and low self-discharge rates which further showcase high efficiency. Furthermore, the Li-ion batteries have a high discharge rate, low emission of toxic gasses as well as high open-circuit voltage. The efficient utilization of these batteries depends on the appropriate charging method. The charging method is determined by considering the essential attributes such as fast charging ability, and its charge storage capability. Therefore, to achieve all the above qualities, a novel charging process based on constant pulse and constant voltage (CP-CV) method has been proposed. The proposed CP-CV charging method uses pulse charging until a maximum cut-off voltage reaches the prescribed limit set by the battery manufacturers. Once this maximum cut-off voltage reaches, the charging algorithm switches to constant voltage (CV) method. The experimental setup used to test two non-identical Li-ion cells (lithium cobalt oxide (LCO) and lithium manganese oxide (LMO)) and one Li-ion battery pack (lithium iron phosphate [LFP]) chemistry. The experimental result of CP-CV is compared with the constant current and constant voltage (CC-CV) method with similar test parameters. The exploratory analysis has been performed for different charge rates while keeping the battery manufacturer datasheet as a reference. The results show that there is a 22.84% reduction in charging time as well as a 2.18% increment in the charge storage and a significant reduction in the temperature of Li-ion cells using CP-CV as compared to CC-CV method.