A precision model of a battery charge equalization controller (BCEC) is developed in this research paper to control a series-connected Li-ion battery with a number of cells (n). The BCEC's main task is to manage each cell individually with monitoring and balancing all cells by charging the over-discharged cell or discharging the overcharged one. An intelligent fuzzy logic controller (FLC) and a single sliding mode controller (SSMC) are evolved to activate bidirectional cell switches and regulate a chopper circuit's direct current (DC-DC flyback converter) with PWM generation. The model can be implemented in electric vehicle (E.V.) applications to get benefit from the Li-ion battery. It consists of individual models of an E.V., cells of Li-ion battery, a fly-back converter, and a charge equalization controller for charging and discharging are integrated with n series-connected cells of Li-ion battery. The simulation results confirm that the proposed schemes have achieved enhanced performance with balancing the Li-ion cells as the state of charge difference between cells is maintained to be 0.1% while maintaining the battery operation with a safe region. The BCEC is compared with the existing controllers based on efficiency, power losses, performance, and cost and has achieved better results.