Active balancing of lithium-ion cells for maximum power discharging

Abstract

The future of Electric Vehicle’s (EV) depends on the adoption of the technology. Currently the limiting factor for EV adoption is mainly the initial cost, the driving range, charging capability, and the battery life. The Battery Management System (BMS) in any Lithium chemistry battery system is used to keep the cells in the optimal operating conditions. The BMS in standard EV batteries employ series cell balancing only while charging. The discharge balancing technique can be used to increase useable capacity from an EV battery because at the end of a cycle the stronger cells have some remaining capacity which can used to assist the weaker cells. This work explores the difference in useable capacity with active cell balancing vs. passive balancing for both new and aged cells near End of Life (EOL). In this work the proposed discharge balancing technique has been researched, simulated, and implemented in hardware testing.