Development and Application of an Active Balancing System for Lithium-Ion Cells

This paper describes the development of an active battery management system for lithium-ion cells and its comparison with passive battery management. For this purpose, the structure of the test hardware is described and its universal possibilities are explained. An iterative balancing algorithm is presented as a central component of the active balancing system. The algorithm is able to determine the capacitance deviations between the individual cells by measuring cell voltages and battery current. In order to compare the system built up in this work with a conventional battery management system, a realistic test is carried out on aged lithium-ion batteries. In this test, the active balancing system is able to significantly increase the removable battery capacity compared to conventional passive balancing. In addition, the disadvantage of passive balancing in second-life applications is clarified.