Development of cell balancing algorithm for LiFePO4 battery in electric bicycles

This paper presents an algorithm of cell balancing of LiFePO₄ battery pack under the constraints of electric bicycle applications. The major purpose of cell balancing is to protect the battery from being overcharged and to equalize the state of charge of each battery cell. The nominal voltage and capacity of the considered battery pack for electric bicycle is 36V and 10Ah respectively. The conventional balancing method detects final voltage of each cell and consumes a long period of time to balance all cells, since the cell balancing will be active only at the end of charging process. This paper proposes an cell-balancing algorithm using the combination between Ah-balancing and delta voltage at the end of charging process in order to shorten the balancing time. A prototype of hardware will be constructed and tested. The functionality of the proposed cell balancing algorithm will be verified by the test results.