Lithium-ion battery lifespan estimation for hybrid electric vehicle

A lithium-ion (Li-ion) battery lifespan estimation method is proposed in this paper. The proposed method can judge service time of Li-ion battery, broaden the use of capacity and ensure the battery life. A nonlinear equivalent circuit is adopted to calculate Li-ion battery state of charge (SOC) considering charging and discharging. Remaining lifespan (RI) and lifespan degrading factor (LDF) are defined. LDF is used to reflect capacity loss of li-ion battery and obtained by SOC. The performance of the proposed lifespan estimation method is tested in experiment by ECE15 and EUDC operation condition. Results show that nonlinear equivalent circuit can describe various working states of Li-ion battery and the validity of the RI and LDF is proved.