A Simple Estimation Method for State of Health of Li-ion Battery with Charging Curve

The aging of the battery is comprehensively evaluated with the state of health (SOH) of the lithium ion battery. A simple SOH estimation method is presented in this paper. Firstly, according to the constant current (CC) charging voltage curve, three features (A1, A2, A3) are extracted. They can be obtained by the most basic and commonly used least square line fitting. These features are highly correlated with real SOH. Secondly, three estimation models are proposed, which are based on the regression models of parameters (A1, A2), (A2, A3) and (A1, A2, A3) respectively. Finally, the estimated errors of the experimental results are less than 3%, and these aging data comes from NASA data repository. The latter two regression models have higher estimation accuracy. This method only needs part of charging data and least square straight line fitting. It has low computational cost, less testing time and good robustness. The proposed method can not only estimate SOH of the battery, but also provides the foundation for battery life management strategy.