Battery State of Charge Estimation Methods – A Critical Review

Abstract: The automobile sector across the globe has undergone a dramatic change in the last decade. It has started to trust something more, which initially was criticized for its inferior performance – the Electric Vehicle (EV). The battery is one of the most important components of an EV, and the Battery Management System (BMS) continues to be the bottleneck of EVs. However, accurate estimation of the State of Charge (SOC) of batteries is still challenging due to the non-linear characteristics of batteries. This led the scholars to propose various methods of SoC estimation. It now poses a challenge to establish a relationship between the accuracy and robustness of the methods, and their difficulties to implement. This paper publishes an exhaustive literature survey of the SoC estimation methods proposed by various scholars. All the more, it also provides feedback on each method, which will help to make an accurate choice of the SoC estimation method to be implemented. This will, in turn, help in the development of a reliable BMS.

Keywords: Battery Management System (BMS), State of Charge (SoC), Electric Vehicle (EV), Look-up table based estimation, model based estimation, adaptive system based estimation.