Song Wenji

A critical review on state of charge of batteries

The accurate and reliable SOC (state of charge) estimation is difficult, although it is a core factor especially for battery energy storage system. Current studies of SOC estimation theories and models are mainly focused on voltage model, current model, resistance model, intelligent algorithm model, and hybrid model. Specific attentions were paid to estimate the model and their impact factors on SOC. Then, a critical review of available literature on major SOC issues was presented. Influencing factors on SOC were studied and analyzed, such as dynamic hysteresis characteristics, temperature, aging, self-discharge, and rate of charge/discharge. The economy and practicability of the SOC estimation are analyzed and compared objectively.