Review of Battery SOC Estimating Methods and Enhanced Algorithm for Estimating SOC based on OCV-AHC Approach

Rechargeable battery assemblies relying on lithiumion (Li-ion) cells would be utilized in a multitude of scenarios, which incorporate electric vehicles (EV), hybrid electric vehicles (HEV) and green energy storage for future need. They are also used in grid energy storage for a variety of functions which includes peak shaving, grid stability and green energy time shifting. It is crucial to assess the battery state of charge (SOC), which will be described by the available capacity (A-h) represented as percentage of its total capacity. The SOC variable is considered as a thermodynamic term that allows anybody to analyze battery energy potential. An assessment of the prediction models for the SOC parameters, specifically the ampere-hour and open circuit voltage approach is discussed. The SOC prediction techniques are provided. This paper will explain the finest SOC approximation algorithm particularly based on ampere- hour counting (AHC) and open circuit voltage (OCV) approaches. This algorithm intends to minimize prolonged standing time periods as well as aggregating error. For a Li-ion battery, this allows to estimate the OCV-SOC relationship in short period of time, drastically reducing the experimental period of OCV approach. Lastly, the evaluation technique as well as the simulation results for a selected SOC algorithm was shown. Experimental results validate the proposed algorithm.