Estimation of SOH for Battery Packs: A Real-Time Mixed Algorithm based on Coulomb Counting Method and Parameter-Varying Circuit Modeling

This paper focuses on estimation of State of Health (SOH) for battery packs used in renewable power plants and in automotive applications. Several advanced methods for SOH estimation are reported in literature. Such methods are designed to improve the accuracy of resulting SOH for specific applications. Their practical implementation is usually a difficult task because parameters tuning must face complexity of aging phenomena, effects of operating temperature, current rate and so on. In this paper, two basic estimation methods are combined in order to get a real-time mixed algorithm. Target of this merging is the estimation of SOH obtaining a satisfactory accuracy while limiting the computational burden. A prediction function is integrated within the algorithm in order to take into account relaxation phenomena in no-load conditions. Validation is carried out through experimental tests on batteries having different size and electrochemical technology. Correctness of results is verified performing experimental comparisons with other common SOH estimation methods.