Evaluation and comparison of two approaches to capture the electrical behaviour of battery cells

Abstract This paper presents a comparison of two models to predict the electrical behaviour of a lithium titanate (LTO), a lithium iron phosphate (LFP) and a lead acid cell. One model is based on a an equivalent circuit (ECM) and the other one is based on the Shepherd equation. The models are compared by evaluating constant current charge/discharge curves and dynamic characteristics of a typical photovoltaic (PV) scenario. The results show that the lead acid cell is better modelled using a Shepherd style model due to its different charge/discharge characteristics. The lithium-ion technologies are better represented by an ECM due to only minor deviation in charge/discharge parameters. Overall the ECM is better suited for depicting the dynamic behaviour of cells while the Shepherd model is more accurate in static charge/discharge curves and where cell characteristics differentiate between charge and discharge.