Date of Publication :27th November 2023

Abstract: This paper presents the research of the significance of the state of charge (SoC) and state of energy (SoE) metrics and their estimation methods for lithium-ion batteries used in an electric vehicle. SoC determines the remaining charge and SoE determines the remaining energy. The SoC-SoE variation is evaluated by simulating the factors while charging and discharging in different conditions. The larger the C rates the larger is the differences in the metrics. The SoC-SoE metric variation increases as the batteries age and hence it can be used as an indicator of the battery’s state of health. This study helps to understand the correlation between both metrics and understand the importance of SoE, SoC, and their functions. Various state estimation methods and their challenges have been discussed. There are various methods that are currently used to estimate these metrics in the literature.

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