State-of-charge estimation for lithium-ion battery pack using reconstructed open-circuit-voltage curve

Abstract

This paper proposes a state-of-charge (SOC) estimation algorithm for a series-connected Li-ion battery pack using a reconstructed open-circuit-voltage (OCV) curve. This method redefines the OCV-SOC relationship based on a cell which has the lowest available capacity and estimates the battery pack SOC and capacity information regardless of the type and existence of balancing circuit. To validate the performance of the proposed estimation method, a constant current profile is used for seven 18650 series-connected Li-ion batteries (7S1P). The experimental results verify the performance of the proposed battery pack SOC estimation algorithm.