An Offsetting-Based Correction to Improve the Accuracy of Low-Rate OCV Curves for Lithium-Ion Batteries

Accurate modeling of the open-circuit voltage (OCV) as a function of state of charge (SOC) is critical for battery management systems (BMS) in lithium-ion battery applications, particularly under varying temperature conditions. Traditional low-rate OCV testing methods, while simple and widely adopted, suffer from limitations at low temperatures due to increased internal resistance. This leads to premature termination of charging and discharging processes, causing inaccuracies in the resulting OCV-SOC curve. In this paper, we propose a novel offsettingbased correction method that extends the charge and discharge voltage curves by extrapolating terminal voltage differences at the SOC limits. This approach restores the full intended OCV range (3.0V to 4.2V) across all tested temperatures without requiring modifications to standard test protocols. The results highlight its potential to improve BMS performance by enabling more accurate OCV characterization, especially for temperatureaware battery modeling.