A scaling approach for improved open circuit voltage modeling in Li-ion batteries

Document Type

Conference Proceeding

Publication Date


Publication Title

2019 IEEE Electrical Power and Energy Conference, EPEC 2019


battery fuel gauge, Battery management system, equivalent circuit model, state of charge, state of charge estimation


Open circuit voltage (OCV) vs. state of charge (SOC) characterization is an important step in the battery management system (BMS) design. The OCV-SOC relationship is very non-linear that is often represented using a polynomial that has log and inverse terms that are not defined around SOC equal to zero or one. The traditional response to this problem was only at the software level, i.e., whenever the SOC approaches zero, a small value is used and whenever SOC approaches one, it was replaced with a value that is slightly less than one. In this paper, we present a formal scaling approach to represent open circuit voltage OCV-SOC characterization in Li-ion batteries. We show that, through formal modeling and optimization, the traditional approach to OCV-SOC modeling can be significantly improved. The proposed approach is tested on data collected from Li-ion battery over various temperatures for OCV-SOC characterization and the results are presented.