Robust battery fuel gauge algorithm development, part 0: Normalized OCV modeling approach

The open circuit voltage (OCV) characterization of Li-ion batteries as it applies to battery fuel gauging (BFG) in portable applications is considered in this paper. Accurate knowledge of the nonlinear relationship between the OCV and the state of charge (SOC) is required for adaptive SOC tracking during battery usage. BFG in portable applications requires this OCV-SOC characterization to be defined with a minimum number of parameters. With the help of OCV characterization data collected from 34 battery cells each at 16 different temperatures ranging from -25°C to 50°C, we present a novel normalized OCV modeling approach that dramatically reduces the number of OCV-SOC parameters and as a result simplifies and generalizes the BFG across temperatures and aging.