The SOC estimation of a lead acid rechargeable battery

Abstract

A model of a lead-acid battery is presented with an equivalent circuit and the parameters are determined with experiments. An inductor is added into the circuit with the consideration from the output of impedance spectrum. Extended Kalman filter for the nonlinear system is used to estimate three state variables and further to calculate the state-of-charge. The algorithm is simplified and it can be implemented for the real-time estimation with an error less than 1% in the testing with the SOC range between 60% and 100%. The testing is also conducted with a battery not fully charged and the estimation error is higher, close to 2%.