Development of the intelligent charger with battery State-Of-Health estimation using online impedance spectroscopy

In this research, a novel intelligent charger with battery diagnosis function is proposed. The diagnosis function is implemented by way of impedance spectroscopy achieved by controlling the charger to create a frequency swept excitation voltage at the battery terminals with no additional hardware. The impedance variation of battery according to the degradation over the life is measured and used for evaluating the State-of-Health (SOH) of the battery. The voltage perturbation and the current response of the battery are measured by the digital lock-in amplifier embedded in the digital signal processor (DSP) in order to calculate the impedance of the battery. The parameters of the equivalent circuit model for the lead-acid battery are extracted by using the complex non-linear least square method and compared to the reference values to estimate the SOH of the battery. The design procedure of the proposed charger is detailed and the feasibility of the system is verified by the experiments.