CHARGING RATE ESTIMATING METHOD, CHARGING RATE ESTIMATING UNIT AND BATTERY SYSTEM

摘要

A method for estimating the charging rate accurately by approximating the open circuit voltage of a secondary battery with high precision. In the charging rate estimating method, initial setting of required parameters is performed in order to estimate the charging rate of a secondary battery for feeding power to a load (step S11), voltage of the secondary battery is measured within a specified time after ending charge/discharge and a plurality of voltage measurements are acquired on the time axis (step S12), sequential calculation is performed using them (steps S14-S21), coefficients of a second or higher order exponential damping function approximating the time characteristics of open circuit voltage of the secondary battery are determined and the converged value of open circuit voltage of the secondary battery is determined at least based on the coefficients thus determined (step S22), and then the charging rate is estimated based on the converged value of open circuit voltage (step S24).