Rechargeable battery remaining capacity detection circuit, electronic machine and vehicle using the same, and state of charge detection method

Abstract

The present invention provides an improved method for detecting the state of charge (SOC) of a battery. A remaining capacity detection circuit detects the SOC of a rechargeable battery. A coulomb counter circuit integrates the charge and discharge currents Iof the battery to generate a coulomb count value CC. A voltage detection circuit detects a voltage Vof the battery. An SOC calculation unit calculates a raw SOC value SOC_cc based on the coulomb count value CC. A discharge correction unit corrects the raw SOC value SOC_cc based on a voltage drop of the battery during the discharging of the battery, and generates a discharge SOC value SOC_dis. A charge correction unit measures a minimum value SOC_dis_min reached by the discharge SOC value SOC_dis during the last discharge of the battery, and calculates a charge SOC value SOC_chg using the minimum value SOC_dis_min during the charging of the battery.