Patent ID: 7355411
Filing Date: 2008-04-08
Classification: G01R,Y02E

Abstract:
1. A method for estimating a state of charge of a secondary battery, comprising the steps of: preparing a switch in a charge/discharge path of the secondary battery; turning on the switch to connect the charge/discharge path of the secondary battery; calculating a no-load voltage of the secondary battery when the charge/discharge path of the secondary battery is in a connected state; turning off the switch to disconnect the charge/discharge path of the secondary battery; measuring an open-circuit voltage of the secondary battery when the charge/discharge path of the secondary battery is in a disconnected state; storing a polarized voltage of the secondary battery; calculating an electromotive force of the secondary battery by subtracting the stored polarized voltage from one of the calculated no-load voltage and the measured open-circuit voltage; and estimating the state of charge of the secondary battery based on the calculated electromotive force.