Patent ID: 7679327

Claim:
A method of estimating a state of charge of a battery, comprising the steps of: measuring temperature in an initial estimation of the state of charge; measuring an open circuit voltage; obtaining parameters indicating a change of the open circuit voltage according to a change of temperature; storing the obtained parameters in a memory; and calculating, in a controller, the state of charge using the parameters and the open circuit voltage which is measured depending on the obtained parameters, wherein the state of charge is calculated by the following equation (5): y = a ⁡ [ 1 + ( b - 1 ) ( - c ⁡ ( x - d ) ) ] 1 1 - b ( 5 ) in which y is the state of charge, x is the open circuit voltage, and a, b, c, and d are the parameters corresponding to the respective temperatures, in which a indicates an upper asymptote, b is a parameter which indirectly settles a deflection point, c is a scaling factor, and d indicates a position of a deflection point with respect to an X axis.