Patent ID: 7091698

Claim:
A method for measuring the capacity of a battery comprising: a step of calculating a reference discharge curve for finding a discharge curve operating as a reference; a correction voltage calculating step of correcting a measured voltage V 1 of the battery by a resistance component of the battery to find a corrected voltage V; and a capacity calculating step of calculating the discharging capacity of the battery from said discharge curve, operating as reference, using said corrected voltage V, wherein, with a voltage derived from an internal resistance of the battery of V 2 , a current dependent resistance derived voltage of V 3 and a voltage dependent resistance derived voltage of V 4 , said corrected voltage V is represented by the following equation: corrected voltage V=V 1 +ΣVn where n≧2, and V 2 ≦0, V 3 ≦0 and V 4 ≦0 if measurement is made during charging, while V 2 ≧0, V 3 ≧0 and V 4 ≧0 if measurement is made during discharging.