Importance

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Abstract

A battery capacity meter and a method for precisely calculating a battery capacity are obtained by measuring a terminal voltage of the battery and sequentially calculating the measured terminal voltages. In a battery capacity meter of the present invention, a calculation process is carried out. After a power source is connected to the battery capacity meter, an initial value S.sub.0 under non-consistent charge state S.sub.i is calculated from an initial value V.sub.0 of a terminal voltage V.sub.i. Next, V.sub.i and S.sub.i are related to a current I.sub.i, and an equation for relating a variation amount .DELTA.S.sub.i of S.sub.i to S.sub.i is formed. Under this relationship, .DELTA.S.sub.i is obtained from V.sub.i and S.sub.i in a time interval .DELTA.t. A value of S.sub.i is updated. Either a remaining capacity or a fuel-gauge normalized remaining capacity are obtained from the updated value of S.sub.i. A process operation is returned to a step where .DELTA.S.sub.i is calculated, and this process is repeated.

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First Claim