Patent ID: 8736232

Claim:
A full charge capacity correction circuit comprising: an integrating unit that calculates an integrated value by integrating a current value of a current flowing through a rechargeable battery; a capacity storing unit that stores a full charge capacity value that indicates a full charge capacity of the rechargeable battery; a first estimating unit that estimates a storage ratio of the rechargeable battery, which is a ratio of a quantity of stored electricity that is stored in the rechargeable battery to an actual full charge capacity of the rechargeable battery, as a first storage ratio when an estimable condition which is a condition that enables to estimate the storage ratio is satisfied; a second estimating unit that monitors whether or not the estimable condition which is a condition that enables to estimate the storage ratio is satisfied after the first storage ratio is estimated by the first estimating unit, and when the estimable condition is satisfied, estimates the storage ratio of the rechargeable battery at that moment as a second storage ratio; a full charge capacity correction unit that estimates a full charge capacity value of the rechargeable battery based on a difference integrated value that is an integrated value integrated by the integrating unit after the first storage ratio is estimated by the first estimating unit and until the second storage ratio is estimated by the second estimating unit and on a ratio of a difference between the first storage ratio and the second storage ratio to 1, and corrects the full charge capacity value by having the capacity storing unit store the estimated full charge capacity value as a new full charge capacity value; an open circuit ratio estimating unit that uses, as the estimable condition, an open circuit voltage condition which requires a current flowing through the rechargeable battery to fall below an open circuit judgment value set in advance in order to judge that a state exists where an open circuit voltage can be obtained as a terminal voltage of the rechargeable battery, and when the open circuit voltage condition is satisfied, estimates the storage ratio of the rechargeable battery based on the terminal voltage of the rechargeable battery; and a correction control unit that uses the open circuit ratio estimating unit as at least one of the first estimating unit and the second estimating unit.