Patent ID: 6972545

Claim:
A battery pack mounted on an external device, the battery pack comprising: a battery cell that is charged and discharged; a current detecting means for detecting electric current flowing when the battery cell is charged and discharged; a capacity integrated value calculating means for calculating a capacity integrated value by integrating the electric current; a reset means for resetting the capacity integrated value to a reference capacity integrated value when the current detected by the current detecting means reaches a prescribed value; a storing means for storing a maximum capacity integrated value and the reference capacity integrated value; and a data calculating means for calculating a remaining capacity data of a battery on the basis of the capacity integrated value, wherein the capacity integrated value calculating means integrates the current by regarding the reference capacity integrated value as a reference, and the data calculating means determines the capacity integrated value calculated by the capacity integrated value calculating means as the remaining capacity data of the battery when the capacity integrated value calculated by the capacity integrated value calculating means is smaller than the maximum capacity integrated value and determines the maximum capacity integrated value as the remaining capacity data of the battery when the capacity integrated value calculated by the capacity integrated value calculating means is not smaller than the maximum capacity integrated value.