Patent ID: 8035395

Claim:
A battery life predicting device comprising: a lifetime data storing unit for storing lifetime data that shows the relationship between the load power applied by a storage battery during discharge and the ambient temperature of the location where the storage battery is installed, and the lifetime of the storage battery; a load power measuring unit for measuring the load power applied by the storage battery; an ambient temperature measuring unit for measuring the ambient temperature; an expected lifetime value selecting unit for selecting, as an expected lifetime value, a lifetime that corresponds to the load power measured by the load power measuring unit and the ambient temperature measured by the ambient temperature measuring unit while referring to the lifetime data stored in the lifetime data storing unit; a discharge cycles counting unit for counting the number of discharge cycles of the storage battery; a first diminution in lifetime calculating unit for calculating a first diminution in lifetime which decreases the expected lifetime value based on a natural logarithmic function that takes the time obtained by converting the number of discharge cycles counted by the discharge cycles counting unit as a variable; a mean value calculating unit for calculating the mean value of the temperature of the storage battery during charging, discharging or an idle state; an elapsed time measuring unit for measuring the time elapsed after the installation of the storage battery, a second diminution in lifetime calculating unit for calculating a second diminution in lifetime which decreases the expected lifetime value based on the mean value of the temperatures of the storage battery calculated by the mean value calculating unit, the ambient temperature measured by the ambient temperature measuring unit and the time elapsed measured by the elapsed time measuring unit; and a remaining lifetime value calculating unit for calculating the remaining lifetime value by subtracting the first diminution in lifetime calculated by the first diminution in lifetime calculating unit and the second diminution in lifetime calculated by the second diminution in lifetime calculating unit from the expected lifetime value selected by the expected lifetime selecting unit.