Patent ID: 7923966

Claim:
A battery control device, comprising: an electric circuit control unit controlling a power supply to a load from a battery; a voltage measuring unit measuring a voltage of the battery; a current measuring unit measuring an electric current of the battery; a power source control unit outputting a control signal to the electric circuit control unit and receiving measurement signals from the voltage measuring unit and the current measuring unit; and a pre-generated map representing a relationship between the open-circuit voltage and a battery residual quantity ratio defined as a value showing a ratio at which a residual quantity of the battery occupies the whole capacity thereof, wherein the power source control unit calculates an internal impedance of the battery by measuring a first voltage defined as the voltage of the battery and a first current defined as the current of the battery in a state where the battery supplies electric power to the load, measuring a second voltage defined as the voltage of the battery in a state where the supply of the electric power to the load from the battery is cut off and dividing a value obtained in a way that subtracts the first voltage from the second voltage by the first current, calculates an open-circuit voltage of the battery by measuring a third voltage defined as the voltage of the battery and a second current defined as the electric current of the battery in the state where the battery supplies the electric power to the load and adding the third voltage to a value obtained in a way that multiplies the internal impedance by the second current, acquires the battery residual quantity ratio of the battery by collating the open-circuit voltage with the pre-generated map, measures a first battery residual quantity ratio defined as a value showing a ratio at which the residual quantity of the battery occupies the whole capacity thereof by calculating the open-circuit voltage in a first battery state as a battery state before the residual quantity decreases and collating the open-circuit voltage with the map, measures a second battery residual quantity ratio defined as a value showing a ratio at which the residual quantity of the battery occupies the whole capacity thereof by calculating the open-circuit voltage of the battery in a second battery state that is a battery state after the residual quantity has decreased and collating the open-circuit voltage with the map, measures a first integrated current defined as an integrated value of the electric current outputted during a transition of the battery from the first battery state to the second battery state, and calculates the full-charge capacity of the battery in a way that divides the first integrated current by a value obtained by subtracting the second battery residual quantity ratio from the first battery residual quantity ratio.