Patent ID: 7109684

Claim:
A charging equipment for a secondary battery, comprising: a voltage supply means for applying voltage to the secondary battery; a current detection means for detecting electric current flowing through the secondary battery; and a charge control device for controlling charge of the secondary battery, the charge control device including a storage means storing equilibrium voltage and special charging voltage corresponding to the secondary battery to be charged, the equilibrium voltage for establishing equilibrium cell potential of the secondary battery in a fully charged condition, and the special charging voltage for supplying the secondary battery with charging electric current of peak or almost peak value, wherein the special charging voltage is larger than the equilibrium voltage and does not reach a region of voltage causing irreversible chemical reaction in the secondary battery, a switching means for switching charging voltage supplied by the voltage supply means between the equilibrium voltage and the special charging voltage, and a judging means for judging whether electric current detected by the current detection means during application of the equilibrium voltage is larger than a preset standard electric current for finishing charging or not, wherein the charge control device controls charge of a secondary battery by first to fourth steps: the first step of applying the special charging voltage to the secondary battery set in the charging equipment for a predetermined time; the second step of switching charging voltage applied to the secondary battery from the special charging voltage to the equilibrium voltage; the third step of detecting electric current flowing through the secondary battery by the current detection means while applying the equilibrium voltage to the secondary battery for a short time; and the fourth step of returning to the first step and repeating the above steps if the judging means judges that the detected electric current is larger than the standard electric current for finishing charging; otherwise, halting the secondary battery.