Abstract: A protection circuit having: a connecting terminal which is connected to an external circuit and which inputs and outputs a charging/discharging current of a secondary battery to and from the external circuit; a voltage detection unit for detecting an output voltage of the secondary battery; a current detection unit for detecting a discharging current of the secondary battery; a power consumption calculation unit for calculating power consumption of the external circuit by multiplying a value of the output voltage detected by the voltage detection unit by a value of the discharging current detected by the current detection unit; and an external protection unit for executing external protection processing of protecting the external circuit when the power consumption calculated by the power consumption calculation unit exceeds a power threshold set to a value that is not less than a maximum value of power consumption of the external circuit.

Abstract: After the initial current set processing is performed, by which a feed amount of a charge current Ic by a charge current feed portion 35 is set to a first current value I1 exceeding a reference current value Ie preset as a current value of the charge current at which the charge current is flown without causing substantially any deterioration in secondary batteries 141, 142, and 143 while negative electrode potential of the secondary batteries 141, 142, and 143 has dropped to substantially 0 V, the charge current is changed in such a manner that the current value keeps decreasing with an increase of a terminal voltage Vt detected by a voltage detection portion 15 until the terminal voltage Vt detected by the voltage detection portion 15 reaches an end voltage Vf, which is the terminal voltage across a set battery 14 when the negative electrode potentials of the secondary batteries 141, 142, and 143 have dropped to substantially 0 V.

Abstract: A protection circuit having: a connecting terminal which is connected to an external circuit and which inputs and outputs a charging/discharging current of a secondary battery to and from the external circuit; a voltage detection unit for detecting an output voltage of the secondary battery; a current detection unit for detecting a discharging current of the secondary battery; a power consumption calculation unit for calculating power consumption of the external circuit by multiplying a value of the output voltage detected by the voltage detection unit by a value of the discharging current detected by the current detection unit; and an external protection unit for executing external protection processing of protecting the external circuit when the power consumption calculated by the power consumption calculation unit exceeds a power threshold set to a value that is not less than a maximum value of power consumption of the external circuit.

Abstract: After the initial current set processing is performed, by which a feed amount of a charge current Ic by a charge current feed portion 35 is set to a first current value I1 exceeding a reference current value Ie preset as a current value of the charge current at which the charge current is flown without causing substantially any deterioration in secondary batteries 141, 142, and 143 while negative electrode potential of the secondary batteries 141, 142, and 143 has dropped to substantially 0 V, the charge current is changed in such a manner that the current value keeps decreasing with an increase of a terminal voltage Vt detected by a voltage detection portion 15 until the terminal voltage Vt detected by the voltage detection portion 15 reaches an end voltage Vf, which is the terminal voltage across a set battery 14 when the negative electrode potentials of the secondary batteries 141, 142, and 143 have dropped to substantially 0 V.