Patent ID: 8305041

Claim:
A battery pack, comprising: an overcharge detecting circuit arranged to compare a voltage between a positive electrode and a negative electrode of a secondary battery with a threshold voltage to detect an overcharge of the secondary battery, and to turn off a switching element in a wiring between a load and the secondary battery or between a charging device and the secondary battery; a series circuit including a thermistor and a resistor connected in series, the series circuit being arranged in a vicinity of the secondary battery and connected in parallel to the secondary battery; a first comparator arranged to compare a voltage at a junction point of the thermistor and the resistor in the series circuit with a first reference voltage corresponding to a first predetermined temperature; a changing unit arranged to change the threshold voltage of the overcharge detecting circuit to a first value when a detected temperature of the secondary battery is below the first predetermined temperature, and to change the threshold voltage of the overcharge detecting circuit to a second value smaller than the first value when the detected temperature of the secondary battery is above the first predetermined temperature; and a non-sensitive time setting unit arranged to receive a temperature detection signal output from the first comparator and output a high-level signal to the changing unit when a high-level period of the temperature detection signal exceeds a predetermined value, wherein, when the high-level signal output from the non-sensitive time setting unit is received at the changing unit, the overcharge detecting circuit outputs an overcharge detection signal, thereby turning off a switching element in the wiring.