Abstract: A small protector is provided for a high energy density battery such as a lithium ion battery. A flat sheet form of leading portion extending from a positive temperature coefficient element is provided thereon with at least one battery protecting circuit element for detecting at least one abnormality selected from overcharging, over-discharging, overcurrent, and unusual temperature to cut off a current passing therethrough. A fail-safe mechanism is achieved for the actuation of the positive temperature coefficient element and the actuation of the battery protecting circuit element.

Abstract: The invention provides a protective device for batteries having a high energy density such as lithium ion batteries. The protective device comprises a battery voltage-monitoring means, an overcharge-detecting means for sending out a charge-finishing signal when a voltage detected by the battery voltage-detecting means is higher than a preset value, a charge-finishing means for finishing charge in response to the charge-finishing signal, an output-counting means for counting the number of charge-finishing signals sent out of the charge-finishing means, and a cutoff means for cutting off conduction of a current in said batteries when a counted value reaches a preset value, thereby limiting the number of permissible overcharging cycles.

Abstract: An overcharge preventing device for a high energy density battery such as a lithium ion battery comprises a voltage sensor means for sensing a voltage of a battery that is being charged, a current feeder means for feeding a current to a heat generating means when a voltage sensed by said voltage sensor means exceeds a preset voltage, and a repeatedly usable thermal actuator means that is thermally coupled to said heat generation means incorporated in a charging current circuit. Upon overcharging of the battery, the thermal actuator means is actuated by heat generated from the heat generating means to interrupt feeding of a charging current to the battery. Upon elimination of an overcharged state, the charging current circuit in the thermal actuator means is resumed to recharge the battery.

Abstract: The invention provides a protective device for batteries having a high energy density such as lithium ion batteries. The protective device includes a current conduction cutoff means having a current-conducting circuit comprising a voltage-detecting means for detecting the voltage of at least one battery being charged, a heat-generating resistance for starting the conduction of a current when the detected voltage exceeds a preset voltage, and a temperature fuse thermally coupled to the heat-generating resistance. When a state where battery voltage is higher than a preset value continues, a charging circuit for the battery is cut off by the temperature fuse and current output from the battery is disabled. The protective device further includes a battery-discharging means actuated upon detection of the fusing-down of the temperature fuse, so that the battery is disabled, and then placed in a dischargeable state.

Abstract: A life indicator is so designed that an electric current flows to a light emitting diode utilizing a battery as a power source when two electrodes are electrically connected. The two electrodes are so installed as to be electrically connected by passing water through a water passage communicating with an objective equipment, and the discharge life of the battery is set equal to the service life of the equipment.