BATTERY PACK

• US 20100201327A1
• Filed: 06/25/2008
• Published: 08/12/2010
• Est. Priority Date: 06/25/2007
• Status: Active Grant

• Current Assignee: Mitsumi Electric Co., Ltd. (Minebea Mitsumi, Inc.)
• Original Assignee: Mitsumi Electric Co., Ltd. (Minebea Mitsumi, Inc.)
• Inventors: Takeda, Takashi
• Granted Patent: US 8,193,774 B2
• Time in Patent Office: Days
• US Class Current: 320/154
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/443 in response to temperature
• CPC Class Codes: H01M 2200/105 NTC
• CPC Class Codes: H01M 50/574 Devices or arrangements for the interruption of current
• CPC Class Codes: H01M 50/581 in response to temperature
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

In a battery pack including a protection circuit, a series circuit of a thermistor and a resistor is disposed in a vicinity of a secondary battery and connected in parallel with the secondary battery. A connection detecting circuit is disposed to detect connection of a charging device to the battery pack. A comparator is disposed to compare a voltage of a junction point of the thermistor and the resistor with a reference voltage corresponding to a predetermined temperature. A gate circuit is disposed to activate an output signal of the comparator only when the connection of the charging device is detected. The protection circuit is arranged so that, when a temperature of the secondary battery exceeds the predetermined temperature, a switch element is turned off in accordance with the output signal of the comparator activated.

Claims

1. A battery pack including a protection circuit which detects an overcharge, an overdischarge, and an overcurrent of a secondary battery and turns off a switch element disposed on a wiring line between the secondary battery and a load or a charging device, the battery pack comprising:

a series circuit of a thermistor and a resistor, disposed in a vicinity of the secondary battery and connected in parallel with the secondary battery;

a connection detecting circuit disposed to detect connection of a charging device to the battery pack;

a comparator disposed in the protection circuit to compare a voltage of a junction point of the thermistor and the resistor with a reference voltage corresponding to a predetermined temperature; and

a gate circuit disposed in the protection circuit to activate an output signal of the comparator only when the connection of the charging device is detected by the connection detecting circuit,

wherein the protection circuit is arranged so that, when a temperature of the secondary battery exceeds the predetermined temperature, the switch element is turned off in accordance with the output signal of the comparator activated by the gate circuit.

2. The battery pack according to claim 1, wherein the connection detecting circuit includes a resistor which pulls up or down a potential of an external terminal to which the charging device is connected, and wherein the potential of the external terminal is pulled down or up by the charging device when the charging device is connected to the external terminal.

3. The battery pack according to claim 1, wherein the thermistor is an NTC thermistor having a negative temperature coefficient.