Batteries and battery systems

• US 5,767,659 A
• Filed: 02/18/1997
• Issued: 06/16/1998
• Est. Priority Date: 10/30/1991
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Farley, Joseph D.
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US08/802,088
• Time in Patent Office: 483 Days
• Field of Search: 320/106, 320/118, 320/132, 320/134, 320/136, 320/144, 320/150, 320/155, 320/153, 320/DIG. 21, 320/128, 320/113, 320/130, 320/138, 320/147
• US Class Current: 320/106
• CPC Class Codes: H01M 10/46 Accumulators structurally combined with charging apparatus circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00036 Charger exchanging data with battery
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Battery pack which includes rechargeable battery cells in conjunction with a charge protection circuit to prevent damage to the battery pack. The battery pack further includes a component in which predetermined battery parameters definitive of a battery pack characteristic may be stored, together with a battery parameter sensor, and a micro-controller responsive to the sensing of a battery parameter for controlling the battery pack characteristic based upon the sensed parameter. In one aspect, the sensed parameter may be the onset of substantially full charge as provided by a current source operably connected to the battery pack and subject to being disconnected when a predetermined cell temperature is reached which is indicative of full charge.

Claims

1. A battery pack comprising:

at least one electrical energy-providing cell forming a battery;

positive and negative terminals connected to said at least one cell and adapted to receive electrical current from a battery charging current source in providing charging of said at least one cell;

a memory in which predetermined battery parameters definitive of a battery pack characteristic are storable, one of said battery parameters in said memory being a battery pack characteristic indicative of full charge in said at least one cell;

means for sensing at least the onset of said one battery parameter indicative of full charge in said at least one cell;

a selective current shunting circuit operably connected to said positive and negative terminals connected to said at least one cell;

said means for sensing at least the onset of said battery parameter indicative of full charge in said at least one cell including a temperature coefficient resistor in said selective current shunting circuit, said temperature coefficient resistor being connected to said positive and negative terminals and extending across said at least one cell;

said selective current shunting current further including

a voltage-controlled switch connected to said temperature coefficient resistor, said voltage-controlled switch being in an open state to render said current shunting circuit inoperable during normal usage of the battery pack, and

a first resistor connected in series with said voltage-controlled switch and to said positive and negative terminals such that said first resistor and said voltage-controlled switch extend across said at least one cell in electrically parallel relationship with respect to said temperature coefficient resistor;

said temperature coefficient resistor being responsive to an increase in the temperature of said at least one cell indicative of the onset of full charge in said at least one cell and decreasing the resistance of said temperature coefficient resistor to adapt the battery pack to provide charge current shunting; and

said selective current shunting circuit being rendered operable in response to an increased voltage applied to said voltage-controlled switch closing said switch by virtue of the resistance decreasing in said temperature coefficient resistor in response to an increase in the cell temperature to provide charge current shunting of electrical current provided from the battery charging current source to said positive and negative terminals in a direction through said current shunting circuit and bypassing said at least one cell in providing protection against overcharge.

2. A battery pack as set forth in claim 1, wherein said voltage-controlled switch of said selective current shunting circuit is a bipolar transistor having base, collector and emitter electrodes;

the base electrode of said bipolar transistor being connected to said temperature coefficient resistor, the collector electrode being connected to said first resistor, and the emitter electrode being connected to the negative terminal;

said bipolar transistor being rendered conductive in response to an increased voltage applied to the base electrode thereof by virtue of the resistance decreasing in said temperature coefficient resistor in response to an increase in the cell temperature such that electrical current from the battery charging current source is transmitted through said current shunting circuit via said first resistor and said bipolar transistor when conductive so as to bypass said at least one cell.

4. A battery pack as set forth in claim 1, wherein said memory includes stored predetermined battery parameters corresponding to a predetermined battery model;

and

said micro-controller being responsive to the sensing of at least one battery parameter and dependent upon the predetermined battery model and the predetermined battery parameters stored in said memory to control the battery pack characteristic in accordance with a desired battery pack characteristic associated with the predetermined battery model.

3. A battery pack comprising:

at least one electrical-energy providing cell forming a battery;

positive and negative terminals connected to said at least one cell and adapted to receive electrical current from a battery charging current source in providing charging of said at least one cell;

a memory in which predetermined battery parameters definitive of a battery pack characteristic are storable, one of said battery parameters in said memory being a battery cell temperature threshold attained when substantially full charge has been restored to said at least one cell;

a temperature detector for sensing the onset of the temperature threshold attained when substantially full charge has been restored to said at least one cell;

a selective current shunting circuit operably connected to said positive and negative terminals connected to said at least one cell;

a micro-controller for monitoring and regulating a battery characteristic as defined by a predetermined battery parameter including the battery cell temperature threshold as a battery pack characteristic indicative of full charge in said at least one cell, said micro-controller being operably connected to said temperature detector and being responsive to said temperature detector detecting a temperature at or exceeding the battery cell temperature threshold indicative of full charge in said at least one cell to adapt the battery pack to provide charge current shunting;

said micro-controller being responsive to the detection of a temperature rise by said temperature detector to a magnitude reaching the battery cell temperature threshold indicative of the onset of full charge in said at least one cell for rendering said current shunting circuit operable to provide charge current shunting of electrical current provided from the battery charging current source to said positive and negative terminals in a direction bypassing said at least one cell;

said selective current shunting circuit including a shunting transistor having a control gate, said shunting transistor being connected across said positive and negative terminals so as to extend across said at least one cell;

said micro-controller being operably connected to the control gate of said shunting transistor; and

said shunting transistor being rendered conductive in response to an increased voltage applied to the control gate thereof by said micro-controller in response to an increase in the cell temperature as detected by said temperature detector such that electrical current is transmitted through said shunting transistor when conductive of said selective current shunting circuit so as to bypass said at least one cell in providing protection against overcharge.

5. A battery pack comprising:

at least one electrical energy-providing cell forming a battery;

positive and negative terminals connected to said at least one cell and adaptive to receive electrical current from a battery charging current source in providing charging of said at least one cell;

a memory in which predetermined battery parameters definitive of a battery pack characteristic are storable, one of said battery parameters in said memory being a battery pack characteristic indicative of full charge in said at least one cell;

means for sensing at least the onset of said one battery parameter indicative of full charge in said at least one cell; and

a selective current shunting circuit operably connected to said positive and negative terminals connected to said at least one cell;

said sensing means being responsive to the detection of the onset of full charge in said at least cell to adapt the battery pack to provide charge current shunting by rendering said current shunting circuit operable to provide charge current shunting of electrical current provided from the battery charging current source to said positive and negative terminals in a direction bypassing said at least one cell in providing protection against overcharge;

said means for sensing at least the onset of said one battery parameter indicative of full charge in said at least one cell including a temperature coefficient resistor in said selective current shunting circuit, said temperature coefficient resistor being connected to said positive and negative terminals and extending across said at least one cell; and

said current shunting circuit including a voltage-controlled switch connected to said temperature coefficient resistor, said voltage-controlled switch being in an open state to render said current shunting circuit inoperable during normal usage of the battery pack;

said current shunting circuit being rendered operable in response to an increased voltage applied to said voltage-controlled switch closing said switch by virtue of the resistance decreasing in said temperature coefficient resistor in response to an increase in the cell temperature to provide charge current shunting of electrical current in a direction through said current shunting circuit and bypassing said at least one cell.