Method and system for battery protection

• US 7,589,500 B2
• Filed: 05/24/2005
• Issued: 09/15/2009
• Est. Priority Date: 11/22/2002
• Status: Active Grant

• Current Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Original Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Inventors: Scheucher, Karl F., Johnson, Todd W., Glasgow, Kevin L., Rosenbecker, Jay J., Zeiler, Jeffrey M., Meyer, Gary D., Brozek, Jeffrey M., Zick, Jonathan Z.
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): BOATENG, ALEXIS ASIEDUA
• Application Number:
  US11/138,070
• Publication Number:
  US 20060091858A1
• Time in Patent Office: 1,575 Days
• Field of Search: 320/134, 320/116, 320/132
• US Class Current: 320/134
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: B25F 5/008 Cooling means
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/4207 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/46 Accumulators structurally combined with charging apparatus circuits for charging H02J7/00
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H01M 2010/4278 Systems for data transfer from batteries, e.g. transfer of battery parameters to a controller, data transferred between battery controller and main controller
• CPC Class Codes: H01M 2200/00 Safety devices for primary or secondary batteries
• CPC Class Codes: H01M 2220/30 Batteries in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 50/204 Racks, modules or packs for multiple batteries or multiple cells
• CPC Class Codes: H01M 50/213 adapted for cells having curved cross-section, e.g. round or elliptic H01M50/209, H01M50/216 take precedence
• CPC Class Codes: H01M 50/227 Organic material
• CPC Class Codes: H01M 50/247 specially adapted for portable devices, e.g. mobile phones, computers, hand tools or pacemakers
• CPC Class Codes: H01M 50/296 characterised by terminals of battery packs terminals of batteries H01M50/543
• CPC Class Codes: H02J 7/00 : Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0014 : Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0016 : using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/00302 : Overcharge protection
• CPC Class Codes: H02J 7/00306 : Overdischarge protection
• CPC Class Codes: H02J 7/00308 : Overvoltage protection
• CPC Class Codes: H02J 7/00309 : Overheat or overtemperature protection
• CPC Class Codes: H02J 7/0031 : using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/0034 : using reverse polarity correcting or protecting circuits mechanical means of polarity protection H02J7/0045
• CPC Class Codes: H02J 7/0045 : concerning the insertion or the connection of the batteries
• CPC Class Codes: H02J 7/0063 : with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/0071 : with a programmable schedule
• CPC Class Codes: H02J 7/04 : Regulation of charging current or voltage
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries

Abstract

A method of conducting an operation including a battery. The battery includes a cell having a voltage. Power is transferable between the cell and the electrical device. A controller is operable to control a function of the battery pack. The controller is also operable with a voltage at least one of equal to and greater than an operating voltage threshold. The cell is operable to selectively supply voltage to the controller. The method includes the act of enabling the controller to operate when the voltage supplied by the cell is below the operating voltage threshold.

Claims

1. A battery pack configured to supply power to a cordless power tool, the cordless power tool having a motor, the battery pack comprising:

a plurality of battery cells operable to supply a battery pack discharge current to the motor of the cordless power tool, each of the battery cells having a battery cell state of charge;

a switch operable to be alternately positioned in one of a conducting state and a non-conducting state, the switch further operable to enable the supply of discharge current from the battery pack to the motor when the switch is positioned in the conducting state and operable to interrupt the supply of discharge current from the battery pack to the motor when the switch is positioned in the non-conducting state;

a controller electrically connected to the switch and to each of the battery cells via a respective connection to each cell, operable to monitor the respective battery cell state of charge of each of the battery cells, operable to control operation of the battery pack, and operable to control the positioning of the switch, the controller including a microcontroller; and

a plurality of electrical paths between the controller and the cell connections, each electrical path being associated with a different one of the cell connections, wherein each electrical path among the plurality of electrical paths is independent of the other electrical paths among the plurality of electrical paths, and wherein no two electrical paths share an electrically conductive component,

wherein the controller modifies operation of the battery pack by causing the switch to move from the conducting state to the non-conducting state to interrupt the supply of discharge current from the battery pack to the motor when the monitored respective battery cell state of charge of one of the battery cells reaches a predetermined threshold.

2. The battery pack as set forth in claim 1 and wherein the controller modifies operation of the battery pack by varying the discharge current being supplied to the motor of the cordless power tool over a time period.

3. The battery pack as set forth in claim 1 and wherein the controller modifies operation of the battery pack by decreasing the discharge current being supplied to the motor of the cordless power tool over a time period.

4. The battery pack as set forth in claim 1 and wherein the controller modifies operation of the battery pack by interrupting the discharge current being supplied to the motor of the cordless power tool such that substantially no discharge current is supplied to the motor of the cordless power tool for a time period.

5. The battery pack as set forth in claim 1 and wherein the controller further modifies operation of the battery pack when the monitored respective battery cell state of charge of one of the battery cells reaches a second predetermined threshold, the second predetermined threshold being different than the predetermined threshold.

6. The battery pack as set forth in claim 5 and wherein the second predetermined threshold is greater than the predetermined threshold.

7. The battery pack as set forth in claim 5 and wherein the controller further modifies operation of the battery pack by causing the switch to move from the non-conducting state to the conducting state to conduct the discharge current when the monitored respective battery cell state of charge of one of the battery cells reaches the second predetermined threshold.

8. The battery pack as set forth in claim 7 and wherein the second predetermined threshold is greater than the predetermined threshold.

9. The battery pack as set forth in claim 1 and wherein the plurality of battery cells includes five battery cells.

10. The battery pack as set forth in claim 1 and wherein the plurality of battery cells includes seven battery cells.

11. The battery pack as set forth in claim 1 and wherein each of the battery cells has a battery cell chemistry that is Lithium-based.

12. The battery pack as set forth in claim 11 and wherein the battery cell chemistry of each of the battery cells is a Lithium-ion chemistry.

13. The battery pack as set forth in claim 11 and wherein the battery cell chemistry of each of the battery cells is a Lithium Manganese Spinel chemistry.

14. The battery pack as set forth in claim 11 and wherein the battery cell chemistry of each of the battery cells is a Lithium Cobalt chemistry.

15. The battery pack as set forth in claim 11 and wherein the battery cell chemistry of each of the battery cells is a Lithium Manganese Nickel chemistry.

16. An electrical combination of a cordless power tool and a battery pack, the electrical combination comprising:

a plurality of battery cells included in the battery pack and operable to supply a battery pack discharge current to a motor of the cordless power tool, each of the battery cells having a battery cell state of charge;

a switch operable to interrupt the supply of discharge current from the battery pack to the motor of the cordless power tool when the switch is positioned in a non-conducting state;

a controller electrically connected to the switch and to each of the battery cells via a respective connection to each cell, operable to monitor the respective battery cell state of charge of each of the battery cells, and operable to control the supply of discharge current from the battery pack to the motor of the cordless power tool, the controller varying the discharge current being supplied to the motor when the monitored respective battery cell state of charge of one of the battery cells reaches a predetermined threshold;

a plurality of electrical paths between the controller and the cell connections, each electrical path being associated with a different one of the cell connections, wherein each electrical path among the plurality of electrical paths is independent of the other electrical paths among the plurality of electrical paths, and wherein no two electrical paths share an electrically conductive component; and

a plurality of transistors, each of the transistors included in a different one of the electrical paths, the transistors reducing parasitic current draw when a connection is not being used to monitor a battery cell state of charge, p1 wherein the controller is operable to control the switch to interrupt the supply of discharge current from the battery pack to the motor when the monitored respective battery cell state of charge of one of the battery cells reaches a predetermined threshold.

17. A method of operating a cordless power tool powered by a plurality of battery cells of a battery pack, the cordless power tool having a motor and a trigger switch, the method comprising:

supplying a battery pack discharge current to the motor of the cordless power tool in response to a user activation of the trigger switch;

monitoring a respective battery cell state of charge of each of the battery cells, by a microcontroller electrically connected to each of the battery cells via a respective connection to each cell, wherein a plurality of electrical paths exist between the microcontroller and the cell connections, each electrical path being associated with a different one of the cell connections, wherein each electrical path among the plurality of electrical paths is independent of the other electrical paths among the plurality of electrical paths, wherein no two electrical paths share an electrically conductive component, and wherein each electrical path includes a transistor to reduce parasitic current draw when a connection is not being used to monitor a battery cell; and

controlling a controlled switch to interrupt the supply of discharge current from the battery pack to the motor when the monitored respective battery cell state of charge of at least one of the battery cells reaches a predetermined threshold, wherein the controlling of the controlled switch to interrupt the supply of discharge current is independent of a user deactivation of the trigger switch.

18. The method of operating a cordless power tool as set forth in claim 17 and further comprising:

re-supplying the discharge current from the battery pack to the motor of the cordless power tool when the monitored respective battery cell state of charge of the at least one of the battery cells recovers to a second predetermined threshold, the second predetermined threshold being greater than the predetermined threshold.