Lithium-based battery pack for a high current draw, hand held power tool

• US 7,944,173 B2
• Filed: 12/09/2008
• Issued: 05/17/2011
• Est. Priority Date: 11/22/2002
• Status: Expired due to Term

• Current Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Original Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Inventors: Zeiler, Jeffrey M., Scheucher, Karl F., Kubale, Mark A., Johnson, Todd W., Glasgow, Kevin L., Rosenbecker, Jay J., Grzybowski, Dennis J., Meyer, Gary D.
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US12/331,088
• Publication Number:
  US 20090087729A1
• Time in Patent Office: 889 Days
• Field of Search: 320/112, 320/114, 320/116, 320/118, 320/122
• US Class Current: 320/112
• CPC Class Codes: H01M 10/052 Li-accumulators
• 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 10/448 End of discharge regulating measures
• CPC Class Codes: H01M 10/46 Accumulators structurally combined with charging apparatus circuits for charging H02J7/00
• CPC Class Codes: H01M 2220/30 Batteries in portable systems, e.g. mobile phone, laptop
• 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 6/42 Grouping of primary cells into batteries H01M6/40 takes precedence
• CPC Class Codes: H02J 7/00038 using passive battery identification means, e.g. resistors or capacitors identification by mechanical connections H02J7/0045
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0044 specially adapted for holding portable devices containing batteries H02J7/0045 takes precedence
• CPC Class Codes: H02J 7/0045 concerning the insertion or the connection of the batteries
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method for conducting an operation including a power tool battery pack. The battery pack can include a housing, a first cell supported by the housing and having a voltage, and a second cell supported by the housing and having a voltage. The battery pack also can be connectable to a power tool and be operable to supply power to operate the power tool. The method can include discharging one of the first cell and the second cell until the voltage of the one of the first cell and the second cell is substantially equal to the voltage of the other of the first cell and the second cell.

Claims

1. A rechargeable battery pack for powering a high current draw hand held power tool, the battery pack comprising:

a housing connectable to and supportable by the hand held power tool;

a plurality of battery cells supported by the housing, the battery cells being capable of producing an average battery pack discharge current greater than or equal to approximately 20 amps, the battery cells having a lithium-based chemistry;

at least one terminal through which the battery pack discharge current flows, the at least one terminal connectable to at least one corresponding terminal of the hand held power tool; and

a locking assembly operable to lock the housing to the hand held power tool.

2. The battery pack as set forth in claim 1, wherein the battery cells have a lithium-manganese chemistry.

3. The battery pack as set forth in claim 1, wherein the battery cells have a spinel chemistry.

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

5. The battery pack as set forth in claim 1, wherein each of the plurality of battery cells has a nominal voltage of approximately 4.2 volts.

6. The battery pack as set forth in claim 1, wherein the battery cells have an ampere-hour capacity of approximately 3.0 ampere-hours.

7. The battery pack as set forth in claim 1, wherein the plurality of battery cells have a combined nominal voltage of at least approximately 28 volts.

8. The battery pack as set forth in claim 1, wherein the battery pack is removably connectable to the hand held power tool.

9. The battery pack as set forth in claim 1, further comprising a protection circuit configured to protect at least one component of the battery pack.

10. The battery pack as set forth in claim 1, wherein the power tool is one of a driver drill and a circular saw.

11. The battery pack as set forth in claim 1, wherein the plurality of battery cells has a combined nominal voltage of approximately 9.6 volts.

12. A hand held power tool operable for use with the battery pack as set forth in claim 1.

13. The battery pack as set forth in claim 1, wherein the locking assembly includes at at least one locking member movable between a locked position and an unlocked position.