Battery pack

• US 8,154,249 B2
• Filed: 04/26/2010
• Issued: 04/10/2012
• 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: Johnson, Todd W., Grzybowski, Dennis J., Kubale, Mark A., Rosenbecker, Jay J., Meyer, Gary D., Zeiler, Jeffrey M., Glasgow, Kevin L., Schuecher, Karl F.
• Primary Examiner(s): Fantu, Yalkew
• Application Number:
  US12/766,965
• Publication Number:
  US 20100236807A1
• Time in Patent Office: 715 Days
• Field of Search: 320/114
• US Class Current: 320/114
• 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: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H01M 10/052 Li-accumulators
• 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 10/441 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 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 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• 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 50/247 specially adapted for portable devices, e.g. mobile phones, computers, hand tools or pacemakers
• CPC Class Codes: H01M 50/262 with fastening means, e.g. locks
• 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 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0025 : Sequential battery discharge in systems with a plurality of batteries
• 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 7/0048 : Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/005 : Detection of state of health [SOH]
• 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: H05K 999/99 : dummy group
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y10T 408/65 : Means to drive tool

Abstract

An electrical combination including a driver drill capable of producing an average current draw of approximately 20-amps, a circular saw capable of producing an average current draw of approximately 20-amps, and a power tool battery pack operable to supply power to the driver drill and to the circular saw, the battery pack including a plurality of battery cells, the plurality of battery cells each having a lithium-based chemistry.

Claims

1. A battery pack configured to be interfaced with an electrical device, comprising:

a battery pack housing;

at least three terminals including a positive terminal, a negative terminal, and a sense terminal, the at least three terminals configured to be interfaced with corresponding terminals of the electrical device;

a plurality of rechargeable battery cells arranged within and supported by the housing, each of the battery cells having a respective state of charge, power being transferable between the battery cells and the electrical device;

a balancing circuit configured to detect a charge imbalance among the battery cells based on a plurality of voltages of the plurality of rechargeable battery cells detected at substantially the same time; and

a control circuit configured to initiate a controlled discharging process to discharge at least one of the battery cells whose present state of charge is high relative to a present state of charge of another of the battery cells, the control circuit including a microprocessor.

2. The battery pack of claim 1, wherein the electrical device is a power tool.

3. The battery pack of claim 1, wherein the microprocessor is configured to detect voltages of the battery cells throughout the controlled discharging process.

4. The battery pack of claim 1, wherein the microprocessor is configured to end the controlled discharging process when a present state of charge of the at least one of the battery cells is approximately equal to a present state of charge of the other of the battery cells.

5. The battery pack of claim 1, wherein the balancing circuit includes a plurality of resistors or a plurality of transistors.

6. The battery pack of claim 1, wherein the control circuit is further configured to identify a battery cell among the plurality of battery cells that is imbalanced.

7. The battery pack of claim 6, wherein the identified battery cell is a low voltage cell.

8. The battery pack of claim 1, wherein the battery pack is configured to balance the battery cells when the battery pack is in a discharging operation.

9. The battery pack of claim 1, wherein the microprocessor is configured to disable the battery pack via a switch when a balanced ratio between the battery cells falls outside a predetermined range.

10. The battery pack of claim 9, wherein the microprocessor is configured to interrupt operation of the battery pack when the balanced ratio between the battery cells falls outside the predetermined range.