BATTERY PACK

• US 20070285055A1
• Filed: 06/07/2007
• Published: 12/13/2007
• Est. Priority Date: 06/07/2006
• Status: Abandoned Application

• Current Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Original Assignee: Milwaukee Electric Tool Corporation (Techtronic Industries Company Limited)
• Inventors: Meyer, Gary, Glasgow, Kevin, Rosenbecker, Jay
• Application Number:
  US11/759,708
• Publication Number:
  US 20070285055A1
• Time in Patent Office: Days
• US Class Current: 320/116
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• 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 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence

Abstract

A rechargeable battery pack. The battery pack includes a plurality of battery cells, a positive terminal, a charging switch, and a negative terminal. The plurality of battery cells are connected in series and include a first battery cell and a last battery cell. The charging switch is electrically coupled between the positive terminal and a positive node of the first battery cell and is configured to open when the battery cells are substantially charged. The negative terminal is electrically coupled to a negative node of the last battery cell.

Claims

1. A rechargeable battery pack, comprising:

a plurality of battery cells connected in series, the plurality of battery cells including a first battery cell and a last battery cell;

a positive terminal;

a charging switch electrically coupled between the positive terminal and a positive node of the first battery cell, the charging switch configured to open when the battery cells are substantially charged; and

a negative terminal electrically coupled to a negative node of the last battery cell.

2. The battery pack of claim 1, wherein the battery pack is rechargeable by a battery charger and wherein the battery cells have a chemistry not supported by the battery charger.

3. The battery pack of claim 1, further comprising a controller configured to control the charging switch.

4. The battery pack of claim 3, wherein the controller controls the charging switch such that the charging switch receives a constant charging current from a battery charger and provides a pulsed charging current to the battery cells.

5. The battery pack of claim 3, further comprising a sense terminal, wherein the controller provides a signal to the sense terminal.

6. The battery pack of claim 5, wherein the signal is equivalent to a signal provided by a second battery pack having a different chemistry.

7. The battery pack of claim 5, wherein the signal indicates when the battery pack is substantially charged.

8. The battery pack of claim 5, wherein the signal indicates when a temperature of the battery pack is within a temperature range.

9. The battery pack of claim 1, further comprising a sense terminal and an identification device, the identification device coupled between the sense terminal and the negative terminal.

10. The battery pack of claim 9, further comprising a sense switch connected in parallel with the identification device.

11. The battery pack of claim 10, wherein the sense switch is configured to open when the battery cells are fully charged.

12. The battery pack of claim 1, wherein the charge switch is a field effect transistor.

13. The battery pack of claim 1, further comprising a discharge switch coupled between the negative node of the last battery cell and the negative terminal.

14. The battery pack of claim 13, further comprising a controller, wherein the discharge switch is controlled by the controller.

15. The battery pack of claim 14, wherein the controller opens the discharge switch when a voltage of a battery cell is below a threshold voltage.

16. The battery pack of claim 1, further comprising a circuit configured to dissipate current when the charging switch is open.

17. The battery pack of claim 16, wherein the circuit provides a voltage indicating to a battery charger that the battery pack is substantially charged.

18. The battery pack of claim 16, wherein the circuit includes a resistor and a bleeder switch, the resistor coupled between the positive end of the battery cells and the bleeder switch, the bleeder switch coupled between the resistor and the negative terminal.

19. The battery pack of claim 16, wherein the bleeder switch is closed when the charging switch is open and the bleeder switch is open when the charging switch is closed.

20. The battery pack of claim 1, further comprising a discharge positive terminal coupled to the positive end of the battery cells.

21. The battery pack of claim 1, further comprising a sense switch coupled between the negative terminal and the negative end of the battery cells.

22. An electrical combination, comprising:

a battery charger; and

a rechargeable battery pack including a plurality of battery cells having a chemistry not compatible with the charger, the battery pack including circuitry to provide one or more signals to the battery charger equivalent to signals output by a second battery pack compatible with the charger and to protect the battery cells from damage caused by the incompatibility of the battery pack and the battery charger.

23. The electrical combination of claim 22, wherein the circuitry prevents a trickle charge, from the battery charger, from reaching the battery cells.

24. The electrical combination of claim 22, wherein the charger provides a constant charging current.

25. The electrical combination of claim 24, wherein the circuitry modifies the constant charging current into a pulsed charging current.

26. A method of charging a battery coupled to a charger, the battery having a chemistry not supported by the charger, the method comprising:

providing a signal to the charger identifying at least one characteristic of the battery to the charger, the signal indicating that the battery is supported by the charger;

modifying a constant charging current provided by the charger; and

blocking a trickle current provided by the charger.

27. The method of claim 26, wherein the modifying act comprises converting the constant charging current into a pulsed charging current.

28. The method of claim 26, further comprising providing a signal to the charger indicating that the battery is fully charged.