BATTERY UNIT BALANCING SYSTEM

• US 20110074355A1
• Filed: 11/04/2010
• Published: 03/31/2011
• Est. Priority Date: 11/04/2010
• Status: Active Grant

• Current Assignee: Elite Power Holdings LLC
• Original Assignee: Elite Power Solutions LLC
• Inventors: Schlanger, William, Dao, Yuan
• Granted Patent: US 8,723,482 B2
• Time in Patent Office: Days
• US Class Current: 320/118
• 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 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• 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 7/1423 with multiple batteries
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A battery unit balancing system comprises a discharging circuit and means for connecting the discharging circuit to a battery unit. The discharging circuit is configured such that it is automatically activated, when a voltage of the battery unit exceeds a predetermined threshold, to draw a constant discharging current from the battery unit until the voltage of the battery unit falls below the predetermined threshold.

Claims

1. A battery unit balancing system comprising:

a discharging circuit; and

means for connecting the discharging circuit to a battery unit;

wherein the discharging circuit is configured such that it is automatically activated, when a voltage of the battery unit exceeds a predetermined threshold, to draw a constant discharging current from the battery unit until the voltage of the battery unit falls below the predetermined threshold.

2. The battery unit balancing system of claim 1, wherein the discharging circuit comprises:

a voltage dividing circuit, a comparator circuit, and one or more current source circuits,

wherein the voltage dividing circuit is configured such that it is connected to a comparator circuit which is activated to conduct when the voltage of the battery unit exceeds the predetermined threshold and wherein the voltage dividing circuit is programmed to generate a predetermined voltage that activates the one or more current source circuits via the comparator circuit, and

further wherein each of the one or more current source circuits is configured such that a substantially stable current flows independent of the voltage of the battery unit.

3. The battery unit balancing system of claim 1, wherein the voltage dividing circuit comprises one or more resistors that are programmed to generate the predetermined voltage.

4. The battery unit balancing system of claim 2, wherein each current source circuit of the one or more current source circuits comprises:

a first terminal of the means for connecting the balancing circuit connected to an emitter of the first transistor and a first terminal of the first resistor;

a base of the first transistor connected to a second terminal of the first resistor and an emitter of the second transistor;

a collector of the first transistor connected to a base of the second transistor; and

a collector of the second transistor connected to a second terminal of the means for connecting the balancing circuit.

5. The battery unit balancing system of claim 1, wherein the comparator circuit comprises a shunt regulator.

7. The battery unit balancing system of claim 1, wherein the comparator circuit does not conduct when the voltage of the battery unit is below the predetermined threshold.

8. The battery unit balancing system of claim 1, wherein each of the one or more current source circuits comprises one or more transistors and one or more resistors and is configured such that the one or more transistors interact to form an equilibrium so that the stable current flows through the one or more resistors, thereby dissipating power.

9. The battery unit balancing system of claim 1, wherein the predetermined threshold is about 3.7V.

10. The battery unit balancing system of claim 1, further comprising a first output device for indicating the system is receiving power from the battery unit and a second output device for indicating the discharging circuit is activated.

12. The battery unit balancing system of claim 1, wherein the battery unit is a single battery cell.

14. The battery unit balancing system of claim 12, wherein the battery cell is a lithium ion cell.

6. (canceled)

11. (canceled)

13. (canceled)

15-16. -16. (canceled)

17. A system for providing a balancing charge cycle for a battery pack comprising a plurality of battery units, comprising:

a plurality of discharging units, each of which is connected to each of the plurality of battery units;

wherein each of the plurality of discharging units is configured such that it is automatically activated, when a voltage of the corresponding battery unit exceeds a predetermined threshold, to draw a constant discharging current from the corresponding battery unit until the voltage of the corresponding battery unit falls below the predetermined threshold.

18. The system of claim 17, wherein the each of the plurality of discharging units is autonomous.

19. The system of claim 17, wherein the discharging circuit of each of the plurality of discharging units comprises:

a voltage dividing circuit, a comparator circuit, and one or more current source circuits,

wherein the comparator circuit is configured such that it is activated to conduct when the voltage of the battery unit exceeds the predetermined threshold and wherein the voltage dividing circuit is programmed to generate a predetermined voltage input to the comparator circuit that activates the one or more current source circuits, and

further wherein each of the one or more current source circuits is configured such that a substantially stable current flows independent of the voltage of the battery unit.

20. The system of claim 17, wherein the predetermined threshold is about 3.7V.

21. The system of claim 17, wherein each of the plurality of charging units further comprises a first output device for indicating the system is receiving power from the corresponding battery unit and a second output device for indicating the discharging circuit is activated.

23. The system of claim 17, wherein each of the plurality of battery units is a single battery cell.

25. The system of claim 23, wherein the battery cell is a lithium ion cell.

22. (canceled)

24. (canceled)

26-27. -27. (canceled)

28. A method for balancing a plurality of battery units, comprising the steps of:

(a) automatically drawing a substantially constant discharging current from the battery unit that is charged to a voltage above the predetermined threshold, by activating a discharging cycle for the battery unit; and

(b) terminating the discharging cycle once the voltage is below the predetermined threshold.

29. The method of claim 28, wherein the method charges the plurality of battery units to a substantially same level.

30. (canceled)