Battery unit balancing system

• US 8,723,482 B2
• Filed: 11/04/2010
• Issued: 05/13/2014
• Est. Priority Date: 11/04/2010
• Status: Active Grant

• Current Assignee: Elite Power Holdings LLC
• Original Assignee: Elite Power Solutions LLC
• Inventors: Dao, Yuan, Schlanger, William
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): BOATENG, ALEXIS ASIEDUA
• Application Number:
  US12/939,889
• Publication Number:
  US 20110074355A1
• Time in Patent Office: 1,286 Days
• Field of Search: 320/116, 320/118, 320/119, 320/122, 320/132, 320/152, 320/121, 320/124, 320/128, 320/103, 320/165
• US Class Current: 320/122
• 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. a discharging circuit configured for connection to a battery unit comprising;

i. a voltage dividing circuit;

ii. a comparator circuit comprising;

1. a shunt regulator configured in parallel with said voltage divider;

iii. one or more current source circuits comprising;

1. current regulator; and

2. an output device;

wherein said output device, said shunt regulator and said one or more current source circuits are connected in parallel with the battery unit, wherein, while connected to the battery unit, the discharging circuit is configured for automatic activation such that, when a voltage of the battery unit exceeds a predetermined threshold, the discharging circuit draws a constant discharging current from the battery unit until the voltage of the battery unit falls below the predetermined threshold;

wherein the voltage dividing circuit is connected to the comparator circuit via a node to the shunt regulator,

said shunt regulator is connected to said current source circuit via a current limiting resistor of said output device,

whereby the comparator circuit is activated to conduct when the voltage of the battery unit exceeds the predetermined threshold,

the voltage dividing circuit is programmed to generate a predetermined voltage,

wherein the predetermined voltage activates the one or more current source circuits via the comparator circuit, and

whereby each current source circuit 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.

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

3. The battery balancing system of claim 1, wherein each current source circuit of the one or more current source circuits comprises:

a. a first terminal connected between the battery unit and the balancing circuit, wherein said first terminal is connected to an emitter of a first transistor and a first terminal of a first resistor;

b. a base of said first transistor connected to a second terminal of said first resistor and an emitter of a second transistor;

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

d. a collector of said second transistor connected to said second terminal,

wherein said second terminal is connected between said battery unit and said balancing circuit.

4. 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.

5. 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, wherein each current source circuit of the one or more current source circuits is configured such that the respective one or more transistors interact to form an equilibrium so that the stable current flows through the one or more resistors, thereby dissipating power.

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

7. 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.

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

9. The battery unit balancing system of claim 8, wherein the battery cell is lithium ion cell.

10. The battery unit balancing system of claim 1, wherein the voltage dividing circuit comprises:

a. a first resistor having a first resistor value;

b. a second resistor having a second resistor value; and

c. a node between said first and second resistors connected to a shunt regulator,

whereby the voltage dividing circuit provides a node voltage to the shunt regulator of the comparator circuit having a value equal to the product of the voltage of the battery and the second resistor value divided by the sum of first and second resistor values.

11. The battery unit balancing system of claim 10, wherein at least one of the first and second resistors are variable resistors that can be adjusted to provide a node voltage to shunt regulator.

12. The battery unit balancing system of claim 1, whereby when said comparator circuit is activated to conduct, said voltage dividing circuit divides the battery voltage by approximately ⅓

to produce a voltage of 1.2V when said battery unit reaches said predetermined threshold at which time said current source is activated.