BALANCING OF BATTERY PACK SYSTEM MODULES

• US 20110089901A1
• Filed: 12/22/2010
• Published: 04/21/2011
• Est. Priority Date: 05/21/2008
• Status: Active Grant

• Current Assignee: Southwest Electronic Energy Corporation (Ultralife Corporation)
• Original Assignee: Southwest Electronic Energy Corporation (Ultralife Corporation)
• Inventors: Benckenstein, Claude Leonard JR., White, David Allen
• Granted Patent: US 8,575,894 B2
• Time in Patent Office: Days
• US Class Current: 320/118
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence

Abstract

A system for balancing a plurality of battery pack system modules connected in series comprising: a plurality of battery pack system modules, wherein a high charge module of the plurality of battery pack system modules has a charge greater than a that of other modules. At least one zener diode connected in series with a current limiting resistor is connected in parallel to the plurality of battery pack system modules. A power source is in communication with a disconnect circuit of at least one of the battery pack system modules. The disconnect circuit is actuated when the battery pack system module reaches a predetermined state of charge. The zener diode enables current from the power source to bypass charged battery pack system modules to charge other battery pack system modules.

Claims

1. An apparatus, comprising:

a first battery pack system module, comprising;

a first terminal;

a second terminal;

a first battery cell in communication with the first terminal and the second terminal;

a first charge switch in communication with the first terminal and the first battery cell, in which the first charge switch, when activated, disconnects the battery cell from the first terminal to prevent charging of the battery cell; and

a first zener diode in communication with the first terminal and the second terminal.

2. The apparatus of claim 1, in which the first battery pack system module further comprises a current limiting resistor in communication with the first zener diode and the first terminal.

3. The apparatus of claim 1, further comprising:

a second battery pack system module, comprising;

a third terminal in communication with the second terminal;

a fourth terminal;

a second battery cell in communication with the third terminal and the fourth terminal;

a second charge switch in communication with the third terminal and the second battery cell, in which the second charge switch, when activated, disconnects the battery cell from the first terminal to prevent charging of the battery cell; and

a second zener diode in communication with the third terminal and the fourth terminal.

4. The apparatus of claim 1, in which the first battery pack system module further comprises a second battery cell in communication with the first battery cell and the second terminal.

5. The apparatus of claim 4, in which the first battery pack system module further comprises:

a balancing circuit in communication with the first battery cell and the second battery cell; and

a controller assembly in communication with the balancing circuit for activating and deactivating the balancing circuit.

6. The apparatus of claim 1, further comprising a discharge switch in communication with the first charge switch and the first terminal.

7. A method, comprising:

detecting that a first battery pack system module has reached a first state of charge;

activating a first charge switch in the first battery pack system module to prevent further charging of the first battery pack system module after detecting the first state of charge;

passing current through a first zener diode in the first battery pack system module to a second battery pack system module; and

charging the second battery pack system module.

8. The method of claim 7, further comprising limiting current through the first zener diode to a level below a limit of the zener diode.

9. The method of claim 7, further comprising providing current to the first battery pack system module and the second battery pack system module through a terminal of the first battery pack system module and a terminal of the second battery pack system module.

10. The method of claim 7, in which the detecting step comprises detecting the first battery pack system module is at a first state of charge unbalanced with a second state of charge of the second battery pack system module during any mode of operation of the first battery pack system module.

11. The method of claim 7, further comprising:

detecting that the second battery pack system module has reached a second state of charge; and

activating a second charge switch in the second battery pack system module to prevent further charging of the second battery pack system module after detecting the second state of charge.

12. The method of claim 7, further comprising balancing battery cells within the first battery pack system module.

13. The method of claim 12, in which the step of balancing the battery cells within the first battery pack system module comprises activating a shunting resistor in communication with at least one battery cell to discharge the at least one battery cell.

15. The method of claim 7, further comprising:

detecting the first battery pack system module and the second battery pack system module are approximately balanced; and

oscillating through a sequence defined by;

charging the first battery pack system module and the second battery pack system module for a first period of time; and

discharging the first battery pack system module and the second battery pack system module for a second period of time.

14. The method of 7, in which the step of activating the first charge switch comprises a controller of the first battery pack system module activating a disconnect circuit of the first battery pack system module, and in which the step of detecting comprises the controller of the first battery pack system module communicating with a pack sensing circuit.

16. A computer program product, comprising:

a computer-readable medium comprising;

code to detect that a first battery pack system module is at a first state of charge and a second battery pack system module is at a second state of charge lower than the first state of charge during any mode of operation of the first and second battery pack system modules;

code to activate at least one shunting resistor in communication with at least one battery cell in the first battery pack system module during any mode of operation; and

code to deactivate the at least one shunting resistor in communication with the at least one battery cell when the state of charge of the first battery pack system module becomes approximately equal with the state of charge of the second battery pack system module.

17. The computer program product of claim 16, in which the medium further comprises code to balance battery cells within the first battery pack system module during any mode of operation of the first battery pack system module.

18. The computer program product of claim 17, in which the medium further comprises code to activate at least one shunting resistor in communication with at least one battery cell to discharge the at least one battery cell during any mode of operation of the first battery pack system module.