RECHARGEABLE SPLIT BATTERY SYSTEM

• US 20090218989A1
• Filed: 02/17/2009
• Published: 09/03/2009
• Est. Priority Date: 02/15/2008
• Status: Active Grant

• Current Assignee: Atieva, Inc.
• Original Assignee: Atieva, Inc.
• Inventors: DAVIS, Kerry
• Granted Patent: US 8,143,855 B2
• Time in Patent Office: Days
• US Class Current: 320/136
• CPC Class Codes: H01M 10/4207 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 7/0025 Sequential battery discharge in systems with a plurality of 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 system is split into first and second battery subsystems. When the first battery subsystem reaches a first discharge level, the first battery system is decoupled from output terminals of the battery system and the second battery subsystem is coupled to the output terminals of the battery system.

Claims

1. A battery system comprising:

output terminals;

a first battery subsystem switchably coupled to the output terminals and having one or more battery cells;

a second battery subsystem switchably coupled to the output terminals having one or more battery cells; and

a control unit to determine when the first battery subsystem has reached a first discharge level and, in response, to decouple the first battery subsystem from the output terminals and to couple the second battery subsystem to the output terminals.

2. The battery system of claim 1 further comprising a battery pack, and wherein the first battery subsystem and second battery subsystem are included within the battery pack.

3. The battery system of claim 1 wherein the control unit monitors discharge of the first battery subsystem in part by measuring a voltage of the first battery subsystem.

4. The battery system of claim 1 wherein the first discharge level is selected from a group consisting of (A) a voltage level, (B) a voltage offset from a dynamically determined voltage level, and (C) a rate of change in voltage.

5. The battery system of claim 1 wherein the first discharge level is programmable.

6. The battery system of claim 1 wherein the control unit comprises a programmable processor.

7. The battery system of claim 1 wherein the control unit comprises a first battery control unit to monitor the first battery subsystem, and a second battery control unit to monitor the second battery subsystem.

8. The battery system of claim 1 further comprising a third battery subsystem switchably coupled to the output terminals, and wherein the control unit includes circuitry to determine when the second battery subsystem has reached a second discharge level and, in response, to decouple the second battery subsystem from the output terminals and to couple the third battery subsystem to the output terminals.

9. The battery subsystem of claim 1 wherein the control unit includes circuitry to determine that an amount of power demanded from the battery system exceeds a power threshold and, in response, to switchably couple the second battery subsystem to the output terminals in parallel with the first battery subsystem.

10. The battery subsystem of claim 1 wherein the control unit includes circuitry to adjust the first discharge level according to a number of completed discharge cycles of the first battery subsystem.

11. A method of operation within a battery system, the method comprising:

switchably coupling a first battery subsystem to output terminals of the battery system to deliver power to a load;

determining that the first battery subsystem has reached a first discharge level;

decoupling the first battery subsystem from the output terminals in response to determining that the first battery subsystem has reached the first discharge level; and

coupling a second battery subsystem to the output terminals in response to determining that the first battery subsystem has reached the first discharge level.

12. The method of claim 11 wherein the first battery subsystem and second battery subsystem are included within the battery pack.

13. The method of claim 11 wherein determining that the first battery subsystem has reached a first discharge level comprises monitoring discharge of the first battery subsystem in part by measuring a voltage of the first battery subsystem.

14. The method of claim 13 wherein monitoring discharge of the first battery subsystem in part by measuring a voltage of the first battery subsystem comprises executing a sequence of program instructions within a programmable processor.

15. The method of claim 11 wherein the first discharge level comprises at least one of a voltage level, a voltage offset from a dynamically determined voltage level, or a rate of change in voltage.

16. The method of claim 11 further comprising receiving a value representative of the first discharge level and storing the value in a programmable register of the battery system.

17. The method of claim 11 further comprising:

determining that the second battery subsystem has reached a second discharge level;

decoupling the second battery subsystem from the output terminals in response to determining that the second battery subsystem has reached the second discharge level; and

coupling a third battery subsystem to the output terminals in response to determining that the second battery subsystem has reached the second discharge level.

18. The method of claim 11 further comprising:

determining that an amount of power demanded from the battery system exceeds a power threshold; and

switchably coupling the second battery subsystem to the output terminals in parallel with the first battery subsystem.

19. The method of claim 11 further comprising adjusting the first discharge level according to a number of completed discharge cycles of the first battery subsystem.

20. A battery system comprising:

first and second groups of battery cells, each including at least one battery cell;

means for switchably coupling the first group of battery cells to output terminals of the battery system to deliver power to a load;

means for determining that the first group of battery cells has reached a first discharge level;

means for decoupling the first group of battery cells from the output terminals in response to determining that the first group of battery cells has reached the first discharge level; and

means for coupling a second group of battery cells to the output terminals in response to determining that the first group of battery cells has reached the first discharge level.