Systems and Methods of Battery Charging with Dynamic Float Voltage

• US 20090295338A1
• Filed: 06/01/2009
• Published: 12/03/2009
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Summit Microelectronics, Incorporated (Qualcomm, Inc.)
• Inventors: Hawawini, Shadi, Hussain, M. Abid
• Granted Patent: US 8,896,272 B2
• Time in Patent Office: Days
• US Class Current: 320/157
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Embodiments of the present invention include electronic circuits, systems, and methods for charging a battery. In one embodiment, the present invention includes a method, which may be implemented by an integrated circuit, comprising charging the battery using a constant current until the voltage on the battery increases to a first voltage level, and charging the battery using a constant voltage, wherein the constant voltage is set to a second voltage level. The constant current charging transitions to constant voltage charging when the voltage on the battery reaches the first voltage level, where the first voltage level is greater than the second voltage level.

Claims

1. A method of charging a battery comprising:

charging the battery using a controlled current until the voltage on the battery increases to a first voltage level; and

charging the battery using a constant voltage, wherein the constant voltage is set to a second voltage level,

wherein the controlled current charging transitions to constant voltage charging when the voltage on the battery reaches the first voltage level, and wherein the first voltage level is greater than the second voltage level.

2. The method of claim 1 wherein the difference between the first voltage level and the second voltage level corresponds to a voltage across a series resistance in said battery.

3. The method of claim 1 wherein the first voltage level is predetermined.

4. The method of claim 1 wherein the first voltage level is determined dynamically.

5. The method of claim 4 wherein determining the first voltage level comprises:

sensing the voltage level of the battery when the current into the battery is at a first current level; and

sensing the voltage level of the battery when the current into the battery is at a second current level.

6. The method of claim 5 wherein the first current level is zero and the second current level is equal to a current into the battery during said controlled current charging.

7. The method of claim 1 further comprising stopping charging between said controlled current charging and said constant voltage charging for a predetermined time period.

8. The method of claim 1 wherein the controlled current is a constant current.

9. An integrated circuit for charging a battery comprising:

a current controller circuit coupled to the battery to charge the battery using a controlled current until the voltage on the battery increases to a first voltage level; and

a voltage controller circuit coupled to the battery to charge the battery using a constant voltage, wherein the constant voltage is set to a second voltage level,

wherein the current controller circuit is inactivated and the voltage controller circuit is activated when the voltage on the battery reaches the first voltage level, and wherein the first voltage level is greater than the second voltage level.

10. The integrated circuit of claim 9 wherein the difference between the first voltage level and the second voltage level corresponds to a voltage across a series resistance in said battery.

11. The integrated circuit of claim 9 wherein the first voltage level is predetermined.

12. The integrated circuit of claim 9 wherein the first voltage level is determined dynamically.

13. The integrated circuit of claim 12 wherein determining the first voltage level comprises:

sensing the voltage level of the battery when the current into the battery is at a first current level; and

sensing the voltage level of the battery when the current into the battery is at a second current level.

14. The integrated circuit of claim 13 wherein the first current level is zero and the second current level is equal to a current into the battery during said controlled current charging.

15. The integrated circuit of claim 9 wherein charging is stopped between said controlled current charging and said constant voltage charging for a predetermined time period.

16. A circuit for charging a battery comprising:

means for charging a battery using a controlled current until the voltage on the battery increases to a first voltage level; and

means for charging the battery using a constant voltage, wherein the constant voltage is set to a second voltage level,

wherein the controlled current charging transitions to constant voltage charging when the voltage on the battery reaches the first voltage level, and wherein the first voltage level is greater than the second voltage level.

17. The circuit of claim 16 wherein the difference between the first voltage level and the second voltage level corresponds to a voltage across a series resistance in said battery.

18. The circuit of claim 16 wherein the first voltage level is predetermined.

19. The circuit of claim 16 wherein the first voltage level is determined dynamically.

20. The circuit of claim 19 wherein determining the first voltage level comprises:

sensing the voltage level of the battery when the current into the battery is at a first current level; and

sensing the voltage level of the battery when the current into the battery is at a second current level.

21. The circuit of claim 20 wherein the first current level is zero and the second current level is equal to a current into the battery during said controlled current charging.

22. The circuit of claim 16 further comprising stopping charging between said controlled current charging and said constant voltage charging for a predetermined time period.