Battery chargers, electrical systems, and rechargeable battery charging methods

• US 8,598,845 B2
• Filed: 04/20/2009
• Issued: 12/03/2013
• Est. Priority Date: 04/20/2009
• Status: Active Grant

• Current Assignee: Lithion Battery Incorporated
• Original Assignee: Valence Technology Incorporated (Lithium Werks B.V.)
• Inventors: Lim, Khoon Cheng, Chow, Lap Wai
• Primary Examiner(s): Hollington, Jermele M
• Assistant Examiner(s): Rhodes-Vivour, Temilade S
• Application Number:
  US12/426,855
• Publication Number:
  US 20100264879A1
• Time in Patent Office: 1,688 Days
• Field of Search: 320/129, 320139-141, 320/145
• US Class Current: 320/119
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Battery chargers, electrical systems, and rechargeable battery charging methods are described. According to one aspect, a battery charger includes charge circuitry configured to apply a plurality of main charging pulses of electrical energy to a plurality of rechargeable cells of a battery to charge the rechargeable cells during a common charge cycle of the battery and to apply a plurality of secondary charging pulses of electrical energy to less than all of the rechargeable cells of the battery during the common charge cycle of the battery to charge the less than all of the rechargeable cells.

Claims

1. An electrical system comprising:

charge circuitry configured to apply a plurality of main charging pulses of electrical energy to a plurality of rechargeable cells of a battery to charge the rechargeable cells during a common charge cycle of the battery and to apply a plurality of secondary charging pulses of electrical energy to less than all of the rechargeable cells of the battery during the common charge cycle of the battery to charge the less than all of the rechargeable cells;

wherein the charge circuitry is configured to apply the main charging pulses comprising constant current charging pulses and constant voltage charging pulses; and

wherein the charge circuitry is further configured to apply the constant current charging pulses to the rechargeable cells having states of charge less than a defined state of charge and to apply the constant voltage charging pulses to the rechargeable cells having states of charge greater than the defined state of charge.

2. The electrical system of claim 1 wherein the charge circuitry applies the secondary charging pulses of electrical energy to the less than all of the rechargeable cells of the battery which individually have a lower state of charge than states of charge of others of the rechargeable cells not receiving the secondary charging pulses of electrical energy during the common charge cycle of the battery.

3. The electrical system of claim 2 wherein the charge circuitry applies the secondary charging pulses of electrical energy to the individual ones of the less than all of the rechargeable cells to charge the less than all of the rechargeable cells at a faster rate of charge compared with rates of charge of the others of the rechargeable cells not receiving the secondary charging pulses of electrical energy during the common charge cycle of the battery.

4. The electrical system of claim 1 wherein the charge circuitry is configured to apply the secondary charging pulses of electrical energy to the less than all of the rechargeable cells of the battery responsive to individual ones of the less than all of the rechargeable cells of the battery having a lower state of charge than states of charge of others of the rechargeable cells not receiving the secondary charging pulses of electrical energy during the common charge cycle of the battery.

5. The electrical system of claim 1 wherein the charge circuitry applies the secondary charging pulses of electrical energy to only one of the rechargeable cells.

6. The electrical system of claim 1 wherein the charge circuitry is configured to apply individual ones of the secondary charging pulses of electrical energy for individual ones of the less than all of the rechargeable cells intermediate respective pairs of the main charging pulses which are immediately adjacent to the individual ones of the secondary charging pulses of electrical energy.

7. The electrical system of claim 1 wherein the charge circuitry comprises a main charger configured to apply the main charging pulses of electrical energy to the rechargeable cells and a plurality of secondary chargers configured to apply respective ones of the secondary charging pulses of electrical energy to respective ones of the less than all of the rechargeable cells.

8. The electrical system of claim 1 wherein the charge circuitry comprises a main charger configured to apply the main charging pulses of electrical energy to the rechargeable cells and a secondary charger configured to generate the secondary charging pulses, and further comprising switching circuitry configured to provide the secondary charging pulses to different ones of the less than all of the rechargeable cells.

9. The electrical system of claim 1 wherein the charge circuitry is configured to apply the main charging pulses and the secondary charging pulses to the rechargeable cells to provide substantially balanced charging of the rechargeable cells during the common charge cycle of the battery wherein the rechargeable cells have substantially the same state of charge during the common charge cycle.

10. A battery charger comprising:

charge circuitry configured to apply different numbers of charging pulses of electrical energy to different ones of a plurality of rechargeable cells of a battery during a common charge cycle of the battery and corresponding to the rechargeable cells having different states of charge;

wherein the charge circuitry is configured to apply the main charging pulses comprising constant current charging pulses and constant voltage charging pulses; and

wherein the charge circuitry is further configured to apply the constant current charging pulses to the rechargeable cells having states of charge less than a defined state of charge and to apply the constant voltage charging pulses to the rechargeable cells having states of charge greater than the defined state of charge.

11. The charger of claim 10 wherein at least one of the rechargeable cells has a lower state of charge compared with states of charge of others of the rechargeable cells, and wherein the charge circuitry is configured to apply an increased number of the charging pulses of electrical energy to the at least one of the rechargeable cells during the common charge cycle compared with individual numbers of the charging pulses of electrical energy applied to the others of the rechargeable cells during the common charge cycle.

12. The charger of claim 10 wherein at least one of the rechargeable cells has a lower state of charge compared with states of charge of others of the rechargeable cells, and wherein the charge circuitry is configured to apply a plurality of the charging pulses comprising main charging pulses to all of the rechargeable cells during the common charge cycle and to apply a plurality of the charging pulses comprising secondary charging pulses to only the at least one of the rechargeable cells.

13. An electrical system comprising:

a battery comprising a plurality of rechargeable cells individually configured to receive charging electrical energy and to discharge electrical energy to a load;

charge circuitry configured to apply a plurality of main charging pulses to the rechargeable cells to charge the rechargeable cells during a common charge cycle of the battery and to apply a plurality of secondary charging pulses to at least one of the rechargeable cells during the common charge cycle of the battery;

monitoring circuitry configured to monitor states of charge of the rechargeable cells during the common charge cycle of the battery and to detect the at least one of the rechargeable cells having a state of charge lower than states of charge of others of the rechargeable cells of the battery; and

control circuitry coupled with the monitoring circuitry and configured to use the monitoring of the monitoring circuitry to control the charge circuitry to apply the secondary charging pulses to the at least one of the rechargeable cells having the lower state of charge than the states of charge of the others of the rechargeable cells to substantially balance the state of charge of the at least one of the rechargeable cells with the states of charge of the others of the rechargeable cells during the common charge cycle of the battery;

wherein the charge circuitry is configured to apply the main charging pulses comprising constant current charging pulses and constant voltage charging pulses; and

wherein the charge circuitry is further configured to apply the constant current charging pulses to the rechargeable cells having states of charge less than a defined state of charge and to apply the constant voltage charging pulses to the rechargeable cells having states of charge greater than the defined state of charge.

14. The system of claim 13 wherein the control circuitry is configured to cease the application of the secondary charging pulses during the common charge cycle to the at least one of the rechargeable cells after the state of charge of the at least one of the rechargeable cells is substantially balanced with the states of charge of the others of the rechargeable cells.

15. A rechargeable battery charging method comprising:

applying electrical energy to a first number of rechargeable cells of a battery at a plurality of first moments in time to charge the first number of rechargeable cells during a common charge cycle of the battery,

wherein applying electrical energy to the first number of rechargeable cells comprises applying charging pulses comprising constant current charging pulses and constant voltage charging pulses;

and wherein applying electrical energy to the first number of rechargeable cells further comprises applying the constant current charging pulses to the rechargeable cells having states of charge less than a defined state of charge and applying the constant voltage charging pulses to the rechargeable cells having states of charge greater than the defined state of charge;

monitoring an electrical characteristic of the rechargeable cells; and

using the monitoring, applying electrical energy to a second number of the rechargeable cells of the battery at a plurality of second moments in time to charge the second number of the rechargeable cells during the common charge cycle of the battery, and wherein the second number is less than the first number.

16. The method of claim 15 wherein the applyings of the electrical energy at the first and second moments in time individually comprise applying a plurality of charging pulses of the electrical energy.

17. The method of claim 15 wherein individual ones of the second number of the rechargeable cells have a lower state of charge compared with states of charge of the rechargeable cells not receiving electrical energy at the second moments in time.

18. The method of claim 17 wherein the application of the electrical energy to the second number of the rechargeable cells is responsive to the monitoring detecting individual ones of the second number of the rechargeable cells having the lower state of charge.

19. The method of claim 17 wherein the application of electrical energy to the second number of the rechargeable cells increases the rate of charge of individual ones of the second number of the rechargeable cells.

20. The method of claim 15 wherein the application of the electrical energy to the second number of the rechargeable cells comprises applying to only one of the rechargeable cells.

21. The method of claim 15 wherein the application of the electrical energy to the second number of the rechargeable cells comprises applying the electrical energy to a first and a second of the rechargeable cells prior to one of the second moments in time and only applying the electrical energy to one of the first and second rechargeable cells after the one of the second moments in time.

22. The method of claim 21 wherein the application of the electrical energy to the second number of the rechargeable cells comprises terminating the application of the electrical energy to an other of the first and the second of the rechargeable cells after the one of the second moments in time.

23. The method of claim 22 wherein the termination comprises terminating responsive to the monitoring detecting a state of charge of the other of the first and the second of the rechargeable cells being substantially balanced with respect to states of charge of the first number of the rechargeable cells.

24. The method of claim 15 wherein the application of the electrical energy to the second number of the rechargeable cells comprises applying the electrical energy at the second moments in time which are individually intermediate a pair of the first moments in time which are immediately adjacent to the individual one of the second moments in time.

25. The method of claim 15 wherein the applications of electrical energy comprise applications of electrical energy to substantially balance the rechargeable cells of the battery during the common charge cycle providing the rechargeable cells at substantially the same state of charge during the common charge cycle.

26. The method of claim 15 wherein the application of the electrical energy to the first number of rechargeable cells comprises applying the electrical energy to all of the rechargeable cells of the battery.

27. The method of claim 15 wherein applying electrical energy to the first number of rechargeable cells further comprises initially first applying a plurality of charging pulses having a constant current and thereafter second applying a plurality of charging pulses having a constant voltage.

28. The method of claim 27 further comprising changing from the first application of electrical energy to the second application of electrical energy after the rechargeable cells have obtained a defined state of charge.

29. The method of claim 15 further comprising providing the electrical energy to charge the second number of the rechargeable cells using a secondary charger, and wherein the applying the electrical energy to the second number of the rechargeable cells comprises selectively coupling the secondary charger with individual ones of the second number of the rechargeable cells at different moments in time.

30. A rechargeable battery charging method comprising:

applying a plurality of main charging pulses of electrical energy to charge a plurality of rechargeable cells of a battery during a common charge cycle of the battery; and

during the common charge cycle of the battery, applying a plurality of secondary charging pulses of electrical energy to charge at least one of the rechargeable cells of the battery having a lower state of charge compared with states of charge of others of the rechargeable cells of the battery;

wherein applying the main charging pulses comprises applying charging pulses comprising constant current charging pulses and constant voltage charging pulses;

and wherein applying the main charging pulses further comprises applying the constant current charging pulses to the rechargeable cells having states of charge less than a defined state of charge and applying the constant voltage charging pulses to the rechargeable cells having states of charge greater than the defined state of charge.

31. The method of claim 30 wherein the application of the main charging pulses comprises applying to all of the rechargeable cells of the battery and the application of the secondary charging pulses comprises applying to less than all of the rechargeable cells of the battery.

32. The method of claim 30 further comprising:

monitoring an electrical characteristic of the rechargeable cells of the battery; and

detecting the at least one of the rechargeable cells having the lower state of charge, and wherein the applying the secondary charging pulses is responsive to the detecting.

33. The method of claim 30 further comprising ceasing the application of the secondary charging pulses during the common charge cycle responsive to the state of charge of the at least one of the rechargeable cells being substantially balanced with the states of charge of the others of the rechargeable cells.

34. The method of claim 30 wherein the application of the secondary charging pulses increases a rate of charge of the at least one of the rechargeable cells compared with rates of charge of the others of the rechargeable cells.

35. The method of claim 30 wherein the application of the secondary charging pulses to charge the at least one of the rechargeable cells having the lower state of charge comprises applying individual ones of the secondary charging pulses between respective pairs of the main charging pulses.