Optimized battery life in multiple battery applications

• US 20040189249A1
• Filed: 03/26/2003
• Published: 09/30/2004
• Est. Priority Date: 03/26/2003
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Pathfinder Energy Services LLC (Schlumberger NV)
• Inventors: Long, David, Beals, Richard A.
• Granted Patent: US 7,009,363 B2
• Time in Patent Office: Days
• US Class Current: 320/116
• CPC Class Codes: H02J 7/0025 Sequential battery discharge in systems with a plurality of batteries
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/007 Regulation of charging or discharging current or voltage
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence

Abstract

Various apparatus and methods of supplying regulated battery power to an electrical device, such as a downhole tool, are provided. In one aspect, a method of providing power to an electrical device is provided that includes providing a plurality of batteries and providing a plurality of controllable regulators for regulating the power output of the plurality of batteries. The plurality of controllable regulators is set so that power is drawn from a minimum number of the plurality of batteries necessary to satisfy demand from the electrical device. The electrical device is enabled to periodically draw power from and thereby depassivate each of the plurality of batteries.

Claims

1. A device for powering a load, comprising:

a first battery;

a second battery;

a first controllable regulator having an input coupled to the first battery and an output for coupling to the load;

a second controllable regulator having an input coupled to the second battery and an output for coupling to the load in parallel with the output of the first controllable regulator, the second controllable regulator being operable to enable the load to draw power from the second battery when an output voltage of the first regulator falls below a voltage setpoint; and

the first and second controllable regulators being operable to enable the load to alternately draw power from either of the first and second batteries even if the output voltage of the first controllable regulator does not fall below the voltage set point;

wherein the first and second batteries are periodically depassivated.

2. The device of claim 1, wherein the first battery has a first predetermined maximum design current and the second battery has a second predetermined maximum design current, the first and second controllable regulators being operable to selectively limit current from the first battery and the second battery respectively to the first and second maximum design currents.

3. The device of claim 1, wherein the first controllable regulator comprises a first inductor and a second inductor coupled to an output of the first battery, a first regulator circuit coupled to the first and second inductors, a first diode coupled to the first inductor and a second diode coupled to the second inductor, the regulator circuit being operable to selectively enable the first and second inductors to alternately energize for periods sufficient to cause the first and second diodes to conduct current from the first battery to the load.

4. The device of claim 3, further comprising a first switch coupled to the first inductor and the regulator circuit and a second switch coupled to the second inductor and the regulator circuit, the regulator circuit being operable to turn the switches on and off to selectively enable the first and second inductors to alternately energize for periods sufficient to cause the first and second diodes to conduct current from the first battery to the load.

5. The device of claim 3, wherein the second controllable regulator comprises a third inductor and a fourth inductor coupled to an output of the second battery, a second regulator circuit coupled to the third and fourth inductors, a third diode coupled to the third inductor and a fourth diode coupled to the fourth inductor, the second regulator circuit being operable to selectively enable the third and fourth inductors to alternately energize for periods sufficient to cause the third and fourth diodes to conduct current from the second battery to the load.

6. The device of claim 1, further comprising a controller for controlling the first and second controllable regulators.

7. The device of claim 6, wherein the controller comprises a microprocessor.

8. The device of claim 6, wherein the controller is operable to set a no-load output voltage of each of the first and second controllable regulators, the voltage setpoint comprising the no-load output voltage of the second controllable regulator.

9. The device of claim 1, wherein the first and second controllable regulators comprise boost regulators.

10. The device of claim 1, further comprising a first depassivation circuit and a second depassivation circuit each operable to selectively depassivate a corresponding one of the first and second batteries.

11. A downhole tool, comprising:

an electrical unit requiring electrical power; and

power unit for supplying electrical power to the electrical unit, the power unit having a first battery, a second battery, a first controllable regulator having an input coupled to the first battery and an output coupled to the electrical unit, and a second controllable regulator having an input coupled to the first battery and an output coupled to the electrical unit in parallel with the output of the first controllable regulator, the second controllable regulator being operable to enable the electrical unit to draw power from the second battery when an output voltage of the first controllable regulator falls below a voltage setpoint.

12. The downhole tool of claim 11, wherein the first and second controllable regulators are operable, even if the output voltage of the first controllable regulator does not fall below the voltage setpoint, to enable the electrical unit to alternately draw power from either of the first and second batteries in order to depassivate the first battery and the second battery.

13. The downhole tool of claim 11, wherein the electrical unit comprises a sensor.

14. The downhole tool of claim 13, wherein the sensor is operable to sense a condition of a subterranean formation.

15. The downhole tool of claim 14, wherein the condition comprises resistivity.

16. The downhole tool of claim 11, wherein the first and second batteries are positioned at a first location and the first and second controllable regulators are positioned between the electrical unit and the first and second batteries.

17. The downhole tool of claim 11, wherein the first and second batteries are positioned in a first housing and the first and second regulators are positioned in a second housing, the first and second housings being disconnectable.

18. The downhole tool of claim 11, wherein the first battery has a first predetermined maximum design current and the second battery has a second predetermined maximum design current, the first and second controllable regulators being operable to selectively limit current from the first battery and the second battery respectively to the first and second maximum design currents.

19. The downhole tool of claim 11, wherein the first controllable regulator comprises a first inductor and a second inductor coupled to an output of the first battery, a first regulator circuit coupled to the first and second inductors, a first diode coupled to the first inductor and a second diode coupled to the second inductor, the regulator circuit being operable to selectively enable the first and second inductors to alternately energize for periods sufficient to cause the first and second diodes to conduct current from the first battery to the load.

20. The downhole tool of claim 19, further comprising a first switch coupled to the first inductor and the regulator circuit and a second switch coupled to the second inductor and the regulator circuit, the regulator circuit being operable to turn the switches on and off to selectively enable the first and second inductors to alternately energize for periods sufficient to cause the first and second diodes to conduct current from the first battery to the load.

21. The downhole tool of claim 19, wherein the second controllable regulator comprises a third inductor and a fourth inductor coupled to an output of the second battery, a second regulator circuit coupled to the third and fourth inductors, a third diode coupled to the third inductor and a fourth diode coupled to the fourth inductor, the second regulator circuit being operable to selectively enable the third and fourth inductors to alternately energize for periods sufficient to cause the third and fourth diodes to conduct current from the second battery to the load.

22. The downhole tool of claim 11, further comprising a controller for controlling the first and second controllable regulators.

23. The downhole tool of claim 22, wherein the controller comprises a microprocessor.

24. The downhole tool of claim 22, wherein the controller is operable to set a no-load output voltage of each of the first and second controllable regulators, the voltage setpoint comprising the no-load output voltage of the first controllable regulator.

25. The downhole tool of claim 11, wherein the first and second controllable regulators comprise boost regulators.

26. The downhole tool of claim 11, further comprising first and second depassivation circuits each being operable to selectively depassivate the first and second batteries.

27. The downhole tool of claim 11, wherein the voltage set point comprises a no-load output voltage of the second controllable regulator.

28. A downhole tool, comprising:

an electrical unit requiring electrical power;

power unit for supplying electrical power to the electrical unit, the power unit having a plurality of batteries and a plurality of controllable regulators, the plurality of controllable regulators being operable to enable the electrical unit to draw power from a minimum number of the plurality of batteries necessary to satisfy a demand from the electrical unit so that the batteries are preferentially discharged; and

a controller for controlling the plurality of controllable regulators.

29. The downhole tool of claim 28, wherein each of the plurality of controllable regulators has an input coupled to one of the plurality of batteries and an output coupled to the electrical unit, the outputs of the plurality of controllable regulators being in parallel, each of the plurality of controllable regulators having a selectable no-load output voltage, one of the plurality of controllable regulators having a selectable no-load output voltage higher than the selectable no-load output voltages of the others of the plurality of controllable regulators;

wherein a given controllable regulator of the others of the plurality of controllable regulators is operable to enable the electrical unit to draw power from its respective battery when an output voltage of the first controllable regulator and output voltages of any of the remainder of the others of the plurality of controllable regulators having a no-load output voltage set higher than that of the given controllable regulator fall to or below the no-load output voltage of the given controllable regulator.

30. The downhole tool of claim 29, wherein the controller selects the no-load output voltages.

31. The downhole tool of claim 28, wherein the first and second controllable regulators are operable to enable the electrical unit to periodically draw power from each of the plurality of batteries even if, in order to depassivate the batteries, the demand of the electrical unit may be met by fewer than all of the batteries.

32. The downhole tool of claim 28, wherein the electrical unit comprises a sensor.

33. The downhole tool of claim 32, wherein the sensor is operable to sense a condition of a subterranean formation.

34. The downhole tool of claim 33, wherein the condition comprises resistivity.

35. The downhole tool of claim 28, wherein the plurality of batteries are positioned at a first location and the plurality of controllable regulators are positioned between the electrical unit and the plurality of batteries.

36. The downhole tool of claim 28, wherein the plurality of batteries is positioned in a first housing and the plurality of controllable regulators is positioned in a second housing, the first and second housings being disconnectable.

37. The downhole tool of claim 28, wherein each of the plurality of batteries has a corresponding predetermined maximum design current, the plurality of controllable regulators being operable to selectively limit current from among the plurality of batteries to their corresponding maximum design currents.

38. The downhole tool of claim 28, wherein each of the controllable regulators comprises a first inductor and a second inductor coupled to an output of its respective battery, a first regulator circuit coupled to the first and second inductors, a first diode coupled to the first inductor and a second diode coupled to the second inductor, the first regulator circuit being operable to selectively enable the first and second inductors to alternately energize for periods sufficient to cause the first and second diodes to conduct current from the respective battery to the electrical unit.

39. The downhole tool of claim 38, further comprising a first switch coupled to the first inductor and the regulator circuit and a second switch coupled to the second inductor and the regulator circuit, the regulator circuit being operable to turn the switches on and off to selectively enable the first and second inductors to alternately energize for periods sufficient to cause the first and second diodes to conduct current from the first respective battery to the electrical unit.

40. The downhole tool of claim 28, wherein each of the plurality of controllable regulators comprises a boost regulator.

41. The downhole tool of claim 28, wherein each of the plurality of controllable regulators comprises a depassivation circuit to selectively depassivate its respective battery.

42. A method of providing power to an electrical device, comprising:

providing a plurality of batteries;

providing a plurality of controllable regulators for regulating the power output of the plurality of batteries;

setting the plurality of controllable regulators so that power is drawn from a minimum number of the plurality of batteries necessary to satisfy demand from the electrical device; and

enabling the electrical device to periodically draw power from and thereby depassivate each of the plurality of batteries.

43. The method of claim 42, comprising limiting the current drawn from each battery to a maximum design current.

44. The method of claim 42, wherein each of the plurality of controllable regulators regulates the power output of a corresponding one of the plurality of batteries and each of the plurality of batteries is regulated by a corresponding one of the plurality of controllable regulators.

45. The method of claim 42, wherein the setting of the plurality of controllable regulators further comprises:

setting a no-load output voltage for each of the plurality of regulators, one of the controllable regulators becoming a high-set regulator with a first no-load output voltage higher than that of the other controller regulators; and

disposing a given one from among said other controllable regulators to enable the electrical unit to draw power from the battery corresponding to the given controllable regulator upon an event, the event including the output of the high-set regulator falling to or below, and the output of any of said other controllable regulators being at or below, the no-load output voltage of the given controllable regulator.

46. The method of claim 45, wherein all of said other controllable regulators are set with different no-load output voltages.

47. The method of claim 45, further comprising resetting the no-load output voltages of said other controllable regulators when the battery coupled to the first controllable regulator is substantially exhausted wherein one of said other controllable regulators is reset to the first no-load output voltage and the remaining controllable regulators are reset to higher no-load output voltages.

48. The method of claim 47, wherein one of the remaining controllable regulators are reset to respectively higher no-load output voltages.

49. The method of claim 42, further comprising controlling the plurality of controllable regulators with a controller.

50. A method of providing power to an electrical device, comprising:

providing first, second, third and fourth batteries;

providing first, second, third and fourth controllable regulators having outputs in parallel for regulating corresponding power outputs of the first, second, third and fourth batteries; and

setting a first no-load output voltage for the first controllable regulator, a second no-load output voltage lower than the first no-load output voltage for the second controllable regulator, a third no-load output voltage lower than the second no-load output voltage for the third controllable regulator and a fourth no-load output voltage lower than the third no-load output voltage for the fourth controllable regulator;

wherein the second controllable regulator will enable the electrical device to draw power from the second battery when an output voltage of the first controllable regulator falls to the second no-load output voltage, the third controllable regulator will enable the electrical device to draw power from the third battery when an output voltage of the second controllable regulator falls to the third no-load output voltage, and the fourth controllable regulator will enable the electrical device to draw power from the fourth battery when an output voltage of the third controllable regulator falls to the fourth no-load output voltage.

51. The method of claim 50, further comprising enabling the electrical device to periodically draw power from and thereby depassivate each of the first, second, third and fourth batteries.

52. The method of claim 50, further comprising limiting the current drawn from each of the first, second, third and fourth batteries to a corrresponding predetermined maximum design current.

53. The method of claim 50, further comprising, when the first battery is substantially exhausted, resetting the second controllable regulator to the first no-load output voltage, the third controllable regulator to the second no-load output voltage, and the fourth controllable regulator to the third no-load output voltage.

54. The method of claim 50, further comprising controlling the plurality of controllable regulators with a controller.

55. The method of claim 50, further comprising controlling the first, second, third and fourth controllable regulators with a microprocessor.

56. A device for powering a load, comprising:

a first battery;

a second battery;

a first controllable regulator having an input coupled to the first battery and an output;

a first switch coupled to the output of the first controllable regulator for selectively coupling the first controllable regulator to the load;

a second controllable regulator having an input coupled to the second battery and an output;

second switch coupled to the output of the second controllable regulator for selectively coupling the output of the second controllable regulator to the load in parallel with the first controllable regulator, the first and second controllable regulators being operable to selectively operate the first and second switches to enable the load to draw power from the second battery when an output voltage of the first regulator falls below a voltage setpoint; and

the first and second switches being operable to enable the load to alternately draw power from either of the first and second batteries even if the output voltage of the first controllable regulator does not fall below the voltage set point;

wherein the first and second batteries are periodically depassivated.

57. The device of claim 56, wherein the first and second switches comprise transistors.

58. The device of claim 57, wherein the transistors comprise field effect transistors.

59. The device of claim 56, further comprising a controller for controlling the first and second controllable regulators.