System and method for estimating battery capacity

• US 8,577,459 B2
• Filed: 01/28/2011
• Issued: 11/05/2013
• Est. Priority Date: 01/28/2011
• Status: Expired due to Fees

• Current Assignee: LivaNova USA, Inc. (LivaNova Plc)
• Original Assignee: Cyberonics, Inc
• Inventors: Cowley, Anthony W., Hussain, Saadat
• Primary Examiner(s): Bertram, Eric D.
• Application Number:
  US13/016,510
• Publication Number:
  US 20120197341A1
• Time in Patent Office: 1,012 Days
• Field of Search: 607/29
• US Class Current: 607/29
• CPC Class Codes: A61N 1/378 Electrical supply
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

A method for estimating capacity of a battery in an implantable medical device includes obtaining a characteristic curve of voltage versus resistance for the battery, periodically determining voltage and resistance of the battery, and comparing the resistance with a third derivative function of the characteristic curve, the third derivative function having roots representing near depletion of the battery and end of service of the battery, respectively. Remaining time of service of the battery can also be determined by comparing the resistance value with a curve of battery capacity versus resistance for the battery.

Claims

1. A method comprising:

accessing, at a computing device, data indicating a characteristic relationship between voltage and resistance for a battery of an implantable medical device;

determining, at the computing device, a voltage value and a resistance value of the battery during a first time interval;

comparing, at the computing device, the resistance value to one or more values indicated by a third derivative function based on the data indicating the characteristic relationship, wherein the data further indicates a first period corresponding to near depletion of the battery and a second period corresponding to end of service of the battery, and wherein the first period and the second period are based on the third derivative function; and

estimating, at the computing device, one or more future performance characteristics of the battery based on a comparison of the resistance value to the one or more values indicated by the third derivative function.

2. The method of claim 1, wherein the data indicating the characteristic relationship is stored in a memory of the computing device.

3. The method of claim 1, wherein the computing device includes a personal digital assistant device, a smartphone, a laptop computing device, or a portable computing device.

4. The method of claim 1, further comprising:

determining a second voltage value and a second resistance value of the battery during a second time interval;

comparing the second resistance value to the data indicating the characteristic relationship;

creating second data indicating an adapted characteristic relationship between the voltage and the resistance of the battery based on a difference between the resistance value and the second resistance value in the battery; and

comparing the second resistance value with one or more second values indicated by a third derivative function based on the second data indicating the adapted characteristic relationship.

5. The method of claim 1, further comprising providing output to a display device indicating a capacity of the battery relative to the first period, the second period, or both, based on comparing the resistance value to the one or more values indicated by the third derivative function.

6. The method of claim 5, further comprising:

comparing the resistance value to one or more second values indicating a battery capacity relationship; and

determining an estimate of time until the end of service of the battery is reached.

7. The method of claim 1, further comprising:

comparing the resistance value to one or more second values indicating a battery capacity relationship; and

determining an estimate of time until the end of service of the battery is reached.

8. The method of claim 1, wherein the characteristic relationship is determined based on a statistical measure of a plurality of battery characteristic relationships, each corresponding to one of a plurality of batteries that is of a same battery type as the battery of the implantable medical device, wherein each of the plurality of battery characteristic relationships is determined based on a relationship between a measured voltage and a measured resistance of one of the plurality of batteries.

9. The method of claim 1, wherein the voltage value is based on an open circuit voltage, a low power mode voltage, a voltage measured at a pre-defined operating mode, or a combination thereof.

10. A computing device comprising:

a processor; and

a memory accessible to the processor, the memory including instructions that, when executed by the processor, cause the processor to;

access data indicating a characteristic relationship between voltage and resistance for a battery of an implantable device;

determine a voltage value and a resistance value of the battery during a first time interval;

compare the resistance value to one or more values indicated by a third derivative function based on the data indicating the characteristic relationship, wherein the data further indicates a first period corresponding to near depletion of the battery and a second period corresponding to end of service of the battery, and wherein the first period and the second period are based on the third derivative function; and

estimate one or more future performance characteristics of the battery based on a comparison of the resistance values to the one or more values indicated by the third derivative function.

11. The computing device of claim 10, wherein determining the voltage value and the resistance value includes receiving the voltage value and the resistance value from the implantable device via wireless communication.

12. The computing device of claim 11, wherein the computing device includes a personal digital assistant device, a smartphone, a laptop computing device, or a portable computing device.

13. The computing device of claim 10, wherein the instructions further cause the processor to:

create second data indicating a modified characteristic relationship between the voltage and the resistance of the battery; and

estimate one or more second future performance characteristics of the battery based on comparing the resistance value to one or more second values indicated by a third derivative function of the modified characteristic relationship.

14. The computing device of claim 10, wherein the instructions further cause the processor to compare the resistance value to second data indicating a relationship associated with battery capacity of the battery, wherein the one or more future performance characteristics indicate an amount of time until end of service of the battery is reached.

15. The computing device of claim 10, wherein the one or more future performance characteristics of the battery indicate a first amount of time until depletion of the battery is reached and a second amount of time until end of service of the battery is reached.

16. The computing device of claim 10, wherein the memory and the processor are included in the implantable device, the implantable device including a pulse generator of a vagus nerve stimulation system.

17. A tangible computer-readable storage device including instructions that, when executed by a processor, cause the processor to:

access data indicating a characteristic relationship between voltage and resistance for a battery of an implantable device;

determine a voltage value and a resistance value of the battery in the implantable device during a first time interval;

compare the resistance value to one or more values indicated by a third derivative function based on the data indicating the characteristic relationship, wherein the data further indicates a first period corresponding to near depletion of the battery and a second period corresponding to end of service of the battery, and wherein the first period and the second period are based on the third derivative function; and

estimate one or more future performance characteristics of the battery based on a comparison of the resistance value to the one or more values indicated by the third derivative function.

18. The tangible computer-readable storage device of claim 17, wherein an output indicating power remaining in the battery indicates a first amount of time until near depletion of the battery is reached, and a second amount of time until end of service of the battery is reached.

19. The tangible computer-readable storage device of claim 18, wherein the first amount of time is determined based on the first period and the second amount of time determined based on the second period.

20. The tangible computer-readable storage device of claim 17, wherein the instructions further cause the processor to:

create second data indicating a modified characteristic relationship between the voltage and the resistance of the battery;

compare the resistance value to one or more second values indicated by a third derivative function based on the second data indicating the modified characteristic relationship;

compare the resistance value to one or more third values indicating a battery capacity relationship, the battery capacity relationship indicating power remaining in the battery; and

provide an output to an output device indicating a condition of the battery, the power remaining in the battery, or both.