Abnormal battery depletion detection in an implantable device

• US 8,214,164 B2
• Filed: 11/24/2008
• Issued: 07/03/2012
• Est. Priority Date: 12/13/2007
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Gandhi, Rajesh K., Linder, William J., Vanderlinde, Scott, Kalgren, James, Propp, Hal M.
• Primary Examiner(s): Schechter, Andrew
• Assistant Examiner(s): Zhang, Haidong
• Application Number:
  US12/277,091
• Publication Number:
  US 20090182517A1
• Time in Patent Office: 1,317 Days
• Field of Search: 702/63, 702/64, 702/57, 702/185, 702/199, 324/320, 324/433
• US Class Current: 702/58
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61N 1/3708 for power depletion
• CPC Class Codes: A61N 1/37247 User interfaces, e.g. input or presentation means
• CPC Class Codes: A61N 1/37258 Alerting the patient
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC

Abstract

Abnormal battery depletion can be detected in an implantable medical device. Battery capacity consumed can be measured using a coulometer and using a capacity-by-voltage device, and the measurements can be blended to determine battery status. A drop in battery voltage below a specified threshold can be detected to identify a high-current depletion fault, and an alarm can be provided to indicate the fault has been detected. The specified threshold can be determined as a function of battery capacity consumed. Other aspects and embodiments are provided herein.

Claims

1. A system, comprising:

a coulometer configured to measure battery capacity;

a capacity-by-voltage device configured to use a sensed battery voltage to measure battery capacity;

a controller, coupled to the coulometer and the capacity-by-voltage device, the controller configured to combine the measurements from the coulometer and the capacity-by-voltage device, using a weighted average of both of the measurements to determine battery capacity consumed, wherein a weight of each measurement in the weighted average is based on capacity remaining of the battery; and

wherein the controller is configured to detect a drop in the sensed battery voltage below one or more specified thresholds to identify a high-current depletion fault, the one or more specified thresholds determined as a function of battery capacity consumed as computed using the weighted average.

2. The system of claim 1, wherein the controller is further configured to provide an alarm to indicate the fault has been detected.

3. The system of claim 1, wherein the one or more specified thresholds include different thresholds corresponding to different portions of battery life.

4. The system of claim 3, wherein the controller is configured to calculate the different thresholds using a substantially continuous function.

5. The system of claim 4, wherein the battery capacity consumed is provided as an input to the substantially continuous function.

6. The system of claim 3, wherein the one or more specified thresholds decrease in voltage over the battery life.

7. The system of claim 3, wherein the different thresholds include at least seven separate threshold values.

8. A method for detecting abnormal depletion for a battery in an implantable medical device, the method comprising:

measuring battery capacity consumed by measuring an amount of charge provided by the battery;

measuring battery capacity consumed using a capacity-by-voltage measurement;

blending, using a weighted average, measurements from the measured amount of charge provided by the battery and the capacity-by-voltage measurement, wherein a weight of each measurement in the weighted average is based on capacity remaining of the battery;

detecting a drop in battery voltage below one or more programmable thresholds to identify a high-current depletion fault, the specified threshold determined as a function of battery capacity consumed as computed using the weighted average; and

providing an alarm to indicate the fault has been detected.

9. The method of claim 8, wherein providing an alarm includes providing the alarm locally to a patient.

10. The method of claim 8, wherein providing an alarm includes providing the alarm remotely over a communication network.

11. The method of claim 8, wherein providing the alarm remotely over a communication network includes providing the alarm over an at least partially wireless network.

12. The method of claim 8, wherein detecting a drop in voltage includes measuring battery voltage daily.

13. The method of claim 8, wherein detecting a drop in voltage includes measuring battery voltage more than once daily.

14. The method of claim 13, wherein providing an alarm includes providing an alarm when at least two battery voltage measurements are below the one or more programmable thresholds.

15. The method of claim 8, wherein detecting a drop in voltage includes detecting and suppressing low voltage measurements that are due to voltage recovery from a non-fault high current draw condition.

16. The method of claim 8, further comprising:

switching from using one threshold to another using one or more blended battery capacity consumed measurements.

17. The method of claim 8, wherein detecting a drop in battery voltage below one or more programmable thresholds includes calculating at least one of the thresholds using a substantially continuous function.

18. The method of claim 17, wherein calculating the thresholds includes setting at least one of the thresholds below a minimum voltage.

19. The method of claim 8, wherein measuring battery capacity consumed using a coulometer includes measuring battery capacity substantially continuously.

20. The method of claim 8, wherein measuring battery capacity consumed using a coulometer includes reporting battery capacity daily.

21. The method of claim 8, wherein measuring battery capacity consumed includes measuring battery capacity in units of Ampere-hours (Ahr).