CAPACITY FADE ADJUSTED CHARGE LEVEL OR RECHARGE INTERVAL OF A RECHARGEABLE POWER SOURCE OF AN IMPLANTABLE MEDICAL DEVICE, SYSTEM AND METHOD

• US 20090273313A1
• Filed: 04/30/2008
• Published: 11/05/2009
• Est. Priority Date: 04/30/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Guy, Dave P., Scott, Erik
• Granted Patent: US 8,314,594 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: A61N 1/3708 for power depletion
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

System and method for estimating the time before recharging the rechargeable power source of an implantable medical device. In a method, the present charge level of the power source is determined by determining the percentage of total charge consumed over a period of time. The present charge level is then divided by the expected power use to determine time remaining before recharging. Another method utilizes a model to determine the faded capacity of the rechargeable power source based on the number of times the rechargeable power source has been charged and the duration of the rechargeable power source'"'"'s life.

Claims

1. A system, comprising:

an implantable medical device having a rechargeable power source having a voltage and a total charge capacity of said rechargeable power source, which said total charge capacity changes over time; and

electronic componentry, operatively coupled to said implantable medical device, configured to;

determine a first state of charge at a first time by measuring said voltage at said first time;

determine a second state of charge at a second time by measuring said voltage at said second time, said second time being later than said first time;

determine a net charge passed through said rechargeable power source between said first time and said second time; and

determine said total charge capacity by at least dividing said net charge by the difference between said second state of charge and said first state of charge.

2. The system as in claim 1 wherein said electronic componentry is further configured to determine a charge level of said rechargeable power source by at least multiplying said total charge capacity by a state of charge of said rechargeable power source.

3. The system as in claim 1 wherein said electronic componentry is configured to determine said net charge passed through said rechargeable power source by determining a charge consumed by said implantable medical device.

4. The system as in claim 3 further comprising a charge counter, said charge counter configured to measure said net charge passed through said rechargeable power source.

5. The system as in claim 1 further comprising an external charging unit for said rechargeable power source and wherein said electronic componentry is configured to determine said net charge passed through said rechargeable power source by determining a charge applied to rechargeable power source by said external charging unit.

6. The system as in claim 1 wherein said electronic componentry is configured to determine said net charge passed through said rechargeable power source by utilizing a characterization of power usage by said implantable medical device.

7. The system as in claim 1 further comprising an external device, said external device being operatively coupled to said implantable medical device, said external device comprising said electronic componentry and a user output, said user output configured to communicate said total charge capacity to a user.

8. The system as in claim 7 wherein said user output is configured to communicate using at least of telemetry, radio frequency, induction, ultrasound, optics, audible sound and passive telemetry.

9. The system as in claim 7 wherein said user output is configured to communicate by at least one of a graphic, digital information, visual, audible, olfactory and touch or vibration.

10. The system as in claim 7 wherein said state of charge can be illustrated by a bar graph.

11. A system, comprising:

an implantable medical device having a rechargeable power source having recharge interval until a time when recharge of said rechargeable power source is desired, said rechargeable power source having a voltage, a total charge capacity which changes over time and a charge level;

electronic componentry, operatively coupled to said implantable medical device, configured to;

record a cycle age by counting a number of recharges of said rechargeable power source indicative of a number of times said rechargeable power source has been recharged;

record a chronological age of said rechargeable power source;

determine said total charge capacity of said rechargeable power source at a first time by subtracting a charge capacity based, at least in part, on said cycle age of said rechargeable power source and a charge capacity based, at least in part, on said chronological age of said rechargeable power source from said total charge capacity at a second time, said second time being earlier than said first time;

measure a voltage of said rechargeable power source;

determine a state of charge as a function of said voltage;

determine a charge level of said rechargeable power source as a function of said total charge capacity at said first time and said state of charge; and

determine said recharge interval as a function of said charge level and a programmed rate; and

a user output, operatively coupled to said electrical componentry, configured to communicate said recharge interval to said user.

12. The system as in claim 11 wherein said cycle age is dependent, at least in part, on said number of recharges and a net charge passed through said rechargeable power source during each recharge of said rechargeable power source and said total charge capacity.

13. The system as in claim 11 wherein said cycle age is comprised, at least in part, of a linear function based on a number of charge cycles.

14. The system as in claim 11 wherein said chronological age is comprised, at least in part, of an exponential function based on time.

15. The system as in claim 11 wherein said user output is further configured to communicate a graphical depiction of said present charge capacity relative to said initial charge capacity to said user.

16. A system, comprising:

an implantable medical device having a rechargeable power source, said rechargeable power source having total charge capacity;

electronic componentry, operatively coupled to said implantable medical device, configured to;

record a cycle age by counting a number of recharges of said rechargeable power source indicative of a number of times said rechargeable power source has been recharged;

record a chronological age of said rechargeable power source;

determine said total charge capacity of said rechargeable power source at a first time by subtracting a charge capacity based on said cycle age of said rechargeable power source and a charge capacity based on said chronological age of said rechargeable power source from said total charge capacity at a second time, said second time being earlier than said first time; and

a user output, operatively coupled to said electronic componentry, configured to communicate said total charge capacity at said first time.

17. The system as in claim 16 wherein said user output is further configured to communicate a graphical depiction of said present charge capacity relative to said initial charge capacity to said user.

18. In an implantable medical device having a rechargeable power source, a method for determining a present charge capacity of said rechargeable power source, said rechargeable power source having a charge level, a total charge capacity and a voltage, comprising the steps of:

determining a first portion of charge remaining at a first time by measuring said voltage at said first time;

determining a second portion of charge remaining at a second time by measuring said voltage at said second time, said second time being later than said first time;

determining a charge consumed by said implantable medical device between said first time and said second time;

determining said total charge capacity by at least dividing said charge consumed by the difference between said second portion and said first portion; and

storing a value indicative, at least in part, of said total charge capacity.

19. The method as in claim 18 further comprising the step of determining said charge level by at least multiplying said total charge capacity by said second portion.

20. The method as in claim 18 wherein said determining charged consumed step measures said charge consumed using a charge counter.

21. The method as in claim 18 wherein said determining charge consumed step determines said charge consumed by utilizing a characterization of power usage of said implantable medical device.

22. The method as in claim 18 further comprising the step of outputting said total charge capacity to a user.

23. In an implantable medical device having a rechargeable power source, a method for determining a recharge interval until a time when recharge of said rechargeable power source is desired, said rechargeable power source having a total charge capacity and a charge level, comprising the steps of:

recording a cycle age by counting a number of recharges of said rechargeable power source indicative of a number of times said rechargeable power source has been recharged;

recording a chronological age of said rechargeable power source;

determining said total charge capacity of said rechargeable power source at a first time by subtracting a charge capacity based, at least in part, on said cycle age of said rechargeable power source and a charge capacity based, at least in part, on said chronological age of said rechargeable power source from said total charge capacity at a second time, said second time being earlier than said first time;

measuring a voltage of said rechargeable power source;

determining a portion of said present charge capacity as a function of said rechargeable voltage;

determining said charge level as a function of said total charge capacity at said first time and said portion of charge capacity remaining;

determining said recharge interval as a function of said total charge level at said first time and a programmed rate; and

outputting said recharge interval to a user.

24. The method of claim 23 further comprising the step of outputting said total charge capacity at said first time and said total charge capacity at said second time to said user.

25. The method as in claim 23 wherein said charge capacity as a function of said number of recharges and said charge capacity as a function of said age of said rechargeable power source are determined using a model.

26. The method as in claim 24 wherein said outputting step outputs a graphical depiction of said total charge capacity at said first time relative to said total charge capacity at said second time.

27. In an implantable medical device having a rechargeable power source, a method for determining a present charge capacity of said rechargeable power source, said rechargeable power source having a total charge capacity, comprising the steps of:

recording a cycle age by counting a number of recharges of said rechargeable power source indicative of a number of times said rechargeable power source has been recharged;

recording a chronological age of said rechargeable power source;

determining said total charge capacity of said rechargeable power source at a first time as a function of subtracting a charge capacity based on said cycle age of said rechargeable power source and a charge capacity based on said chronological age of said rechargeable power source from said total charge capacity at a second time, said second time being earlier than said first time;

outputting said total charge capacity at said first time and said total charge capacity at said second time to a user.

28. The method as in claim 27 wherein said outputting step outputs a graphical depiction of said total charge capacity at said first time relative to said initial charge capacity at said second time.