Methods for estimating remaining battery service life in an implantable medical device

A method for estimating a remaining service life of a battery of an implantable medical device, the battery having a known initial capacity and a known characteristic discharge model, the discharge model defining battery voltage as a function of an average current drain and discharged capacity, and the method comprising:

• tracking time;
• measuring battery voltage at least one point in time;
• estimating an average current drain corresponding to the at least one point in time of the battery voltage measurement, the estimated average current drain based upon an incremented initial current drain, the initial current drain being characteristic of the battery prior to a start of service;
• estimating a depth of discharged capacity based on the estimated average current drain, the known initial capacity and the time of the at least one point in time;
• iteratively calculating battery voltage until the calculated voltage converges on the battery voltage measured at the at least one point in time, wherein each iterative calculation is based on the characteristic discharge model, and wherein each subsequent iteration of the iterative calculation is further based on an incremented estimated depth of discharged capacity and a corresponding incremented estimated average current drain, each incremented estimated average current drain being based upon a difference between a previously calculated voltage of the iterative calculation and the measured voltage;
• and
• determining an estimated time of remaining battery service life according to the incremented estimated depth of discharged capacity that corresponds to the converged calculated battery voltage and the corresponding incremented estimated average current drain.

A system comprising an implantable medical device and a computer readable medium programmed with instructions for executing a method to estimate a remaining service life of a battery of the implantable medical device, the battery having a known initial capacity and a known characteristic discharge model, the discharge model defining battery voltage as a function of an average current drain and discharged capacity, the method comprising:

• tracking time;
• measuring battery voltage at least one point in time;
• calculating an average current drain from each measured battery voltage and the corresponding elapsed time of the measurement point in time;
• estimating a depth of discharged capacity based on the calculated average current drain, the known initial capacity and the elapsed time of the measurement point in time;
• and
• determining an estimated time of remaining battery service life according to the estimated depth of discharged capacity.