Patent ID: 8588913

Claim:
A method of operating an implantable device comprising power circuitry including at least first, second and third batteries, the implantable device further comprising control circuitry for controlling device operation and sensing circuitry for sensing a biological state of a patient in whom the implantable device is placed, the method comprising: at a first time, providing power for the control circuitry and sensing circuitry of the implantable device using each of the first, second and third batteries, wherein the implantable device comprises a plurality of switches enabling one or more of the first, second and third batteries to be isolated from the other batteries such that, at the first time, the switches are configured to allow each of the first, second and third batteries to provide power to the control and sensing circuitry; testing the first, second and third batteries to identify whether one or more of the first, second and third batteries is at or approaching end-of-life (EOL); identifying one of the first, second and third batteries as being at or approaching EOL; and at a second time after the identification of a battery that is at or approaching EOL: manipulating the switches to isolate the battery that is at or approaching EOL; and providing power for the control circuitry and sensing circuitry of the implantable device using the remaining batteries excluding the battery that is at or approaching EOL; wherein the implantable device is an implantable defibrillator comprising high power circuitry including a delivery capacitor for delivering defibrillation therapy and converter circuitry for receiving power from the power circuitry and charging the delivery capacitor.