Patent ID: 8823382

Claim:
A system for monitoring a battery of an implantable medical device, comprising: a first current source associated with a current having a first predetermined amplitude; a second current source associated with a current having a second predetermined amplitude; a circuit adapted to be coupled to receive power from the battery, the circuit comprising at least one of a therapy module adapted to deliver therapy to a patient and sensing circuitry adapted to sense a signal from the patient; and a control circuit adapted to activate the first current source and obtain a first voltage measurement across the battery while the first current source is activated, to activate the second current source and obtain a second voltage measurement across the battery while the second current source is activated, and to determine impedance of the battery from the first and the second predetermined amplitudes and the first and the second voltage measurements, wherein the control circuit is adapted to obtain the first and second voltage measurements across the battery while the circuit that is adapted to be coupled to receive power is coupled to the battery.