Embodiments are directed to an implantable medical device comprising therapeutic stimulation circuitry for controlling delivery of a medical therapy to a patient, the therapeutic stimulation circuitry having at least one lead having electrodes for delivering the medical therapy. The implantable medical device further comprises measurement circuitry for determining characteristics of the at least one lead, a processor for controlling the IMD according to executable code, and memory for storing data and executable code, wherein the executable code comprises instructions for causing the processor to receive a plurality of voltage measurements associated with the electrodes, and calculate values for an impedance model of the electrode/tissue interface.