Abstract: A method of inverter capacitance diagnosis for detecting an imminent failure of one or more inverter capacitors in an electric power supply system for a machine detects that the generator has ceased generating electrical power takes a plurality of current samples on the DC link between predetermined voltage points. The plurality of current samples are integrated as a function of time to create a discharge integral, which is compared to a previously obtained discharge integral if available. The process sets a diagnostic flag to indicate an imminent failure of the one or more inverter capacitors if the discharge integral varies from the previously obtained discharge integral by more than a predetermined value.