Control apparatus of an electric vehicle controls a power supply system of the electric vehicle equipped with a first direct current power supply apparatus for supplying direct current power to a traction inverter, and a second direct current power supply apparatus connected in parallel with the first direct current power supply apparatus via a DCDC converter. Its principle of operation and simulation results regarding capacitance loading, leakage current, degradation to RF performance are disclosed. Methods of manufacturing a photomultiplier and of tuning the gain of a photomultiplier are also disclosed. In response to an indication that the measured voltage is faulty during a drive cycle, the controller instead alters the voltage between the battery and the electric machine based on a substituted battery voltage signal such that the electric-machine remains operable for the drive cycle.