An electrical supply system including: a) a voltage converter including: i) a voltage converter input (110.1) electrically coupled to a supply for receiving a supply signal; and, ii) a voltage converter output (110.2) for supplying an output signal, the output signal having an output voltage (Vo) different to a supply voltage (Vs) of the supply signal; b) a bus electrically coupled to at least one of a load and a battery; c) a first voltage sensor for detecting the output voltage; d) a current sensor; and e) an electronic processing device coupled to the sensors (140, 160) for detecting a fault in the electrical supply system; characterised in that: the system further includes a diode including: a diode input (120.1) electrically coupled to the voltage converter output (110.2), and a diode output (120.2), wherein the bus electrically coupled to the diode output (120.2); wherein the current sensor detects a diode input current ( I DI); and wherein the electronic processing device is configured such that it: selectively controls the voltage converter to change the output voltage ( V O); monitors the resulting change in the diode input current ( I DI) and the output voltage ( V O); and, detects the fault in the electrical supply system based on at least the diode input current ( I DI) change and the output voltage ( V O). a) a voltage converter including: i) a voltage converter input (110.1) electrically coupled to a supply for receiving a supply signal; and, ii) a voltage converter output (110.2) for supplying an output signal, the output signal having an output voltage (Vo) different to a supply voltage (Vs) of the supply signal; i) a voltage converter input (110.1) electrically coupled to a supply for receiving a supply signal; and, ii) a voltage converter output (110.2) for supplying an output signal, the output signal having an output voltage (Vo) different to a supply voltage (Vs) of the supply signal; b) a bus electrically coupled to at least one of a load and a battery; c) a first voltage sensor for detecting the output voltage; d) a current sensor; and e) an electronic processing device coupled to the sensors (140, 160) for detecting a fault in the electrical supply system; characterised in that: the system further includes a diode including: a diode input (120.1) electrically coupled to the voltage converter output (110.2), and a diode output (120.2), wherein the bus electrically coupled to the diode output (120.2); wherein the current sensor detects a diode input current ( I DI); and wherein the electronic processing device is configured such that it: selectively controls the voltage converter to change the output voltage ( V O); monitors the resulting change in the diode input current ( I DI) and the output voltage ( V O); and, detects the fault in the electrical supply system based on at least the diode input current ( I DI) change and the output voltage ( V O). characterised in that: the system further includes a diode including: a diode input (120.1) electrically coupled to the voltage converter output (110.2), and a diode output (120.2), wherein the bus electrically coupled to the diode output (120.2); wherein the current sensor detects a diode input current ( I DI); and wherein the electronic processing device is configured such that it: selectively controls the voltage converter to change the output voltage ( V O); monitors the resulting change in the diode input current ( I DI) and the output voltage ( V O); and, detects the fault in the electrical supply system based on at least the diode input current ( I DI) change and the output voltage ( V O). selectively controls the voltage converter to change the output voltage ( V O); monitors the resulting change in the diode input current ( I DI) and the output voltage ( V O); and, detects the fault in the electrical supply system based on at least the diode input current ( I DI) change and the output voltage ( V O).