Hybrid electrical power source

A hybrid electrical power supply (100) for supplying current to a load connected to an output of the power supply, the power supply comprising:

• first and second electrical energy sources (110, 120) configured to supply current to the output wherein the first energy source (110) is a fuel cell and the second energy source (120) is a battery;
• a voltage regulator (140) electrically coupled between the output and the first or second electrical energy source configured to regulate the voltage provided to the output by regulating the voltage provided by one of the first or second electrical energy sources;
• a controller (160) configured to receive a signal indicative of the current being drawn at the output (150) and to compare the output current with a reference current level characterized in that:
• the voltage regulator (140) is configured to regulate the voltage provided to the output by regulating the voltage provided by one of the first or second electrical energy sources;
• the controller (160) is configured to use the voltage regulator to set the output voltage provided by the one of the first or second electrical energy sources such that:
• when the output current is lower than the reference current level the voltage regulator sets the voltage provided to the output to a first level such that the fuel cell, as the first energy source supplies current equal to the output current;
• and,
• when the output current exceeds the reference current level the voltage regulator sets the voltage provided in the output to a second level greater than the first such that the first energy source supplies current equal to the reference current level and the second energy source supplies the remaining current required by the load.