An engine drive power supply, comprising: a combustion engine coupled to an electric generator which generates an output power when said combustion engine is operating, said electric generator coupled to an output circuit, where said output circuit generates an output power signal to be used by a load, wherein said output power signal is a welding power signal; a control electronics system having at least a controller and a user interface, where said control electronics system controls an operation of said engine drive power supply; a first energy storage device comprising an engine starting battery coupled to said control electronics system and said combustion engine; characterized by a second energy storage device coupled to said control electronics and said output circuit, wherein said engine drive power supply is so constructed that in a first state said first energy storage device provides all power used by said control electronics system and is used to provide all power to start said combustion engine, and wherein said engine drive power system is further so constructed that in a second state said second energy storage device provides all power used by said control electronics system and provides all power used by said output circuit to generate said welding power signal, and wherein the control electronics system determining that the second energy storage device has sufficient stored energy for a detected load on said second energy storage device, the control electronics system is so constructed that the following actions are done: - switches the engine power supply from the first state to the second state for providing all power used by said engine drive power supply, so long as said second energy storage device has a voltage above a threshold level - switches the engine power supply from the second state to the first state, when the voltage supplied from the storage device drops below the threshold value. a combustion engine coupled to an electric generator which generates an output power when said combustion engine is operating, said electric generator coupled to an output circuit, where said output circuit generates an output power signal to be used by a load, wherein said output power signal is a welding power signal; a control electronics system having at least a controller and a user interface, where said control electronics system controls an operation of said engine drive power supply; a first energy storage device comprising an engine starting battery coupled to said control electronics system and said combustion engine; characterized by a second energy storage device coupled to said control electronics and said output circuit, wherein said engine drive power supply is so constructed that in a first state said first energy storage device provides all power used by said control electronics system and is used to provide all power to start said combustion engine, and wherein said engine drive power system is further so constructed that in a second state said second energy storage device provides all power used by said control electronics system and provides all power used by said output circuit to generate said welding power signal, and wherein the control electronics system determining that the second energy storage device has sufficient stored energy for a detected load on said second energy storage device, the control electronics system is so constructed that the following actions are done: - switches the engine power supply from the first state to the second state for providing all power used by said engine drive power supply, so long as said second energy storage device has a voltage above a threshold level - switches the engine power supply from the second state to the first state, when the voltage supplied from the storage device drops below the threshold value. - switches the engine power supply from the first state to the second state for providing all power used by said engine drive power supply, so long as said second energy storage device has a voltage above a threshold level - switches the engine power supply from the second state to the first state, when the voltage supplied from the storage device drops below the threshold value.