Abstract: A vehicle mounted engine generator system is disclosed for supplying electricity to external electrical appliances and equipment used inside a camping car or outdoors in the camping site, which comprises a secondary water-cooled internal combustion engine of relatively small size and an engine generator electrically connected to the engine. The secondary engine has its cooling jacket connected to a cooling line supplying it with cooling water for engine cooling. Also, the cooling line is connected to a radiator connected to the main internal combustion engine of water-cooled type so that the heated cooling water through the secondary engine is cooled by the same radiator as for the main engine. Also, the secondary engine is electrically connected to the battery for the main engine in such a manner that the battery can be recharged from the secondary engine as well.