FUEL BATTERY SYSTEM

A fuel cell system of the present invention has a separation unit for separating gas-liquid mixed fluid discharged from the fuel cell stack. The separation unit has a tank for storing the separated liquid. A pair of metal electrodes is disposed on the side surfaces of the tank opposed to each other. The electrodes are used to measure the amount of the liquid in the tank and also promote the heat dissipation of the liquid in the tank. This can suppress the transpiration of the liquid in the tank and cool the liquid to a temperature suitable for the reuse in the fuel cell stack.