Fuel cell system

A fuel cell system comprising:

• a fuel cell in which a plurality of cells are stacked;
• a radiator configured to cool a cooling liquid that has passed through the fuel cell;
• an ion exchanger provided in a bypass flow path branched off from a circulation flow path for allowing the cooling liquid to circulate between the fuel cell and the radiator;
• a multi-way valve provided in a branching point at which the bypass flow path is branched off from the circulation flow path;
• a pump which circulates the cooling liquid;
• and
• a controller programmed to control the multi-way valve such that a percentage of the cooling liquid that is made to flow through the bypass flow path, wherein
• in a case in which a stop time is longer than a threshold time when the fuel cell system is started up, the controller is programmed to control the multi-way valve such that all of the cooling liquid is circulated through the radiator, and then the cooling liquid is circulated through the bypass flow path at a percentage of 80% or more until an electrical conductivity of the cooling liquid becomes less than a threshold electrical conductivity, and
• wherein the percentage of the cooling liquid when it is circulated through the bypass flow path is switched in such a way that this percentage in a case in which the fuel cell system is used by a user becomes higher than that in a case in which a pre-shipment test is performed.