Fuel cell system and method for time-controlled start-up / shut-down of a fuel cell system

Fuel cell system, comprising an auxiliary power source which provides auxiliary power for starting up the fuel cell system and a switch by means of which the fuel cell system can be switched from energy uptake from the auxiliary power source to an energy output mode of a fuel cell stack. Furthermore, a timing control device regulates the aforementioned switch, whereby said switch or said timing control device can be connected to an energy buffer such as a capacitor. After switching to an energy output mode, a temperature-controlled cooling device cools the fuel cell stacks.