Acquisition method and fuel cell system

The invention relates to a determination method (200) for determining a passage rate (CR) of at least one fuel cell (10) of a fuel cell system (100) for controlling the fuel cell system (100), comprising the following method steps: detecting (202) a fill level (F) of water (W) in a water separator (20) of the fuel cell system (100) by means of a fill level detection device (24), discharging (204) water (W) from the water separator (20) by means of a discharging device (22) of the water separator (20), measuring (206) a first time (t1) between a first level (F1) and at least one second level (F2) of the water (W) in the water separator (20) during the discharging (204), determining (208), by means of a computer unit (30) of the fuel cell system (100), a crossing rate (CR) of the at least one fuel cell (10) from the measured first time (t1) and the at least two measured filling levels (F1, F2), the crossing rate (CR) corresponds to a rate of transit of water (W) from the cathode side (K) of the at least one fue