A method for operating a battery system. The battery system includes parallel-connected strings. Each string includes at least one battery module. In the battery module, multiple battery cells are interconnected in a series connection and/or in a parallel connection. The strings are switchable on and off from one another. The battery cells and/or battery cell packets are switchable on and off from one another and are bypass-able. The method includes: recognizing a fault of a battery cell; switching off and bypassing the faulty battery cell and/or the faulty battery cell packet which includes the faulty battery cell; switching off the faulty string, which includes the faulty battery cell and/or the faulty battery cell packet; comparing the string voltage of the faulty string to the string voltage of intact strings, in which no fault was recognized; discharging the intact strings if voltage differences between the strings exceed a voltage threshold value.