Abstract: The disclosure presents a method for starting up a battery system having a battery and a DC voltage intermediate circuit which is connected to the battery. The battery has a plurality of battery modules which are connected in series and which comprise a first battery module having a first number of battery cells and at least a second battery module having a larger second number of battery cells. At the beginning of the method, all of the battery modules are deactivated, and therefore the output voltage of the battery is zero. During the course of the method, the output voltage of the battery is increased by successive second battery modules being activated. In the process, the first battery module is activated in each case between the activation of two second battery modules and is deactivated again when the further second battery module is activated.