Abstract: A method for checking an insulation state of a battery or battery system comprising at least two batteries, comprising the following steps: measuring a voltage between a connection element of the battery and a ground over a predefined time; evaluating the measured voltage and determining whether a change in the measured voltage is present at time point that corresponds to a predefined temporal threshold value; and outputting a safety signal characterizing the insulation state on the basis of the established result.

Abstract: The present invention relates to a battery system for a motor vehicle, comprising a battery management system and at least two battery packs each having battery cells, at least one switch for switching the respective battery pack and a measuring device for measuring operating parameters of the battery cells, where the battery management system is arranged in precisely one of the battery packs and the switches of the other battery packs are controlled by the battery management system.