Abstract: A method for detecting a fault state of at least one battery cell of a battery having multiple battery cells. A cell voltage of a respective battery cell of the multiple battery cells is registered at a measurement time and a comparison value is determined as a function of at least one of the cell voltages and is compared to a provided first reference value. The fault state is detected as a function of a result of the comparison. A scatter value is determined, which represents a scatter of at least part of the cell voltages registered at the specific measurement time, and the fault state is determined as a function of the scatter value.

Abstract: A method for determining a state of charge of at least one battery cell, having the following steps to enable an improved determination of the state of charge of a lithium iron phosphate cell: generating an alternating current pulse in a circuit connected to the at least one battery cell, determining an impedance of the at least one battery cell on the basis of the alternating current pulse and determining the state of charge by comparing the impedance to predefined map data, wherein a relationship between the impedance and the state of charge of the at least one battery cell is determined from the predefined map data.

Abstract: A method for checking a battery state for at least one battery of at least one motor vehicle. A. determination of cell voltage differences of particular cell voltage values of at least two battery cells of the at least one battery at different points in time. B. comparison of the cell voltage differences with at least one predetermined cell voltage reference value assigned to the at least two battery cells, and determination of respective deviation values between the cell voltage differences and the at least one cell voltage reference value. C. determination of the battery state of the at least one battery, wherein, based on the particular deviation values, it is determined whether an inadmissible degradation of the battery state is imminent.