Abstract: A method for determining the state of an electric energy storage unit is described. An extension of the electrode assembly and/or a force exerted by the electrode assembly, and at least one electric variable of the electric energy storage unit are detected. A first and a second state variables, which represent the first state of the electric energy storage unit, are ascertained using the detected extension and/or the detected force and also a first mathematical model stored in a data memory and the detected at least one electric variable and also a second mathematical model stored in a data memory. This is followed by carrying out a first comparison of the first state variable with the second state variable. The first and/or the second mathematical model and/or the first and/or the second state variables are/is changed depending on the first comparison.

Abstract: A method is provided for determining the state of an electric energy storage unit having at least two pole connections and an electrode. An extension of the electrode assembly and/or of a force exerted by the electrode assembly is detected, a first state variable, representing a first state of the electric energy storage unit is ascertained using the detected extension and/or the force and a first mathematical model is stored. An electric variable of the electric energy storage unit is detected and a second state variable, representing the first state of the electric energy storage unit is ascertained using the detected electric variable and a second mathematical model is stored. The first state variable is compared with the second state variable and the first mathematical model and/or variables ascertained by the first model are/is changed depending on the comparison, and/or the second mathematical model and/or variables ascertained by the second model are/is changed depending on the comparison.

Abstract: A method for operating a secondary battery which comprises multiple interconnected, bridgeable battery subunits and is situated in a compartment of an electrically driven vehicle, in particular a watercraft, includes detecting an accessibility of each battery subunit, and activating the battery subunits in accordance with the accessibility of the particular battery subunits.

Abstract: The invention relates to a method for operating a secondary battery (1, 4) which comprises multiple interconnected, bridgeable battery subunits (A, B) and is situated in a compartment (3) of an electrically driven vehicle, in particular a watercraft, characterized in that the accessibility of each battery subunit (A, B) is detected, and the battery subunits (A, B) are activated in accordance with the accessibility of the particular battery subunits.

Abstract: A battery cell (2), comprising at least one electrode assembly (10), containing an anode (11) and a cathode (12) that are divided from one another by a separator layer (18), and at least one sensor element (30) for detecting defects in the electrode assembly (10). The least one sensor element (30) is at least partially integrated in the separator layer (18).