Abstract: Subjecting batteries with a plurality of cells to a balancing is known. Active balancing is carried out between adjacent cells or cell groups by means of a bus across uninvolved cells. Using this charge transfer for electrochemical impedance spectroscopy is known. The problem is to provide a system and method with which EIS measurements can be carried out on a battery using significantly less equipment outlay, with as little energy loss as possible, on batteries with high capacity and also on those with low excitation frequencies. The problem is solved in that charge is transferred back and forth between a first number of accumulator cells and a second number of accumulator cells during determination of at least one voltage value. The first and second numbers of accumulator cells are wired in series, and the first and second number is at least two.

Abstract: An exciter unit, a battery system including the exciter unit, and a method for determining a battery state of at least one battery cell. The method includes: a. applying a current-exciting signal; b. recording an impedance spectrum of the battery cell; c. determining an evaluation variable on the basis of a measured impedance spectrum. At least one of the amplitude, frequency and relative phase difference of at least one component of the current-exciting signal is modified as a function of the first measured response signal such that a measuring error is minimized, a further measured response signal is determined and evaluated, the value evaluated is used as an evaluation variable, and the battery state variables of the battery cell are determined on the basis of a comparison of at least one diagnostic variable with at least one reference value and/or with at least one further diagnostic variable.

Abstract: An exciter unit, a battery system including the exciter unit, and a method for determining a battery state of at least one battery cell. The method includes: a. applying a current-exciting signal; b. recording an impedance spectrum of the battery cell; c. determining an evaluation variable on the basis of a measured impedance spectrum. At least one of the amplitude, frequency and relative phase difference of at least one component of the current-exciting signal is modified as a function of the first measured response signal such that a measuring error is minimized, a further measured response signal is determined and evaluated, the value evaluated is used as an evaluation variable, and the battery state variables of the battery cell are determined on the basis of a comparison of at least one diagnostic variable with at least one reference value and/or with at least one further diagnostic variable.