This abstract presents an ensemble of solutions to combat this issue. Parallel EIS, automatic drift correction of the measured time dependent signals, time interpolation by series measurements, and the application of the Z-HIT algorithm as post-processing of the data are the tools of choice. Simultaneous EIS is an effective time saving procedure. Otherwise, sequential EIS evaluation of n single cells in a stack increases time consumption by the factor n. Also, comparing the results for each individual cell to other cells is no longer directly comparable to an exact degree because the measurement drifts due to time effects are difficult to correct for. Second, precautions must be provided during the data acquisition phase in order to suppress the erroneous assignment of drift signals to the system response . Furthermore, “non causal” spectra in the meaning of the Kramers-Kronig relations can be converted into correct spectra by interpolation of spectra series vs. time and, by removal of residual non-causalities with the help of the Z-HIT transform, which has the capability to reconstruct drift-affected data . In many cases, the user would favor the comfortable possibility to significantly reduce the time for recording the EIS spectra by the application of multi-sine excitation. However, conventional multi-sine excitation normally is accompanied by significant losses of accuracy. An advanced technique provides the features of automatic drift correction and error detection known from single-sine excitation . As a result, substantial loss in accuracy can be avoided.
Experimental data obtained from a four-cell Li-FePO4 stack (13.2 V / 40 Ah) using this new multi-sine algorithm will be presented upon approval of this abstract for presentation.
Keywords: Multi-sine, Battery stacks, EIS, True parallel measurements, Z-HIT
 C. A. Schiller, F. Richter, E. Gülzow 3, N. Wagner; J. Phys. Chem. Chem. Phys. 3 (2001) 374
 W. Ehm, R. Kaus, C. A. Schiller, W. Strunz, New Trends in Electrochemical Impedance Spectroscopy and Electrochemical Noise Analysis, ed. F. Mansfeld, F. Huet, O. R. Mattos, Electrochemical Society Inc., Pennington, NJ, 2001, vol. 2000-24, 1
 C.-A. Schiller, R. Kaus; Bulgarian Chemical Communications, Volume 41, Number 2 (2009), pp. 192-198