## 3 Results
### Data Analysis--Evaluation Process  
The next step in the analysis was to fit the data in the row and look for possible errors. No significant variation in cell voltages was observed for constant vehicle speeds, so the dynamic case was highlighted. Figure 7 shows the voltage values from the dynamic test.  
Figure 7 shows the voltage values of all 88 cells as a function of time with different color lines. In the figure (Figure 7), one section of the whole measurement is highlighted to observe the data shift better. It can be stated that the cell voltages are very similar, but  
Figure 6: The current of the e-Golf system under different loads.  
Figure 7: Data slippage analysis in Dynamic test 2 (the different color lines indicate the 88 battery cells).  
they show a time shift. The reason for the shift is due to the continuous request-response messages. While voltage values of each cell are queried, in turn, a load arrives in the meantime (vehicle accelerates), and thus, the voltage of intermediate cells differs. For example, if a cell with ID 1... 33 is sampled at a constant load of 10 A, but at the moment of acceleration, a load of 100 A occurs, cells with ID 34... 88 are sampled at a lower voltage. A problem can arise when these values are assigned to the same time value. However, the unit time is unavoidable as it is the best way to determine the cell voltage difference. Figure 8 shows the exact measurement as before, presented over an even smaller time range.  
In Figure 8, a relatively small 14 s section has been analyzed, in which case the cell voltage values for the time point can be plotted. It can be seen that the voltage value associated with a time instant has a relatively large scatter. It is important to note that the recorded time point was always the last timestamp of the last data read or the maximum time read during a sampling round. However, significant deviations can occur if the cell voltage deviations are examined simultaneously, and many good battery cells can be misclassified. (A solution could be to increase the query speed, but in the question/answer procedure, this is set to maximum, see Section 2). Figure 9 shows the differences in the measurements.  
Figure 9 shows all measurements, dynamic and constant cases. It indicates that there are significant deviations, in some cases up to 0.3 V, most likely due to the data mentioned  
Figure 8: Data slip analysis in a short time range in Dynamic test 2 (the different color lines indicate the 88 battery cells).  
Figure 9: Deviation from the average voltage under different loads.  
above the readout slip. One solution to \"smoothing\" out the differences is to average the individual cell data. In this approach, the voltage values for a given cell (ID) are averaged over three or five data points, and the window continuously shifts in time. Figure 10 summarizes the results of the various averaging.  
The upper left corner of the figure (Figure 10) shows the raw measurement data; the other sub-figures show the 240 s... 280 s region at magnification. It is the region where the most significant load has been applied and is, therefore, the most likely to have the most significant variations in cell voltages. The upper right part shows the raw data values; the lower left sub-figure shows the values from averaging the three data (that is, the average of the previous and next values is used to determine the voltage value). Moreover, in the bottom right plot, the value under the test is substituted as the average of the two values preceding and following (averaging the five data). However, it is essential to note that this type of aggregation also involves data loss and those individual cell discrepancies are less likely to be detected.