As you know, I have some doubts about the SoC% readings of the China monitors. The reason is that they are only an interpretation of the voltage and not a calculation based on the charged/discharged currents and time of a battery.
@Lollo050968 kindly made his long-term recordings available to me and I made a graph out of them that seems to confirm my suspicion.
You see a rendering of around 11'000 value pairs. As it is an x/y plot, and the resolution of the voltage is only 0.01V, we have anyway only 12.30 to 14.95 values and thus coordinates which yield 265 line segments in the end - some of them actually being plotted twice on the same area.
The chart is
not a timeline visualization but an x/y plot to fit all recorded voltage/SoC% tuples into a fixed grid. So it shows which percent values were shown at a particular voltage.
View attachment 7825708
You see that the same voltage is interpreted as different SoC percentages. It would take some arithmetic algorithms to filter the
charging/discharging differences high/low values out from the results
and to calculate the averages - which I have done and describe in the following.
Such a diagram doesn't tell you the real problem as the amount of data and the continuous line in this x,y plot is misleading. Therefore, I have reformatted the input to a format which contains high, low and average in one single line for each distinct voltage value in the 11k records . For what I got from
@Lollo050968 this finally boils down to 168 distinct voltages.
The diagram below shows the errors and the resulting averages which were calculated from all SoC% values for each voltage seen in the dataset.
Apparently there a some spikes which you should simply ignore.
View attachment 7825733
As you can see, there are values without an error indication. These values actually have only one single record in the data set, so no error can be calculated. Also interesting is that there are many readings in the 12.5V to 13.2V range and also some in the 14.1 to 14.2V range but only a few in the other ranges.
Remember that this chart does not visualize the voltages but the SoC% values of the monitor.
While I'm tempted to interpret the results, I'll leave that to you for now, as I'm not sure I'm competent to do so.
factual correction
added text in italics