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I recently got a battery analyzer which includes a voltage waveform recorder, and just to try out the tools I decided to take a drive with my 2019 Mercedes GLE400 (W166) and see how the battery and alternator are working, The car is starting and running fine, though the auto-start feature usually doesn't work anymore unless I just recharged the battery, and there is a code that the battery's condition no longer supports that function.
So anyway, here is the graph of the entire drive:
And here is the zoom on that graph of the engine start sequence:
What concerns me in these graphs, of course, is the high voltage periodically coming out of the alternator. The peak is 15.60 volts! It does seem to come in spurts, perhaps reading higher when the car isn't moving. Close-up on the starting graph shows that it is actually fluctuating at these times, like some AC is coming through the diodes, I can only imagine.
I'm not exactly sure how many milliseconds between each sample, but the fact the voltage gets so high at times is what concerns me that maybe the alternator or voltage regulator is developing a problem? Or am I just looking too closely at the vehicle's electrical operations?
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