Dear fellows,
to inform you about the progress of my problem, here is the story.
After checking all power connections of the plane, I dismantled the batteries and performed a capacity check. They were both better than 82%.
I made a run-up and switched the alternator on and off to see the development. I realized, there was an improvement in the reactions. Many other guys set their focus on the ground connection to the buss. In my case, the one and only ground buss on the plane was connected via an AWG2 wire and ab AN4 bolt to the engine block.
We measured this connection by a milliohm meter (Bob Nuckolls) and found a resistance much higher than acceptable. We removed the bolt, scratched the surface, used some connectivity grease and washers and reinstalled everything again.
The run-up showed a fully functional engine monitor system, with all parameters with the correct values.
Thanks to anybody for the hints and advices to my problem. I appreciate the assistance within this community.
Best regards from Bavaria
Stephan
PH-LRV