EMS Current Reading

[tedmonds]

On my airplane with Rotax 912ULS engine, the current reading fluctuates rapidly form positive to negative, i.e. -4 amps to +12 amps at a rate of once or twice a second but steady -5 amps with engine off and just avionics load. The current sensor is located just off the battery. The engine monitor is a Dynon D120. I had always thought this is just the way the engine regulator works but discovered from two different friends with the same engines and engine monitors that they do not have this rapid fluctuation but a rather steady reading. I have been in contact with Dynon and they think it unlikely the monitor is the problem. I have carefully checked sensor wiring and even tried switching from a shunt sensor to a hall effect sensor with the same results. I am suspecting the problem to be an over active regulator even though it is charging the battery verified by voltage reading. Anybody have comments on this?
Thanks
Terry Edmonds

 

[Dynon]

It's possible for grounding issues to cause amps fluctuations, but not if two very different current measuring methods are showing the same behavior. In this case, you're probably looking at a regulator / charging system issue as you suspect.