Electrical issue

[Foley]

Problem with oscillating engine instruments and low voltage on 2 freshly charged Batteries. Dynon skyview system. swapped  out voltage regulator and no change. any ideas? may rewire plug in for voltage regulator.

[mikeschumann]

I had a similar problem a number of years ago.  It turned out to be defective EFIS circuit breaker.

[Foley]

Tell me about it and how you replaced it. Are we talking about a fuse? What were specific symptoms? Where was it located.

[Foley]

Video

 

 

[Foley]

Other video

 

[Barry.h]

Did you say “lithium” then “lead acid”? Do you have 2 batteries with a 1 + 2 switch? You can’t put dissimilar batteries in parallel, as they have different voltages. I believe you will have charging problems.

When the engine stopped both voltages were very low. The Lithium battery will (should, better) have a battery management system and that might be getting upset having a lead battery across it.

When my engine starts it also runs rough for a second or so then smooths out. I have never watched the voltage, but I have also never run with such low voltage.

I would start with similar/compatible batteries.

Barry.

[Foley]

Only use one battery at a time. Trickle charged separately. Load tested 2 weeks ago. Never used in parallel. EFIS battery tested as well.

[mikeschumann]

My problem was the EFIS pushbutton circuit breaker on the panel.  It is soldered to the PC board behind all of the pushbutton breakers, so you need someone with the necessary soldering skills to replace it.

I was having very strange symptoms with the Skyview system cycling on and off.  Replaced the Skyview display, which didn't make any difference.  Finally ended up putting a volt meter on the output from the circuit breaker, which showed the voltage going up and down.  At the same time, the voltage going to the 12V plug on the panel was stable.

[Foley]

Mike are we talking about the bus bar? Mounted to the panel

[Barry.h]

On 7/28/2022 at 9:55 PM, Foley said:

Only use one battery at a time. Trickle charged separately. Load tested 2 weeks ago. Never used in parallel. EFIS battery tested as well.

Hmm. Well when the engine is off you are only showing 10.n volts… on both batteries. If the batteries are charged I think you have to trace the voltages from the battery (should be 13.n Volts) And see where it is dropping.

[Foley]

Thank you everyone. Will rewire ground from battery directly to engine. Used jumper cables and this solves the problem. Will also ground batteries separately to the frame instead of in series. Mechanic says it back fills the battery not in use. Even though hot pole not connected.

[mikeschumann]

22 hours ago, Foley said:

Mike are we talking about the bus bar? Mounted to the panel

I'm talking about the pushbutton breakers located in the center of the panel right above the throttle, which let you turn on and off the EFIS, Nav Lights, Fuel Pump, etc....

[Alex Ress]

The "something wierd" that happens on startup is the advanced start system that delays the ignition timing for 3-8 seconds after the starter relay is not powered anymore.  This is normal and is described in the service instruction added below.

https://rotax-docs.secure.force.com/DocumentsSearch/sfc/servlet.shepherd/version/download/06812000002q89iAAA?asPdf=false

[Foley]

Found out the strobes are also causing pulses

[Foley]

problem solved. cant believe I didnt see it. the connector sheared off perfectly where it attached to the engine so it was not noticeable. and the ground was kind of hidden.