Low voltage hdx indicator any advice please random goes low but system is charging fine ok

[Yleg]

 

[airguy]

Are you certain your actual battery voltage is not going down? If the alternator is not charging (which is indicated by the -3 amps displayed) then the battery voltage will decay, and the voltage indication may actually be correct.

If you're absolutely sure the alternator and battery are both working correctly, then you need to chase down the voltage sensing wire from the EMS to the voltage source, you may have a bad connection there.

 

[GKC Aviation]

Your voltage sense and your amps are two different sources giving you the same information.
It really looks like your charging system is not working.

 

[Yleg]

I carnt attach video but it goes fro 0-10 v up and down when I start engine it says 2 v but starts fine and hi have and old fashion charge light that shows me it charging and battery volts says 12 when hdx shows sy 4 volts
Where is the sense wire for the hdx to show and test the voltage going into the hdx ?

 

[Yleg]

Think I have found the problem some moisture into ems220 Eng sensor plug green death hopefully some contact cleaner will fix it til I get home 5000km away then repair and replace maybe mount ems220 on its side so moisture drains and carnt sit in the plug recess

 

[airguy]

Yep, I think you have found your problem...

 

[jakej]

I’ve seen the exactly the same issue years ago,cleaned the pin contacts with a soft wire brush then flushed the gunk out with contact cleaner - the EMS still works.
The tip up canopies can be notorious for this IF you don’t ‘shield’ the avionics from water ingress - I’ve used heavy aluminium foil, seems to work well.