SOLVED: EarthX fault light when connected to Dynon

jefish

jefish

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May 25, 2021
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Kent, WA
Found the answer. Should have used better search terms.

I'm working on a new install of a Rotax 912iS in a Zenith 750 with a Dynon HDX in the panel. I recently noticed that my EarthX fault LED indicator was on, started troubleshooting, and this is what I've found:
- With main relay on, engine off, no fault
- When the main relay is switched off, and while the Dynon is in its "powering off in n seconds" countdown mode with its backup battery providing power, no fault
- As soon as the Dynon powers itself off, FAULT
- If I disconnect the general purpose input lead from the Dynon EMS-221 from the fault wire on the battery, no fault in any power state

I've tried various GP inputs from the yellow, green and blue classes outlined in the Dynon HDX installation manual pages 7-13 and 7-14, no change. Disconnected the Dynon backup battery and re-tried all of the above, no change. LifePO4 charger says battery is full, issue repros with charger connected or not.

Somehow just having the the general purpose input lead from the Dynon EMS-221 connected to the EarthX battery, when everything is shut down, causes the battery to fault. If either the lead is disconnected, or the system is powered up, the fault state is cleared and does not return.

Ideas?
 
Last edited:
Rhino

Rhino

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Jul 20, 2009
Messages
1,295
So you haven't really found the answer. You just found the cause. Is this one of the enhanced type C general purpose inputs (pins 8, 22, 23, and 31)? They have a constant bias voltage applied of about 4 volts when the Skyview is turned on, so they don't 'activate' with an input voltage to turn them on. They're always on by default. They 'deactivate' with an input ground to turn them off. This is the reverse of what many folks think of when they look at an on/off indicator input, and it often causes confusion. I don't know what state the pins revert to when power goes off. Maybe that unusual 'reversed' condition is what's causing your problem, or somehow contributing to it.
 
jefish

jefish

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May 25, 2021
Messages
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Location
Kent, WA
Seeing in the EarthX documentation that it's normal and expected is enough for me, for now. :)
 
pacecapt

pacecapt

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Aug 11, 2019
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Location
Pace, Florida
I am in the process of connecting the Fault Monitoring Wire to my HDX. Are you saying that the Dynon is giving you a 'fault reading" or that the light on the Battery is showing a fault reading? Note, I have also read the disclaimer at the bottom of the Earth X manual (pg. 27) that talks about the LED being "dimly lit", but I assumed they were talking about the one on the battery...Which wire did you end up using? BTW, I have a 750 Cruzer with a UL Power 350is.
 
soarhead

soarhead

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Joined
Mar 2, 2021
Messages
41
When I installed my EarthX, I had the choice of wiring it into my Dynon or just having a remote LED. I chose the latter for it’s simplicity and reliability.
 
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