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AMP shunt problem (Read 899 times)
Feb 26th, 2017 at 5:19pm

Yoda   Offline
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I love flying!

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Have a Skyview with the Dynon amp shunt. Amp indications reads perfect with engine off or at low power but as soon as the engine gets up to about 1600 or better RPM the amps jump to negative 30 or higher amps then the panel indicator goes red X. Indications flux off and on, mostly Xed, after that but are never accurate. Have a Planpower 60 amp alternator. Shunt is configured in position A and I have 1 amp fuses in both amps + and - lines. I double checked the alarm and alarm limits configuration in the SV. I have double checked the polarity pins 24/25 and rang out the wiring all the way back to the Dynon EMS wiring harness. Any suggestion on where to go from here?
« Last Edit: Feb 26th, 2017 at 5:39pm by Yoda »  
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Reply #1 - Mar 1st, 2017 at 8:30am

Robski   Offline
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Yoda wrote on Feb 26th, 2017 at 5:19pm:
Amp indications reads perfect with engine off or at low power...
Define 'perfect', please.

And what engine are we talking of? A Lycoming or a Continental I would guess from having a PlanePower alternator, but we could do with confirmation.

I have to admit to not being a Skyview expert, only a D series installer/user, but the above would enable the SV experts to hazard an opinion.

I can't remember / don't know for SV where position A is.

However...
My gut tells me that you have the shunt back to front.
Maybe it should read negative at low revs/off when the battery takes the load, and pick up to positive when the alternator kicks in.

Sorry for the vagueness - but thought I'd wade in as no one else has so far.
Hopefully if you respond to the questions above it will stimulate some further responses.
 

Rob Swain
Software Developer (Retired)
Shropshire, UK
Van's RV-6

If the good Lord had intended man to fly He would have given him more money.
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Reply #2 - Mar 1st, 2017 at 2:38pm

Yoda   Offline
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I love flying!

Posts: 22
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Lycoming O320-E3D engine in an RV-9A that has been flying and perform perfectly for almost two years before this happened. Perfect means that the amp meter shows the battery recovering from starting or the nominal system draw if the engine is not running and up till now the proper load indications at higher power. Shunt leads definately not wired backwards, tried both ways to prove it.  I can only guess that the EMS unit has an issue as everything up to that point has been checked and rechecked. The fact that the amp meter shows proper response up to higner engine RPM is quite troubling when you consider the simplistic way an amp shunt works. It measures the voltage drop across a know resistance. The voltage remains stable at about 14.5 VDC thru out the entire time and cycling the alternator off and on has no real effect on anything except the system voltage drops to 12.5 VDC as it should with no alterantor excitation and returns back to 14.5 VDC when the alternator is turned back on. If no one has a good suggestion I guess I am going to have to install a Grand Rapids CS01 current xformer and hook it as Dynon suggest to a GP input and bypass the pin 24/25 and associated EMS logic. Undecided
 
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Reply #3 - Mar 1st, 2017 at 7:00pm

Dynon Avionics   Offline
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<yodavoice> Run the following test you must do </yodavoice>

Start the engine, but before you turn on your alternator, rev into the zone that you normally see the problem. Do you still see it with the alternator off?

Once the alternator is on, rev until you juuuust see the problem. Then turn on big loads (heated pitot, landing lights, etc) to drop the voltage as much as you can (without changing the speed/output of the alternator). Is there a voltage that is the trigger?
 

Please do not use Private Messaging on form to contact. For private support:
Email: support at dynonavionics dot com
Phone: 425-402-0433 (7am-5pm Pacific weekdays)
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Reply #4 - Mar 2nd, 2017 at 4:18am

Robski   Offline
Junior Member
Hang on! I've got an idea!

Posts: 80
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Dynon Avionics wrote on Mar 1st, 2017 at 7:00pm:
<yodavoice> Run the following test you must do </yodavoice>

Grin

Apologies, Yoda.
I hadn't realised that this was an existing installation. Good luck finding the solution.
 

Rob Swain
Software Developer (Retired)
Shropshire, UK
Van's RV-6

If the good Lord had intended man to fly He would have given him more money.
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Reply #5 - Mar 9th, 2017 at 4:08pm

Yoda   Offline
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I love flying!

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Reloaded sensor file and upgraded to SV 15.0.4 and the problem has gone away, at least for now. Corrupted sensor file ????????? Wink
 
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Reply #6 - Mar 9th, 2017 at 4:50pm

Dynon Avionics   Offline
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Dynon Technical Support

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Perhaps, but that's odd. Have you seen any "system event" alerts?
 

Please do not use Private Messaging on form to contact. For private support:
Email: support at dynonavionics dot com
Phone: 425-402-0433 (7am-5pm Pacific weekdays)
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