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912 ULS Ammeter

The ammeter is my RV12 shows a negative reading. I understand that the two battery wires can be interchanged. Also the two generator wires. I have tried any combination on my current and a new rectifier and get the same results. Any advice would be appreciated.
 
Ditto what Scott says. Also, it is troubling to me when you say you have been swapping wires around hoping for a better result. That is a real good way to damage additional expensive components. Suggest you take a big step back and look for the basic cause of the problem. There are people here on the forum that will be glad to help you, but we need much more complete information about your configuration and the circumstances of the failure.
 
Assuming that you have Dynon avionics, interchange the two wires going to
EMS pins 24 and 25. Like BigJohn said, switching other wires could cause big
problems. What is the voltage? If less than 13, then negative amps is
expected and normal.
 
Jay, your ammeter should fluctuate between positive and negative amps. Reading into your post, I assume you are telling us your system is not charging, and you are referring to the wiring at the voltage regulator connector. Yes, the individual wires within those pairs can be swapped, but doing so is pointless because the the two “generator” wires supply AC and the two white battery wires are jumped together in both the harness and inside the regulator.

If your system is not charging you need to measure the voltage at the regulator “C” terminal (referenced to ground.) you can measure this with the engine OFF and master switch ON. The C pin voltage be must equal battery voltage.
 
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I never thought to read between the lines like Mike Miller did. So is the problem actually a low voltage problem and not an ammeter problem?
If so and this RV-12 has Van's original control board, then a burned circuit board trace will result in no voltage on regulator terminal C. There is no fuse protecting the terminal "C" wire. If that wire shorts to ground, even for a second, the control board will be damaged. Some people elect not to have the control board repaired. Instead, they jumper regulator terminals "B" and "C" together. The disadvantage to doing that is that it will not be possible to shut off electrical power if there is smoke in the cockpit, unless the engine is stopped.
 
As Mike noted above, during the course of a normal flight (RV-12 w/ 912ULS) the ammeter will likely show you "plus" and "minus" readings. Typically the "minus" readings occur at low RPM settings (e.g., taxiing, power-off approach, etc.) when the 912's dynamo/generator does not supply sufficient power to supply all of your electrical demand -- the battery is then providing the additional power required and is slowly being discharged. As you add RPMs you should see your ammeter stabilize at a small "plus" reading -- in cruise, my readings are stable at 13.9 volts and +1 amp. If you constantly see a "minus" ammeter indication at high RPMs then that is another problem.
 
Question for Joe. The electrical diagram for the RV-12 shows a 1 amp fuse in the line that powers the C terminal of the Voltage Regulator. I blew the one in my airplane last summer. I called Van's asking for the location of it, I could not find it, and they told me it is internal to the circuit board of the switch module. They also said that it could only be repaired at Vans.

Before I shipped it back to them, they gave me the alternative wiring which you mentioned of jumpering the C and B terminals.

You mention a circuit board trace which melts or separates. Does that circuit board trace function as a fuse or is there really a 1 amp fuse soldered onto the circuit board?

Thanks.

JOhn
 
You mention a circuit board trace which melts or separates. Does that circuit board trace function
as a fuse or is there really a 1 amp fuse soldered onto the circuit board?
The answer is both. It all depends on which version of the control board you have. The original D-180
control board did not have a fuse. In that case a short circuit caused a circuit trace to burn open.
Newer control boards have a fuse. Since my RV-12 has the original control board, I do not know
where the fuse is physically located or how to replace it on newer control boards.
 
Send me an email

Anyone have an idea what it would cost to replace a D-180 with a Skyview D1000 Touch, with GPS 2020 receive antenna, on an older RV-12, pre 2013 finish build date?

NineBikes,

Send me an email at [email protected], and I can get that info.

There is a post earlier today that has a couple year old NIB D1000 Touch for $2800. The GPS-2020 costs $590, and you would need the EMS box which costs $600, unless you have a D120 installed.

I think Vans has a pre made wiring harness that will convert the RV-12 D-100 to SkyView.

Brian
 
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Joe,

Thanks for the information. Mine is the newer version with the Skyview and the switch module in the middle of the panel at the bottom. So I presume it has a fuse.

John
 
The ammeter is my RV12 shows a negative reading. I understand that the two battery wires can be interchanged. Also the two generator wires. I have tried any combination on my current and a new rectifier and get the same results. Any advice would be appreciated.

When I bought my already-flying RV-7, I noticed the same thing on my Skyview system. System was keeping the battery charged, but showed a discharge when the engine ran but positive current when the it wasn't...

I found the amp shunt under the panel and reversed the two small "sense" wires located on it. Apparently, the original builder just had them reversed.

That made the indications normalize and all good now in the ~400 hours since...

Obvious question...is it showing a discharge but is the system keeping the battery charged?

If so, perhaps go looking for the shunt...

Edited to add:

Skyview System Install Guide V15.3 Page 7-62 has a detailed description. Install guide found on Dynon's website.
 
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Regardless of what the ammeter says, if electrical system voltage is 13 or
greater, the battery is not being discharged. If system voltage is 13.8 or
greater, the battery is being charged.
 
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