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Amps=0

blueflyer

Well Known Member
Plane has been flying for several years, No problems. Last flight, on my Dynon D120, I noticed the Amps was 0. Voltage rock steady. So I replaced my voltage regulator. Went flying, and Amps still show 0. Then I ran wires directly from the amp shunt on the firewall to the pin connector on the D120. Ground run, and still amps showing 0. Voltage is always rock steady, so I believe the alternator is charging, just not getting an indication of amperage on the D120. What else can I check?
 
Dynon recommends a fused connection to the signal wires at the Shunt. I know my D180 has a fuse in each of the two signal wires from the shunt. Might check and see if you have fuse. Best I remember they were small amp glass type ( old Style) auto fuse.
 
Yep, the fuses are in and checked. I even swapped them out for new ones, but no change, still reading 0 amps.

I would have thought if it was trouble in the wiring between the amp shunt and the D120, I would have seen good amp readings when I installed the test wires straight from the amp shunt to the D120.
 
What is the "rock steady" voltage reading?

If the alternator is working, it should be around 13.7 or so. If near 12v or less, the alternator isn't working.

Ammeters can be hooked up to show charging current, or draw on the battery, depending on how they are wired.
 
Voltage reads 14.1 throughout the flights. If I turn the alternator off during flight, voltage starts to drop as expected. Amps read 0 the entire time.

Mine is wired to show the amp draw being used, i.e. if I turn on my pitot heat, amp reading increases.
 
D120?

Possibly a fault in the D120? I would check the current flow with a suitable multimeter to help isolate the problem.
 
Might go into the D120 set up and be sure something hasn t changed as for set up ? Would think that loss of ONE of the signal wires would drive amp reading either max high or min low. Would take loss of both signal wires to continually get zeros!
 
Since my test didn't reveal an issue with the currently installed wiring from the amp shunt to the D120, i'll buy an ammeter gauge from the auto store to see what it reads. If its reads correctly, I think its a problem with the D120 box itself. That seems very unlikely to me, but I guess all things can and do fail.

Rechecking the settings in the box isn't a bad idea either. Check all the easy stuff...
 
I’m having a problem with my 120 amps also, but mine jumps around from 0 to 13 and in between. The Vans round gauge still hooked up works as advertised. I was thinking on checking with a ammeter also. Are you going to “ break “ the line to hook up meter ? If so where are you going do that? Shunt ?
 
Remember that if it is an amp meter it will need to be in series with the current carrying wire. . The D120 is actually measuring voltage drop accross a calibrated resistor(shunt). So the two signal wires off the shunt are actually reading voltage and the D120 is reading that small voltage differential and calculating amps.
 
Yes, I should have more specifically said the auto parts ammeter will be tied into the two large lugs on the shunt, not the small wires where the D120 gets it's reading.
 
I don’t know about the d120; but in the sky view you can look at the voltages of every input. If it has that function, you should be able to see the voltage input from the shunt. Have you checked the shunt to see if it’s burnt? You should be able to read a resistance across the shunt leads with no power on and the two shunt leads disciponnected.
 
I dont think the D120 is as robust as the Skyview, but I did verify there is continuity between the two ends of the shunt. The shunt visually looks normal we well.

That does bring up a good idea. I could just use my voltmeter rather than buying an ammeter.
 
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I dont think the D120 is as robust as the Skyview, but I did verify there is continuity between the two ends of the shunt. The shunt visually looks normal we well.

That does bring up a good idea. I could just use my voltmeter rather than buying an ammeter.

The standard shunt should have a voltage across it of 1 millivolt for every amp of current flowing.
 
Does the ammeter give any useful information (when it was working)? If your voltage is steady the alternator/voltage regulator/etc is working just fine. If amps = 0 it must be a gauging fault. But do you really care? What do you do differently with the amps information? How does the knowledge of the current demands change the actions you take?
I realise this isn't the answer you were looking for but delete the shunt and reconfigure the dynon to remove the display. When the volts drop to battery voltage it is time to be concerned.
 
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