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Amp reading

Allan Stern

Well Known Member
I am not reading any amps on my GX3 engine screen. I do have voltage. Could someone provide me with how you wired up your shunt? I think it is wired up correctly but I want to see how others wired it in.

I put the shunt in between the alternator wire and the wire going into the avionics buss. With two wires screwed onto the top of the shunt.

Thanks
 
I hate to ask the obvious...but if it is in the alternator wire then the engine must be running and the alternator working to read amps. Also there is supposed to be fuses between the shunt and GEA 24.

Jay
 
Shunt

No fuses between shunt. According to Stein, I do have it wired properly so he is investigating. Might be a setting issue on G3X as it was with volts.
 
Shunt Input

I am not reading any amps on my GX3 engine screen. I do have voltage. Could someone provide me with how you wired up your shunt? I think it is wired up correctly but I want to see how others wired it in.

I put the shunt in between the alternator wire and the wire going into the avionics buss. With two wires screwed onto the top of the shunt.

Thanks

Allan,

This is the wiring diagram for interfacing a shunt to the GEA 24:

i-ckBmRB8.jpg


There are fuses installed in line with the sense wires.

It sounds like the purpose of this shunt is to measure alternator output? What configuration setting are you using for the shunt input?

Thanks,

Justin
 
Mine read "0" until the engine was running. Then read system load the rest of the time while flying. I just now (45 minutes ago) finnished my second hour with my new panel.
 
Just finished an RV8 panel with a Stein harness, FWIW, the blue/white wire from the GEA24 is attached to the battery side of the shunt.
 
Amp Reading

I would like to thank everyone that has answered my post and gave me some great suggestions to look at. I did a lot of investigation and took all suggestions to heart and had an had a brain fart to discover the reason why.

Mea Culpa, it was my fault and admit to a greivous error. I discovered that I was not turning the master switch all the way on to turn on the alternator/master after I started the engine. Was only turning on the battery to start it.

It now works fine and I feel a tad stupid for it, but will admit I was at fault.

Thanks for the help.
 
Hey Allen, I'm all for starting the engine with the alternator turned off. IMO there's no reason to have it on during start. Just gotta remember to turn it on after start ;)

Marc
 
Reviving this thread instead of asking the same question in a new one.

Allen found his problem but I haven’t.

I have a Dynon shunt (60a/60Mv) in line with the alternator B lead, wired per Garmin drawings for my GEA24.

No amperage indicated when the is engine running, volts look good.

I checked the continuity between the shunt and the GEA24 pins, no blown fuses.

On the config page, I have alternator selected but am unsure what to set the scale factor to on the config page, the default is 1.0.

Any thoughts on why this might be happening?
 
The G3X "default" settings assumes a 50mv/100A shunt -- at 60mv/60A you'll need to do some scale adjustments.

With the engine running, and the alternator field enabled, put the G3X into configuration mode, select Engine & Airframe, GEA 24 Inputs Tab, then Scroll down to Shunt 1.

Does your G3X show something like the attached pic? What's the value for "Sensor Value?"

If nothing, then it's time to chase the wires - Hi to the Alternator, Lo to the Battery side of the shunt. Is the alternator actually running -- volts measured on the "B" lead at 14.4 - 14.6Vdc?
 

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The G3X "default" settings assumes a 50mv/100A shunt -- at 60mv/60A you'll need to do some scale adjustments.

With the engine running, and the alternator field enabled, put the G3X into configuration mode, select Engine & Airframe, GEA 24 Inputs Tab, then Scroll down to Shunt 1.

Does your G3X show something like the attached pic? What's the value for "Sensor Value?"

If nothing, then it's time to chase the wires - Hi to the Alternator, Lo to the Battery side of the shunt. Is the alternator actually running -- volts measured on the "B" lead at 14.4 - 14.6Vdc?

If my hi and lo are swapped, would it show zero?
Also, not sure about going to config mode with the engine running… would my engine sensors still work and display?
 
If my hi and lo are swapped, would it show zero?
Also, not sure about going to config mode with the engine running… would my engine sensors still work and display?

It will show a negative number.

Reboot the unit by pressing [nrst]+[menu]+[back] simultaneously. Then press the [menu] button until it says "Configuration Mode"...works great, very useful for checking on things like this in real-time....
 
It will show a negative number.
Well thats a bummer...I'm not getting anything :confused:
I've checked the continuing and pin positions on the shut wires...not sure what else to check?

Reboot the unit by pressing [nrst]+[menu]+[back] simultaneously. Then press the [menu] button until it says "Configuration Mode"...works great, very useful for checking on things like this in real-time....
Great tip, Thanks.
 
If you have the shunt wires reversed, it might show a negative number - but if you have a minimum value of zero set on the gauge display range, I don’t think it will display a negative number.

This happened to me recently on our RV-10. Had confirmation of alternator operating with voltage increase, but zero amps. Found shunt to GEA wires reversed. The gauge minimum value was set at zero, so I don’t think it would have displayed negative current reading.
 
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If you have the shunt wires reversed, it might show a negative number - but if you have a minimum value of zero set on the gauge display range, I don’t think it will display a negative number.

This happened to me recently on our RV-10. Had confirmation of alternator operating with voltage increase, but zero amps. Found shunt to GEA wires reversed. The gauge minimum value was set at zero, so I don’t think it would have displayed negative current reading.

Thanks, you’re right. I went into the config menu and there’s not an option to setup a negative number.

Next time I have my cowl off, I’ll swap the wires!
 
Thanks, you’re right. I went into the config menu and there’s not an option to setup a negative number.

Next time I have my cowl off, I’ll swap the wires!

If you look at the current calibration page it should show you the raw amps reading, which would indeed be a negative number for an alternator shunt wired backwards.
 
High amps reading

I have a situation where the amps (70amp alt) are reading ~85 amps in cruise however volts are ok - any ideas, please ?
 
I have a situation where the amps (70amp alt) are reading ~85 amps in cruise however volts are ok - any ideas, please ?

If you’re using the G3X, you might look at the config page and check your settings for whatever shunt you’re using.

The G3X looks at the shunt and measures the millivolts across the shunt. My shut is 60 millivolts when the shunt is maxed out at 60 amps. The Garmin shunt is 50 millivolts at 100 amps. The G3X needs the info to know what the amps to millivolt factor is. If it’s wrong, the amps will read higher or lower depending which way the error is. I’ve asked The G3experts twice how to figure the factor and have not been given a clear answer yet.

My rudimentary understanding is, my shunt would be a factor of 1 (60 mV/60 amps). The Garmin shunt would be a factor of .5 (50 mV/ 100 amps) but this is the part where Garmin was not clear on.

Hopefully someone with a better understanding of this will educate us.
 
The G3X looks at the shunt and measures the millivolts across the shunt. My shut is 60 millivolts when the shunt is maxed out at 60 amps. The Garmin shunt is 50 millivolts at 100 amps. The G3X needs the info to know what the amps to millivolt factor is. If it’s wrong, the amps will read higher or lower depending which way the error is. I’ve asked The G3experts twice how to figure the factor and have not been given a clear answer yet.

The software allows you to enter the mV/A value directly, why not just do that?
 
The software allows you to enter the mV/A value directly, why not just do that?

Scale Factor: 17.50 as depicted on the config page.

So for my shunt which is 60mV/60amp I would input 60.60 and if someone has the Garmin shunt which is 50mV/100amp, it would be 50.100.

Does that sound correct?
 

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60 mV / 60 A = 1 mV / A...

So I'm not sure what you're saying? I tried inputing 60.60 into the scale factor field and it didn't like that.

For a shunt that is 60mV, 60amps, what should I enter int the scale factor field?
 
Just what I said... 60 millivolts per 60 amps is 1 millivolt per amp. Select "mV/A" and enter 1.0.
 
in this subject i read the thread> my RV-8 with a G3x panel shows consistenly between 11 to 9 amp draw with a voltage of between 13.5 to 14.0
the voltage increases with a load (lights, fuel pump, www, etc.)
what should the amp read be? Are the parameters inverted?
I assume that my G3X is telling me the draw in amps. My battery does not decay after flying.
 
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