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Fuel Capacitance plates / Dynon issue ??

Speedbird1

Active Member
Hello -

I have an issue with incorrect fuel tank readings. Issue resolved by re-calibration.
 
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I have your same set up for six years. I have found that a poor electrical connection at the tank to converter will give me a false reading, sometimes even an empty tank reading. The connection plug that passes thru the tank can leak a drop of fuel over time making this poor connection. For me it has only been on one wing tank and a spray of cleaner will clean it up and restore the gauge?s readings. Now just part of the yearly service list.
 
Your experience is normal. The changes between pours is small but measurable and goes out many decimal places, which cannot be seen in the calibration screen.
 
Thanks for the information. Is there any chance you can post your voltage readings for the levels? Mine are SO close together and I was wondering if yours are any different.

IMG_7673.JPG

Sure, I?ll snap a pic tonight, but Ray is right...
 
Are both you guys getting accurate reading from the tanks? If we put 42 gallons in and burn 21, the fuel flow transducer is right on the money but the tank gauges will, for example say that there are 5 gallons left in the left tank and 7 in the right. Mis-match is a big delta.
 
Are both you guys getting accurate reading from the tanks? If we put 42 gallons in and burn 21, the fuel flow transducer is right on the money but the tank gauges will, for example say that there are 5 gallons left in the left tank and 7 in the right. Mis-match is a big delta.

I have your exact issue as well. I think I am going to have to do another calibration.
 
Your experience is normal. The changes between pours is small but measurable and goes out many decimal places, which cannot be seen in the calibration screen.

This is not normal. On my setup I had to install a cap in series with the tank plates to bring the swing into the 0-5V output range of the Dynon converter. My plates are bigger than Van's though.

I suggest measuring the capacitance and resistance across the tank plates with a nice instrument to get a quantitative idea what's going on. There might be a short. Epsilon of gasoline is 2, so if your converter barely registers doubling of capacitance something is wrong.
 
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I did recalibrate after flying about 30 hours. Now I am within a gallon or two almost all times.
My dipstick is the most accurate, then my fuel flow red cube then my gauges, but close as a gallon or two.
 
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Thanks for posting this. I appreciate it. You are using the Dynon Capacitance to voltage converter, correct? Also, do your plate look like this:

PA140018.jpg

Yes, to the Dynon converter and as I remember yes to the plates. It?s been 8 years since I built my tanks, I used Van?s plate kit. And the Dynon converter from 6 years ago. So things could have changed.

One note: after the second calibration, I was still not quite happy with the gauge readings, so I made some manual adjustments to the numbers you see. It took some time, tracking fuel burn, dip sticking before and after each flight, writing a log. And I was also adjusting the Dynon for the red cube fuel flow, that was easier.
 
Yes, to the Dynon converter and as I remember yes to the plates. It?s been 8 years since I built my tanks, I used Van?s plate kit. And the Dynon converter from 6 years ago. So things could have changed.

One note: after the second calibration, I was still not quite happy with the gauge readings, so I made some manual adjustments to the numbers you see. It took some time, tracking fuel burn, dip sticking before and after each flight, writing a log. And I was also adjusting the Dynon for the red cube fuel flow, that was easier.

Thank you for the help, Bruce. It's very much appreciated.
 
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