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  #11  
Old 03-27-2017, 03:00 PM
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9GT 9GT is offline
 
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Location: Southern Michigan
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I put Princeton single point set probes in the tanks when I built the Cozy MKIV. They were dead accurate with the original Blue Mountain EFIS and also the Dynon Skyview that replaced it. Still working perfect after 10 years. I installed the Princeton 5 point set probes in my RV-10 with Garmin G3X. I NEVER trusted them and re calibrated the probes numerous times, along with pin-out checks. Sometimes they read accurate and other times they would be all over the place. I ended up making a Fuel Hawk type dip fuel level gauge and always dipped the tanks before each flight and kept track of fuel burn using the red cube. Wished I had the tanks built using the floats.
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  #12  
Old 03-27-2017, 03:06 PM
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RV7A Flyer RV7A Flyer is offline
 
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Quote:
Originally Posted by 9GT View Post
I put Princeton single point set probes in the tanks when I built the Cozy MKIV. They were dead accurate with the original Blue Mountain EFIS and also the Dynon Skyview that replaced it. Still working perfect after 10 years. I installed the Princeton 5 point set probes in my RV-10 with Garmin G3X. I NEVER trusted them and re calibrated the probes numerous times, along with pin-out checks. Sometimes they read accurate and other times they would be all over the place. I ended up making a Fuel Hawk type dip fuel level gauge and always dipped the tanks before each flight and kept track of fuel burn using the red cube. Wished I had the tanks built using the floats.
I used the Princeton 2-set-point converters, and they've been absolutely steady for years.

Itried to use the Dynon converters but didn't have very good luck with them (they used a tiny portion of the 0-5V range). Others have had better luck.
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  #13  
Old 03-27-2017, 04:45 PM
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ppilotmike ppilotmike is offline
 
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Location: Denver, CO
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Default Princeton Converters..

..for me too.
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  #14  
Old 03-28-2017, 02:29 PM
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longranger longranger is offline
 
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I don't remember the dielectric constant of ethanol, but it is WAY higher than the value of approximately 2 for gasoline. It doesn't take much ethanol to throw the calibration off. I have read of a small capacitive plate being installed in the bottom inboard end of the tank that is (almost) always immersed in fuel, to make the system self-calibrating. The extra plate would send a separate signal from the tank, and you would need a special converter and/or software to make use of it. I thought about doing that, but decided to just stick with a steady diet of 100LL.

Also, maybe there is a way to implement a software function in the EIS so you can tell it when the tank is full (or tell it how much fuel is in the tank) and let it compensate from there?
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  #15  
Old 03-28-2017, 11:04 PM
Andy who? Andy who? is offline
 
Join Date: Jun 2013
Location: Royal Oak, MI
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Does anybody know where to find a kit or plans for the discontinued vans capacitive kit? I'm getting started on my 7 wings and like the installation of the capacitive sender I have seen in other build websites.
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  #16  
Old 03-29-2017, 09:11 AM
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airguy airguy is offline
 
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Quote:
Originally Posted by Andy who? View Post
Does anybody know where to find a kit or plans for the discontinued vans capacitive kit? I'm getting started on my 7 wings and like the installation of the capacitive sender I have seen in other build websites.


I've got the scanned drawings from the install that I got from Vans, PM me an email address and I'll forward them to you.

Quote:
Originally Posted by longranger View Post
I don't remember the dielectric constant of ethanol, but it is WAY higher than the value of approximately 2 for gasoline. It doesn't take much ethanol to throw the calibration off. I have read of a small capacitive plate being installed in the bottom inboard end of the tank that is (almost) always immersed in fuel, to make the system self-calibrating. The extra plate would send a separate signal from the tank, and you would need a special converter and/or software to make use of it. I thought about doing that, but decided to just stick with a steady diet of 100LL.

Also, maybe there is a way to implement a software function in the EIS so you can tell it when the tank is full (or tell it how much fuel is in the tank) and let it compensate from there?
This is probably part of my problem - I was trying to dial in the calibration curves and was not meeting with any success - but the ethanol levels are known to vary in automotive fuel between summer and winter blends, and I crossed that threshold twice while trying to dial in the calibration without taking that into account. The third probe for ethanol content calibration would be a great way to determine that, but at this point I'm not interested in chasing the rabbit any further down the hole, the juice ain't worth the squeeze. I'm going forward with the floats.
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Last edited by airguy : 03-29-2017 at 09:15 AM.
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  #17  
Old 03-29-2017, 10:13 AM
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ArVeeNiner ArVeeNiner is offline
 
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Location: San Jose, CA
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Default I WISH mine were accurate

I must be the only guy in the Van's world that has INACCURATE capacitive fuel senders using only 100LL. I've calibrated them a couple of times (I have a Dynon D-180) and I get some warning that the difference between calibration points is small. I just went ahead and continued the calibration and what I get are gauges that are accurate when full but show that I have a lot more fuel than I have when empty. I can't remember exactly how much they are off but they are significantly off. My primary fuel gauge is the totalizer.

It's such a PITA that I haven't readdressed this in years but I've been checking so many things off on my squawk sheet that this issue is starting to bubble up to the top of my list. Maybe I'll get around to solving this issue this year.
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Last edited by ArVeeNiner : 03-29-2017 at 11:27 AM.
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  #18  
Old 03-29-2017, 10:41 AM
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RV7A Flyer RV7A Flyer is offline
 
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Quote:
Originally Posted by ArVeeNiner View Post
I must be the only guy in the Van's world that has INACCURATE capacitive fuel senders using only 100LL. I've calibrated them a couple of times (I have a Dynon D-180) and I get some warning that the difference between calibration points is small. I just went ahead and continued the calibration and what I get are gauges that are accurate when full but show that I have a lot more fuel than I have when empty. I can't remember exactly how much they are off but they are significantly off. My primary fuel gauge is the totalizer.

It's such a PIA that I haven't readdressed this in years but I've been checking so many things off on my squawk sheet that this issue is starting to bubble up to the top of my list. Maybe I'll get around to solving this issue this year.
This was why I switched out the Dynon capacitance to voltage converter and went with Princeton. The Dynon ones don't allow you designate empty as 0V and full as 5V, and I, too, ended up with almost no difference in voltages as I was adding fuel for the calibration. That made it very inaccurate in use.

Once I swapped to Princeton converters and did the calibrations (which is a PITA because you have to empty a tank, set the Princeton device to E, fill the tank, set the device to F, then *empty the tank* and start the whole EFIS 2-gallon-at-a-time calibration, then do the same thing on the other side....arrrrrgggghhhh) it has worked fine for years (albeit off by about 1 gallon from about 12 gallons on down, it's consistently off by that amount, and I don't have the patience to recalibrate things).
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  #19  
Old 03-29-2017, 10:58 AM
jimgreen jimgreen is offline
 
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Location: Vancouver island, BC Canada
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I been chasing problems with Van's capacitive senders and Dynon D120 for a long time. Before flight the readings are steady but not always very accurate - often out by up to 2 gallons. After about 10 minutes in the air they become erratic, often scrolling up and down, and giving the D100 a panic attack. I've checked the grounds and the rest of the wiring and recalibrated twice but no improvement. I'm out of ideas.
The red cube is deadly accurate but I want functioning fuel gauges.
Should I put new senders?
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Last edited by jimgreen : 03-29-2017 at 11:03 AM.
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  #20  
Old 03-29-2017, 11:16 AM
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RV7A Flyer RV7A Flyer is offline
 
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Quote:
Originally Posted by jimgreen View Post
I been chasing problems with Van's capacitive senders and Dynon D120 for a long time. Before flight the readings are steady but not always very accurate - often out by up to 2 gallons. After about 10 minutes in the air they become erratic, often scrolling up and down, and giving the D100 a panic attack. I've checked the grounds and the rest of the wiring and recalibrated twice but no improvement. I'm out of ideas.
The red cube is deadly accurate but I want functioning fuel gauges.
Should I put new senders?
It's not the senders (if by senders you mean the plates in the tank)...it's the converters, I'll wager. What converters are you using?
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