Brantel

Brantel

Well Known Member
Anyone care to list their Dynon fuel tank calibration values when using Vans capacitive senders? I want to cross reference mine and see how they compare.

Thanks!
 
Here are my results....

Here are my results after calibrating a second time.

The left looks OK but the right bothers me. How can two tanks built exactly the same way be this different? There is no reason I can think of why that right tank has several points the same right in the middle of its range????

3518j2f.jpg


rjgm8i.jpg
 
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The tanks are the same, but the converters may not be, if one is not operating to spec. Did you try swapping the converters and see if the problem follows?
 
RV8RIVETER said:
The tanks are the same, but the converters may not be, if one is not operating to spec. Did you try swapping the converters and see if the problem follows?
Click to expand...


Thought about that but for $50 I may just buy a new one....Too much hassle to flip them.

One of the other things is that on the bottom and the top, both tanks read similar numbers.

It seems that Dynon did not take advantage of the complete range available to them (0-5v) to increase the resolution of these converters. They are only using a small part of that range. Looks like the Van's senders have a much smaller capacitance change ∆ empty to full than they expected.

Sure wish they had built some trim pots into their design so we could adjust our zero and span values to make the converters match the senders better....or designed them to match the Van's units better since most likely 95% of these are used with Van's units.
 
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Brantel said:
It seems that Dynon did not take advantage of the complete range available to them (0-5v) to increase the resolution of these converters. They are only using a small part of that range. Looks like the Van's senders have a much smaller capacitance change ∆ empty to full than they expected.

Sure wish they had built some trim pots into their design so we could adjust our zero and span values to make the converters match the senders better....or designed them to match the Van's units better since most likely 95% of these are used with Van's units.
Click to expand...

I wonder if this explains the $163 additional cost (per tank) for the Princeton/AFS converter (Vans P/N: IE ACS CAPAC. CNVTR.) over the $45 Dynon unit.

I had been planning to use the cheaper $45 Dynon units to save $326 in an AFS instsallation, but it looks like this will result in a significantly reduced resolution on fuel quantity.

Can anybody confirm that the higher priced units from Princeton / Vans have gain and zero adjustments so that the converter is putting out the full range of 0-5V when properly adjusted?
 
I just spoke to Todd at Princeton regarding the output range for his converters. He makes and sells 3 different models. The model ending in 1S has one setpoint, you press a button on his unit when powered up, tanks empty and this defines 0 volts. The range on this unit in a Vans installation is about 0-3V. The upper range is not settable.

The 2S has two setpoints. When the unit is powered and with tanks empty, you press a button on the converter and this defines 0V, empty. Then you fill the tanks and hit a button which defines full and this sets the output at 5V. Hence with this unit you are getting the full 0-5V output. Both the 1S and the 2S are $95 purchased direct.

The 5S has five setpoints, so you start at zero, hit the button to define 0V = empty. Add 25% tank capacity and hit the button - repeat 3 times to give you a fairly linear 0-5V output signal with tank level. The 5S unit is a little more $.

With all these units you THEN have to do a separate software calibration in your EFIS/EIS where you fill the tank in small increments of 2 or 3 gallons (follow the manual) and define setpoints in the EFIS/EIS to indicate the tank level corresponding with the voltage being sent by the converter. Bottom line, any of these will work but if you want the highest resolution (use of the full 0-5V EIS input signal), you don't want the Dynon converter or the Princeton -1S model - buy the -2S or -5S.
 
Brantel said:
Here are my results after calibrating a second time.

The left looks OK but the right bothers me. How can two tanks built exactly the same way be this different? There is no reason I can think of why that right tank has several points the same right in the middle of its range????

3518j2f.jpg


rjgm8i.jpg
Click to expand...

mine looks just like yours;)
 
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