Digital Fuel gauge

johns4104 · May 05, 2009, 08:10:34 AM

I built Jerry Leiber's fuel gauge.
It works great and reads down to 1/10 gallons.
Thanks for you help Jerry!

John

Jerry Liebler · May 05, 2009, 08:34:30 AM

John,
CONGRATULATIONS!! I really like mine and I'm sure you'll enjoy yours. It's so nice to have a really accurate high resolution fuel guage. It has saved me much money as I was able to notice excessive fuel consumption and stop, for repairs, before loosing too much fuel, when a fuel return line broke.
Regards
Jerry 4107 1120

John316 · May 05, 2009, 08:42:18 AM

How do we find out how to build the gauge? I am interested.

Thanks.

God bless,

John

Jerry Liebler · May 05, 2009, 09:05:49 AM

John & all who are interested.
The basic documentation is in the " files" section of the Yahoo group " gmc-busnuts". you may have to join the group to gain acess to the files. The guage is based on the 0 to 5 volt output Centroid products sender and a digital panel meter. The sender is the secret, it is amazingly linear and precise. Since my bus and most have an essentially rectangular tank the reslts are really impressive. If you have any questions, feel free to send me an email with your phone # & I'll call & we'll discuss them.
Regards
Jerry 4107 1120

John316 · May 05, 2009, 09:15:40 AM

Thanks Jerry. That helps.

God bless,

John

Tim Strommen · May 05, 2009, 12:21:37 PM

For the Hobbyist/DIY'er, the Centroid sender is a capacitive device. If you really want to try and do it yourself, there was an article in Nuts and Volts written by a guy at Parallax (a hobby micro controller company) on how to build one yourself...

Since you can't buy the really old back issues of N&V, Parallax is kindly hosting those articles on their website - the specific article is available here....

I have met/spoken with these people at the embedded systems conference, they are nice people and the community is very strong (but they don't/haven't pay me to speak of them - they're just neat people

).

-Tim

P.S. The basic jist is that you can take a hollow piece of acrylic tubing cut to the depth of your tank, put two vertical/separated strips of copper tape from top to bottom, solder a wire to each strip and wrap the whole thing in fiberglass to make a custom sensor for your tank with no moving parts (all for about $4 US). -T

John316 · May 05, 2009, 01:20:06 PM

Thanks for the info Tim.

God bless,

John

Jerry Liebler · May 05, 2009, 02:58:15 PM

Tim,
Yes it is, no doubt, possible to home brew the sender, I felt it is hardly worth the effort. The Centroid sender includes complete signal conditioning and a good mounting method that doesn't leak custom made for the depth specified for about $50. In addition the Centroid is a proven design and fully debugged.
Regards
Jerry 4107 1120

Tim Strommen · May 05, 2009, 05:53:21 PM

Quote from: Jerry Liebler on May 05, 2009, 02:58:15 PM...the Centroid sender includes complete signal conditioning and a good mounting method that doesn't leak custom made for the depth specified for about $50...

Granted, and the signal conditioning is done in software (a microprocessor in the sender - here they mention that they are moving to all digital sensors for better post-processing), which a hobbyist or DIY'er could write if so compelled. The "slosh detect" is a basic "box-car averaging" process over a long period, the tank dimension compensation is a simple equation that acts on the determined level from the sensor, and their auto-empty/full correction is simply a max/min variable compare (the highest value becomes the new "Full", the lowest value measured becomes the new "Empty" - the scale is automatically compensated).

I believe preventing leaks is just a matter of properly utilizing the fittings/sealant...

If you added a few more sensor "poles" to the tank, and did the post processing in one microprocessor, it could give an even better picture of the tank status (not that better than 0.1gallons resolution is needed when the bus is getting 6.8MPG... does one really need to know more than that they have about 90 bus lengths left in the tank?

). Biggest advantage to avoiding analog in my opinion is that there is less data open to interpretation on the display side (where the voltage may have dropped a bit giving a different value).

If you can measure the real-time fuel consumption from the engine, you can get a very accurate "miles until empty" readout on your dash...

-Tim

Jerry32 · May 05, 2009, 07:19:43 PM

It would be nice to have a more accurate gauge than the original. Mine looks like It's getting empty and is only down 90-100 gallons with fifty remaining, Just makes you nervous when out in the wild west with station a 100 miles aprt. Jerry

belfert · May 05, 2009, 07:28:35 PM

I think I will order one of those new Centroid senders. I have one of the analog now, but I screwed it up.

My original float based sender was rusted all to heck so my gauge would read empty when the tank was 50% full.

JohnEd · May 05, 2009, 08:25:41 PM

Hey! I did this for cheap and it works well.

Mine only reads to the gallon, it uses the garden variety of sender that is usually found in the tank....all aren't compatable but the one that works is a trip to NAPA ville. My gauge is a digital read out that is a few inches tall...sorta. But big enuff to be read from the back bedroom on a clear night without distractions. The gauge has a adjustment screw(S) on the back....one is set for zero when the tank is empty. The other is set for the number of gallons you just pumped to fill that tank. Then you are good to go.

Tenths of a gallon? What are you paying for that detail of info.?

In civil Service we have a definition for "precision": 1. Measure with a micrometer. 2. Mark with chalk. 3. Cut with an AX. Got it?

This tech is being applied to a DD two stroke....right?

John

Lin · May 05, 2009, 09:27:44 PM

I do not have a gauge. As the bus did not have one originally, I do not think that there is any sender. I have had the Centroid thing on my list for quite some time now. The tank has an easily accessible plate on the side near the filter tube. It seems that Centroid has units that will work with that.

John,

Are you talking about getting everything, sender and gauge from Napa? Which did you use? How did you calibrate it to "empty"? I do not think I would ever want to get within 20-30 gallons of really being that low.

JohnEd · May 05, 2009, 11:55:04 PM

Lin,

here you go: http://www.autometer.com/cat_gaugesearch.aspx

Go to advanced search, select the category "fuel meter", size "all", model/series "all", type "digital". They list three.

I know I didn't buy this brand but the name isn't on the outside/front of the meter. That "autometer" sight should get you started. I noted that they have a new innovation...0 to 280 ohm max sender compatible B U T you have 7 settings to select from to get compatibility with your sender. Given you will be installing a new sender this info lets you select from many for price and convenience.