Fuel gauge - voltage or current?

[ThatDippyTwat]

Does a fuel gauge work on voltage or current?

I know newer ones are probably CANBUS, but I've been asked about the feasibility of a custom dash on a couple of older, fighter'd bikes, oil cooled GSX, Z1000 and Z750 Turbo, Also if the kid likes it, the kids YBR (Go figure). The rest I'm fine with, but I realised I have zero idea on which principle a fuel gauge works.

Any pointers? I'm fine with electronics, it's just the principal that I have no idea about.

[Nobby the Bastard]

Most fuel guages I've looked at tend to have 3 wires, one earth, one constant 12v and the one from the sender (which is just a variable resistor) with a voltage between 0 and 12v depending on position.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[stinkwheel]

Motorcycle fuel guages run on lies, modulated by hearsay and guesswork.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[ThatDippyTwat]

[The Shaggy D.A.]

It wouldn't be too hard a project to make an accurate fuel gauge - read the sender value with an Arduino (or PIC of choice), then output a corrected value to the display (gauge/LEDs/screen/whatever).
____________________
Chances are quite high you are not in my Monkeysphere, and I don't care about you. Don't take it personally.
Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5

[weasley]

Do the bikes in question already have fuel gauges? I only ask as I looked at the possibility of adding a fuel gauge to mine (rather than just a low level warning) and the difficult bit is adding a level sensor/sender.
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Yamaha XJ600 | Yamaha YZF600R Thundercat | KTM 990 SMT | BMW F900XR TE

[ThatDippyTwat]

The YBR will have a working system, the kids bike is on the road and used daily. It'll be no problem to measure that.

The others are all without clocks, hence me being asked to do some custom ones. I've shown them everything from full digital race systems to cheapy Chinese, and they want none of them.

I'm not going to argue if I'm being paid for it, but I don't want to say "yeah, sure" and then realise I cant do a fuel gauge. I would assume they have senders of some type in them already.

[WD Forte]

Older cheaper gauges I've come across usually worked on current.
Both temp and fuel gauge used this in opposite ways
The sender as a variable resistor where as the float drops, resistance lowers or rises ( usually in a non linear way)
and the increased/decreased current in the clock distorts a bimetal strip acting on the needle.

Early K series used a god awful thyristor array circuit where the only effect of this complexity was a light to warn you at low fuel levels

Voltage based gauges were basically expanded scale voltmeters
again with variable resistors in the tank

Out of interest and wondering if it could be done without drilling holes in tanks ( Nooooooooo!)
I did once make a gauge for my CX based on the slight pressure differences between full empty tanks read between tap and carb.
It worked !
MKI was a bit too sensitive and suffered from the slooshing about as the bike was ridden of course, so MKII had damping to smooth this out which helped.

By MkIII I was going to use a microcontroller to read and average the readings, but I'd lost interest by then
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bikers smell of wee

[ThatDippyTwat]

If I was going to do one from scratch, a flex sensor attached to a float sounds about right. Even a basic PIC or Arduino should have plenty of oomph to display it on whatever you choose.

[The Shaggy D.A.]

If I could trust the local scum to leave it alone, I'd like to steampunk the Enfield with some brass/glass arrangement :-

https://s-media-cache-ak0.pinimg.com/736x/75/05/b6/7505b6b61d28c26a1086601b9ae4be94.jpg
____________________
Chances are quite high you are not in my Monkeysphere, and I don't care about you. Don't take it personally.
Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5

[andym]

[NutsyUk]

[The Shaggy D.A.]

[ThatDippyTwat]

That ^^^^^

Empty tank, 1 trimmer per led, fill it by one "segment" and adjust the trimmer accordingly. Trimmers aren't exactly expensive, and it's a one-time calibration.
I'll regulate the line to 12v, and bung in something like an LM339 (per 4 LED's), and bob's your mothers brother.

Just waiting on parts now, I'll mock the fuel gauge up. I have a spare sender with the same resistance range.

[WD Forte]

The bimetal (current)type gauges have the built in advantage of reacting slowy
to current/heat changes which damps out the effect of the float bobbing about when riding.
Most use a regulator of around 7-8V as well

If you're going to read/display a voltage alone I doubt you'll get steady readings
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bikers smell of wee

[ThatDippyTwat]

Once we've proven the principle, we're going to put it on his Lads YBR first. That'a a standard 8-10/390-400ohm sender as far as I can determine, so we'll prototype based on that. I could pop it all on a µC via a voltage divider and "damp" the input, but it's massive overkill really. If sloshing is really problematic, we'll do that.

I have a few µ's and Comparator's kicking around the house, just waiting on pots really.

[NutsyUk]

ahh fair do's if your making it just for your bike... on my project im building it as if its going to be a universal jobby...

Sure its not going to be 100% accurate but as you said irregular tank and float.

I noticed at least on my tank theres about a 6th of a tank left when the fuel float is at empty position and when at full theres still a good 2 6ths left to go on my tank.

As for filtering out the noisy volt read wth a float bobbing about... You take several readings... Say 10 or 20. Then average them out. Should filter most of the noise out.

Its how im doing the RPM reading. Adding a sample to an array and periodically add up and divide the results
____________________
Yamaha FZ8/Fazer800 (split headlight one) 2014, gingerly getting used to the massive increase in HP and not killing myself in the process! That was easy to get used to.
Kawasaki ER6F 2007 650 Gonna sell as a project bike!
Lexmoto XTR S 125 Sold!

[ThatDippyTwat]

[NutsyUk]

heh
Im currently putting together a lightbox and UV exposure box... but I must admit i really want to get back on with my project... Ive not touched it in a couple of weeks.
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Yamaha FZ8/Fazer800 (split headlight one) 2014, gingerly getting used to the massive increase in HP and not killing myself in the process! That was easy to get used to.
Kawasaki ER6F 2007 650 Gonna sell as a project bike!
Lexmoto XTR S 125 Sold!

[Pete.]

The sender is a variable resistor so in it's simplest form the gauge and sender form part of a voltage splitter circuit.

Looking at an old Fazer wiring schematic that seems to be the case, as the meter has only power and ground then a third wire goes through the sender to ground. With the float level high, resistance across the sender is low so the gauge gets more volts. As the fuel level drops resistance at the sender increases and gauge voltage reduces giving you a lower reading.

Usually sender resistance is very non-linear, presumably because the sender swings through a progressively wider arc as the fuel level drops. When the tank is full, taking out an inch of fuel level will cause the float to drop an inch. When the tank is near empty however, taking out an inch of fuel can cause several inches swing of the float arm. How well this is accounted for in the design will determine how accurate the gauge is.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[ThatDippyTwat]

[NutsyUk]

*cough sneezes and farts...

https://www.ebay.co.uk/itm/2-52mm-Fuel-Meter-LED-Digital-Display-Fuel-Gauge-For-Car-Motorcycle-DC12V-/201388391024?hash=item2ee3aefa70:g:Rw8AAOSwQItUGm~7


I mean sure its not making it yourself but, given the price it might be worth buying one and taking it apart to see what its doing as well...
____________________
Yamaha FZ8/Fazer800 (split headlight one) 2014, gingerly getting used to the massive increase in HP and not killing myself in the process! That was easy to get used to.
Kawasaki ER6F 2007 650 Gonna sell as a project bike!
Lexmoto XTR S 125 Sold!

[Pete.]

Fill tank to brim, ride 100 miles, fill tank to brim. Divide miles by litres used then multiply by tank capacity. This will give your full-tank range. Reset trip meter every time you fill up.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[ThatDippyTwat]

They said they had a look online for weeks, and saw nothing they like, and they're specific with what they want. They're paying for it, so who am I to argue? If they want 4 LED's, they get 4 LED's.