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Using Arduino => General Electronics => Topic started by: firashelou on Nov 15, 2017, 08:30 am

Title: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 15, 2017, 08:30 am
hello,
I am looking for a way to make a level sensor for a fuel tank on an RC car. I made some research on google and found some info but i need some help please.
I was thinking about a liquid level sensor then an Idea came to my mind which is the use of a pressure sensor and place it under the fuel tank which will give a feedback about the weight of the tank. So please help me with this by telling which way is better and any suggestion of the sensors ?

thanks in advance :)
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: slipstick on Nov 15, 2017, 12:07 pm
What sort of RC car? How is it being used?

Unless your RC car is going to be running in a straight line at a constant speed a liquid level sensor is going to have problems. The amount of slopping round under acceleration or cornering will be fairly extreme.

I'm not too sure about weight sensing either if the car is going to be bouncing around.

Interesting problem.

Steve
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 15, 2017, 03:53 pm
What sort of RC car? How is it being used?

Unless your RC car is going to be running in a straight line at a constant speed a liquid level sensor is going to have problems. The amount of slopping round under acceleration or cornering will be fairly extreme.

I'm not too sure about weight sensing either if the car is going to be bouncing around.

Interesting problem.

Steve
it's an F1 car of 1/4 scale using fuel engine, so what solution can be used for this ?
i found this fuel sensor which i have been told it uses capacitance to work, what do you think ?
http://www.goodluckbuy.com/telemetry-accessories-fuel-guage-sensor-fgs-01.html (http://www.goodluckbuy.com/telemetry-accessories-fuel-guage-sensor-fgs-01.html)
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Paul_KD7HB on Nov 15, 2017, 04:17 pm
You HAVE to have a small segment of the tank where the fuel can slowly run in/out, but not slosh around. Then you can measure the level in that small segment. At least that is how the big tanks are made.

Paul
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 15, 2017, 08:28 pm
You HAVE to have a small segment of the tank where the fuel can slowly run in/out, but not slosh around. Then you can measure the level in that small segment. At least that is how the big tanks are made.

Paul
thanks Paul for the reply, so what sensor must be used ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Paul_KD7HB on Nov 15, 2017, 08:39 pm
thanks Paul for the reply, so what sensor must be used ?
Well, the one you asked about is out of stock, so hard to test. Also, it was meant for a plastic tank. Is your tank plastic? And, would the 5 possible levels work for you?

What accuracy are looking for?

Paul
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: hammy on Nov 15, 2017, 08:46 pm
The tank level will never be steady enough to weigh or measure that level.
Most people just measure the time of the run and stop before it runs out .

Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: polymorph on Nov 15, 2017, 08:49 pm
Is the tank plastic, and does it have one side that isn't near anything metal? You can make your own capacitive sensor with copper or aluminum tape strips on the tank. As stated, you'll need a baffle in the tank to make the level by the sensors stay relatively constant.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: dougp on Nov 16, 2017, 02:59 am
Would a flowmeter (http://www.btflowmeter.com/en/flow-meter-products/flow-meters-lowflow-flowmeters-low-flow-turbine-flow-meter-fuel-flow-meters-diesel-fuel-flow-meter-watermeters-paddlewheel-flow-meter-oil-flow-meter-oilflowmeter-waterflowmeter-water-meters-turbineflowmeter-oilflowmeter.html) work?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 16, 2017, 08:24 am
Well, the one you asked about is out of stock, so hard to test. Also, it was meant for a plastic tank. Is your tank plastic? And, would the 5 possible levels work for you?

What accuracy are looking for?

Paul
the RC tank is plastic yes
what I am looking for is to make a percentage capacity level which goes down from 100% to 0% with a step of 1 but if that wouldn't work it would be ok with 5 levels
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 16, 2017, 08:28 am
Is the tank plastic, and does it have one side that isn't near anything metal? You can make your own capacitive sensor with copper or aluminum tape strips on the tank. As stated, you'll need a baffle in the tank to make the level by the sensors stay relatively constant.
this is the tank that i have
RC tank (https://rc-car-online.de/en/products/fg_7348-7348-fg-carson-smartech-tank-complete-without-ventilation-1pce-.html)

it won't be near anything metal, there is the engine but between the tank and engine there is a plastic wall

So how to make the sensor ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 16, 2017, 08:28 am
Would a flowmeter (http://www.btflowmeter.com/en/flow-meter-products/flow-meters-lowflow-flowmeters-low-flow-turbine-flow-meter-fuel-flow-meters-diesel-fuel-flow-meter-watermeters-paddlewheel-flow-meter-oil-flow-meter-oilflowmeter-waterflowmeter-water-meters-turbineflowmeter-oilflowmeter.html) work?
I don't think it is possible to read from it with arduino, is it ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: dougp on Nov 16, 2017, 02:35 pm
I don't think it is possible to read from it with arduino, is it ?
If you get one providing an electrical pulse per unit passed, yes.  Condition the signal if necessary, feed to a digital input and then just count pulses.  One pulse equals xx cc., oz., etc.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 16, 2017, 02:47 pm
If you get one providing an electrical pulse per unit passed, yes.  Condition the signal if necessary, feed to a digital input and then just count pulses.  One pulse equals xx cc., oz., etc.
I think this one is difficult to do with this small tank
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: vinceherman on Nov 16, 2017, 04:28 pm
Help us out a bit more on the project.
What is the purpose of having a fuel level reading?  What are you intending to do with that data?

Are you trying to determine if/when you need to pit to refuel?
Are you putting in telemetry so that you have access to this data in the pit?

Since there are many challenges with trying to get an accurate physical reading, I would consider approximating the fuel consumption.
Keep a running of of the throttle positions in small time slices. 
Assign a fuel used number for each throttle position, small amount at low throttle, large amount at fuel throttle.
Add those numbers.
Multiple by a factor to adjust for real word measurements.

Then adjust that multiplication factor over several runs, where you compare the estimated fuel used to the actual fuel used.

Possibly adjust the assignment of fuel used at various throttle positions.

The advantage of this is that there will be no physical change to the fuel system.

Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 16, 2017, 07:43 pm
Help us out a bit more on the project.
What is the purpose of having a fuel level reading?  What are you intending to do with that data?

Are you trying to determine if/when you need to pit to refuel?
Are you putting in telemetry so that you have access to this data in the pit?

Since there are many challenges with trying to get an accurate physical reading, I would consider approximating the fuel consumption.
Keep a running of of the throttle positions in small time slices. 
Assign a fuel used number for each throttle position, small amount at low throttle, large amount at fuel throttle.
Add those numbers.
Multiple by a factor to adjust for real word measurements.

Then adjust that multiplication factor over several runs, where you compare the estimated fuel used to the actual fuel used.

Possibly adjust the assignment of fuel used at various throttle positions.

The advantage of this is that there will be no physical change to the fuel system.


what I am trying to do is tracking fuel while running like a real F1 car

what do you mean exactly by your method ? I did not understand it :/

what do you mean by "The advantage of this is that there will be no physical change to the fuel system." ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: vinceherman on Nov 16, 2017, 08:07 pm
what I am trying to do is tracking fuel while running like a real F1 car
No, that does not answer my questions.  "Track Fuel" does not tell me what you are doing with the data.

Let's say that together, we all create a system that lets an on-board system determine that you have 47% fuel remaining.  What should that on-board system do with that data?

Is it going to remain on board for some decision making process?
Is it going to be transmitted to the pit?  If so, what is going to be done with the data in the pit?  Just displayed on some device for the driver to know?  How does this info help the driver?

Quote
what do you mean exactly by your method ? I did not understand it :/
I will be glad to give better detail but let's wait until you help us understand what you are trying to do.

Quote
what do you mean by "The advantage of this is that there will be no physical change to the fuel system." ?
Here too, let's wait until you help us understand your goals.

Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: MarkDerbyshire on Nov 16, 2017, 08:39 pm
it's an F1 car of 1/4 scale using fuel engine, so what solution can be used for this ?
i found this fuel sensor which i have been told it uses capacitance to work, what do you think ?
http://www.goodluckbuy.com/telemetry-accessories-fuel-guage-sensor-fgs-01.html (http://www.goodluckbuy.com/telemetry-accessories-fuel-guage-sensor-fgs-01.html)
Hitec use this type of sensor as well.  Only works with Glow fuel
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 17, 2017, 08:29 am
No, that does not answer my questions.  "Track Fuel" does not tell me what you are doing with the data.

Let's say that together, we all create a system that lets an on-board system determine that you have 47% fuel remaining.  What should that on-board system do with that data?

Is it going to remain on board for some decision making process?
Is it going to be transmitted to the pit?  If so, what is going to be done with the data in the pit?  Just displayed on some device for the driver to know?  How does this info help the driver?
I will be glad to give better detail but let's wait until you help us understand what you are trying to do.
Here too, let's wait until you help us understand your goals.


ah ok, well what i am trying to do is help the driver to know how much fuel is left so he knows when to pit and refuel
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 17, 2017, 08:32 am
Hitec use this type of sensor as well.  Only works with Glow fuel
glow fuel you mean the nitro, well I asked the engine seller about what type of fuel can I use and he said that I can use the Unleaded 95 which is used in normal cars
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: MarkDerbyshire on Nov 17, 2017, 09:03 am
glow fuel you mean the nitro, well I asked the engine seller about what type of fuel can I use and he said that I can use the Unleaded 95 which is used in normal cars
The sensor won't work then.  What engine are you running in this car?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 17, 2017, 09:20 am
The sensor won't work then.  What engine are you running in this car?
a tuned version of this Zenoah g320rc (http://www.rossmod.co.uk/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/A/3/A383D59F083BA73D4EAB93E545CF0DD8.jpg)
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: MarkDerbyshire on Nov 17, 2017, 09:29 am
a tuned version of this Zenoah g320rc (http://www.rossmod.co.uk/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/A/3/A383D59F083BA73D4EAB93E545CF0DD8.jpg)
Nice.  It's not a small 1:24 scale then :D
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 17, 2017, 10:39 am
Nice.  It's not a small 1:24 scale then :D
no it is a 1/4 scale but even for a small scale that runs on fuel it would be a nice option to have
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: vinceherman on Nov 19, 2017, 07:00 pm
ah ok, well what i am trying to do is help the driver to know how much fuel is left so he knows when to pit and refuel
Awesome.
Reading through this thread, it is clear that it will be difficult to get an accurate physical reading.
Instead, I propose that you estimate the amount of fuel consumed.
I would think that a formula could be created that uses throttle position and engine RPM to estimate the fuel consumption.  
It might not be very accurate at first, but you can tweak it by running the estimate program while running the car.  After some number of laps, pit and measure the actual amount of fuel used. (fill the tank).  Then compare that to the estimated value.  Is the estimate too low?  Bump up the factor and try again.  Too high, bump down the factor and try again.

Something like this:
Code: [Select]
fuelConsumed += throttle * rpm * factor;

At some fixed time period, read the throttle and RPM.
Perform the calculation.
Transmit it to the pits.
Repeat.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 21, 2017, 08:53 am
Awesome.
Reading through this thread, it is clear that it will be difficult to get an accurate physical reading.
Instead, I propose that you estimate the amount of fuel consumed.
I would think that a formula could be created that uses throttle position and engine RPM to estimate the fuel consumption. 
It might not be very accurate at first, but you can tweak it by running the estimate program while running the car.  After some number of laps, pit and measure the actual amount of fuel used. (fill the tank).  Then compare that to the estimated value.  Is the estimate too low?  Bump up the factor and try again.  Too high, bump down the factor and try again.

Something like this:
Code: [Select]
fuelConsumed += throttle * rpm * factor;

At some fixed time period, read the throttle and RPM.
Perform the calculation.
Transmit it to the pits.
Repeat.

i did not get this method  :smiley-confuse:  is there any way you can explain more what is happening here ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: vinceherman on Nov 21, 2017, 03:00 pm
Ok, let me break this down into smaller bites.  I will number my points so that later, you can refer to individual items on the list for further discussion.


Read through that list.  Let me know if any of the points do not make sense.  If there is confusion, let me know where.  Then we can dive in to more detail.




Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: MarkDerbyshire on Nov 21, 2017, 05:43 pm
Ok, let me break this down into smaller bites.  I will number my points so that later, you can refer to individual items on the list for further discussion.

  • Actual, physical measurements of your fuel level are hard.
  • I am suggesting that rather than a physical measurement, you programmatically estimate the amount of fuel being consumed.
  • The estimation process will use 2 inputs
    • Throttle
    • Engine RPM

  • You will need a sensor to read the engine RPM
  • You will need a method to read the throttle position
  • Throttle reading will be easy if you are using typical RC control - there are many tutorials on reading receiver output
  • Once you have the ability to read the throttle and RPM, you can compute an estimate of the fuel being used
  • The estimate will need to be tweaked to more closely match actual, physical fuel consumption measurements

Read through that list.  Let me know if any of the points do not make sense.  If there is confusion, let me know where.  Then we can dive in to more detail.





Or put one of these in line with the fuel pipe and read the square wave output

Flow Sensor (http://www.btflowmeter.com/en/flow-meter-products/flow-meters-lowflow-flowmeters-low-flow-turbine-flow-meter-fuel-flow-meters-diesel-fuel-flow-meter-watermeters-paddlewheel-flow-meter-oil-flow-meter-oilflowmeter-waterflowmeter-water-meters-turbineflowmeter-oilflowmeter/chemical-oil-flowmetes-series-fch-pp-pvdf-alu-q-004-75-lpm/fuel-flowmeter-oilflowmeter-fch-alu-80-lmin.html)

Simples :)
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: JohnRob on Nov 21, 2017, 09:01 pm
I've done some work on automotive level sensing.  It is a PIA.   As said before at any given time you have no idea where in the tank the fuel is.  And a section of tank where fuel can run in and out slowly doesn't work either.

I think vinceherman had very good suggestion regarding trying to measure fuel consumption.

I have no expedience with RC engines, however if you could measure the inlet air flow you might get a better indication of fuel consumption.   If there is a inlet air filter or passage, perhaps the pressure drop across it could be useful.   And I'm not sure if it is practical but a hot wire anemometer might work as well.  Similar to the mass air flow sensors in some of the older vehicles.




Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 22, 2017, 10:35 am
Ok, let me break this down into smaller bites.  I will number my points so that later, you can refer to individual items on the list for further discussion.

  • Actual, physical measurements of your fuel level are hard.
  • I am suggesting that rather than a physical measurement, you programmatically estimate the amount of fuel being consumed.
  • The estimation process will use 2 inputs
    • Throttle
    • Engine RPM

  • You will need a sensor to read the engine RPM
  • You will need a method to read the throttle position
  • Throttle reading will be easy if you are using typical RC control - there are many tutorials on reading receiver output
  • Once you have the ability to read the throttle and RPM, you can compute an estimate of the fuel being used
  • The estimate will need to be tweaked to more closely match actual, physical fuel consumption measurements

Read through that list.  Let me know if any of the points do not make sense.  If there is confusion, let me know where.  Then we can dive in to more detail.

ok my system will have RPM reader by placing a wire around the spark plug and get the rpm from that, and will have a rotary switch to control the throttle pedal input, so what i did not understand is number 7 I how to get fuel info from throttle and rpm ?

what do you think about this method of making Liquid capacitive sensor (http://www.instructables.com/id/Building-a-Capacitive-Liquid-Sensor/)?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: vinceherman on Nov 22, 2017, 03:04 pm
and will have a rotary switch to control the throttle pedal input
You can do that.
Or you can read the value coming out of the receiver in the car.

Quote
what i did not understand is number 7 I how to get fuel info from throttle and rpm ?
This is the core of my proposal.
The engine uses fuel when it is running.
At any particular RPM, the engine is using more fuel at higher throttle settings.
At any particular throttle setting, the engine is using more fuel at higher RPM.

I doubt that either of these relationships are linear, but let's assume they are for a starting point.

At the start of your program, set a fuelConsumed variable to zero.
Set up a method to count revolutions of the motor.  I guess external hardware or an interrupt.

In a loop, read the throttle position.  If you are reading the throttle channel from your receiver, I would guess that the throttle reading would return the number of microseconds of the throttle servo pulse, maybe a value ranging from 500 to 1500.  Map that to a range that starts at zero.

Now, multiple the throttle reading by the number of revolutions since the last pass through.
Add the result to the fuelConsumed variable.
Reset the number of revolutions to zero.
Transmit the fuelConsumed number to the pit.
Repeat the loop.

The number transmitted can be translated to an estimate of the fuel consumed.
It will be some goofy number.  But a number that grows at a similar rate to the rate of fuel consumption.
You just need to multiply it by some factor to get a usable fuel consumed number.

What value for the factor?  You need to determine that.  And adjust it through trial and error.


Quote
what do you think about this method of making Liquid capacitive sensor (http://www.instructables.com/id/Building-a-Capacitive-Liquid-Sensor/)?
Try it out.  Calibrate it to read Full when the bottle is full.  Empty when the bottle is empty.  And a percentage in between.
Then fill the bottle with 1/10 of the full capacity.  Now shake the bottle and see what reading you get.
Is that usable?
I am not saying that it is not doable.  But I think it is hard to do it well.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Gerry48 on Nov 22, 2017, 09:12 pm
The normal way to measure fuel is with a float and pot.   Measure voltage with Arduino.  You'll have to cut hole in tank to insert float and glue electrical connector in place.  

https://www.ebay.com/itm/Fuel-Level-Sensor-Gas-Gauge-Direct-Fit-for-Chevy-GMC-Isuzu-Oldsmobile-Pontiac/132034473951?hash=item1ebdde2fdf:g:htAAAOSwG7lZwRaA:sc:ShippingMethodStandard!93117!US!-1&vxp=mtr (https://www.ebay.com/itm/Fuel-Level-Sensor-Gas-Gauge-Direct-Fit-for-Chevy-GMC-Isuzu-Oldsmobile-Pontiac/132034473951?hash=item1ebdde2fdf:g:htAAAOSwG7lZwRaA:sc:ShippingMethodStandard!93117!US!-1&vxp=mtr)
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 23, 2017, 07:03 am
You can do that.
Or you can read the value coming out of the receiver in the car.
This is the core of my proposal.
The engine uses fuel when it is running.
At any particular RPM, the engine is using more fuel at higher throttle settings.
At any particular throttle setting, the engine is using more fuel at higher RPM.

I doubt that either of these relationships are linear, but let's assume they are for a starting point.

At the start of your program, set a fuelConsumed variable to zero.
Set up a method to count revolutions of the motor.  I guess external hardware or an interrupt.

In a loop, read the throttle position.  If you are reading the throttle channel from your receiver, I would guess that the throttle reading would return the number of microseconds of the throttle servo pulse, maybe a value ranging from 500 to 1500.  Map that to a range that starts at zero.

Now, multiple the throttle reading by the number of revolutions since the last pass through.
Add the result to the fuelConsumed variable.
Reset the number of revolutions to zero.
Transmit the fuelConsumed number to the pit.
Repeat the loop.

The number transmitted can be translated to an estimate of the fuel consumed.
It will be some goofy number.  But a number that grows at a similar rate to the rate of fuel consumption.
You just need to multiply it by some factor to get a usable fuel consumed number.

What value for the factor?  You need to determine that.  And adjust it through trial and error.

Try it out.  Calibrate it to read Full when the bottle is full.  Empty when the bottle is empty.  And a percentage in between.
Then fill the bottle with 1/10 of the full capacity.  Now shake the bottle and see what reading you get.
Is that usable?
I am not saying that it is not doable.  But I think it is hard to do it well.
well not easy at all, what should the factor be like how to determine it ?

and what do you think of the sensor that Gerry48 suggested in reply #31 ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 23, 2017, 07:04 am
The normal way to measure fuel is with a float and pot.   Measure voltage with Arduino.  You'll have to cut hole in tank to insert float and glue electrical connector in place. 

https://www.ebay.com/itm/Fuel-Level-Sensor-Gas-Gauge-Direct-Fit-for-Chevy-GMC-Isuzu-Oldsmobile-Pontiac/132034473951?hash=item1ebdde2fdf:g:htAAAOSwG7lZwRaA:sc:ShippingMethodStandard!93117!US!-1&vxp=mtr (https://www.ebay.com/itm/Fuel-Level-Sensor-Gas-Gauge-Direct-Fit-for-Chevy-GMC-Isuzu-Oldsmobile-Pontiac/132034473951?hash=item1ebdde2fdf:g:htAAAOSwG7lZwRaA:sc:ShippingMethodStandard!93117!US!-1&vxp=mtr)
I was looking for a sensor like this but how to get the value to be read by arduino ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Boardburner2 on Nov 23, 2017, 08:58 am
Is there enough space in your model to accomodate one of these, they tend to be physically large.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 23, 2017, 09:30 am
Is there enough space in your model to accomodate one of these, they tend to be physically large.
oh right i think not because the tank is 750ml
but what about the sensor used in it ? maybe i can find something similar but small
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Boardburner2 on Nov 23, 2017, 09:34 am
I doubt that either of these relationships are linear, but let's assume they are for a starting point.

  But I think it is hard to do it well.

My thoughts exactly.

There could b considerable work in getting an accurate map.

oh right i think not because the tank is 750ml
but what about the sensor used in it ? maybe i can find something similar but small
Even with a baffled tank i doubt you will get reliable measurements in a mooving vehicle.
(Smaller system less damping.)
Best i would hope for is 1/2 1/4 full.


Others have suggested a flowmeter which could be much simpler to implement
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Boardburner2 on Nov 23, 2017, 09:49 am
Perhaps an older idea could be used, use a separate much smaller reserve tank.

Do not know how to physically implement such a fuel system though.
EDIT
Perhaps use a conical base tank with a simple float level switch at the top of the cone.
These used to be available in 1 Litre sizes for testing fuel consumption on full size cars.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Gerry48 on Nov 23, 2017, 05:09 pm
Glue a micro switch to the bottom of the tank.  Tie a string to the end of the switch and connect the other end of the string to a fishing bobber.  The bobber holds the switch closed until fuel level is lower than the string length.  The switch opens. 
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Boardburner2 on Nov 23, 2017, 06:05 pm
Good idea.
The fishing bobber could then stop the fuel flow from the main tank to stop air entrainment and draw from a reserve.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 24, 2017, 07:11 am
Glue a micro switch to the bottom of the tank.  Tie a string to the end of the switch and connect the other end of the string to a fishing bobber.  The bobber holds the switch closed until fuel level is lower than the string length.  The switch opens. 

looks interesting but i can't drill an extra hole for the bobber and string, and it would give only when the tank is low
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Gerry48 on Nov 24, 2017, 05:14 pm
No need to make holes in the tank other than for the two small wires.  You assemble the micro switch with bobber through the fuel tank fill hole.  You don't even need a string on the bobber.  Just clip the bobber to the switch lever and glue it in place.

You could also attach a small potentiometer inside the tank and use a float (small bobber) to get analog measurements.  Again, all assembly can be make from the tank fill hole.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Nov 27, 2017, 06:51 am
No need to make holes in the tank other than for the two small wires.  You assemble the micro switch with bobber through the fuel tank fill hole.  You don't even need a string on the bobber.  Just clip the bobber to the switch lever and glue it in place.

You could also attach a small potentiometer inside the tank and use a float (small bobber) to get analog measurements.  Again, all assembly can be make from the tank fill hole.

ok but the tank fill hole will be closed with a cap so how should that be done ?
and about the potentiometer  how would it take it's place back to default position ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: polymorph on Nov 30, 2017, 09:09 pm
Pick the pulse off of pin 3 before the RC smoothing network, the pulse width after subtracting the empty tank width should be a linear function of how full the tank is.

(http://www.polyphoto.com/tutorials/ElectronicCircuits/Dual555CapMeter150dpi.jpg)

The tough part is vibration foaming up the fuel.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Gerry48 on Nov 30, 2017, 09:51 pm
Don't understand you question.   You open the tank fuel fill hole and glue in the potentiomenter.  Attached to the pot shaft is a 90deg elbow.  Attached to the other end of the elbow is a short rod.  Attached to the other end of the rod is a float.  All these items are scaled to the size of your tank.  You attach two wires to the pot and use a voltage divider to measure voltage.  That's how virtually all car fuel tanks are measured.  It's simple and accurate.

ok but the tank fill hole will be closed with a cap so how should that be done ?
and about the potentiometer  how would it take it's place back to default position ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Qdeathstar on Nov 30, 2017, 10:41 pm
What about mounting the tank on a scale, would solve the vibration issues?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: polymorph on Dec 01, 2017, 06:22 pm
If you use my dual 555 circuit with the RC smoothing network and measure the DC level, that may act to average out variations due to tank vibration.

I'm not sure how mounting the tank on a scale solves the vibration problem.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: Qdeathstar on Dec 02, 2017, 12:22 am
Well, I mean, of you measured the weight of the fuel, you wouldn't have to worry about froth... I hadn't considered g-forces in my intial post, however.
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: firashelou on Dec 04, 2017, 10:17 am
Don't understand you question.   You open the tank fuel fill hole and glue in the potentiomenter.  Attached to the pot shaft is a 90deg elbow.  Attached to the other end of the elbow is a short rod.  Attached to the other end of the rod is a float.  All these items are scaled to the size of your tank.  You attach two wires to the pot and use a voltage divider to measure voltage.  That's how virtually all car fuel tanks are measured.  It's simple and accurate.

i meant my tank has a closing cap, do you mean i must place the pot inside the tank under the closing cap ?
Title: Re: Looking for a way to measure the fuel level for an RC car tank ! help !
Post by: superair78 on Feb 26, 2018, 04:58 am
https://superair78.wordpress.com/4-la-technique/4-1-les-sondes-de-mesures/4-1-2-realisation-dun-temoin-de-reserve-de-carburant-avec-un-arduino/