Looking for a way to measure the fuel level for an RC car tank ! help !

[firashelou]

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

[slipstick]

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

[firashelou]

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

[Paul_KD7HB]

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

[firashelou]

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 ?

[Paul_KD7HB]

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

[hammy]

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 .

[polymorph]

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.

[dougp]

Would a flowmeter work?

[firashelou]

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

[firashelou]

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

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 ?

[firashelou]

Would a flowmeter work?

I don't think it is possible to read from it with arduino, is it ?

[dougp]

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.

[firashelou]

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

[vinceherman]

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.