An update to the arduino lpg volume measurement project.
The idea of measuring the weight of the tank works theoretically. However, I ran into several things. Firstly, it is difficult to properly fit the senors under the tank frame. The tank is built clamped between two steel strips which are connected to the floor of the trunk. By attaching the strips, the reading of the sensors does not have a good effect on increasing volume in the tank.
Mounting an extra frame underneath is also not possible in the Volare sedan. There was too little space between the tank and top of the trunk.
In short, nice idea, but it is difficult to apply to this car. I will use this method once for another project.
Given this reason, looking for another method to measure the volume more accurately.
The tank is standard equipped with a float system. This has not worked yet when I bought the car.
After disassembling the level float and control of the sensor (a type of potentiometer), both proved to work well. Only I came to discover that the level float in the tank came into contact with the 80% filling limiter (for safety). This filling limiter also includes a float. This limiter closes off the supply of the liquid gas when refueling. Both floats crossed each other.
So I also removed this 80% filling limiter from the tank. This allowed you to clearly see that it was bent obliquely (probably happened by a previous assembly).
The whole is bent straight and mounted in the tank.
And yes the float level floats fine on the LPG liquid.
In order to measure the level, I used the original level sensor of the level float. This gives a resistance between 10-90 ohms. To translate this resistance into liters, I use the analogue readout of the arduino.
By setting 5 volts on the potentiometer and connecting to the analogue input, the remaining voltage can be measured. This can be translated into resistance.
Now it was necessary to gain insight into the increasing resistance when filling the tank. This is created by recording the resistance every 5 liters. The increase in resistance to volume of LPG is not linear, as expected. Given the round shape of the tank and sinus movement of the level float.
The table below shows the measured value. Based on these values in arduino script translated into an increase of LPG.
If the potentiometer gives a resistance between two measuring points, an accompanying LPG volume is calculated. By means of substitution. For example measuring point 1: 10L liquid at 20 ohm, measuring point 2: 15L at 25 ohm.
If 22.5 ohm is measured, the arduino displays a volume of 12.5 liters.
The script seems to work. the accuracy of the measurement includes (arduino uno) 0.5 lter. Sufficient for this application.
Who knows, maybe I have inspired someone to apply on a petrol tank!
[tank installation weight sensors]
[level float]
[measure points]
[Final test with lcd display]
