Fuel Efficiency Computer (FEC)
This 2 by 2 sized micro-controller will provide you with real time estimated (updated every second) kilometers per liter and range in kilometers that you can travel based on your current speed and fuel consumption rate.
To use this:
1. Connect your directional linear speed to the FEC’s "Speed" input
2. Connect your fuel quantity to the FEC’s "Fuel Remaining" input
3. Connect the FEC’s "km / L" output to a suitable display
4. Connect the FEC’s "Range (km)" output to a suitable display
Brief description of how it works under the hood:
Every second, a blinker triggers a pulse which stores the fuel remaining value in one of two number registers depending on whether the blinker is going from on to off, or from off to on. The absolute value of the difference of those two numbers represents the amount of fuel consumed over 1 second.
Notes:
* For the first moments of operation, there may appear to be no output to displays. However, information should begin to appear at the same time that your fuel gauges start changing value.
* The estimates update once every second, and will vary from one update to the next. Usually this variance is around 5%, but can sometimes be much higher for a brief period and is affected by many dynamic factors such as waves, wind, etc.
* (edit) 12/28/2019 I have noticed that the variance of the displayed value can be a lot greater than I described in my above note of 5% in many situations (for example severe waves where the load on the engine is constantly changing). To counter this, my suggestion is to modify the logic so that you make a calculation based on, for example, 5 seconds worth of fuel consumption instead of 1 second. By doing that, you can get a more stable average value.
