Originally Posted by IceWind
For that you'd need to know the maximum current draw at max throtle and had to assume that the current draw change is linear to the throtle change, or I'm getting the wrong idea here.
You could make a calibration and get a good approksimation. But as the batteries gets discharged - full throttle would suddenly result in a much lower current draw etc.
All in all, a cheap solution is great - but at this point I would rather spend 10$ on a current sensor