I'm looking at a schematic like the following:
I understand that this will be a very rough resolution as the drop will be in the 25 to 75 mV range and a single count in the Arduino ADC is around 5mV. Perhaps I'll look into amplifying the signal at a later stage but that is enough for me as a start.
In my case, my Arduino is also powered from within the load circuit, through a non-isolated buck converter. iIn't connecting its ground to potentially 35.9-something volts going to cause a short circuit?