Today I thought about how to measure the energy quick and easy and after some research I found these handy watt meters for RC models:The are used to monitor battery charging, power consumption and other stuff. With external power they have a voltage range 0-60V, the can handle currents up to 180A and measure the energy with a resolution of 0.1Wh, which should be sufficient for the first prototype with the stepper motor up to the coming, much bigger, prototypes. Off course it would also be possible to measure voltage and current with an Arduino and then make the energy calculation myself, but sometimes you have to take the quick route.