There is no such thing as a perpetual motion machine. Every machine in the world will have losses from friction on the moving parts, the sound created, etc. This means that machines will need constant energy input to keep it moving, similar to that setup.
Voltage drop is simply V = I*R. I for the maximum current and R for the round-trip resistance of the wire. To get this resistance, multiply the specific resistance of the size of your wire to its round-trip length.