Newbie from NZ

[Doddy]

...and one other thing - with heavy duty motors (or rather, heavy current draw on a low voltage supply) - remember Ohm's law. I'd personally slave a lead-acid battery close-by and trickle-charge it from the vehicle battery. Then use the shortest, beefiest cable runs to the controller and to the motor, maybe even bi/tri wiring it to reduce the power loss in the cable.