I have an underwater scooter Cuda 650.... http://www.dive-xtras.com/pages/products/cuda650.asp
that uses a BFA42-2d-200 motor http://www.magmotor.com/brushless/bfa-ba42.pdf
Battery pack is a 34 serial 14 ah NiMh pack (41v nominal)
What is involved in making a new contoller for it based on Arduino?
As it is the controler has a 7 speed contol. It starts off in 3rd and a double click on the triger will increase speed while a single click will decrease speed.
What I would like to see is perhaps a change in speed options, a soft start, low battery warning and speed memory. These dont seem too difficult to implement being PWM, and voltage reading functions. But I have no idea on whats involved in running these types of higher voltage motors.