Hi Lim,

I bought the Acro 90 controller "programming-box". The box is neat and simple to use. You plug in the box to the controller, and to its own 4.8 pack. Then, you plug the motor batteries (yes) to the contoller. The controller will let you step through functionality. Although I don't know what the timing actually does, the effect is to INCREASE amp draw (and power) I believe. Anyway, you get more power .

Thanks,
Jim - PS - I'm not an expert, just learning like everyone else.