[BrianG]

You're welcome paul. There was effort made to make my version as easy to use as possible. :)

As to the battery voltage rating: I do understand that the battery voltage will drop under heavy load. But that load happens under heavy acceleration (anytime the motor is forced to change speed in a short amount of time). Once you get near the top speed, the rate of acceleration will be less, therefore less load and therefore less voltage loss, so you get closer to the nominal voltage. What I do is make a worst case and best case scenario. I figure everything using low battery voltage (~1v/cell) and then again at a more ideal battery voltage (~1.3v/cell). The real figure is usually somewhere in the middle.

Generally, you match your motor and battery voltage so that you don't exceed ~35k rpm. If using a low KV motor, you can use higher voltage. If you are using a faster motor, you use less voltage. Then, you try to gear approriately for the speed you want ... within reason. Usually, you get less losses using higher voltage and a low kv motor since current will be less. But there are usually limits to how many batteries you can physically fit, not to mention the capacility of the ESC.

If you are going to use this buggy for racing on an offroad track, then 35mph seems to be the common desired top speed. If on-road racing, you can go faster more easily since there is more traction control and the terrain is easier to accelerate on.