Basic Understanding Of Brushless Motors

Update:01 Nov 2019

The Term  Brushless Motors  or  brushless  is being pas […]

The Term  Brushless Motors  or  brushless  is being passed around in the rc world.

So what is it and is it better ?

Brushless basically says what it is, a motor with no brushes inside this means minimal maintenance is needed, so turn it on and away you go. With the old electric motors (brushed motors) they were rated in turns e.g. 21t, 17t, 15t and so on the lower the turn the higher the speed but the lower the torque.

In brushless you get turns mostly on the 1/10 scale motors and Motor For Cooker Hood Manufacturerskv ratings on all the motors, if it is not displayed on the motor the manufacturer will display the kv rating in the instructions. To understand KV is like understanding the turns on a motor the higer the KV the faster it will be, but the less torque it will have.

So for instance a 5700KV motor will be faster than a 3900kv motor in 1/10 scale but the 3900kv motor could go in a truck where as the 5700kv would get very hot as there  s not much torque. To get the heat down you would have to add a larger spur gear and a smaller pinion gear. To work out the RMP of a motor you times it buy the voltage of your battery.

3900kv x 7..4 (2s lipo) = 28,860 rpm

5700kv x 7.4 (2s lipo) = 42,180 rpm

In a truck everything changes as you also need to torque as well as speed on paper the 5700kv motor would be faster but it would get very hot as the torque wouldn't be there. On a 3s lipo battery you would destroy the motor with the drag on it. Saying that the 3900KV would be faster in a truck on 3s and as there's more torque it would handle it better.

5700KV x 7.4 (2s lipo) = 42,180 rpm

3900kv x 11.1 (3s lipo) = 43,290 rpm

To summarize a higher kv motor will be faster but have less torque, in trucks this covers stadium trucks, short course trucks, truggies and monster trucks its much better to run a lower kv motor on a higher voltage than a higher kv motor on a lower voltage. The KV ratings above are based on 1/10 scale motors, the same rules apply for all other scales the only changes will be the KV ratings on the motors.