Jump to content

Help Support IntlWaters by donating using the link above.

KV rating on same size motors?

Whats the difference?

  • Please log in to reply
4 replies to this topic

#1 Buddy Benedict

Buddy Benedict

    Club Racer

  • Members
  • PipPipPip
  • 526 posts

Posted 24 December 2017 - 11:37 AM

The two motors listed below are the same size but have different KV ratings. Besides the voltage and amperage difference, what is the reason for having the different KV.   Is it for more RPM's or more torque or what?





#2 Steven Bryant

Steven Bryant

    Club Racer

  • Members
  • PipPipPip
  • 572 posts

Posted 24 December 2017 - 11:47 AM

Different KV allows the motors to be used at different voltages, I.e 8s, 10s etc

Sent from my iPhone using Tapatalk

#3 BrianTooms



  • Members
  • PipPip
  • 257 posts

Posted 24 December 2017 - 03:43 PM

KV x Volts = RPM :)

#4 LohringMiller


    Beginner Boater

  • Members
  • Pip
  • 238 posts

Posted 25 December 2017 - 08:44 AM

KV has NO influence on power.  It's a measure of the ratio of rpm to voltage as posted above.  Power is volts times amps.


Lohring Miller

#5 HTV Boats

HTV Boats

    World Racer

  • Members
  • PipPipPipPipPip
  • 2,043 posts

Posted 26 December 2017 - 09:34 AM

On the same size motors different windings produce a range of KV ratings. As stated for different voltages. If you had a 4400kv on 2S it would produce the same rpm as a 2200kv on 4S and 1100kv on 8S. Amp draw on same boat and prop approximately would be X on 2S, 1/2 X on 4S and 1/4 X on 8S. if the 2S was 200 amps the 4S would draw 100a and on 8S down to 50a. Work done with volts over amps.
Or consider KV like gears. With the same voltage and prop going from 1800kv to 2030kv speed would increase if you weren't over propped. Or same kv's and a prop that was on the edge heat wise going down on kv should run cooler for the same laps.