What is KV?
KV is the term used in the brushless motor workspace to specify the number of rotations per minute that a motor will turn for each volt applied to the motor/ESC with no load on the motor.
Example: a 500KV motor being run on 12 volts will be expected to turn at 6,000 RPM unloaded. 500 *12 = 6,000.
Neutronics specifications are +/- 5%.
Example: a 500KV motor can test between 525 and 475 RPM.
KV should not be confused with “kV” which is the official abbreviation for kilovolt. We trust no kilovolts are used anywhere near these products.
How is KV measured?
There has been a trend to debate the methodology used to measure KV. Neutronics measures KV via the electrical RPM on the circuit from the ESC to the motor divided by the number of motor poles and voltage.
There are many ways to measure KV. No one method results in a better motor or reading assuming that the measurement is done rigorously…
- Physically measure shaft RPM and divide by voltage
- Use an oscilloscope to measure the commutation frequency. Then calculate KV with reference to pole count and voltage.
- Use a commutation measuring tool to automatically count the commutations on a phase, divide by the number of poles, and divide by the voltage.
- Read the commutation frequency – and probably the KV itself – from the GUI and data logs generated by most quality electronic speed controllers.