How to determine the Kv of a motorMethod 1 (by Ron van Sommeren)
A quick'n dirty method:
Drive your motor with a power drill.
Measure RPM and voltage generated.
Kv = RPM / voltage
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Method 2 (by Neil Stainton)
Run the motor without a load at full throttle
at various input
voltages and measure the RPM and controller input voltage.
You can measure the no load RPM by marking two stripes
on the bell with an indelible pen. Then shine a torch on the
rotating bell and tach the reflected light.
To find Kv either:
a) graph RPM vs Voltage, the slope of the line is Kv
or
b) for each voltage divide RPM by voltage, and
average your results.
Theoretically, a) is more accurate.
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