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Old 03-19-2021, 07:02 AM   #2 (permalink)
JimJW
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Join Date: May 2018
Location: Mosquito Farm
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Motor Kv is probably the easiest thing to measure. It is very simply the RPMs the motor spins per volt.

All you need is a way to measure the motor RPM and ESC voltage (telemetry valves are sufficient)

Just disengage the motor pinion, and spin the motor at 100% throttle. Record the Main battery Voltage and RPMs. 100% throttle is important to get a good measurement. If you have batteries of different voltage/cell count; you can take the measurement at different voltages. (My ISDT chargers have an adjustable voltage supply function as well)

When measuring the RPM, you’ll need to make sure it’s the motor Rpm by setting the gear ratio to 1:1. Also make sure the motor poles are set correctly.

Once you have a measurement, just divide the RPM by the Volts:

Kv=RPM/Volts

If you have several measurements they should result in similar Kv values regardless of the battery voltage. (That’s why it’s called a ‘motor constant’)
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