How Do I test brushless motors for short circuits?

By Tim S.
Motor Test Feature

Troubleshooting a motor can be quite a hassle unless you understand a bit about how brushless DC motors work.

A brushless motor uses electromagnets to spin the motor by pushing and pulling the magnets attached the bell of the motor.
Electromagnets can also be used to generate power. When you spin a motor by hand it generates power. Many modern generators use this same process to create power.

  • If you short any two of the wires together you can create resistance within the motor when you try to spin the motor by hand.
  • A brushless motor should spin freely when all the wires are separated as there is not a complete circuit.
  • If the motor resists your rotation regardless of the wire connections, it’s likely that your motor has an internal short circuit.


On the left, I have shorted two of the motor wires.
On the right, the motor wires are not touching.

This test should be done without the ESC connected.

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