Blew up a motor - post mortem


#1

Parts:

  • Turnigy Aerodrive SK3 - 3542-800kv Brushless Outrunner Motor
  • CUI - AMT102 encoder
  • Custom 3D printed mount for the motor and the encoder
  • ODrive 3.2 configured step/dir
  • Teensy 3.2 controlling the process

Setup:

Somehow the mounting screw of the encoder mount touched the base of the motor. In my mind it should not be a problem since the base of the motor should not be connected to one of the input leads.

Story:

  • At a certain point while the motor was running I saw a spark striking between the case of the encoder and the screw mounting the encoder to the 3D printed mount. Which in his case was touching the motor case/base.
  • I turned everything off, remounted the encoder differently, using different mounting holes, who don’t touch the encoder case and don’t touch the case/base of the motor.
  • At this point I should have realised that the case/base of the motor should never conduct current.
  • Anyway, I repower the ODrive, the calibration sequence seems to work correctly.
  • At this point I trigger the Teensy to start the installations initiation process and nothing happens.
  • While reaching over the ODrive to push a button connected to the Teensy I noticed that the ODrive is radiating a lot of heat. I immediately turned off the power.
  • At that point I notice the smell of the melting PLA motor mount.

Cause of failure

Overheating damaging the insulation of the windings causing a short to the base of the motor, causing a short between ground via the encoder casing.

Side notes

  • Teensy survived
  • Odrive looks fine as far as I can tell
  • It happened during the documentation process of my projects writeup for the ODrive Community :roll_eyes:

#2

Whoops. Maybe get one of the D5065’s with thermistors for the next one? :slight_smile:


#3

The D5065’s are out of stock in the EU shop.
I went for the "Turnigy Aerodrive SK3 - 5045-500KV "
For my application I need more speed then torque. After consulting the “ODrive motor guide” it seemed like a good choice.

Since I’m probably make a custom shaft, I can also add thermistor to the mix.

Second I might rewind my “Aerodrive SK3 - 3542”, just for the learning experience.