Yep, smoke and flames are usually a sign that your electronics aren’t functioning as expected. This is actually the second failure encountered while learning about brushless motor controllers.
[Michael Kohn] purchase the motor while working on a different project and it went unused for quite some time. When he came across it again he decided he should learn the not-so-dark art of BLDC control.
The first hurdle was to figure out how to drive the three-wire motor when he had been expecting only two. The answer required him to come up with switching mechanism that allows three states for each wire: positive, negative, and not connected. His solution was to use MOSFETs. It’s a good idea, but unfortunately during the first iteration they were under-spec’d and he scared the crap out of himself when one of them blew up during testing (clip #1 below). After sourcing a more robust set of MOSFETs [Micheal] went back to testing which is when this little fire broke out. The 22 gauge wires connecting the Lithium battery to the driver just couldn’t cut it. See for yourself in the second clip.
It’s been awhile since we’ve said it: Please remember the Fail of the Week is not about ridiculing the hacker who was gracious enough to document his or her failure. It’s about learning from the mistake and discussing alternatives that can help others in the future. For instance, in this case some advice in determining MOSFET specs and wire gauge for any type of motor would be quite helpful. Have at it in the comments.

Fail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story – or sending in links to fail write ups you find in your Internet travels.

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