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E-skateboard motor burned out, what are my options? Can't get spares

Posted: Jun 26 2020 6:49am
by Gargravarr
Hey folks,
So a few years ago, I bought a SkateMaster UK-branded board and modified it to use li-po batteries instead of SLAs. It actually worked pretty well, but I got relatively little use out of it before, during a trip to work in 2017, it stopped working and smoke started escaping the motor. I haven't touched it much since. The manufacturer had gone under before I even bought the board, so spare parts don't exist.

I took the motor apart and the permanent magnets seem to have flaked quite a lot - there's lots of metal shavings in the motor casing. However, the rotor seems to be in good condition - the windings don't show any evidence of burning or melting, and there's still electrical continuity. As I'm guessing is a common design, the motor housing that mounts to the rear truck is the casing itself, with the magnets attached, so there's no real option to mount a replacement motor in the same housing.

Now with COVID giving me plenty of time at home, I've taken another look at it. I'm tempted to clean up the metal shavings, reassemble the motor and try it - in theory, I can't make it any worse, although there's nothing to stop this happening again. As I've spent rather a lot of money on the li-po kit, I'd like to salvage it rather than replacing the whole board.

If I can't salvage the motor myself, what are my options? The motor is 24V/350W, but some casual eBaying hasn't turned up much in that power range that would be mount-able on a skateboard; there's also a third wire to the motor which I assume is some sort of RPM sensor for the ESC, which these motors don't have. There's plenty of skateboard motor listings, but I'm struggling the read the ratings in KV. And of course, there's the mounting issue - it doesn't have to look perfect, but it does need to be reliable, seeing as how the motor on a skateboard is both power and brakes so the last thing I want is the motor coming loose!

I heard that motors can be refurbished by specialists when my car starter motor had issues (turned out to be unrelated to the actual motor), but I'm unsure if it's cost-effective to try this approach.

Any suggestions?

Re: E-skateboard motor burned out, what are my options? Can't get spares

Posted: Jun 26 2020 9:34am
by district9prawn
Do you know if the motor is a brushed or brushless type?

If the windings have cooked rewinding the motor is an option especially if you have plenty of spare time.

Re: E-skateboard motor burned out, what are my options? Can't get spares

Posted: Jun 26 2020 11:03am
by amberwolf
Pics of the stuff in question, especially of hte disassembled motor, and the motor mounts and drivetrain, would be helpful in helping us to answer your questions and find a replacement motor (as it sounds like the old one is toast).

Pics in the other thread don't show up; probably because photobucket screwed over their users a while back and put it all beyond a paywall.

I'd recommend attaching all images directly to your post using the attachments tab, since if they're uploaded to the forum they'll be visble to anyone that can see your post, and wont' disappear whenever the external hosting site goes down or changes their mind about who gets to access the content the users posted there. :/

Based on your post here
it is a brushed motor. If so, the bits of metal you describe are probably parts of the commutator, or bits of debris sucked into the motor off the road if it has any openings.

If they are parts of the magnets themselves, and the magnets were actually scraped by the armature, there must be serious bearing or armature shaft damage to allow taht much misalignment, or it got hot enough to destroy the adhesive holding the magnets to the casing.

If the windings are actually burned as well, you'd have to unwind it carefully, noting the number of turns on each armature slot and the winding pattern and which commutator bar each is connected to. Then use the same size wire and rewind it the same way (or it won't operate the same as it did before).

The brushes may be damaged as well, if there is commutator damage. Sometimes the commutator pieces come undone from the armature and rise up a little bit without coming off, and that can be repaired, but the brushes are often destroyed by this. If the commutator segments actually came off, they're probably trashed and unreplaceable.