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How did I mess up my hub motor system?!!

Posted: May 14 2022 1:01am
by ions82
I have an old BMC V2T hub motor that I use to power a mobility trike that I put together. It's been working amazingly for the last several months. However, I recently realized that I had only put two bolts in the brake rotor :shock: So, I decided to put the rest of them in there. However, I forgot that this motor uses very short brake disc bolts. I put some standard-length bolts in there and damaged it. Some small pieces of metal broke away and got into the gears.

Anyway, I immediately realized my error and got to tearing it apart. I removed all the little metal chips and smoothed out the damaged gears. Fortunately, they would still be serviceable. Upon reassembly, the motor wouldn't work properly (sounded awful and ran slowly). It acted as though I had the hall sensor wires mixes up. I checked them all multiple times. All appeared fine. I took it back apart to see if something was damaged. Everything inside seemed good. Turned smoothly. Put it back together, and it did the same thing. However, this time, it started pulling so much current that the XT90 connector at the battery started burning. Yikes!

Anyway, I'm now here scratching my head. I have no idea what might cause this. Is there a trick to reassembling a geared hub? It still seems like hall sensors crossed up would be a likely culprit, but I checked them all multiple times. Thank you for reading my long-winded post. A new wheel and motor will set me back about $800, but I'd like to give this one another shot before I give up.

Re: How did I mess up my hub motor system?!!

Posted: May 14 2022 3:17am
by eee291
It could be that you've got some damaged windings or controller. In order to melt a XT90 you'd have to pull way over 120A, what controller are you using?
Check If the motor runs smooth in the opposite direction (rolling it backwards or by hand) with and without the controller plugged in.

Re: How did I mess up my hub motor system?!!

Posted: May 14 2022 12:25pm
by ions82
The motor and gears turned smoothly when I took it apart. I checked the movement at each step of reassembly, too. The XT90 didn't melt down. I saw a bit of smoke and yanked the connector. It may not have been seated all the way. I was testing it with the wheel elevated, so there was no resistance on the wheel. The windings and hall connections all looked good in tbe motor. No idea what I've done wrong. I guess I can take it all back apart again, but I think I just need to order a new system. I use this thing to run my dogs and to get groceries, so it's important to my daily living. And now I'm without it because of a stupid mistake! :(