Repairing a commutator?

[deronmoped]

My Gaint LaFree bike thru a commutator segment from running the 24 volt motor at over 50 volts. Too much heat and too many RPM's was probably the reason the segment came loose. I'm thinking some epoxy and dental floss might work. Dental floss would be used to wrap the commutator and epoxy would be used glue the segment. I will test the floss to see how much heat it can tolerate. Any other ideas to secure the segment. Stainless steel wire would work good, but it conducts, so something as strong and thin would be ideal.

 

[Chalo]

Kevlar can take a lot of heat and is available as thread.

You'll need to find a high temperature adhesive, too.

 

[deronmoped]

I wonder how hot these commutators can get.

The only reason I bothering to fix this motor is, Gaint LaFree Sports are pretty hard to find and parts are non-exsistant.

 

[amberwolf]

They can get awfuly hot when overvolted, b because brush arcing is worse and higher currents make the heating worse.

Under normal conditions they don't get *too* hot, but they aren't going to be anywhere near as cool as a brushless motor would bbe under the same loading (*relative to it's specs).

Brush arcing will always make them at least a little hotter (and less efficient) than the brushelss stuff.


Some poeple have experimented with various liquid cooling methods, but simple forced-air cooling will help enough in most cases. (using a fan on a duct that sucks air thru the motor--better performance than trying to bblow air into it, for most of the typical fans people adapt to the purpose).

 

[deronmoped]

Yeah, I noticed that my Ebikes when run at stock voltage produce almost no heat. One bike, I run a 24 volt motor at 36 volts and it still stays cool to the touch. Only when I went to 60 volts did the 24 volt motors start to produce tons of heat and fail. It seemed kinda strange, when overvolting to 60 volts, even if I was very easy on the load, the motor would still get hot. I figured that had something to do with how the controller works.

 

[amberwolf]

Not the controller, but the commutator.