Motor wires broken -> repair?

whitepony

whitepony

10 kW
Joined
Feb 19, 2015
Messages
663
today we had great weather, so I went out with my tesseract -> up a hill, poof, engine brakes hard, couldnt drive anymore. at home I disassembled the motor (rspecc 6355) and found that a few copper strains of the 3 main wires were cooked.

do you know if I can just solder -> shrinktube these parts and fiddle everything back in? :?

the motor is just 100-200kms old, but sending it in to enertion will be pointless due to germany<->australia.

at least 2 strains of the main wires were burnt
rspeccfail1.jpg


and you can see the evaporated metal/spark traces that were left on the metal
rspeccfail2.jpg
 
ah well, I just soldered a little and used thick double shrink tube to protect the wires from each other. looks better and more solid than stock tbh. end of story: motor works again, back to skating!! :D

rspeccrepair1.jpg


rspeccrepair2.jpg
 
I have an old turnigy motor in a box because of that issue. How was soldering solid wire together? difficult? I may try your fix and ressurect this motor just for fun.
 
psychotiller said:
How was soldering solid wire together? difficult?
Click to expand...

hmm, lets say I dont have much confidence in that soldering connection, but its just 2 single solid wires in total anyway. :p most important was shrink tubing so they wont short I think.
 
I fixed an NTM motor like this. Since then I have had several motors do the same thing and was unable to fix them. I guess it depends on how much of the wires are fried.
 
it can get worse. A shorted motor burned both my vescs. Still waiting to get them fixed. Worth testing the resistance of all the phases to make sure there's no shorts before running it if you're not sure. A short can cook hidden parts.

It's really multistrand wire not solid.
 
What would cause this ?,...is it from the constant movement of wires between motor and enclosure ?
 
randyc1 said:
What would cause this ?,...is it from the constant movement of wires between motor and enclosure ?
Click to expand...

I think it's more a case of inconsistent shit wiring...
if you leave enough slack in your wires between enclosure/motor it shouldn't matter.
 
psychotiller said:
I think it's more a case of inconsistent shit wiring...
if you leave enough slack in your wires between enclosure/motor it shouldn't matter.
Click to expand...

I took some time to investigate the failure reason so it wouldnt happen again and I kind agree here:

my motor exit wires were constantly moving a little while carving and maybe the arc was chosen a little tight, so the motor exit wires were under stress:
tesseract_firstfit.jpg


the 2nd issue with the rspecc is: the last 4-5cm of each copper phase is wound loosely around the stator before exiting the motor, so if you start wiggling the 3 cables on the motor exit, the bare copper strain phases with their protective layer will rub against each other, eventually removing the protective layer and shorting out. Im 100% sure that this is what happened to my motor.

what I learnt from this:
* exit cables should probably leave the motor in a generous radius and
* ideally the last centimeters of copper windings that can work on each other while they are loosely wound around the stator should really be protected by some shrink tube

Ill rework my tesseract motor cables and Ill rework my remaining rspeccs with that additional protection! :)
 
Hi Whitepony

Good analysis and repair report, always nice to have this sort of info should someone have similar issues.
Hope your repair last the test of time. looks like you did a great job there.
 
The issue with my NTM motor is that the stator started moving and it sucked the wires in the motor while I was riding up a small hill. Sparks, then nothing.
 
Whitepony, you could have faced where the wires exit your motor toward the enclosure.
That way they would have more of a straight shot instead of having a bend.
 
I think this is a common way a motor dies on a board. I'm gunna pot the motors and use grommets. Thermally conductive resin and the motors should have a higher wattage ability.
 
psychotiller said:
Whitepony, you could have faced where the wires exit your motor toward the enclosure.
That way they would have more of a straight shot instead of having a bend.
Click to expand...

nope, tried that first and when I leaned motorside they would get totally squeezed between motor and board. turning them further would mean they are exposed roadside. there wasnt really any good way to turn the motor and Im confident I already found the best compromise. maybe Ill try a larger loop, maybe even around the truck or so. :?
 
Hummina Shadeeba said:
I think this is a common way a motor dies on a board. I'm gunna pot the motors and use grommets. Thermally conductive resin and the motors should have a higher wattage ability.
Click to expand...

I thought about using epoxy to fixate the last stator loops so they wouldnt be able to work on each other. do you have any details about that procedure (cause it sounds really nice!)? :)
 
There are so many thermal resins that I think would work. for a regular motor I've wanted to pot the stator in the most conductive stuff I could get and even add tiny fins. Make a silicone mold using the motor covered with a wax or oil. Always wanting to use coconut oil in the cold and then maybe smell coconuts while I ride.

Im going to use omega brand resin (in my mind now) because the set time is quick and no heat cure necessary. Simpler. Maybe not the best. ive got some others coming as well

You could probably get away with a 10$ Syringe of Arctic silver epoxy to pot them. I'll have 18 motors beyond what I'm sending to people and will pot them all in some different stuff and tell you how it goes.
I bet even some paste (not epoxy) between a motor mount plate and the motor would help a lot. But who knows how much temp their motors can take anyway.
 
I was thinking,..If those wires in the pic were attached (tyrwaped) to axle , there would be no more movement between there and motor since they more together.

As long as you have enough play beween tywraped wires and enclosure, all the movement will occur there. ?
 
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