Hub motor winding surgery (HS3548)

[Cowardlyduck]

So, after a long time a HS3548 that I accidentally damaged venting years ago, has found it's way back to me.

I hooked it up and it still runs fine, as Philistine had mentioned to me, which is great but I wanted to be sure it would do more than just freewheel if I build a wheel onto it.
So I've opened it up, cleaned it out and carefully picked at and pried back the damaged windings:

It's a bit hard to see from the photo's but there are 5 broken wires total. 3 are on the loop to the right hand side and 2 are on the loop to the left.

As the windings are tightly wound, I can't just solder them back together as is as they don't meet close enough together for this.

I'm thinking I will have to use some 24awg silicone wire cut to (very short) length to join them all back up. I'll try and put some heatshrink on the joins, but I don't like my chances of it not shrinking when soldering given the short run.
Then, once done, I will put a bunch of epoxy in there to make sure nothing shorts or moves about.

Any thoughts from others? Has this been done before?

Cheers

 

[docw009]

Nice work if you were able to identify which wires to reconnect. That seems like the hardest part of this job. Well, here's my comments, as an long time solderer.

Yeah, there would be no way to heat shrink this if you had enough slack in the wire for one joint, but since you are adding a piece in the middle, it should be feasible. If you start by attaching a long wire of wire first, then you can heat shrink the first join w/o much fuss. Then cut the wire to length, and slide on a second piece of heat shrink for the other join. Have someone grip that wire with a needle nose pliers as a heat sink. while you solder it. Then slide the second piece over the joint. If it gets cooked anyway, maybe your epoxy would hold up.

I wouldn't try to twist the wires together either. I would bend the ends into hooks like I was connecting two bungee cords, squeeze them flat, and put a drop of solder in the middle. Good luck. Make sure you get all the enamel off so it solders.

 

[Cowardlyduck]

Nice work if you were able to identify which wires to reconnect. That seems like the hardest part of this job. Well, here's my comments, as an long time solderer.

Yeah, there would be no way to heat shrink this if you had enough slack in the wire for one joint, but since you are adding a piece in the middle, it should be feasible. If you start by attaching a long wire of wire first, then you can heat shrink the first join w/o much fuss. Then cut the wire to length, and slide on a second piece of heat shrink for the other join. Have someone grip that wire with a needle nose pliers as a heat sink. while you solder it. Then slide the second piece over the joint. If it gets cooked anyway, maybe your epoxy would hold up.

I wouldn't try to twist the wires together either. I would bend the ends into hooks like I was connecting two bungee cords, squeeze them flat, and put a drop of solder in the middle. Good luck. Make sure you get all the enamel off so it solders.

Thanks for the feedback.
Yeah, your described approach with heat-shrinking seems like the only realistic way to make it work. I've also had success in the past by wrapping a wet baby wipe around the heat-shrink you don't want to shrink during soldering, so I might try this also.

I like your idea of making hooks also. I think I will try this. Thanks!

Cheers

 

[Cowardlyduck]

Well I had a crack at doing this today.
I missed a few wires previously and there were actually 6 broken strands. 3 from the left most group, and 3 from the right.

I hope my understanding of how hub motor windings work is correct as I ended up grouping the paralleled strands of each group together and doing 2 x wires instead of 3 for each.

I also couldn't do the hook idea as the wire was too short and stiff for that to work. I found that a bit of flux on the grouped strands really helped the solder wick onto them and soldering wasn't too difficult.

I couldn't get the second length of heat-shrink not to shrink when soldering as it was just too close to the join. So instead I cut some heat-shrink length way's then overlapped 2 of them top and bottom. Then when I heated it a bit more than usual, while holding it with tweezers, the 2 pieces melted into each other.

I also added epoxy after flattening it all down as best I could. It sticks out a few mm more than the hall sensor wires already do on this side. Hopefully it doesn't touch the inside of the side cover. Here's the end result:

I'll try and test it later today and report back how it goes.

Cheers

 

[Cowardlyduck]

Ok, looks like basic testing was successful.
As I don't yet have proper connectors on the wires, and I didn't want to go to the effort of adding them if the motor wasn't going to work, I just rigged it up very dodgely to work with the controller on one of my bikes.

I think there could be a variation in the strength of the repaired pole as I can feel/hear a slight pulsating action when the motor is rotating. It could also just be an imbalance in the side covers/magnet ring. Either way I'm not too worried about it as it shouldn't drastically effect normal operation of the motor.
[youtube]HIkiJU9pI_c[/youtube]
Oh and in case your wondering, just out of view, my foot is holding down a spanner which is holding the axle on the other side.

The ultimate proof of this repair job will be in lacing the motor to a wheel and running it on a bike. Right now though, I have zero need for another motor laced into a wheel, and I'm hesitant to buy a rim/spokes and lace it all up if there's a chance it might not last.
I currently have a HS4080 and a Leaf motor '1500W' both laced into stock Stealth Rim's/spokes. If either of those were to die, the spokes/rim would be a perfect drop-in replacement for this motor to be laced into. So for now, I think I will just keep it as a spare.

So if the question wasn't already answered previously...yes it is possible to perform 'surgery' on the damaged windings of a hub motor.

Cheers

 

[Philistine]

So did it end up working when you put it back in the hub? Awesome work bro! If you want a job soldering halls back into a x5303 give me a call....

 

[jonescg]

Phil! Where you been mate? Long time between drinks eh?

 

[Philistine]

Phil! Where you been mate? Long time between drinks eh?

Been spending a lot of time coming up with internet memes...I just wrote this ten minutes ago:




I know this is the worst place for that joke....

How are you bro? Are you still racing with the bike? Sorry for my ignorance but have been out of the EV loop for a while begging my wife not to divorce me.... is Voltron still going?

 

[markz]

My first thought for insulation was Liquid Tape, but I dont know about the heat of the motor.
High Heat Epoxy would work great as an insulator, but be absolutely sure the windings are perfectly repaired.

 

[Cowardlyduck]

So did it end up working when you put it back in the hub? Awesome work bro! If you want a job soldering halls back into a x5303 give me a call....

Hey mate, Yes! it worked as far as you can see in the video above, but I guess I won't know for sure until I lace it up into a wheel and mount it to a bike. A project for another time as I'm currently embarking on quite a few other E-Bike related projects.
Fixing up some halls should be a pretty easy job though, so maybe when I've sorted out a few other obligations I can do that for ya.

Cheers

 

[jonescg]

How are you bro? Are you still racing with the bike? Sorry for my ignorance but have been out of the EV loop for a while begging my wife not to divorce me.... is Voltron still going?

Fortunately nothing that intense :lol:. Stopped working at UWA in 2012, was underemployed for about 3 years, then got a job in Albany at the sandalwood factory this year. Raced Voltron Evo (with a fast guy on it, not me) in 2014 and 2015 and won both championships. Hoping to go for a threepeat this year

You still a 'learned friend'?