Re-winding a hubmotor

[Thud]

its been argued ad-nauseum in the rc groups.....bigger brains than mine come to the consensus Litz wire is of no benifit at rc controller frequency ranges.

I think it is used in CISRO motors to fight eddy curent heating.(in the windings themselves)

 

[bearing]

Litz-wire have a bad fill factor. For the same length of completed wire, the litz-wire strands will be longer (since it's braided), and also have less area (since a lot of the area is insulation and air). So, the resistance will be a lot high higher. It depends on the type of litz, but the resistance can be 70% higher in the same space.

 

[Farfle]

more pictures, its a monster!

Going to do more frame work today.

 

[Arlo1]

Awesome!!!!

 

[Farfle]

Ok, took more accurate dimensions, and then lowered it by 2x the thickness of the fish paper, and came out with a 2x parallel strands of 15awg four turns.

 

[Farfle]

Ok, the statorcalc is giving me some interesting but concerning numbers for all the winds I want, the stock resistance is 60.8 mohm, a 5302 is around 61 mohm. Why are these winds so low? and wtf is the stock wind so low? for example:

Stock: 6 turn wye: 61 mohm Kv of 7.44

2-turn in wye: 20 mohm, Kv of 11.16


3-turn in delta 15 mohm, Kv of 12.648

4 turn in delta 20 mohm, Kv of 9.486



For comparison, the Kv of a 5304 is 8.84,the KV of a 5303 is 12.12 the Kv of a 5302 is a whopping 18rpm/v

 

[parabellum]

interesting but concerning numbers

Yes, they are more concerning then everything else. There must be linear correlation between kv and turns.

 

[Farfle]

Well, the stock wind is 60 mohm, is that correct? Even a 5303 is a fairly low resistance motor at 105 mohm. what is going on here?

 

[Farfle]

I like these numbers, but its still at 30 odd mohm.

 

[parabellum]

Well, the stock wind is 60 mohm, is that correct? Even a 5303 is a fairly low resistance motor at 105 mohm. what is going on here?

Do you have 60mOhm from the calculator or did you measure it before cutting?

 

[Farfle]

Do you have 60mOhm from the calculator or did you measure it before cutting?

Thats from the calculator.

 

[parabellum]

Do you have a link to download this "wire & stator calculator"?

 

[Farfle]

Googlesearch drivecalc

 

[parabellum]

I got 75-87mOhm depending if your wire is .51 or .55. It is just 1 phase wire, connecting in delta will lower phase to phase R to about 50-57 mOhm. Big difference to X5 motors is that MP has a huge amount of unused cooper on stator tooth ends. Thick stator, low tooth count permits more useful cooper fill. Inductance of MP will be significantly higher then X5 because of much more turns in total.
I do not have X5, I got R5303 (actually it turned out 3 turn HS in star wound) but burned it before had a chance to measure resistance.

 

[Farfle]

aah, well, ill order in some 16 awg, and do a four turn delta wind. and start with a low-voltage low amperage controller before I sacrifice my 24-fet.

 

[Farfle]

ok, the 16 awg is on the way, looks like a 3 paralled strand four turn gets me a %46 increase in copper fill, and a %32 faster Kv. works for me, Ebikecalc is giving me a 62mph top speed, 90.8% efficiency and a maximum wattage of around 16kw, assuming ill be getting 10v of sag out of a 15 ah pack of nano-tech batteries, and assuming 200f windings.

 

[Farfle]

Fish paper is here, and wire will be here tomorrow . What would be the best method to round off the sharp corners of the lam stack without connecting them?

 

[Thud]

the mighty Dremel....& a bullet shaped stone.

 

[Farfle]

Mmk, stator is prepped for wire, problem is, theres still no wire . So I check the tracking, and it hasnt been shipped yet . Does anybody else get a little peeved when you pay for 1 day shipping, and the mfg still hasnt shipped it 4 days later. /rant end. Anywho, have been experimenting with the calendered nomex paper, its pretty tough stuff. I ended up getting two sheets of the thicker .020 stuff.

 

[Farfle]

wire got in today . so, What do I do? i am winding three strands in paralell, so do I take the statorcalc winding length plus a little margin and cut if off then wind three at once? Or do I wind one paralell strand, then the next, then the next?

 

[parabellum]

wire got in today . so, What do I do? i am winding three strands in paralell, so do I take the statorcalc winding length plus a little margin and cut if off then wind three at once? Or do I wind one paralell strand, then the next, then the next?

Winding all together is better idea. They will have about same length and if they short somewhere with each other it will not be a big deal. you need 3 rolls to spin them on to have it less messy.

 

[Thud]

Definatly strip off enough for a phase & all three strands.
I use a bucket to house each strand of the wind.I use the plastic buckets from menards with the lids. A hole for the wire to feed out will keep them from tangling as you wind.

Having all 3 buckets on a lazy susan will make it easyer to keep the inevetiable twisting from becoming a problem as you wind the teeth. ever seen an auto kniting machine? think of it as the anti kniting set up. it can be as simple as a floor creeper for working under a car. just some thing to unwind the twists you'll develop as you wind.

Maypole dancing with 16g copper is not much fun....(better than 14g though) :wink:
the paper is definatly uber tough....best paper cuts on the planet!
looking foward to seeing your results.
enjoy!
T

 

[Farfle]

Got the wire in, 200c 16 awg heavy. I'll start winding tonight, wish me luck!

 

[Harold in CR]

Hope you post some photos. I may have to do the same thing.

 

[fechter]

That's going to be a workout getting those windings tight. I thought 18ga was bad, and that was just a single.

I'm not sure if winding one strand at a time or doing all 3 at once is going to be better. The main thing is to make damn sure you have exactly the same number of turns on each coil. One turn off and it's scrap. With that heavy of wire, I don't think I would be physically strong enough to pull 3 strands at once. Maybe you can pull all 3 but tighten them one at a time as you go. Wear gloves!

It's also fairly important that you keep the coils tight as you go. You don't want them vibrating against each other when the motor runs. Some kind of varnish or epoxy over the whole thing when you're done helps with this too.

I had a tendency to lose count on the turns as I was going and in some cases had to unwind a coil to get the count back. Too many fried brain cells I guess. Think about a good way to keep track as you go.

Stripping the insulation off at the ends is sort of a challenge too. I used a tiny flat file followed by sand paper. Some guys use a flame to burn it off but that sort of messes up the copper and you still need to sand it or something.