Gaui 1100kv 1500W Motor details needed

[Kailee]

Hi all,

I have been using this motor in my normal planes for a while now and have been very happy with it... Unfortunately I had a little mishap where my prop met a bag of compost violently and shredded it - see pic. Needless to say my motor did not survive the exercise (see other pics) and I now have decided to take it apart and rewind it as a learning exercise.
However; I don't know how many turns it was wound with (the copper was a great big mess after opening up the bell), nor do I know for sure how it was all connected electrically (i.e. delta or star config), nor do I know the combined strands' gauge.

Does anybody know any of these? It would be really good to get this thing in the air again because it did work really well in my hotliner!

many thanks in advance,


Kailee.

[nexgen]

Man that's a tough one. you may be able to email gaui and get the info. On another note, if tourer rewinding it anyway, you could probably do it however you want depending on what you want out of it (wind, pattern, etc....). RCG has a section with tons of info about rewinding motors.

[JimLerch]

OK, I can help here! I just re-wound that very same motor! :-) Btw, the factory winding on my motor was done wrong, the start and end of one phase was connected backwards with respect to the other two phases. This produces a motor that still works but has insanely high idle currents and gets stupid hot.

Start with background data on winding motors here:
http://www.rcgroups.com/forums/showthread.php?t=240993s

http://www.bavaria-direct.co.za/models/motor_info.htm

Your motor (our) is wound as a 12 tooth Delta ABCABCABCABC All this means is all the coils are wound in the same direction and the end of one phase connects to the beginning of the next. This is an image for a 9 pole stator, ours is the same just add one more tooth to each phase winding.



A neat trick with this winding scheme is you can wind the entire motor with one long piece of wire. (about 12 feet or so). Start by winding one stator with between 4 and 6 turns (loops) of wire, then skip two teeth, wind the next tooth, repeat, repeat. You now have 4 coils wound evenly spaced around the stator. Draw out a 6 in 'loop' of wire, this will be one of the phase connections to the ESC.. Now, after your 6 inch loop, start winding again making sure to wind next to the FIRST coil you formed. Wind your four coils for your second phase, make a loop for the ESC connection, wind the final four coils for your last phase. Now, cut the wire and connect it to the beginning of the first coil.

The only gotchas are

• Each coil around a stator tooth must be wound the same direction on all teeth
• Each coil around a stator tooth must have the same number of windings
• The 4 coils that make a phase needs to be in the same order for each phase

Also, I see some of the green insulation has popped off your stator, you need to fill that in with some epoxy (or something) to prevent the windings from rubing against bare steel. I happen to have a small powder coating setup, so I just powder coated my stator.

Finally, what you need to know with regards to number of coils and Kv.

• 4 turns per tooth = 1500kv
• 5 turns per tooth = 1200kv
• 6 turns per tooth = 1000kv
• 7 turns per tooth = 860kv

I used 20 gauge wire with GREAT results. if you wind 4 turns per coil, you can wind with two parallel strands of 20 gauge wire, else just a single strand will be fine.

Here's some pictures of my latest motor. (click to enlarge)

[nexgen]

Originally Posted by JimLerch

OK, I can help here! I just re-wound that very same motor! :-) Btw, the factory winding on my motor was done wrong, the start and end of one phase was connected backwards with respect to the other two phases. This produces a motor that still works but has insanely high idle currents and gets stupid hot.

EXCELLENT writeup Jim. ^^^maybe this^^^ is why folks all say the Stock 850, and 1100 motors are amp hogs and get very hot. Maybe Gaui just had the designe wrong on these two....

[Mikej]

Originally Posted by nexgen

EXCELLENT writeup Jim. ^^^maybe this^^^ is why folks all say the Stock 850, and 1100 motors are amp hogs and get very hot. Maybe Gaui just had the designe wrong on these two....

I was thinking exactly the same - it would be interesting to know if they are all like that - btw the 850kV runs hot but isn't an amp-hog as such

[JimLerch]

From the factory I measured 800kv (for what should have been an 1100kv motor) and 8.6 amps of Idle Current at 24v (6s)!

Same motor after rewind with 6 turns per stator tooth ended up as 1058Kv and 2.4 amps of idle current.

I'm curious to know if others are wound the same defective way..

[Mikej]

Originally Posted by JimLerch

I'm curious to know if others are wound the same defective way..

Is it easy to tell without taking to pieces ?

[JimLerch]

Originally Posted by Mikej

Is it easy to tell without taking to pieces ?

Yea, if you can measure motor RPM, voltage and current at 100% throttle no load. The Kv should be as advertised and the idle amp draw should be under 3.5 amps..

[JimLerch]

BTW, I forgot the neatest trick I learned yesterday. To remove the insulation on the magnet wire for soldering purposes, all you have to do is find an aspirin. (or a pill with aspirin in it).

Place the aspirin on the table, put the end of the magnet wire on top of the aspirin, then with a hot iron and some solder, use the aspirin as a form of 'flux' The aspirin will melt and as it does so will the enamel insulation, making painless work out of tinning the ends of the wires!

These were done without any mechanical intervention on my part other than cutting them to length.

[nexgen]

now THAT's a pretty sweet trick, I have always hated messing with the motor wires, I'll definitely have to try this trick.

[Mikej]

Agreed - very cool - it's always been a real pain before - I usually resort to sand-paper

[adam crosby]

My Kv gets really hot, maybe I should rewind it.

[Alouette III]

Originally Posted by JimLerch

BTW, I forgot the neatest trick I learned yesterday. To remove the insulation on the magnet wire for soldering purposes, all you have to do is find an aspirin. (or a pill with aspirin in it).

Place the aspirin on the table, put the end of the magnet wire on top of the aspirin, then with a hot iron and some solder, use the aspirin as a form of 'flux' The aspirin will melt and as it does so will the enamel insulation, making painless work out of tinning the ends of the wires!

These were done without any mechanical intervention on my part other than cutting them to length.

JimLerch that has to be one of the neatest tips ever! Got to get some asprin! That's going to save me half my life if it works! So you machined off the bell case to save removing the stator - good decision.

Kaileee - how did you remove the Stator??? Heatgun and some kind of custom puller? What kind - cannot see any damage?

[JimLerch]

Originally Posted by Alouette III

JimLerch that has to be one of the neatest tips ever! Got to get some asprin! That's going to save me half my life if it works! So you machined off the bell case to save removing the stator - good decision.

After doing a little more today, the trick is to allow the end of the wire to float in puddle of molten aspirin with the iron providing the heat from the top with a little rubbing action.(stinks to high hell!) When you lift the wire out of the puddle, the insulation will fall down like it melted. Very COOL!

BTW, Its neat to be able to rewind at will to change KV, my last wind at 880kv was a little slow but had great endurance, so Re-wound for 1100 to see how that flies. Total cost to rewind was under $2.00 and about 2 hours of work.

[Kailee]

Well this suddenly turned into a useful thread! Though I must admit already having red about the aspirin trick elsewhere - it's the ascorbic acid that melts away the lacquer on the wire when heated enough.

I have actually rewound my motor today, unfortunately *before* this thread started going, as I didn't incorporate the loop trick. I wound a straight ABCABC etc pattern according to powercroco.de, and it worked fine. Used 4 turns 1.12mm wire (that's a 17guage I think) and man was it hard work - this was my first ever wind of a motor so I learned *a lot*. But - I got it done! It runs smooth, I connected it star for a start, and gave me 16250rpm at 20.2V and 2.2A, so not bad, it translates to ca. 800kv. I will though connect it delta tomorrow as I would prefer the higher kv that will give me.

I did re-insulate the stator with some 0.5mm grp cyano-ed to the endplates after sanding the green stuff off, this has the advantage of softening the corners also. Just to make sure (call me paranoid) I also laid some kapton tape into the slot just in case some of the green insulation there was also coming off.

I'm actually using this motor in a hotliner and so far with the 1100kv and 6s it gave me about a 100Amps using a Freudenthaler 18x19 prop with a 1:3.7 gearbox, so going to 1400kv would enable me to use 5s instead, saving me some weight...

Will post pics and a unilog log of the no-load runs tomorrow, gotta go to bed!

Thanks for all your posts!!


Kailee.

@Alouette III: I removed the stator just by heating it with a heat gun, then twisting with some leather gloves... Came off surprisingly easily, when I finish rebuilding this thing I will tap a thread between stator and stator holder so it's stronger but can easily be taken apart...

[Alouette III]

Kailee - sweet - leather gloves! Will give it a go. I just put mine thru the electronic kva tester before I re-wire it - It has 8 magnets - so 4 pairs punched into the tester - Meter showed 1376kva ! (So that's different from the claimed Gaui Factory Hurricane 550 motor 1100kva )?? Tester is pretty accurate.

[Kailee]

The 1376kv you measured is also much nearer what mine was doing before I used it to distribute compost throughout my car. The wrongly-connected second phase might increase kv btw, so maybe it *is* true that all of the 1100kv motors are wired wrong... Hmmmm. I have already sent gaui an email asking for their wiring details but heard nowt back it so far. Anyway, gotta pull those pictures of my rewind off my camera and post them - back later.

About removing the stator again; the mounting post and the bell have neat groves in them. Line them up and you can stick a 1.06mm wire in to counteract the torque, it fits nice and stiff. I was considering doing this but I'm going one step further and tapping an M2 thread in there so the whole assembles without glue/loctite. Now where's that pesky tap?!

Kailee.

[Kailee]

Hey guys,

just finished my write-up of the rewind.

head on over to https://www.helifreak.com/showthread.php?t=220329 for an illustrated run-through.

Cheerio,


Kai.

[farazuaf]

Excellent Info!

[iceman09]

great job thanks for info love helifreak happy heli flying guys