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Brushless Can't Decide Which Way To Turn

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Brushless Can't Decide Which Way To Turn

Old 02-12-2010, 08:09 PM
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cobrajocky
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Default Brushless Can't Decide Which Way To Turn

Gentlemen -

This is a new one on me, I've personally never seen this before though a couple friends say they have had it happen, but also don't know the reason or how to remedy it. I hope that there is a motor / ESC guru out there who does.

I have a new Suppo Model brushless A2212-10 that is reputedly the same as an AXI A2212/10. This looks like a very well made motor as the AXI is and Suppo Model supposedly makes motors for AXI among others. It is a perfect match for my World Models SkyRunner "very warm-liner"

I have tried two (2) completely different brands of ESC's with this motor and in both cases the motor cannot decide which direction it wants to start up rotating in. With a TowerPro Mag8 ESC it never would start rotating, it would just keep "balking" by jerkingly going continuously from one direction to the other - the ESC got pretty warm! (I tested that ESC on another ElectriFly motor and no problem!)

With the second ESC, an EMax Platnum (same as a Hobby Wing Premium) the motor at first balks for a couple seconds and then revs up fine. BUT in flight when I cut the motor to Soar (the SkyRunner is a Glider), it has a few time refused to start while in the air. I had to repeatedly 0 the throttle stick and try restarting the motor, which them started again. WHEW!!

I have a EMax programming card and have tried different "timing" settings, but can't see any difference.

Bad motor? Why? Thanks for your education on this matter.
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Old 02-12-2010, 10:43 PM
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huck1199
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Default RE: Brushless Can't Decide Which Way To Turn

The motor is made to run from 2-3 lipos or 7-10 nicads and a 30 amp esc. What is your setup?
Old 02-12-2010, 11:47 PM
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Default RE: Brushless Can't Decide Which Way To Turn


ORIGINAL: huck1199

The motor is made to run from 2-3 lipos or 7-10 nicads and a 30 amp esc. What is your setup?
A 1500mAh 3S 20C LiPO. Actually this motor is only rated for a 18A ESC according to the Suppro website and I'm only spinning a 10x6 folder. Never the less, the two I've tried are both 25A.

When the motor spins up right, my Amp meter reads only 15Amps at WOT.

I know I hear a lot of people say (most that even know what they are talking about) that some brushless motors "like or don't like" certain brands of ESC's, and I've run into that on occasion. But this is the first time I've ever seen anything crazy like an Epileptic brushless motor in convulsions!
Old 02-13-2010, 01:50 AM
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nmking09
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Default RE: Brushless Can't Decide Which Way To Turn

Sounds like a disconnected motor wire. Either that or a disconnect or short in the motor. Happens a lot on foamys when a motor wire breaks, or becomes un-soldered to the esc. Also a possibility that the speed of the ESC doesn't work with the motor, IE motor KV is too high, but I would put my money on the motor wire thing.
Old 02-13-2010, 02:13 AM
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Default RE: Brushless Can't Decide Which Way To Turn


ORIGINAL: nmking09

Sounds like a disconnected motor wire. Either that or a disconnect or short in the motor. Happens a lot on foamys when a motor wire breaks, or becomes un-soldered to the esc. Also a possibility that the speed of the ESC doesn't work with the motor, IE motor KV is too high, but I would put my money on the motor wire thing.

I know it's not a disconnected connection plug (banana plug ESC to Motor), because I checked them and it happen both on a test bench and in the plane with both ESC's.

This is a medium low KV motor, only 1400KV and I've used these ESC's with higher and lower KV motors with no problems.

But your thoughts on a broken wire in the motor, or an "ify" solder joint in one of the three wires to the motor sounds like a possible. I'll have to pull the motor apart and check all the continuity of the wires.
Old 02-13-2010, 10:31 AM
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Default RE: Brushless Can't Decide Which Way To Turn

Shorted windings will cause the problem too. All it takes is for the varnish on the wire to get nicked, which can happen very easily during assembly, when the motor is jarred, or from debris in the motor.
Old 02-13-2010, 12:38 PM
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Tall Paul
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Default RE: Brushless Can't Decide Which Way To Turn

I have an Eflite 400 outrunner that does the same thing.
Probably something broken inside the motor.
Sloth has held me from sending it it to the guy for a fix/replacement.
Old 02-13-2010, 06:05 PM
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Default RE: Brushless Can't Decide Which Way To Turn

Thanks gentlemen - firstplaceaviator and Tall Paul - I was beginning to think I had some kind of satanic possession going on here and no one had seen this before. Tall Paul, those Eflight 400's have a good reputation, I have one in a 1/12 scale P-40; but if you've got the same situation, then I'll rule out bringing in the Monseigneur for an exorcism. I assume you tried other ESC's with it to rule out a flakey ESC??

It is beginning to stack up against the motor being healthy, even though it's new. I'd send it back to Suppo in China, but it would likely cost as much to send it as I paid for it. For the $12 I paid, it'll go in the garbage, or maybe I'll save it to rewind it myself "someday" just for the experience.
Old 02-13-2010, 08:54 PM
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Tall Paul
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Default RE: Brushless Can't Decide Which Way To Turn

I have two Eflite 400s labeled "erratic" some time ago.
One of them acted strangely when installed yesterday after a long sit on the bench.
I just tried both of them, without props, with 2 and 3 cell batteries.
Both started with lots of vibration and hesitation, and settled down to steady running at full throttle.
Possibly the load of a prop brings out the "erratic" operation.
It's really difficult to hold onto one of those things with a prop installed!
I may try that, mounting the motors on something and adding the prop.
Old 02-13-2010, 09:11 PM
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Tall Paul
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Default RE: Brushless Can't Decide Which Way To Turn

Done.
Both motors turning the same 9x4.5 prop start running erratically, at partial throttle, sometimes stopping and appearing to reverse, then running properly.
Or not starting at all, then beginning to run.
Not something I would put on a plane.
Old 02-14-2010, 06:11 PM
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Default RE: Brushless Can't Decide Which Way To Turn

ORIGINAL: Tall Paul

Done.
Both motors turning the same 9x4.5 prop start running erratically, at partial throttle, sometimes stopping and appearing to reverse, then running properly.
Or not starting at all, then beginning to run.
Not something I would put on a plane.
Boy, TWO bad EFlites! Now you are shaking my confidence in that brand. When my military pension budget isn't strangling me, I try to by EFlite's!

Just out of curiousity, did you try a different ESC? And a different brand ESC during this recent test?

I keep hearing people say that some Brushless motors are finicky about which ESC will work with them and of course some motor brands want you to buy just there's. Buy I'm not sure I believe this "works with / doesn't work with" claim.

I'd like to hear from long time E flyers what their actual experiences are. And if there's any engineers out there, is there any technical basis in this old wives tale?

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