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Old Jan 11, 2013, 06:59 PM
Whatever goes up must go BOOM
joker24458's Avatar
United States, OH, Kent
Joined Mar 2012
2,196 Posts
Question
Motor stuttering?

I didnt really know where else to post this, but it happened on a foamy so I put it here.

I was running a 7x6 prop on an HK 20g motor with a Red Brick 10amp ESC. This setup has worked well for me before, but when I started it up today it didnt work properly. Without the prop the motor ran fine, but when I put the prop on and increased throttle, it would "stutter" for about a second and the ESC would beep and the motor would stop. I did this on a fully charged 350mah 2s batt. I dont think that the motor was pulling too many amps because I have used this setup very succesfully before. Can anyone explain this unexplained problem???

-joker
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Old Jan 11, 2013, 07:25 PM
Registered User
Joined Mar 2012
82 Posts
prop pushing the limits of the ESC? I've had some of the 20g motors get old and start doing this. Perhaps they begin to start drawing mor eamps. Maybe prop got slightly bent, or the shaft. Not enough to see, but enough to push the ESc over the limit? I'm guessing here.
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Old Jan 11, 2013, 07:33 PM
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maurice076's Avatar
United States, MI, Warren
Joined Aug 2011
642 Posts
Hi joker,I have had this problem too a few times.All but one motor I fixed by finding a bad solder joint.That other one still baffles me,maybe a bad winding?
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Old Jan 11, 2013, 07:50 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Sounds like you have a bad connection or intermittent short in the windings. That is easy to check with a cheap multi meter.

Set the switch to Rx1 and short the probes to each other. You should see nice steady reading of a fraction of an Ohm. Like 0.6 or so. If you have an auto-calibrating meter you may see 0.0. And when you take them apart you'll see OL (open line) or something like that to indicate that is no conductivity at all.

Put one probe on one of the three motor lead connectors and then touch it to one of the other two. You should see a steady reading that might be the same or just a little higher than you saw with the shorted probes. That is a good winding.

Touch the other connector and look for the same reading. Try all three combinations 1-2, 1-3, 2-3 and see if all are good. If you see any flickering values or OL readings your winding are damaged somewhere between the test points. The cure for this is to rewind the motor or replace it.

A second test is to find a spot on the stator (up near bearing tube hole or on the ends of the hammerheads is usually a good area) where you can touch both of the probes to the bare metal of the stator and get a steady reading. Again, it will be about the same reading as the shorted probes had.

When you have the steady reading with both probes on the stator, remove one probe and touch each of the three ESC connectors. All three of those should read OL or no conductivity between the wire and the stator. If there is any reading at all you have a winding that is shorted to the stator. The same cure applies, rewind or replace it.

If the motor will run at low RPM, get it running the jiggle each of the connectors and push and pull the motor leads a little where they enter the motor. If that makes the motor stutter or stop you have a bad solder joint or a intermittent connection inside the insulation somewhere.

Jack
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Old Jan 11, 2013, 08:32 PM
Whatever goes up must go BOOM
joker24458's Avatar
United States, OH, Kent
Joined Mar 2012
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Ok, I will check the soldering joints since it's easier to fix for me (I know how to solder but dont have a multimeter..........) and if that doesnt work I will tell my dad to bring his multimeter home from work on Monday. If neither works, it's always a cheap replacement, but my HK carts always turn into giant lists that sum up to $150 but I have like 30 things in there..........plus I hate the shipping.

-joker
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Old Jan 12, 2013, 09:08 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Because of the way the wires are brought out on the smaller motors, and the drive to keep things as light as possible, the motor leads on those small motors can be fragile and easily damaged.

Many would rewind the motor to fix a broken winding. And if they did that they would also probably end up with a better running and more powerful motor. It you looked for your motor over on the Electric Motor Design and Construction forum you might be able to find more info on that.

Rewinding motors is just another facet of the addicted to RC disease. It does not always make sense economically and many will not have the time, interest, or even tools and skills to do it. But it can be enjoyable.

Jack
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Old Jan 12, 2013, 01:00 PM
Whatever goes up must go BOOM
joker24458's Avatar
United States, OH, Kent
Joined Mar 2012
2,196 Posts
Well......I resoldered the motor and ESC.........no luck. Still the same stuff happening. I may just swap out the motor for a 24g one since I dont have any more 20grammers.........I will look into rewinding the motor though.

-joker
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Old Jan 12, 2013, 04:20 PM
Damn this gets addictive.
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United Kingdom
Joined Oct 2011
530 Posts
I rewound a 20g motor that I burnt out because it was not the KV I ordered (that's my story and I'm sticking to it). I went on the forum listed above, got some advice, bought some wire and had a go. A reel of wire cost me about the same as a replacement motor but will re-wind a couple of hundred motors. It takes an hour or so to do once you've read up on it and got the process clear in your head. Not hard and extremely rewarding when you get it working. Plus you get to choose your kv and get a much more efficient motor at the end of it.

I'm not sure it's worth it financially and wonder how they knock these motors out so cheep but I'd do it for the experience.

tCF
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