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Crazy motor

Old 04-06-2011, 02:23 PM
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mobaddawg
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Default Crazy motor

OK, today I went out to fly like normal.
The wind was at about 4 mph so takeoff was at full throttle hard.
So as soon as I get up in the air and I'm coming back around for a down wind pass to gain speed the motor locks up.
I had to glide my F-15 down into the field just to get it down safe.
Not a scratch.
My motor is 4100kv and my battery is a 3s 11.1v 2200mah 25c pack.
The esc is a 60a hobbywing esc.
What happend to my motor?
I don't think I over charged or over powered it because it is reccomended for a 3s battery.
I originally ran a 3s 1300mah 20c pack on it.
But the reccomendation for it originally was a 3s 1300mah 25c pack.
But I look at this as a chance to get that 3800kv or 3500kv motor and 4S battery i have been looking at!
Help on what happend to my motor?
Thanks,
Andrew
Old 04-06-2011, 03:03 PM
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Default RE: Crazy motor

Andrew,

Sounds like your motor had a defect from the factory.  I assume when you say "locked up" you mean the motor won't turn over at all, even by hand.  Going to a larger capacity battery shouldn't cause a motor to self destruct.  I say shouldn't because a few years ago, I wasa flying a HET F-20 with a HET 2W-20 motor.  I had been using early PolyQuest 8/16 C (advertised more like 6/8C real world) 4400 batteries and was pulling about 44 amps and 650 watts.  Those PQ's started wearing out, so I replaced them with Apache (made by Enerland) 20C 3700's.  I got an immendiate power increase to 48 amps and 720 watts.  On the second flight with the new batteries, my motor self-destructed and locked up to the point it was impossible to turn over at all.  The post mortem was the motor had a defective rotor and the power increase from the better performing battery pushed it to failure.  HET replaced the motor under warranty since I was operating it within specs.

You may have a similar issue.  The higher capacity battery will suffer less voltage depression, allowing a slightly higher amp draw.  The higher amp draw and the reduced voltage depression yields more watts (10 to 20 percent more, depending on set-up), and sometimes it's more than a marginal motor can handle.

Hope this helps.
Old 04-06-2011, 08:45 PM
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Default RE: Crazy motor

Andrew ... sometimes you get a lemon, I got a HC one that seized up after I powered it up for a few secs. It threw a magnet. It does happen. I also realised that the new 40C or 45C batts hold the voltage a lot better and the amp draw does go up BUT not to a point like you are adding another cell to the system.
Old 04-07-2011, 01:35 AM
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Default RE: Crazy motor

You dont say what the motor is, if its a 20mm inrunner then it could easily overheat and seize by going to a much higher power battery, it used to happen a lot 4 years ago when 2030 and 2040 inrunners were setup up by the factory with small battery packs to try and protect them from cooking. These days not so common, most have gone to cheap outrunners as while they are inneficient they hang together better in the RTF style models.
Old 04-07-2011, 03:32 AM
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Default RE: Crazy motor

I've gotta ask, are you sure it's the motor? I've had some experiences with other than brand name speed controls that just quit inflight.
Old 04-07-2011, 04:35 AM
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Default RE: Crazy motor

I'm pretty sure it is the motor because everything else worked fine. I plugged it back in and went up on the throttle and the motor just jittered. IT is  not black on the inside. I have not taken the motor out to look at it yet.All servo's worked fine.
Old 04-07-2011, 07:08 AM
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Default RE: Crazy motor

Jitters? Can be a burnt motor or ESC issue. Check both on their own. Once my ESC got some water and the motor jittered too.
Old 04-07-2011, 12:27 PM
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Default RE: Crazy motor

Wow I never thought a 60a ESC could burn up on only 3 cells
Old 04-07-2011, 12:29 PM
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Default RE: Crazy motor

Wait how could it burn up? There wasn't any smoke from either one.
Old 04-07-2011, 04:17 PM
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Default RE: Crazy motor

Doubt it would be a HW 60A burning up unless the throttle was left on with a shorted motor. Pull the motor and try turning it over unconnected, then hold 2 of its wires together and turn, then all 3, if the turning resistance does not change the motor is shorted. A brand new motor will turn freely on its own, and become progrssively harder as you short the windings to each other.
Old 04-07-2011, 05:40 PM
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Default RE: Crazy motor

That was a close one. I just tested the motor on a E-flite 30A ESC and it didnt even run at all. I triend my HW 60A ESC on a motor from my old Blitz-RC 50mm F-16 and it worked just perfect. I'm going to rder the HK of Freewing 3500kv outrunner for my F-15. Thanks for the help!

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