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Old Apr 15, 2003, 11:46 PM
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Vulgar Vulture's Avatar
Fayetteville, PA
Joined Dec 2002
233 Posts
geared 280 motor stutters

I'm having a problem with a motor setup in one of my planes and I'm hoping someone can help me out. Here's the setup; geared 280 motor with the capacitors soldered on by myself, wattage 5amp controller with old style push button safety switch plugged into a HiTec feather receiver in channel 3. I'm using a HiTec charger to charge an 8 cell, 300mAh battery used in the setup. Hate to admit it but I haven't broken in the motor yet. Here's the problem; It will throttle up ok but after 1-2 seconds it will instantly reduce itself (the motor) to about 1/3 throttle then 1 sec. later go to about 2/3-3/4 throttle. Idle is ok, albeit a little noisy, coming from the gears I figure. This problem only occurs at full or near full throttle. Any help would be appreciated. Thanx.
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Old Apr 16, 2003, 05:11 AM
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Captain Carlton's Avatar
Fairfield, CA
Joined Apr 2002
1,513 Posts
Wow,

Thats wild. I have a M250 which I believe is a geared 280. Anyway, my problem was that when the unit was throlled off, or at 100%, it was fine, but I was getting a very "fine" but serious high frequency stuttering at all other power settings. It made a buzzing sound, and feeling if you were holding the 280 in your fingers.

Changing the ESC fixed the issue. The ESC works find with "can" 380 or 400 motors. I think this was a case of the cycling frequency being too slow for the Geared 280. But thats an educated guess. The ESC being used was a discontinued Hitec 15 AMP esc.

Your speeding up and slowing down issue maked me wonder. Does it perform this was consistently?

- Rick
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Old Apr 16, 2003, 05:58 AM
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N. Staffs, UK
Joined Jan 1997
5,654 Posts
Have you checked what current it's taking ? It could be the ESC shutting down because you're trying to overload it or the battery voltage dropping because it can't take the load. What prop and gear ratio are you using ? What type of battery NICd/NiMH etc. ? It's also worth checking that the gearbox isn't binding, that can shoot the current up.

Steve
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Old Apr 16, 2003, 11:30 AM
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Vulgar Vulture's Avatar
Fayetteville, PA
Joined Dec 2002
233 Posts
280 Geared Motor Stutters

Hey guys,
Capt. Carlton: Yes it's consistent. I change to another 5 amp esc I have and same problem, but again, only at full or near full throttle.
Steve: I don't know what current it's taking, I don't have an Ohmmeter. It's not binding, I checked that before install. It's a NiMH batt, 8 cell, 300 mAh. Sorry, I don't know the gear ratio and I haven't counted the teeth, probably should have . That's interesting what you say about "overloading it". Battery too big? "Battery voltage dropping because it can't take the load", "it"meaning battery or esc or motor? Oh yeah, I don't know the prop dimensions either, nothing is printed on it. Diameter is 9 1/4". Blades are those type that fit into a slot individually.

I swapped the setups to a brand new geared motor for my switchback and everything works great, no stuttering or surging. I'm convinced it's the motor. I've included a picture if that helps any. Thanks.
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Old Apr 16, 2003, 06:18 PM
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Los Angeles, California
Joined Apr 2002
923 Posts
Looks like it is the Kavan 9x7 hub and blades that HL sells. I think using a Wattage 5A ESC would be pushing it. But then, it also depends on the gearbox ratio you are running it with. Try to put one more capacitor on if you don't think you are pushing against max. amps. on the ESC.
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Old Apr 16, 2003, 07:46 PM
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Fairfield, CA
Joined Apr 2002
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Steven and AU007 are on thr right track: I'll explain (if for no other reason, so it is clear in my head).

Situation: Battery cannot delivery load at 100% throttle. Often a battery can delivery sufficent power at a lower throttle setting, but at some point, if the battery can't hack it (i.e. the amps being pul;led by the motor exceeds the delivery ability of the battery), the voltage will drop. The ESC will see this and cut power to the motor to protect power to the receiver. The voltage on the battery a milli-second later comes back up (no load), and the ESC re-engages the battery to the motor. The motor spins ups, voltage drops again, at which point the process repeats itself.

My M250 with an 8 x 6 APC slow flyer prop pulls 4.8 amps at max power with 8 cells. I drive my pack with 8 AAA 720 mah NIMH cells. These AAA cells are not good for much more than that. My guess is the 300 mah cells can probably only deliver 2 or 3 amps, so you would be short, giving you the problem you see. Try a bigger pack.

If you are overloading the ESC, then the motor will cut out, and then typically wait for you to reset it. I guess ESC overload situation are different for each ESC manufacturer. Some ESCs will reset themselves after they cool.

- Rick
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Old Apr 17, 2003, 01:35 PM
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Fayetteville, PA
Joined Dec 2002
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I see what you're saying about the esc shutting down. I have neither a bigger pack nor a bigger controller so I'm changing to a dual IPS-A motor. Thanks to all who replied. RC Groups Rules!
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