E-Flight Power Sources Ask questions or read about power sources as they specifically relate to e-flight including Lithium-ion, Li-Poly, Nimh and Nicad battery packs.

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Old 02-15-2013, 04:03 PM
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turnnburn
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I bought a ready to fly but never flown Eflite Super Cub. The airplane is equipped as per the manual with an E flite .25 brushless outrunner, a 60 amp pro speed control and an eflite 4s 3200mah 30c battery pack. I have minimal experiance with electric power. On my first 4 or 5 flights the motor would shut-off after approx 2 minutes flight time. I would reduce throttle stick to idle/off (trim low stick low) and then readvance the trottle and regain motor control for enough time to land. I finally decided the esc was overheating as it was buried in the fuse with oittle or no airflow over the cooling fins. I concluded that this was the likely problem when I felt how hot the speed control was after a short flight of less than two minutes time. For the next flight I moved the speed control into the engine cowl directly behind the left cooling hole in the cowl. On this flight I got just shy of 4 minutes flight time with no shutting down of the motor when suddenly the motor shut down and would not restart by going to low throttle and then back to normal power setting (about half stick). The prop was not free wheeling as I landed a dead stick but rather turning slowly making very few full revolutions of the prop. When I picked up the airplane I checked the speed cntrol and it was warm but hot like it had been on the previous flight. The cooling airflow had clearly helped. but, there was a distinct burning smell and the motor was quite warm. I came home and let everything cool off, recharged the battery to full (required 2663 mah to charged the battery to full. I plugged every thing back in even thou the motor is clearly more difficult to turn over than it had been or is supposed to be. I went ahead and trned the tX on, plugged in the battery but there was none of the usual beeps from the speed control. The servos are working but the motor is not.

Im pretty sure I need a new motor, like 99.9% sure. Do I need a new speed control too. Why isnt mine beeping and going thru the normal start up sequence ?

Any and all helpl is GREATLY appreciated ! ! !

Im told the OS electric motors are some of the very best so Im thinking or replacing with OS. Comments on OS electric motrs ??
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Old 02-15-2013, 04:24 PM
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Default RE: HELP

I'm also about 99% sure you need a new motor. The esc is sure questionable too , but even though the esc is what controls the beeping it is the motor that is doing the beeping. Perhaps the bad motor will no longer beep even with a good esc? I take it that it doesn't even spin up propless either.

I will tell you what I think happened , but I sure don't know why unless it was over propped or over volted (like using 4s when 3s was called for)

I think that your first few flights overheated the esc because of the motor/prop pulling too much current. The esc saved the motor by doing what it's supposed to do and cutting out in 2 minutes. The last flight allowed the motor to overheat for a longer period and didn't get saved by the esc.

A 4 minute flight tells me that your set-up is pulling 37-28 amps average and possibly peaking over 60 amps. I'm not sure about the plane , but that's a "hotrod" flight , not a lazy flight. The cub should probably fly over twice that long. Was the plane very fast for a cub? It should've been.

Here's one thing you can do is to disconnect the motor wires from the esc and make sure they are'nt touching each other. Spin the motor by hand and if it's still hard to spin then it's tied up. I'm not sure how to diag the esc other than just using a different motor or esc to eliminate one component.
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Old 02-15-2013, 04:30 PM
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It is fairly zippy but not crazy fast. Overly fast for a Cub for sure. This is the exact setup right down to the prop that the instruction manual calls for. It should work.

The motor is not imposible to spin but its not as free as it was or should be, something is clearly partially binding or dragging.
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Old 02-18-2013, 01:51 PM
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As a general rule, if the motor was too hot to touch, then either the motor is defective/damaged, or the motor is of the wrong kV, or the prop is too large.

When you get your new motor, check the power system on a wattmeter to be sure you are not drawing more current than specified for the motor and ESC. Excessive current could damage the motor, the ESC, or both. If you are using the recommended Power 25 870 kV motor, its maximum continuous current rating is 32A with brief bursts up to 44A. As guver suggests, you may have been drawing quite a bit more than that, for whatever reason. A wattmeter is a must!

- Jeff
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Old 02-18-2013, 02:36 PM
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http://www.horizonhobby.com/content/...der-contact-us

I would recommend product support phone. This is the best place to get accurate advice about your airplane.
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Old 02-19-2013, 08:47 AM
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I just now discovered whats causing my problems. This is supposed to be an eflite 25 870kv motor. I bought the airplane ready to fly from a guy and it has an E-flite 25 1250 kv motor.

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Old 02-19-2013, 05:00 PM
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That'll do it in a hurry. Can you use 3s instead?
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Old 03-14-2013, 06:14 PM
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The 1250Kv motor would be grossly overloaded with a 4c Lipo and a 13x6.5 prop
A 12"x6 or smaller prop would be about the maximum.
E Flight motors are usually under rated, but not that much!

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