One motor of e-flite twin otter sometimes cannot start

[long-love-rc]

Hello:

I have a 1.2m Twin Otter from Horizonhobby. I noticed that sometimes the port side motor cannot start. It appears trying to start, but cannot spin up. While the starboard side motor always spin up. If I push the port side motor a bit and let it rotate several turn, throttling up, it will spin up. Once it spins up, it will keep running as long as my throttle is not zero. But if I cut the throttle, the rarely but surely, it may not spin up again.

I use 3S 2200 mAh batteries.

As info provided on Horizonhobby.com, it has two 20A ESCs. So each motor is driven by seperate ESC.

What could be the potential problem? I am a bit worry cause this may lead to crash, actually I believe it has lead to some mild crash when I cut throttle trying to land.

Thanks a lot.

[Alpha]

"But if I cut the throttle, the rarely but surely, it may not spin up again." Is the only way to get it spinning again to unplug the battery? Or is there anything you can do, once it stops spinning, to get it spinning again? What is your throttle's trim setting in your radio? Have you calibrated your radio's throttle range? Which receiver/stabilizer are you using?

With twins, it's often normal for one to spin up just a hair behind the other, but it's not normal for one to stop and never start up again unless the battery is reset. That implies an ESC issue.

[long-love-rc]

Alpha, thank you.

To get it spinning, I may have to push the propeller a bit, or cycle throttle up and down several times. Nonetheless to say, it is happen midair, it is not good. My throttle idle place is -100, highest is 100.Trim is -2. No, I have never calibrated it. The thing is, another motor on the same model is working fine. it comes with stock receiver the AR637.

It is fine for one starts up a bit later, but mine doesn't seems like that case.

[Gilatrout]

Alpha, thank you.

To get it spinning, I may have to push the propeller a bit, or cycle throttle up and down several times. Nonetheless to say, it is happen midair, it is not good. My throttle idle place is -100, highest is 100.Trim is -2. No, I have never calibrated it. The thing is, another motor on the same model is working fine. it comes with stock receiver the AR637.

It is fine for one starts up a bit later, but mine doesn't seems like that case.

call horizon. Almost certainly a bad esc.

If you've been flying on floats over water and you dunked the plane, that could also cause an esc to fail. A little corrosionX on the electronics can prevent water damage to your float planes.

[xviper]

Alpha, thank you.

To get it spinning, I may have to push the propeller a bit, or cycle throttle up and down several times. Nonetheless to say, it is happen midair, it is not good. My throttle idle place is -100, highest is 100.Trim is -2. No, I have never calibrated it. The thing is, another motor on the same model is working fine. it comes with stock receiver the AR637.

It is fine for one starts up a bit later, but mine doesn't seems like that case.

It doesn't matter what your throttle "idle" place is (not that an electric motor has an idle). One motor may understand where your zero throttle is while the other motor see zero throttle in an entirely different place. Until you do a throttle calibration, your motors are not necessarily in sync. Once you calibrate them, at least they both know where zero and max throttle is. Check the manual to see where they want you to put the throttle trim tab. Some Eflite planes want you to lower it to the bottom, while others tell you the leave it alone. Then if it still doesn't work correctly, you might suspect a bad ESC or something else.
If you don't know how to calibrate throttles, search YouTube and you'll find it there.

[long-love-rc]

It doesn't matter what your throttle "idle" place is (not that an electric motor has an idle). One motor may understand where your zero throttle is while the other motor see zero throttle in an entirely different place. Until you do a throttle calibration, your motors are not necessarily in sync. Once you calibrate them, at least they both know where zero and max throttle is. Check the manual to see where they want you to put the throttle trim tab. Some Eflite planes want you to lower it to the bottom, while others tell you the leave it alone. Then if it still doesn't work correctly, you might suspect a bad ESC or something else.
If you don't know how to calibrate throttles, search YouTube and you'll find it there.

Thank you Xavier! But the thing doesn't happen consistently. So if a motor has different idea on when throttle is enough to start spin, I guess it should always behave so. Is that true?

[xviper]

Thank you Xavier! But the thing doesn't happen consistently. So if a motor has different idea on when throttle is enough to start spin, I guess it should always behave so. Is that true?

Not necessarily. As you move the throttle stick, the signal imparted to the receiver and then to the ESCs change in minute amounts and the differences in these (in terms of millivolts or microvolts) can be enough for each ESC to activate a motor or not. The exact explanation is more complicated than what I just wrote down. Nevertheless, you're trying to find a reason for why something is happening or not happening. It's been nearly a week since you brought this issue up, so the main point is .................................. HAVE YOU DONE THE THROTTLE CALIBRATION? Until you do, you can speculate till the cows come home. If, after you've done the calibration and your problem is resolved, you can stop wondering why. If the problem persists, then you can move on to other possible reasons.

[long-love-rc]

Not necessarily. As you move the throttle stick, the signal imparted to the receiver and then to the ESCs change in minute amounts and the differences in these (in terms of millivolts or microvolts) can be enough for each ESC to activate a motor or not. The exact explanation is more complicated than what I just wrote down. Nevertheless, you're trying to find a reason for why something is happening or not happening. It's been nearly a week since you brought this issue up, so the main point is .................................. HAVE YOU DONE THE THROTTLE CALIBRATION? Until you do, you can speculate till the cows come home. If, after you've done the calibration and your problem is resolved, you can stop wondering why. If the problem persists, then you can move on to other possible reasons.

Thanks! Sure, will check to see how to do calibration, which is something new to me to learn!

[xviper]

Thanks! Sure, will check to see how to do calibration, which is something new to me to learn!

It’s very easy to do and should be done with every new electric plane. It only needs to be done once until you change an electronic component of the plane.