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Author Topic: Motor Stops then restarts.  (Read 263 times)

Online Ken Culbertson

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Motor Stops then restarts.
« on: August 04, 2025, 06:21:50 PM »
What can cause an electric motor to stop then start again (no it is not a Fox).  Last session I took off and after my level laps I pulled up into the RWO and it felt sluggish, so I turned upright.  One of the guys yelled at me (bless electric sound) "You only have One Motor - the Inboard.  So I did the most boring thing a stunt flier can do - 40 laps at 5'. Nice landing.

I can only think of two causes.  Low voltage cutoff and a loose wire.  The low voltage is at 3.0 and I am using 5s 4200 batteries.  Not likely at the beginning of a flight.  I would change it to 2.8 but I can't get the stupid SkyColor 50's to respond.  Others use them as-is so I am probably ok to do the same. Then there is the most likely cause a lose connection but will an ESC restart?  It would have to be a power wire but they were all solid. It is more likely that it went to full idle somehow. Now here is the piece of evidence I would rather ignore but I am not a Democrat, so I don't select my facts.  The prop was not turning for what I was told was 2-3 laps. It should have windmilled.    Back in the shop it worked as advertised.  Don't they always  HB~>

Any brainstorms from a sprinkle to a hurricane are welcome - Ken

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Offline Mike Alimov

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Re: Motor Stops then restarts.
« Reply #1 on: August 05, 2025, 04:54:10 PM »
I think you can exclude the battery brownout. Since the same battery feeds both motors, you would feel the loss of power on both sides.
If you are confident that your power connections (battery to ESC, and ESC to motor) are solid, this leaves a timer-to-ESC connection. If that connection was lost momentarily, the ESC would lose logic power and reset. And even if the 5V and timer signal got restored in flight, the ESC would not resume its operation without going through the initialization sequence from the timer.
Depending on the ESC you are using, it may do something on the output during the initialization process that would prevent the prop from freewheeling for a few seconds.
That is the most likely scenario, in my opinion.
While tedious, there is a way to disassemble those 3-pin connectors and give each sleeve a gentle squeeze to ensure better contact with the male pins.
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Online Ken Culbertson

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Re: Motor Stops then restarts.
« Reply #2 on: August 05, 2025, 05:37:32 PM »
Got two flights in today.  The motors ran without interruption.  Using the 5s settings I flew it on a 6s and some nose weight.  It was a beast, right up to where the battery caved. Turned out to be a bad battery so I am no further along than I thought I was last week.  Good thing I didn't push it.  Turned out to be a bad battery and I would have had one of those "Look Mom, it's raining airplanes" moments.  One more try on Friday with a brand new and shiny 6s 3000.  If I can't get a flat on the top of the hourglass it is time for bigger motors.  I wish I could afford some CF props.  I will give the BA 10x5 another shot.  The APC 10x5 thin sounds funny but has good thrust.         

Live and learn - Ken
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Online Ken Culbertson

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Re: Motor Stops then restarts.
« Reply #3 on: August 05, 2025, 05:47:14 PM »
Quote from: Mike Alimov on August 05, 2025, 04:54:10 PM
If that connection was lost momentarily, the ESC would lose logic power and reset. And even if the 5V and timer signal got restored in flight, the ESC would not resume its operation without going through the initialization sequence from the timer.
Depending on the ESC you are using, it may do something on the output during the initialization process that would prevent the prop from freewheeling for a few seconds.
That is the most likely scenario, in my opinion.
You may be on to something.  Whatever I did in the shop cured the one motor stopping scenario.  I made sure the wires in the connectors could not pull out and ohms tested every connection.  That being said the time 2-3 laps pretty much matches the time it would take an ESC to recycle.  Since the battery and the timer both control two motors I doubt the problem can be anything other than the ESC.  The FlyColor is a very fast drone esc, far faster than the Spin Pro but quality, not so much.  I guess I am going to have to file this one away in the "Things that can't happen -  that did" drawer and move on.

Ken
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