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Motor Issue

#1
SO today I was flying my FT Bushwacker when about 30 seconds after take-off my motor started spooling down in air. Luckily, I was able to put it down without breaking anything. When I brought it inside, I ran up the motor to full throttle and sure enough. After about 30 seconds the motor spooled down. The video shows exactly what happens.
Anybody know what happened?
 

DamoRC

Well-known member
Mentor
#2
Probably the low voltage cut-off setting in the ESC. Once it detects the voltage per cell dropping below a certain level it will cut back the throttle automatically. You can normally set the level at which this behaviour happens. What kind of ESC are you running?
 
#8
I was using a Blheli 30 amp esc. The normal one that is used in the C Pack
Absolutely the right advice - safety first.

Sometimes for this type of testing however (battery and ESC under load) you will need to have the prop on - just need to be really careful.
 
#9
W
I agree with @DamoRC, likely low voltage. Possibly a bad cell in the battery. What did the watt meter show?
The watt meter showed a regular voltage from the battery. I don't think the battery is the culprit here. I might have accidently changed the esc voltage cutoff though. I'll have to see how to reset the esc.
 

jtuttle11

Junior Member
#10
Did you check the motor temperature? These motors run VERY tight clearances and can expand as they heat up. This might cause the motor to drag resulting in power loss that disappears when the motor cools off.
 
#11
Did you check the motor temperature? These motors run VERY tight clearances and can expand as they heat up. This might cause the motor to drag resulting in power loss that disappears when the motor cools off.
Yea I felt the motor and esc. Both were just warm, nothing out of the ordinary.
 

mayan

Well-known member
#12
I had a similar issue it was a faulty ESC, changed the ESC and everything was fine again. Check the motor with a different ESC and see if it still happens. Otherwise check the current ESC with a different motor either way will make it quite simple to understand what is the issue.
 
#13
I had a similar issue it was a faulty ESC, changed the ESC and everything was fine again. Check the motor with a different ESC and see if it still happens. Otherwise check the current ESC with a different motor either way will make it quite simple to understand what is the issue.
I'm gonna have to try that to. I'm REAAALLLLY hoping that it's just a programming issue but I have a feeling that the issue is with the hardware itself. :( Oh well, that's just how the cookie crumbles...
 
#15
Yeup that's definitely true. There are plenty of components that you can use from faulty parts. Still, it sucks to know that an esc or motor is smoked.
 

Merv

Well-known member
#16
The ESC is acting like it is a low voltage cutoff. If you battery voltage is good, then t's either the ESC programing or a faulty ESC.
 

DamoRC

Well-known member
Mentor
#17
Yeup that's definitely true. There are plenty of components that you can use from faulty parts. Still, it sucks to know that an esc or motor is smoked.
Don't give up on it until you know it's not the ESC programming. If your sure the ESC is faulty (and you can't return it) go ahead and remove the heat shrink cover and see if you can see any burnt out components. Also it's nice to identify the parts on the board. Post pics of you like! You might be able to replace a component. Either way, it's a good learning experience to see how these things are put together.
Maybe you could become a FET stacker! (Wonder why folks don't do this as much with rc flight stuff).
 
#18
Don't give up on it until you know it's not the ESC programming. If your sure the ESC is faulty (and you can't return it) go ahead and remove the heat shrink cover and see if you can see any burnt out components. Also it's nice to identify the parts on the board. Post pics of you like! You might be able to replace a component. Either way, it's a good learning experience to see how these things are put together.
Maybe you could become a FET stacker! (Wonder why folks don't do this as much with rc flight stuff).
Yeup. I still need to test the esc as I have been swamped with work recently and I haven't had much time to work on this much less actually fly anything. Once I do start doing some testing I'll be sure to post my results here.