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Esc intermittently won't spin up

#1
Hi all,
This is the second issue I am having with my scratch built H-Quad. I had two escs that had a problem where after arming they would just slowly jerkily spin. I got a replacement ESC from FT and that fixed the one that was really bad, but the other one still has it. The one that doesn't work is properly calibrated, and if I arm it sometimes it will just work normally, other times not. Any ideas as to what could cause this? Here is a video of what's happening: https://www.youtube.com/watch?v=VqVL-u4vUKc
Thanks for the help!
luketheduke
 

Flat4

Senior Member
#2
I would guess a bad solder connection between the esc and one of the phases of the motor. That weird twitch your getting is normally when only 2 of the 3 phases are firing. My guess would be it's the same thing causing your quad to randomly fall from hover.
 
#3
I would guess a bad solder connection between the esc and one of the phases of the motor. That weird twitch your getting is normally when only 2 of the 3 phases are firing. My guess would be it's the same thing causing your quad to randomly fall from hover.
It seems highly improbable that it is a bad solder connection for 3 reasons:
A) When I replaced the esc, the problem went away on that one. The only problem is that I had it on 2 of the escs...
B) When I swapped the esc with another motor, the problem still occured.
C) After I crash, the motors still turn fine, including the one with the problem.

Is there anything else that could be causing it?
Thanks,
luketheduke
 
#4
It seems highly improbable that it is a bad solder connection for 3 reasons:
A) When I replaced the esc, the problem went away on that one. The only problem is that I had it on 2 of the escs...
B) When I swapped the esc with another motor, the problem still occured.
C) After I crash, the motors still turn fine, including the one with the problem.

Is there anything else that could be causing it?
Thanks,
luketheduke
so when you swap ESC's does the fault FOLLOW the ESC OR stay with the motor
if stays I would inspect the motor closely including the wires where they go into the motor body
 

Flat4

Senior Member
#5
It seems highly improbable that it is a bad solder connection for 3 reasons:
A) When I replaced the esc, the problem went away on that one. The only problem is that I had it on 2 of the escs...
B) When I swapped the esc with another motor, the problem still occured.
C) After I crash, the motors still turn fine, including the one with the problem.

Is there anything else that could be causing it?
Thanks,
luketheduke
How do you have the esc's connected to the motors? Are they directly soldered, or connected with bullets? How are the motors mounted to the booms with bolts through the boom to the motors or zip ties? Can you take a few close up pics of the connections?

I'm still thinking one of the phases aren't firing, what's causing that could be a few different things. If you could answer the questions above, and get some pictures we'll see if we can't track down that gremlin.
 
#7
I investigated the issue more, now that I have my quad flying, and I found it may have a correlation to temperature. If the temp is over ~100 degrees Fahrenheit, it won't spin up. Is there some mechanism in the EMAX escs that could cause this to happen or is it just a fluke?
Thanks,
luketheduke