motor failure crash - please help !

glowingturnip

glowingturnip

Well-Known Member
So I was flying the other day, and all of a sudden, in steady level flight, one of the motors stopped temporarily, so the quad ended up falling end over end, from quite a high altitude - broken frame :-(

This was a problem I've seen a few times before, but only very intermittently, and I actually thought I'd fixed it since I've since flashed to firmware steveis 1.19 on my KK 2.1.5 and replaced my txrx with a new FlySky FSi6 6 channel. However, it seems the problem is still there, and I need to fix it if I'm not going to go around busting frames and dropping quads on people.

It happens rarely (that was once in about 2 hours flight time), and in a split second, so it's not easy to tell exactly what happens, but it looks like it's just one of the motors (no 4 I suspect), and looks like it stops dead for a split second before starting again. Everything seemed to spin up again as normal afterwards (though of course it was then unflyable)


What do people think the likely problem will be, and how can I go about diagnosing it ? Anyone had similar problems ?

I'm thinking...

- probably not the FCB because a) it's been flashed with different firmware since last time, and b) if it was an FCB crash then more likely all the motors would stop. There were no errors showing on the FCB when I collected it.

- probably not a motor (they're Sunnysky x2212's) - if a mechanical problem I'd expect it to be malfunctioning afterwards

- so I suspect it's the ESC (Emax 25A) ? Should I look at replacing it, or should I be looking at flashing the ESC's with up-to-date firmware ? (and how do I do that ?)


Would appreciate any help, want to get this fixed,

Cheers,

Stuart
 
Well it sounds like the ESC, plenty of posts concerning the loss of sync even with SimonKs. But it seems that Emax SimonKs are not true SimonK but some sort of bastardization, Emax says "based" on SimonK. It also apears that they should not be re-flashed with official SimonK either, gotta jump to BLheli.

Have gone in and set the timing for all of them?

I'd try swapping it and see if the problem moves with the ESC.
 
setting the timing - is that the buttons a+d with throttle up then down thing ? Done that.

Might look at getting a replacement, is there a more recommended brand than emax, and can I just replace one or are they like tyres and I have to do all of them ?

Thanks,

S
 
got it, and have ordered one of those programming cards, think it would make it easier, I can see myself getting lost with all the beeping. Will get a spare ESC and try swapping them over too.

Would you agree with the video guy's recommended settings:

brake type: off
timing mode: mid or mid-high (my motors are 980kv (whatever that is), so I guess mid for me)
startforce: 0.75
Curve mode: off
control freq: 22khz
Low volt protn: off
(low volt cut off mode: soft/hard – doesn’t matter)


Should I look at flashing them to the latest BLheli firmware too ? And if so, how do I do that, can't seem to find any youtube vids for the Emax's ? I have a USBASP if that's any use.

Thanks for your help mate,
 
ok, I've been doing a lot of googling on this issue and I'm now convinced it's an ESC/Motor Sync issue.

In fact I think I'm probably getting it quite frequently, I have moments in-flight where I get a wobble and a beep (not a low-battery beep), but without a catastrophic engine stop - I'd not really given much thought to the in-flight beeps (assuming it was just the quad complaining about my poor pilot skills), but I'm guessing those are the ESC's beeping complaining they've lost sync. The motors are fairly noisy - I'm not sure if that qualifies as the 'screeching' others mention when ESC/motors are losing sync, since I don't have a basis of comparison, but at least it will give me feedback straight away if I change the timing.

The most informative post I could find about timing was post #4 here. I like that the timing on these is equivalent to a combustion engine timing, makes it much easier to understand. Looks like I need to increase my timing advance (or use a smaller prop)

Regarding the PWM frequency, there's a calculation on post 4 here - that would suggest the default of 8kHz is right for my motors.


So a few quick follow-up questions if I may:

- do I really need to flash the ESC's with new firmware ? Looks like a nightmare, different from ESC to ESC, I can't find anything for the EMAX 25A, and seems to involve removing the heatshrink and soldering signal wires to pins. So nowhere near as easy as flashing the FCB. I'd rather avoid it if I can

- if I change the timing of my ESC's, do I need to change my PID tunings ? I just got a tune I quite liked.

- am I running too big a prop ? 1045's on these motors and 25A ESC's on a 450 frame
 
yeah, spare ESC on order, and spare frame as well, won't hurt to have a few spare legs around, and I can use the extra middle plates for mounting stuff, and an ESC programming card.

It fell from about 10m when it broke the frame, flipped over immediately and fell end over end so no chance of saving it, just had to cut the throttle and safe-mode it before it hit the ground.
 
Hi guys!
I have exactly the same issue.
My current build setup is:
-apm 2.8 with arducopter 3.2.1
-S500 frame
-Sunnysky x2212 980kv
-Mystery M-30a (flashed with SimonK firmware)
-1045 Nylon props
-5000mah 3s lipo
-walkera devo 10 rx/tx

I am flying in X mode.
The down left motor (aka. number two motor) , stops and starts immediately and make my quadcopter to lose height.
This has happened the last two times.
I think it might be the ESC and i'm planning to test it on another motor.
Have you found a solution to your problem?

P.S Sorry for my English if you find a mistake.
 
I'm pretty sure it's the ESC not syncing with the motor properly, and I have an ESC programming card now, will be trying to increase the advance timing to see if that fixes it.

I haven't been able to test anything yet though, still waiting for replacement frame parts from China
 
did yours beep before crashing ? i think that might be the ESC's beeping when they're losing synch. Let me know how you get on, as will I
 
First of all, thank you very much for your quick responses!
Well, the problem was a bad connection inside esc's cable, that we didn't realize earlier.
We soldered it and here it is, up again!
I will upload a video in the next hours.
Be aware, the quality is poor (240p) because my friend uses an iphone and he send it to me via viber.
 
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