Hello everybody,

I'm a beginner having some troubles. I am running the following setup:

EMAX 2205 2300kv
Dys Xms30a - flashed with Blheli 14.85 multishot
Brainfpv rev1 (8k/8k)

After a short maiden flight (40sec of pretty much hovering and slow forward flight in acro mode with no issues) I disarmed the quad and crashed from 1m into tall grass. I recovered the quad, disconnected the lipo and brought the quad back to start again.

I checked the motors for debries and everything seemed all right.
When connecting the lipo again the ESC did not make the usual sounds (as I could tell one of them did not jeep as usual, but don't remember exactly how it beeped). One second afterwards (with quad disarmed) motor 2 gave up smoke, and had 3 burned coils.

I disconnected the lipo and checked everything for shorts (there weren't any). As I had a backup motor I replaced it. As soon as I connected the lipo motor twitched (the quad was not armed, tx wasn't even on) and burned also (same coils).

Do you have any ideas on what I could be missing?
Is 8k/8k too much for these escs running multishot?

I checked and the motor screws were not touching the coils, they weren't even visible.

Thanks!

It sounds to me like you have a bad ESC. I assume that the ESCs are properly insulated from the frame?

Yes, they are properly insulated, there isn't anything touching the frame.

Most likely the esc. When it crashed, did you disarm or were the motors still running?

(06-Jun-2017, 07:03 AM)unseen Wrote: It sounds to me like you have a bad ESC. 

I have to agree, not just cos unseen knows everything (we're not worthy! )  but after the info on motors, in this post which I haven't yet thanked for, or responded to (my bad!) I had been overthinking the theory of it, (maybe a solder joint on a 'star' config) but if you haven't even armed, then surely it can only be an ESC sending power in error to one of the 3 phase windings?

edit to add ; I no experience with brushless hence my opinion shared in the form of a question!

(06-Jun-2017, 05:26 PM)Tom BD Bad Wrote: I have to agree, not just cos unseen knows everything (we're not worthy! )  but after the info on motors, in this post which I haven't yet thanked for, or responded to (my bad!) I had been overthinking the theory of it, (maybe a solder joint on a 'star' config) but if you haven't even armed, then surely it can only be an ESC sending power in error to one of the 3 phase windings?

edit to add ; I no experience with brushless hence my opinion shared in the form of a question!

Tom, your deduction that it must be the ESC is right on the mark. Only the ESC provides power to the motor; only the ESC could cause the problem. The flight controller can't actually tell the ESC to burn the motor so logically, the ESC must be malfunctioning.
 

As I'm sure you understand, there are no shortcuts to understanding mutirotor craft. It requires that you understand basic electrical and electronic concepts and practice. It also helps if you understand a little about microprocessors and sensors and have a basic idea of how computer programs work.

Once you have that foundation, you have a much better chance of working out why things don't work as expected and what could and also could not, be the cause.

The deeper you dig into this hobby, the more you must learn about computer programming, electronics, materials science, physics and aerodynamics.

How deep anyone wants to go is up to them, but if you are going to build your own, starting without some basic understanding is always going to be a recipe for disaster. When people say that learning the foundations of the hobby seems like too much effort, is too difficult, or 'I don't want to learn, I just want to fly', then I'd say they should find a different hobby. Both for their own, and other's safety.

I'm lucky when it comes to this hobby as I have two head starts on most people, I'm a computer programmer by hobby and trade, plus, I started learning about electronics when I was just eleven years old and soldered my first computer together from a kit when I was thirteen.

When I started in this hobby, it was easy to understand the firmware and electronic aspects of our craft. I'm still learning about motors, propellers, PID controllers, Mayhony and Kalman filters and much more. I'm also having to go back and teach myself some of the maths I missed at school so that I can properly understand some of the calculus and vector maths that comes up when you dig really deeply into the theory side of the hobby. It's always fun to be learning new things and expanding my understanding of how things work!

I wish you the best of luck in your journey.

(06-Jun-2017, 03:55 PM)CaptainSlow88 Wrote: Most likely the esc. When it crashed, did you disarm or were the motors still running?

I disarmed while the quad was still in the air.

So something must have happened to that ESC during the crash, just hope that the future ones won't be as fragile

Thanks for the advice and wishes!

What ESC are you using on this build ?
I burned (fire/flames/smoke/fireworks) 3 ESCs already but mostly for crashing and keeping throttle ... sometimes it happened in less than a second. Just be aware it can happen especially if you are using cheap ESCs ...