Smelly motor - how dangerous was this?

[Mastiff]

I am very new to this hobby, and totally new to this forum, so please don't hammer me if I say something wrong!

I bought a Phantom 3 Pro about a week ago, and I managed to lock one of the propellers today. I landed (with prop guards) in a field, and there was one thin root I hadn't noticed sticking up from the ground. It locked up one of the motors for maybe five to ten seconds before I could stop them (it felt like a couple of hours, but realistically it was between five and ten seconds). That was enough for that motor to get very hot and it smelled almost like an electrical fire or short circiut. I let it cool for a little while and tested very carefully, and the drone took off normally up to the meter I dared togo and seemed to have the same balance and handling a before. I hovered for a minute or so and landed again. It took 15-20 minutes before it was completely cool again, which I find almost incredible with such a small lump of metal! Turning the motor doesn't feel any different from the three other motors.

But the question is what I should do now. I really don't want to ditch more than 1000 dollars of drone when the motor is so cheap, of course. I was planning to try it out over a sandy beach tomorrow, hovering a meter or so above it and fly back and forth. How long should I be careful before I can say that I only got a scare this time?

 

[ronbo]

If the one motor gets hot there is something wrong. Don't fly. Likely the ESC is toast. Easy enough to replace if you can solder.


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[Mastiff]

Oh, if it matters, it's the 2312A motors, with the flat top and the propeller clamp.

 

[neven]

If the one motor gets hot there is something wrong. Don't fly. Likely the ESC is toast. Easy enough to replace if you can solder.

Motor was obstructed. That's why it got hot.


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[ronbo]

Right! It smelled because the ESC circuit board started to burn. That means components are dying. When you order a new ESC get the proper motor which you may have to replace.

 

[Mastiff]

OK, so I should not use it at all, then? It takes time to get stuff like that here. It still smells a bit, but not heavily. I'm used to electronics, and I have smelt worse from working stuff. And about the ESC: Is that the name of the whole motor unit? So when I order a 2312A I get all I need?

 

[Mastiff]

Does that mean an ESC Circiut board? For several hundred dollars?!

 

[John Locke]

I'd fly it on some easy nearby missions and see how it does, but that's me. The esc is part of the motherboard, you can't replace just the esc, so the risk is worth trying it out a few flights. If it does fine you should be ok. By the way, take off the prop guards unless you're flying indoors. They are a liability when flying outdoors, assuming you're away from people. The esc portion of the motherboard is likely causing the smell, not the motor. Sniff the vents and compare that to sniffing the motor. The esc portion is near the vent that's near the motor. It likely overheated but that doesn't mean it's ruined. I'd fly it.

 

[Mastiff]

Yeah, if I have to replace that insanely expensive part I'll for sure test it first. I can' afford to buy that without being sure! And destroying a part with that price ate stopping the propeller for 5-10 seconds just sounds insane to me.

 

[KyleMaxxUAV]

I'd fly it on some easy nearby missions and see how it does, but that's me. The esc is part of the motherboard, you can't replace just the esc, so the risk is worth trying it out a few flights. If it does fine you should be ok. By the way, take off the prop guards unless you're flying indoors. They are a liability when flying outdoors, assuming you're away from people.

Agree with john,
Remove the camera .. Fly it hard close by in a field (somewhere safe / nothing to crash into or hurt) If it doesn't crash and burn after 2-3 batteries through it .. You are probably fine. How bad are the coils looking in that motors? Probably some of the insulation started to burn off the coils.


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[Mastiff]

Thanks, P3p! Another thing I have noticed: It doesn't smell at all closer to the center of the arm, it's only when I sniff hard straight down the engine (and that smell's fading away too). Shouldn't that indicate that the centrally placed circiut board is not damaged, and that it's only been a bit of coil burn?

 

[ronbo]

Well, I've only replaced an ESC ($30) and motor ($20) on a P2+, also a new shell ($60). The P3 may be more if they redesigned the board. If you're handy open it up or send it to a repair shop. Good luck.

 

[neven]

Since you landed ESC was supplying constant idle power to the motors and not adding power to try to turn the obstructed motor. Thats why smell is from motor coils and not ESC. If it was in air it would have been different.
Try easy flying without camera as suggested or replace that motor.


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[JackTheTexan]

From what I understand the main board of the P3 is fully integrated, and around $400 to replace. No separate ESCs.


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[Mastiff]

Ronbo, the P3 has a joint ESC board in the middle, which supplies power to all the motors. And which costs several hundred dollars to replace!

Neven, I will try easy flying, thanks! And yes, it was on idle, and I pressed the controller down a soon as it happened. I have now examined the thing even closer, and there is not a hint (and now there is only a hint) of smell anywhere but in the middle of that motor. No smell at all further in. So I am pretty sure that this wasn't as bad as it could have been. I will try a bit of gradually rougher flying to see what happens. I just have to figure out how I get those securing pins in the camera off first...

Edit: Simultaneous posting, Jack. And you would be right.

 

[Mastiff]

Well, I did it. First I checked the camera, and I have made a rookie mistake: Putting all the four pins in! Of course they were not in any mood to budge. At all. So any smart guy would cut them to take off the camera and make sure nothing more happened to the expensive thing. Right. Any smart guy would. Did I mention that I'm smart? Well, I'm pretty intelligent (academic job and all that), but that does in no way, shape or form equal smart! Oh, another smart thing would be to wait until tomorrow to test it. Preferably in a wide open field with soft moss, or something. Far away from trees and stuff. Right? So did I mention that I'm not smart? I might have.

I did what any self-respecting redneck moron would do: I went out in the pitch black night with my Black Diamond headlamp (which is about as powerful as the headlights on my car) and I first flew for a few minutes in almost hover, one meter up. Got bored. Started moving slowly back and forth. Got bored. Started doing a (OK, pretty slow and careful, but still...) slalom in the dark between the trees in the garden. That was not boring at all. In fact if I had crashed doing it, it would still have been the most fun I've had with my clothes on for quite some time! So I flew the battery empty, spent the last minutes traning on what happens when I turn the thing 180 degrees and have to react exactly opposite on all controls. No incidents, and only a couple of "darn, I need to go the other way now so I don't hit the bush", but none of them anywhere near stronger words than "darn". The pope could have followed me around without being offended at all! So I got to the low battery warning, and then critically low. At which point I landed. After that flying there was no difference at all in how hot (rather how cold, I forget to mention that it's below zero outside) the engines were. Still the very faint smell of hot electronics from the blocked motor, but nothing else.

So tomorrow I'll go to the beach, which is probably the softest thing around and fly up another battery cyclus to see what happens. I will still fly pretty low most of the time. Up to a few meters would probably be good. Btw generally (yeah, I know there are a billion factors, but generally as in guesstimat) how high can a Phantom drop and still not be smashed? And will the air resistance from the propellers keep them up and the landing gear down, or is it more like bread with peanut butter on it? (Which of course reminds me of the old way of creating hover - taping a peanut butter sandwich with the peanut butter side up on the back of a cat!)

Finally, will a slightly fried coil likely fail pretty soon, or is that anotherone of those "you'll never know" scenarios?

 

[KyleMaxxUAV]

Ronbo, the P3 has a joint ESC board in the middle, which supplies power to all the motors. And which costs several hundred dollars to replace!

Neven, I will try easy flying, thanks! And yes, it was on idle, and I pressed the controller down a soon as it happened. I have now examined the thing even closer, and there is not a hint (and now there is only a hint) of smell anywhere but in the middle of that motor. No smell at all further in. So I am pretty sure that this wasn't as bad as it could have been. I will try a bit of gradually rougher flying to see what happens. I just have to figure out how I get those securing pins in the camera off first...

Edit: Simultaneous posting, Jack. And you would be right.

Mastiff,
You may have got lucky !!
If the motor spins just like the others when off / by hand, No wierd sounds , etc. I would remove the camera and fly it hard !!! You don't want to baby it / but it back together just to have it crash tomorrow. If there is any chance that it's not 100% in your mind .. Swap the motor out, it's cheap & relatively easy !!! If you are still under warranty ... It's kind of iffy because if it crashes and burns a week from now you may .. Or may not get DJI to cover it under warranty.

I personally would remove the camera .. And fly 3 battery's through it , flying as hard as I can. I would do this in a grassy field rather than over concrete or asphalt and keep it low to the ground in case it does fail to mitigate crash damage.

That's just me.


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[Mastiff]

As you can see in my post over I did test, a bit more risky, maybe. Tomorrow I'll keep on running. I have read a bit around and it seems like this is not at all uncommon, especially if tipping over when landing. The common advice seems to be to do some heavy testing and if it doesn't fail or smell more it is probably good. But I will get extra motors so I can replace it if it ever gets warmer or smell more after a trip. I just hate soldering...

 

[KyleMaxxUAV]

As you can see in my post over I did test, a bit more risky, maybe. Tomorrow I'll keep on running. I have read a bit around and it seems like this is not at all uncommon, especially if tipping over when landing. The common advice seems to be to do some heavy testing and if it doesn't fail or smell more it is probably good. But I will get extra motors so I can replace it if it ever gets warmer or smell more after a trip. I just hate soldering...

Ah very nice !! Sorry I missed that one !!
As far as "will it fail soon" I don't think there's any normal way to know. Maybe if you had some high tech equipment & a very strong knowledge on that kind of thing , but for the average person "you just never know" sounds like you are good though !! The only thing I would say is avoid the beach until you know Its good !! Lol If it went down the sand removal process would be worse than anything I can think of ha ha ha !!
But from your post , I'm going to say you should be pretty good !! Any discoloration on the coils ??


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[frostacaust]

Hi there , just wanted to let Mastiff know that I had the same thing happen to my p3a, it tipped while landing and the prop brought up in the side of a fence. It also started to let a loud squeeze and some smoke and burn smell. I ran over immediately and killed the power , I let the motor cool down , removed top shell and never noticed anything burned anywhere inside the phantom . What I did notice with a magnifying glass Is a slight discoloration on the armature / windings of that motor as compared to the rest of them.

The motor still spins freely , bird flies just fine after bout 10 flights. Before I started flying again though I did run down several batteries while on the ground and again no issues to report.

If I was to guess, I think the smell could be the epoxy type of substance that helps keep those motor windings in tact .

Cheers