Vision Plus Lost

[patrickpernell]

Sorry this is so long but here it goes:

Today I went out in my back yard to fly my Phantom. I live on a river and was launching out back on my dock. I have done this over 300 times. It was a beautiful day out, and I started up the Phantom just like I normally do, all according to DJI instructions. On my way out to my dock, one of the motors started, turning on one of the props, (I normally turn on the controller, range extender and Phantom while I walk out to the dock). I turned the battery off, which was the only way it would turn off. After a couple minutes I powered it back on and waited for GPS signal. I had 12 satellites. I was attempting to connect my phone to the WIFI, and while I was doing this, all four motors turned on and the Phantom started to lift off the ground. I hadn't even touched the controls yet. It lifted off and immediately darted towards the water and crashed and of course sunk. I didn't have any control while it was doing this.

A couple things I will add:

1). This drone was purchased new by myself. I let my son fly it one day and he crashed it into the river. I sent it to have it fixed, and they fixed it (DJI authorized service center in Miami Florida). I don't know what exactly they did, but it was good as new. At least for a week until this happened. I received it back from service on Saturday, October 11 and it crashed today, October 15. I flew several flights in between receiving it back and the crash today, all without incident.

2). My dock does not have a roof, so there was no interference.

3). The battery was fully charged, as well as fresh batteries in controller and charged wifi extender.


Does anyone have any idea why this would happen? Could it be something that went wrong with service? Was this just a glitch? Should I spend another $1300 on a new one?

 

[MapMaker53]

Sounds like the first sign of trouble was when that one motor turned on by itself. No way would I have attempted to fly it after such an unusual event. I'd have shipped it right back at that point. Probably some sort of electrical short.

 

[4wd]

Possibly something shorting out internally would allow it to start itself.
The previous dunking could well have some involvement, unless they replaced all the electronics, a it of corrosion somewhere gradually ate through?

 

[patrickpernell]

I am new to the Phantoms, and didn't really know what to do, I defiantly shouldn't of flown it.

 

[BennyGca]

Sorry for your loss.. That's brutal..
Can you recover the drone? If/when you do find it, I would bring it straight back to that dealer and have them do it all again! Sounds like they didn't work all the bugs/water out from the 1st swim.

 

[patrickpernell]

Well it's at the bottom of a river and I'll have to do some diving to try recovering. Does this sound like a flyaway? Well a flyaway from the ground?? Or something electrical

 

[BennyGca]

Sounds like there was still humidity/damage in the electronics.. Maybe flight controller or ESCs shorted causing full RPM on the motors.

 

[BlackTracer]

Do you recall what the rear LEDs were doing when it took off and you had no control? I would think the only time you would have no control and the phantom would be in "auto-pilot" is if it was in RTH mode. I mean when else do the sticks do nothing and it flies on its own (not counting ground station)? Problem is if it was in this mode, it probably did not store the home point at your location, but rather was returning to some unknown location, depending on what the firmware does when it has not stored a home pint but does RTH anyway. Maybe (0, 0, 0), which would send it on a line through the earth probably.

 

[phantomguy]

At one time on DJIs page on the repair section(I think it was DJI's page..or perhaps one of their dealers?) it specifically mentioned that they did not even attempt to repair Phantoms that had gone into water? Often times electrical gremlins dont pop up until days or even weeks later after water has made its way through things..

 

[phantomguy]

and in DJI's defense, their owners manual states to not fly over or around water...

 

[vortigern]

Should I spend another $1300 on a new one?

Definitely

 

[burlbark]

This is why I scrub all components with a mild acid after dunking and esc's 99% of the time replaced. The mineralization that occurs in conjunction with electrolysis can allow enough voltage and current to power on MOSFET circuitry. It's basic repair knowledge.

Just like never spray your gimbal down with wd40, it's a dust and debri magnet.

 

[pterrill]

This might be a stretch, but check and see if Ground Station is toggled on in the setup section of your software. I had one startup and take off on its own while I was programming way points. Sorry for the loss, been there

 

[rrmccabe]

Cant say what happened with the one motor but sounds like it was going to do a 60' RTH.

Reminds me of a recently time I landed the Phantom about 100' away and was going to walk to it. I thought I had things shut down and I powered off the controller as I walked. It considered it RTH time.

The fact you had one motor turning sounds like a glitch for sure. One I have not seen here on the forums.

 

[DrJoe]

I'd bet on a flight controller issue, with a kicker on ESC failures. Sad. Sorry for your loss.

 

[buddhacanooda]

You guys understand that a short circuit would create a current path that would bypass the motors, right? I am going to assume no based on some of the science fiction suggestions in this thread. In other words, a true short circuit would not provide electricity to the motors.

Sounds like there was still humidity/damage in the electronics.. Maybe flight controller or ESCs shorted causing full RPM on the motors.

 

[N017RW]

Absolutely !

Aside from the under-arm LEDs, the DJI ESCs expect the same PWM signals that a typical servo would look for or respond to.

This can be found in the Naza Quick Start Guide:

"ESCs, Motors·
Motors and ESCs in DJI multi-rotor kit are recommended. Please make sure you are using the ESCs and motors recommended by the manufacturer of your multi rotor first. NAZA output is 400Hz refresh frequency. If you use 3rd party ESCs, please make sure the ESCs travel midpoint is at 1520us. DO NOT use 700us travel midpoint ESC, as it may lead aircraft to fly away or cause injury and damage. After connect ESCs to motors, calibrate all your ESCs one by one through the receiver directly before connect them to your MC, make sure program all of them into Governor off, Break off and Normal Start up to get best experience."

Shorts in the power or conrol signal circuits will not create the results the OP has described.

 

[___]

It's stories that this that scare the crap out of me! So sorry to hear it buddy.

 

[unity]

So the batteries are not the actual "switch" for power? Proper procedure says to power up from launch point. Not power up and walk aways.

Yet you say yourself you power things up as you walk out. Not AT the dock?

 

[burlbark]

You guys understand that a short circuit would create a current path that would bypass the motors, right? I am going to assume no based on some of the science fiction suggestions in this thread. In other words, a true short circuit would not provide electricity to the motors.

Sounds like there was still humidity/damage in the electronics.. Maybe flight controller or ESCs shorted causing full RPM on the motors.

Wow.... Some people dont know how the esc's work. Do you understand return to source and potential? :roll:

With the Vision on and battery installed the esc's have power. The esc mosfets have power to them. It takes very little power to turn them on. In fact I can turn some mosfets on in the vision with using my finger as a conductor and bridging gate to source. The pins to supply power to the mosfet gate are around 1.5mm away, any mineralization will cause the power to run that 1.5mm.

This causes the windings on the motor to energize. Since this is not a pulsed signal, modulated, or of the proper value the esc can go into thermal run away. Sometimes the motors spin sometimes it goes up in a flash of fire.

You will have to research source to gate voltage to understand. This same principle is why a majority of water landing never operate again. People put power to it after drying it out and the damage may have not been yet. You must remove all oxidized paths.

Jeremy James
I cant put my link in here to substantiate who I am or my expertise. It is considered advertizing. I have contacted mods and have not heard back.