Iphone lost connection to Remote

[ReturnoftheQuack]

I was hoping to get some insight while I wait for DJI customer service to open up this morning.

Yesterday evening I was flying over a baseball field and an adjacent open field when the lightning cable connection in my iPhone wiggled and lost connection to the remote which in turn said 'disconnected to Phantom 4' on screen in the top left corner . It's my understanding that when this happens the P4A should RTH. Instead it just fell out of the sky from 341ft. The log just stops at that point because it wasn't connected any longer . I was able to locate the drone and battery that got ejected on impact in the field and it seems to turn on again after cleaning the mud and leaves off of it. I want to make sure I don't have a lemon, its only my 2nd day of ownership.
Phantom 4 Advanced - Firmware says up to date for PHA and remote.
Flight mode P-GPS
14satellites
Home Point Recorded. RTH Altitude: 30m.
Log cuts off while at 341.2 ft altitude with 81% battery

Any advice or similar circumstances?

Thanks in advance!

 

[Fly Dawg]

It's my understanding that when this happens the P4A should RTH. Instead it just fell out of the sky from 341ft. The log just stops at that point because it wasn't connected any longer

This is incorrect. The device has nothing to do with RTH in this instance. Yes, the logs will stop because there is nothing to record to. RTH will occur upon loss of remote signal for 2-3 seconds. As to why the aircraft fell, you will most likely need to look at the arcraft .dat file on the aircraft itself.

 

[Fly Dawg]

If you care to do so, you can upload the device .txt log file to the link below and we can take a look for any anomaly that might be present. Place a link to that uploaded log back here.

DJI Flight Log Viewer

 

[ReturnoftheQuack]

Thank you. Here is the link DJI Flight Log Viewer - PhantomHelp.com

 

[Fly Dawg]

Ok, just at first look ( and I cant verify this 100% from this file), it appears as though one of two things occurred. A) A sudden power loss of some sort OR B) The battery dislodged. Just for informational purposes, I have seen quite a few P4's eject batteries around here. It is a known design flaw, which was changed in the P4 V2 series. ( May not be any better, just to add). Most of the time it appears to be heavy braking which causes a battery to dislodge. Not neccessarrly coming out of the housing, but disconnecting from the contacts. I say this because looking at the last few seconds, you gave the aircraft full elevator and were traveling at 20mph and you released the stick. This causes the aircraft to pitch upward very quickly to brake ( Unless you changed the braking settings). When this happens, the battery can dislodge. ( See Charts Below ). As I said, I cannot confirm this, however, since there have been quite a few ( More than there should be) of these batteries dislodging, that is my initial guess. If you can pull the .dat file from the aircraft that could provide more info, but probably not much.

 

[Fly Dawg]

Additionally, as for the phone disconnect, there is really no way to tell if this data is accurate as far as what I looked at above. Mainly because there is no way to know if the phone disconnect was at the end of the data stream, or mere milliseconds before. Simultaneously, if you will. Take the above with a grain of salt. You will need to get the aircraft .dat file from the aircraft to verify the power loss and at what point. If you wish to do that, see the link below. Instructions are there. These files can be tricky to get the correct one for the flight. When you get the file (or files ) you will need to upload them to a sharable location such as Dropbox or Google drive and place a link back here to share them. This is about all I can gather from the device file.

How to retrieve a V3 .DAT File from the AC

 

[ReturnoftheQuack]

Thank you for the helpful insight and I'll get to work on pulling that DAT file. No braking settings changed.

 

[Fly Dawg]

Looking back closer at the above chart, that last braking maneuver did indeed occur before the loss of telemetry and only milliseconds before. The .dat file should confirm that, if indeed the power loss was near simultaneous to your device disconnect.

 

[ReturnoftheQuack]

I'm fairly certain this is .DAT file based on the time and battery cap percentage matching up with the txt file and where it stops.
Link to file: Dropbox - FLY013.DAT

Again, I appreciate your help in looking into this!

 

[Fly Dawg]

This certainly appears to be a sudden power loss of some sort as the data matches up with the device data. This occurred mere milliseconds after braking, which still leads me to believe that the battery disconnected. I am going to see what @BudWalker can determine from this. It is definitely a power loss, but where is the question. Your device USB connection is a completely separate issue and had nothing to do with the aircraft falling. Below is the matching .dat pitch chart to the device one posted earlier.

 

[ReturnoftheQuack]

Wow, that's incredible. That would make sense of showing the these conditions: AC disconnected message on screen, AC went silent, phone vibrates like the its not charging any longer, USB is still connected but loose in iPhone socket. It happened so quickly its tough to remember the exact sequence of events.
I filed a ticket with DJI to inspect it and make sure everything is working properly. Cosmetically it looks ok, just missing two small plastic covers from the legs.

 

[BudWalker]

This certainly appears to be a sudden power loss of some sort as the data matches up with the device data. This occurred mere milliseconds after braking, which still leads me to believe that the battery disconnected. I am going to see what @BudWalker can determine from this. It is definitely a power loss, but where is the question. Your device USB connection is a completely separate issue and had nothing to do with the aircraft falling. Below is the matching .dat pitch chart to the device one posted earlier.

View attachment 100504

The only thing I can add is that the .DAT exhibits file corruption like what is often seen with the battery being dislodged. The last values from this flight were recorded at 333.542 secs. But, then there are some data recorded at time 388 secs with nothing in between. These last values are actually from another flight. The battery being dislodged caused the .DAT to not close properly.

If you run DatCon at the highest sample rate and then look at the .csv you can see a few gyroZ values from the other flight.

 

[ReturnoftheQuack]

The only thing I can add is that the .DAT exhibits file corruption like what is often seen with the battery being dislodged. The last values from this flight were recorded at 333.542 secs. But, then there are some data recorded at time 388 secs with nothing in between. These last values are actually from another flight. The battery being dislodged caused the .DAT to not close properly.

If you run DatCon at the highest sample rate and then look at the .csv you can see a few gyroZ values from the other flight.
View attachment 100526

Appreciate you looking through data. It took me 5-10 minutes to find the P4A and when I did the battery was still on but 10 ft away. Turned it off then. After a cleaning of the mud from the battery and P4A I put it back in to check the status of the camera and gimbal. Could that be the next flight?
Also, would you classify the battery ejection as defect, user error, combo of both?

 

[Fly Dawg]

Also, would you classify the battery ejection as defect, user error, combo of both?

Really not our call to make....personally after the many issues I have seen it is a design flaw.....DJI...from what I have seen would consider this as user error.....but that can be debated. Have see it go both ways. This is about all we can tell you at this point, IMHO.

 

[BudWalker]

Appreciate you looking through data. It took me 5-10 minutes to find the P4A and when I did the battery was still on but 10 ft away. Turned it off then. After a cleaning of the mud from the battery and P4A I put it back in to check the status of the camera and gimbal. Could that be the next flight?
Also, would you classify the battery ejection as defect, user error, combo of both?

Yes, that would be the next "flight".

If the battery was properly seated then that has to mean it's a defect. If it wasn't seated properly then that's a pilot error. IMHO.