Hi Everyone
I’m after some advice … i have DJI refresh, and im going to speak to support but essentially my partner was flying out Mavic 2 pro - over a river in brisbane australia. In the middle of the river, 50m height, nothing above her - higher than the tree line
https://www.phantomhelp.com/LogViewer/FXUABQ2WA8N0AFMNV5BF/
She was moving back to line up a shot … drone said it had lost connectivity. She looked back up at the drone - it was gone… no noise, no visibility. She recalls slowing down right before it stopped, which looks to be what the logs recorded - and was nowhere close to the treeline.
Absolutely no clue what happened. Last location is in the middle of a wide river, lost all GPS right before its last transmission. Any thoughts ?
She looked around, both side of the river… nothing.
/Adrian
Seems there was some problem with the battery. At time 85.031 secs SMART_BATTERY:status changed from None to BatteryCommunicationError. The M2 was here at the yellow A symbol
At the very end of the recorded data the throttle had been at about 60% and the elevator at -100%. They were then both abruptly returned to neutral. I’m guessing that the battery was partially loose (indicated by the BatteryCommunicationError) and then the acceleration caused by the abrupt stick inputs caused the battery to depart the M2.
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Agreed with @BudWalker It appears there was a battery issue of some sort, likely a disconnect. As was mentioned in the status change, the battery telemetry ceased updating transmission at approx the 80 sec mark and remained that way for the rest of the flight until the Nav Health and Num sats both went to zero and transmission was lost.
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@acantril, did you check the DAT flight log to see if any notable error messages were logged there? If not, you can retrieve that log file like this.
I did download a DAT file - the timing seems slightly off (maybe its a Mavic/Controller timing issue) - it was too big to upload but here is the file
https://www.dropbox.com/s/050d67cwe9y43jj/19-05-25-01-29-14_FLY098.DAT?dl=0
Not sure if this gives additional information.
Thanks for all your comments so far, really appreciate them.
Here are the last messages logged in the DAT file:
497.514 : {task_e}INFO:i2c3 core recovery||
497.514 : 27816 [L-BATTERY][ERROR] smbus_read CMD_POWER_STATE error||
I’m not sure what they mean, but I know @sar104 reviewed a few other logs with those errors and DJI replaced the drones under warranty. So, it would be worthwhile mentioning those messages when you contact DJI Support for help.
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If those error messages really indicate a battery communication problem, then I’m wondering why DJI replaced a few Mavics under warranty that showed those errors. I suppose we’ll never know since they never explain why they are replacing aircraft under warranty. And if they stumble upon the explanation you linked above, perhaps those free replacements will come to an end 
Thanks for everyones help on this - DJI are replacing the aircraft free of charge.
I would say I understand went south.
One thing I can say for sure, you will need aa lot of luck with DJI. They are penny pinchers. Anytime they can screw a person they will. Even with the care refresh. THEY HAVE NO CUSTOMER SERVIICE. AT ALL!
Mike
My experience with DJI was actually pretty good … they responded quickly and agreed to replace the drone. That being said, I did have some expert guidance regarding my logs.
One of many strange battery error crashes with the M2. Hope this is not a problem with FC or battery logic. But something appears to be up. I can’t believe that many people are not locking the battery in correctly. Starting to wonder if the M2 has an issue with harsh flight controls which may cause some form of battery separation during flight.
The fact DJI replaced it is both good for owner but wondering now about a design flaw.
Paul C
