My First Crash

[CashCache]

What happened.... Well where can we start.. The further away from the you the Mavic flies, the narrower the frequency field becomes between the controller and the craft. Its called band splitting. Think of it as a rubber band being stretched. The more u pull the thinner it gets. The further away you are the higher ther chance of having something disrupt comms with the drone. Anything that comes in between u and the drone can cause the issue. The further away you are the higher the chance of a frequency clash with a radio tower... TV tower. If you happened to fly ib line of a high frequency transmission that oscilates in 2 to 4 ghz range you could have lost it. My first question to you would be, when last did you do a flight system check on your settings in your app. Look at your action settings on controller disconnect ? RTH settings etc ? Then there are anomalies like birds, if had everything from crows to vultures and sparrows go for my drone. Ive also seen craft been taken our by the critters. Then you have the golf club deciding they dont want you flying over their property and raking you out. Here in South Africa most golf courses the management have frequency guns and they shoot the drone out of the sky. So what happened .... ? Difficult to tell because at 5000 ft you have long lost sight and visual orientation of the drone. Hence the golden rule. Fly within line of sight

Had the camera not shut off at the exact same time I lost connection, I would consider wildlife or a frequency gun as a possible scenario.

Your tale is eerily similar to that in this thread (ie sudden loss of connection etc.Mavic Fly Away this evening. Shes Gone!
You'll see on P8 that it's been diagnosed as a loose battery.

Yikes, I just started reading that thread, but so far you are right - including the sport mode.

 

[CashCache]

What elevation above ground was it last reported at?

393 feet. Right after takeoff, I took it to this altitude and left it here for the duration of the flight.

 

[CashCache]

I know it's prob not related to this, but what firmware were you running? Also what was the temperature in Arizona?

I've never been to Arizona but does it have gusty sand storms at all? Just a thought.

The temperature was 72 degrees. There was no wind at all and clear skies. I'm going to try and find a way to post the actual flight video.

 

[Bintryin]

I think Loose battery maybe the culprit ! if only one side locked in. throw in a bit of sports mode, just to upset the battery then, loss of power drone hits the deck and the battery is thrown clear because its holding in with just with one clip!

 

[Robbyg]

My opinion is also a loose battery. Sports mode would either jostle it further out or it could increase current conspiring on a bad connection enough to cause a voltage drop and shutdown the system .

Rob

 

[erkme73]

Were any of the video files on the SD card corrupt? If not then a sudden power loss is less likely the culprit. When the power is cut suddenly, the MP doesn't close the file properly and it becomes unplayable.

Do you recall if you powered up the MP with the SD card still in it after getting it back? Doing so would fix that corruption, putting the loose battery possibility back in play.

Either way, pull the DAT file off the MP and upload it to your Google Drive or Dropbox and post a link to it here. @BudWalker will be able to provide you with a very good analysis like he did in the other thread.

Do it soon because the space on the MP is limited and your crash DAT will get overwritten after a few flights.

 

[AlanTheBeast]

Thanks for the .TXT file.
Winds were SSW at about 5 mph for most of the flight. Does not seem to be gusting.

At the very end of the data the voltage drops significantly, however, this is correlated to a doubling of ground speed, so likely normal. In the graph orange is voltage, blue is battery charge and yellow is ground speed.

A separate plot of all three battery cell voltages shows them correlating to each other. The battery health seems ok.

It would seem the loose battery theory may be holding up. Indeed, if you had not gone to a higher speed you might have gotten home even with the loose battery. The change in pitch and possibly vibration may have been the final thing to break electrical contact.

Pure speculation, but the battery probably rode the drone down to the ground.

 

[dewster]

I think it has to do with Sport Mode. I think the lipo and the intelligent power management of the battery system kills power in the event of over discharge. I imagine this could happen in windy conditions too if flying in P mode and the craft is expending a lot of power to maintain course stability.

These are just theories so don't take this as gospel.

Maybe DJI should dial back Sport Mode and or outfit the Mavic with a 4S lipo.

It makes me wonder why DJI would display an RPM gauge of the props on their remote. Is it related to power issue? Are the props rated at a certain RPM before breaking etc. Or is it a gauge to see if you are expending too much power in a short period of time.

 

[Strafe1]

What happened.... Well where can we start.. The further away from the you the Mavic flies, the narrower the frequency field becomes between the controller and the craft. Its called band splitting. Think of it as a rubber band being stretched. The more u pull the thinner it gets. The further away you are the higher ther chance of having something disrupt comms with the drone. Anything that comes in between u and the drone can cause the issue. The further away you are the higher the chance of a frequency clash with a radio tower... TV tower. If you happened to fly ib line of a high frequency transmission that oscilates in 2 to 4 ghz range you could have lost it. My first question to you would be, when last did you do a flight system check on your settings in your app. Look at your action settings on controller disconnect ? RTH settings etc ? Then there are anomalies like birds, if had everything from crows to vultures and sparrows go for my drone. Ive also seen craft been taken our by the critters. Then you have the golf club deciding they dont want you flying over their property and raking you out. Here in South Africa most golf courses the management have frequency guns and they shoot the drone out of the sky. So what happened .... ? Difficult to tell because at 5000 ft you have long lost sight and visual orientation of the drone. Hence the golden rule. Fly within line of sight

LOS had nothing to do with this event. You are not helping this thread. SD card recording does not stop because of 5000' distance.

 

[CashCache]

Were any of the video files on the SD card corrupt? If not then a sudden power loss is less likely the culprit. When the power is cut suddenly, the MP doesn't close the file properly and it becomes unplayable.

Do you recall if you powered up the MP with the SD card still in it after getting it back? Doing so would fix that corruption, putting the loose battery possibility back in play.

Either way, pull the DAT file off the MP and upload it to your Google Drive or Dropbox and post a link to it here. @BudWalker will be able to provide you with a very good analysis like he did in the other thread.

Do it soon because the space on the MP is limited and your crash DAT will get overwritten after a few flights.

The video file was fine. It was the first thing I looked at - even before turning on the Mavic. As for the DAT - I wish I was more educated about the DAT a week ago. Unfortunately, it's long gone. All I have is is the TXT file which I've already posted.

 

[CashCache]

Thanks for the .TXT file.
Winds were SSW at about 5 mph for most of the flight. Does not seem to be gusting.

At the very end of the data the voltage drops significantly, however, this is correlated to a doubling of ground speed, so likely normal. In the graph orange is voltage, blue is battery charge and yellow is ground speed.

A separate plot of all three battery cell voltages shows them correlating to each other. The battery health seems ok.

It would seem the loose battery theory may be holding up. Indeed, if you had not gone to a higher speed you might have gotten home even with the loose battery. The change in pitch and possibly vibration may have been the final thing to break electrical contact.

Pure speculation, but the battery probably rode the drone down to the ground.



View attachment 8757

Thank you for taking the time to dig into the data. I'm with you and think the battery came loose, but I may never know for sure.

 

[AlanTheBeast]

I think it has to do with Sport Mode. I think the lipo and the intelligent power management of the battery system kills power in the event of over discharge. I imagine this could happen in windy conditions too if flying in P mode and the craft is expending a lot of power to maintain course stability.

These are just theories so don't take this as gospel.

Maybe DJI should dial back Sport Mode and or outfit the Mavic with a 4S lipo.

It makes me wonder why DJI would display an RPM gauge of the props on their remote. Is it related to power issue? Are the props rated at a certain RPM before breaking etc. Or is it a gauge to see if you are expending too much power in a short period of time.

I looked at the data he posted. Wind appears to be a smooth and constant 5 mph out of the SSW. Nothing about the wind speed or vehicle speed suggested gusts.

When he went to S mode and a higher speed, voltage dropped (see graph above) and the cell voltages all dropped in unison (I didn't post that graph) as the the current rose. Nothing to be surprised at.

You do get over-current warnings, low battery temperature warnings, high temperature battery warnings and RPM max speed limit warning. The drone won't allow over-RPM. (Such a warning may mean it must reduce overall power to maintain altitude but I'm not sure about that).

4S Lipo - the props are very small - enough "wing area" to suck up all that power w/o changing to non-folding props?

 

[AlanTheBeast]

Thank you for taking the time to dig into the data. I'm with you and think the battery came loose, but I may never know for sure.

But I bet you'll check the battery latching more carefully! (So will I !!!!!)

 

[CashCache]

But I bet you'll check the battery latching more carefully! (So will I !!!!!)

That's for sure. I'm even considering a few wraps of duct tape!

 

[Oingo Boingo]

LOS had nothing to do with this event. You are not helping this thread. SD card recording does not stop because of 5000' distance.

I never said it does, his question was WHY DID HE CRASH ! I think the fact that his SD stopped recording is a minor concern. Its like saying yes I crashed my car, BUT WHY DID THE RADIO TURN OFF

 

[AlanTheBeast]

I never said it does, his question was WHY DID HE CRASH ! I think the fact that his SD stopped recording is a minor concern. Its like saying yes I crashed my car, BUT WHY DID THE RADIO TURN OFF

If you've read this thread you'd see that a leading suspected cause is that the battery was incorrectly latched, came loose and disconnected. Nobody knows the cause, but what you propose is really not on the list at all.

I've looked at his logs using HealthyDrones and the signal level was ideal throughout his flight up until the time it was lost. (below).

 

[Capt Drone]

I had the exact same thing happen, except I was a lot closer in. About 2000 feet. Thanks to the guys here, my Mavic was located in a tree a few days later. The battery was laying on the ground. I messed around with the battery and found that it is completely possible to install it a little loose. It is actually hard to get it attached to to point where it works but will eventually come completely void of the contacts but yes, you can get it to do that. From now on I will be very very careful to make sure I hold the Mavic and apply pressure on top and bottom. I remember simply dropping the battery into the Mavic setting on the ground and not picking it up. Here is the complete story of mine.

Mavic Fly Away this evening. Shes Gone!

 

[newnan3]

Ive built up a few racers and usually when something unexpected happens its a bad solder joint (due to my poor soldering skills at the time). So until you know it was a loose battery for sure maybe its better to send it back to DJI....Just my $.02

 

[CashCache]

I've since flown more than 50 times since the big day with no issues at all. In my case, I'm convinced the battery disconnected mid flight.