P4P: In-Flight Power Failure

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The law of averages always reveal base flaws. Loss of current points to a source no one can deny barring a 4 motor failure.... All the graphs and power point presentations can Blah, blah, state the monontonous, but the simple explanation pointed out in the crowd best shows a direction that should be at least examined. G-forces even produced by short movement can exhibit surface changes in the very important heart of the Phantom, the battery. Even slight disruptions in the voltage can and will result in the pilot weeping, gathering up the fragments of the eggshell we call "Baby". The drone itself is a miracle, but as all man made tech. has it's fatal flaws. Along with other error prone components, the high current, much needed battery and it's engineered capsule should always be considered as a primary concern. Fly on, but know, it is not without potential devastating result, this beautiful eye of the sky.
 
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Without the aircraft DAT file and an examination of the aircraft, it's really not possible to reach a definitive conclusion on whether this was a battery disconnect. Historically, that's the most common cause, especially with the P4P, but solder joint failures on the main board have also been seen, at least with earlier models.

If it was a battery disconnect then it's also not completely clear whether that is failure to secure the battery latches properly or if there is a design flaw with the P4P. DJI added a latch sensor to the v2. It does seem to be a somewhat common problem though. I recovered a P4P last week from dense forest that apparently suffered the same fate. Interestingly, while the aircraft DAT file clearly showed the voltage collapse when the power was lost, it appeared that the relatively soft impact (a large bush) reconnected the battery, because it rebooted and reconnected to the RC, although the operator was unable to figure out its location. When I found it the battery was in the aircraft but the bottom latch was not secured.

The data analysis and graphing was done in Igor Pro.
I see. It was a relatively new aircraft - we only had 10 hours on that one. First time flying this particular aircraft on the project. It would be nice to have a coin cell battery or something continues to write to the DAT file for 10 more seconds after power-off/power loss. If the aircraft is recovered, you would be better able to analyze what happened.

That data analysis software looks sweet - thanks for sharing.

@GrammatonxXXxCleric, that is worded perfectly.
 
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Thanks for pulling the data and analyzing it. What software are you using to get the display?

Based on the analysis, are we able to come to the conclusion that this was a battery dislodge and was caused by pilot error? Or is it possible that the battery could have dislodged by itself and pilot error cannot be definitely proven?


@Timinator, sounds great idea - I've noticed that electrical tape in close to 100°F weather usually ends up leaving lots of residue. May very well implement that method.
That's the beauty of the medical tape - great adhesion, no residue, reusable, and it won't move.
 
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There's always the Phantom Rain Wetsuit: Home

If battery dislodge is the actual root cause, would anyone be able to explain how the abnormal flight path of the P4P 4 seconds prior to the in-flight power failure links with the dislodge theory? There was no controller input when that occurred. Trying to make sure that all the facts align with the theory before closing the case.
Tape works well and is much cheaper.
 
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It is with no surprise that I hear batteries coming out of p4’s, from day one I was horrified that wiggling in particular one of my batteries caused it to unclip both top and bottom latches. I notice in all p4 crashes and tumbles that batteries are thrown out! I have 3 batteries, 2 of my batteries clip in quite well but they don’t fit properly like my P3 which grips them vice like. I use a little electric tape either side with a folded over end (a tag)enabling me to grip it without having to pick it at the edge to tremor it. There is clearly a design fault.
The batteries are designed to separate from the craft on a crash to avoid a fire that would engulf the quad but maybe DJI should rethink that.
 

PhantomWetSuits

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See, that's the thing - I am very well aware of that issue and make sure the batteries are fully seated prior to take-off (hard press in, check tabs). I had thought of this as a possibility (did not have a graph to reference) and even listed it as the first possibility in the write-up. ...but I also did not keep this as the top theory because the P4P was in the air for approximately 4 more seconds after the last maneuver (throttle up, pitch back, which you referenced) before it cut power - based on DJI GO 4 Flight Records log. Since it was in P-Mode, the P4P did do its "forward pitch" thing to stop once I let go of the controls...not sure if that jolt could cause the battery to become unseated...but the jolt didn't take 4 seconds to happen and the P4P was hovering during those seconds but also did a weird "hook" - see attached image. It sure doesn't look like it was self stabilizing during those moments and there was 0 pilot input during that time. I couldn't see it do that because I was looking at the screen and it was too small of a difference for the VO to pick up but that's what the DJI Flight Record and AirData charts are showing.

Now that you've shown me the graph, I can see also see how the data could align with the other battery dislodge cases. How possible is it for the battery to dislodge without actually moving out from the latch? I know that if you flip the P4 series over and press down, you can get the bottom tab to show but not lose power. Thanks for pulling that graph for me.
So let me give you my DRIVE BY:

Lets forget about the battery as I do not think that was the issue because of these two critical factors you mentioned.

The mistake you made was simply ignoring the Magnetic interference warning thinking it went away. This is not the case , as I show below in this video we made demonstrating that. Once you get that warning , your drone is compromised .

That Compromised means that at any time you drone can loose GPS and Atti mode and or Compass errors are all going to make you crash.

The next thing that was really interesting was the Hook your drone took, this was the key for me as to what most likely happened and that was your drone was crashing most likely before you lost power because a drone cannot hook when it looses power .

We have posted about 300 times about the Issue with the Battery and how we solved it and all the other problems that many have with drone , and even if you have both clips in , if the battery is loose than it can become disconnected for a spit second , just enough to loose power , but the Hook was the doom from the dark shadows of magnetic interference you attempted to navigate in .

Next time , just land and move 15 ft and you have to restart from scratch as this video we made will show you.

That magnetic Interference is no joke and neither is that Battery we have talking about for 2 years now.

Phantomrain.org - Its more than a wet suit , its a suit for armor for your drone.

 
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Oh no you didhnt...

Did someone say drive by? (Sout Centrawl)
 
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Indeed! I actually just watched the whole thing.. ddn't notice the language at the end at first. Homey took that back. Hear meh?
 

Fly Dawg

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Lets forget about the battery as I do not think that was the issue because of these two critical factors you mentioned.
First, you can not discount this factor as a non-cause.

but the Hook was the doom from the dark shadows of magnetic interference you attempted to navigate in .
Second, the hook was explained in Post#16 by @sar104 . A quite credible and normal explanation. This had nothing to do with the incident.

The mistake you made was simply ignoring the Magnetic interference warning thinking it went away.
This is true, that was a mistake, but again that has nothing whatsoever to do with a complete power loss.
 
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sar104

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First, you can not discount this factor as a non-cause.


Second, the hook was explained in Post#16 by @sar104 . A quite credible and normal explanation. This had nothing to do with the incident.


This is true, that was a mistake, but again that has nothing whatsoever to do with a complete power loss.
I completely agree. The magnetic interference issues might have been the main factor had the aircraft switched to ATTI and drifted off, but they are not relevant to sudden power loss. The only explanations for that are a battery disconnect (now looking like a definite issue with the P4P) or a main board power supply or FC failure.
 

PhantomWetSuits

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First, you can not discount this factor as a non-cause.


Second, the hook was explained in Post#16 by @sar104 . A quite credible and normal explanation. This had nothing to do with the incident.


This is true, that was a mistake, but again that has nothing whatsoever to do with a complete power loss.


I did not discount the Battery failure, but I the OP did state that they were very aware of the battery issue and made sure the battery was locked into both clips , now I have to give some RESPECT to that .

So that is why I think the drone was crashing before the power failure , and if the battery was in fact clipped in, it was possible that the jarring of the drone while crashing caused the disconnect to take place if the battery was all loose.

The obvious was the battery, but the OP was sure the battery was in correctly. So that why I was thinking outside the box .
We have video on are site showing how a loose battery can disconnect , and that may be the case.

Do we know for sure yet ?
 

sar104

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I did not discount the Battery failure, but I the OP did state that they were very aware of the battery issue and made sure the battery was locked into both clips , now I have to give some RESPECT to that .

So that is why I think the drone was crashing before the power failure , and if the battery was in fact clipped in, it was possible that the jarring of the drone while crashing caused the disconnect to take place if the battery was all loose.

The obvious was the battery, but the OP was sure the battery was in correctly. So that why I was thinking outside the box .
We have video on are site showing how a loose battery can disconnect , and that may be the case.

Do we know for sure yet ?
Of course we know - we've looked at the log, which simply stops mid-flight in a stable hover. If the aircraft had flight issues, due to magnetic interference, and crashed then that would have been recorded.
 

PhantomWetSuits

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Of course we know - we've looked at the log, which simply stops mid-flight in a stable hover. If the aircraft had flight issues, due to magnetic interference, and crashed then that would have been recorded.
The surface we were launching from is responsible for the errors that you are seeing. After bringing the sUA away from the magnetic surface, the errors went away - as expected. The last minute of the data is what I am curious about. If you can provide any insight on that, please let me know. Otherwise, thanks for the comment. Taking off in that location was a risk that I accepted (being on a construction site) and I paid for it - either because of the location, batteries, humidity, RF interference, other pilot error, or something else.

I was answering this thread above , I was not aware it was so cut and dry already. So according to the LOG , none of this ever happened, well **** that changes everything, **** battery fell out again. lollll

Guess it time for this video again.
 
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Fly Dawg

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The last minute of the data is what I am curious about. If you can provide any insight on that, please let me know. Otherwise, thanks for the comment.
This has already been reviewed and stated. Did you actually look at the previous posts and analysis? If not then @sar104 , may be able to give you a better explanation of the events, although those have been stated already. I would like to hear your alternative version that does not relate to any "errors" that were involved. As was stated, these had nothing to do with the power loss.
 

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The surface we were launching from is responsible for the errors that you are seeing.
By the way, this has nothing to do with your video......no offense to that. But that is completely irrelevant to the discussion.
 

sar104

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This has already been reviewed and stated. Did you actually look at the previous posts and analysis? If not then @sar104 , may be able to give you a better explanation of the events, although those have been stated already. I would like to hear your alternative version that does not relate to any "errors" that were involved. As was stated, these had nothing to do with the power loss.
I'd be happy to help, but I seem to have lost the plot. Are we still discussing the OP's event? What on earth is post #36 about?
 
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On my thread --
Where on God's Green Earth can a person find a P4P Gimbal YR ESC Board?
I mentioned my drone had fell as well. I launched mine from my upstairs porch out over my yard. It's been very hot and humid here in Florida but nice in my home. Potential cause #6 from your report could be the reason on my end. I could still hear the drone motors while it was nose diving to the ground, though the sound was not the same due to motors not loading under the weight anymore, I guess, so I'm assuming voltage was still present.

I feel for you jhPdrones17. I always hate hearing about folks experiencing this. It's almost like loosing a best friend. I may get mine to fly again but just to know it does. I'll never be able to truly trust it completely so I ordered another, the P4P Obsidian. Boy this hobby sure is a financial account kicker, lol.
 

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