P3A fell out of sky... can someone look at data and explain???

[skipilot1]

I guess that means that not everyone on the internet has read your posts.

There's too much victim blaming on this board. How would a new DJI customer know that their batteries need to be fully charged? Is there some kind of warning before you buy one? Is it on the box? No, well then DJI should replace it, fully charged before flight or not.

I've also never seen anything but anecdotal evidence that this is true. I know frank will come say, "Every time I see a post about a bird falling from the sky, they took off with less than 100% battery." Well, duh, most people take off and land multiple times per session. Odds are that most failures will hit people who have taken off with less than 100%.

The manual is quite clear, so yes there is a warning. My best guess from reading these posts is the battery percentage is incorrect. What you may be seeing is something analogous to the software telling you there is 35 per cent of a battery that started with a 65 per cent charge.

To really know what is going on, the pilot should always be using a pre-flight check list no matter how many times it has flown. This should include checking the sensor readings for IMU and compass along with a battery check. I bet a look at the cells and the voltage would indicate it is not safe to fly.

 

[Rommel]

I saw the a bit of a voltage drop in one cell, but the AC corrected the situation and continued. I didn't see any data of the actual crash though. In my eyes it shouldn't have crashed. DJI is mass marketing these drones. This is not marketed towards the pro who would pick up a small variance and recognize it as a hazard.

Could this be like the old laptop batteries. After a while they can't hold a full charge and just die when the computer "thinks" the battery is at 30%

 

[msinger]

Billisminimus, your log indicates that your flight ended here:

Is that accurate? Or, is there another log file?

 

[kirk2579]

That's telling me to go find proof, do you expect me to read every post on the forum to back up YOUR claim? People who make up stuff always do that. You just believe the hive-mind wisdom here, which is fine, but don't try to make up reasons why it's true because you look silly. If you have some proof, lets see it. You're basically saying the phantom is the only device that can't factor load into it's battery calculations. My cellphone can accurately measure the battery at near 0%(less than 1%) load, my roomba can do it, my tablet can do it.

yep I am telling you to find what you want to know!

does your romba have a coded discharge point that auto discharges your battery in some manner, does your cell? didn't think so.
so maybe there is a difference between those products and how they use/control the battery...

I know what has worked for 6 phantoms so far without loss, so even if its voodoo I'll keep believing.. and unless your my wife I have nothing to prove to you or care too.
besides I doubt anyone will be able to prove anything to you... but that's only opinion.

 

[kirk2579]

I don't know that it is an issue to fly on a partially charged battery anymore. I do know that they have addressed the issue in firmware updates. That being said, I still don't fly unless I have a fully charged battery. About all I will do is takeoff and after checking exposure... Land make an adjustment and take off. If I actually put the bird away to change locations I use a new battery.


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+1
its just so easy to do and it has brought all my phantoms home in one piece by doing so!

 

[Mark The Droner]

...
besides I doubt anyone will be able to prove anything to you... but that's only opinion.

Yes - that's the thing about internet forum discussions debating two ideas - the discussions are only worthwhile if both parties are reasonable.

 

[Billisminimus]

I posted flight log if anyone wants to look....


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[Mark The Droner]

Pls see post 103

 

[HWCM]

Voltage sag is real enough, but that doesnt explain the misinterpretation by the phantom or its smart battery. Regardless if you take off with a full or partially depleted battery, if 32% indicated charge can result in a voltage dip below cut off, then either the battery was not at 32% or the battery has a woefully inadequate C rating. Either way, it would mean you should never fly a battery that low, even if you took off with a full battery. That doesnt make sense.

As for the battery reading after a crash; with a regular lipo you will see the voltage restore after a flight (or crash), but its capacity of course remains the same. You can not deduce capacity from voltage alone, you need to take load in to account (and thus voltage sag), which the phantom surely and clearly does.

Either way, I would recommend everyone to monitor battery voltages in flight. The capacity indication may be bugged or not accurate, but voltages dont lie. At least I hope they dont lie on the phantom. Interpreting voltages under load/no load requires a bit of understanding of lipo discharge curves, but just look at them and learn, so you'll be able to tell when the smart battery is being utterly stupid.

Well said.

 

[Billisminimus]

My bad, no it actually crashed about 50 feet to the south of there is I guess it was close....


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[Billisminimus]

It's odd that when I got to drone it was still powered up and trying to run gimbal even though it broke off, looking at log and the flight it seems as though it shut off completely


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[msinger]

My bad, no it actually crashed about 50 feet to the south of there is I guess it was close

Do you have another TXT flight log for the end of the flight?

 

[Billisminimus]

That was last file, there was nothing after it


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[msinger]

FYI, here's the complete CSV from DatCon.

 

[msinger]

According to the DatCon KML and CSV (and your TXT flight log), you did a CSC on top of your neighbor's house. Your sticks were in this position at that time:

 

[m0j0]

The dreaded CSC again. That is no bueno! I have said this before. I think the app should provide options for the operator to select. I still would like to know why the OP had his sticks in that position.

 

[ElGuapo]

The dreaded CSC again.

I am sorry for the ignorance but what is "CSC" ??. trying to learn from this forum as much as I can, and I hate to say this, but trying to learn from OP's errors..

 

[msinger]

CSC = Combination Stick Command

 

[Billisminimus]

Didn't know what csc was, was turning a spinning drone in the down position just showing friend how responsive, so that's a pilot error then huh? I didn't know that would shut motors off what is it anyways?


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[msinger]

Yes, it was pilot error. See my link above.