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

[JamesG2571]

A lot of people have mentioned good stuff but there's no point us arguing over this as we don't know the circumstances of the ops flight due to no flight data.

So until we know what the data is we can't be sure what it is! Has anyone checked to see if the ops been active recently?


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[Vertigo]

Here is what happens and to help clear this up.
It's called voltage sag.
So he took off with 32% battery on a cold battery. 32% was correct, the phantoms flight controller is basically a computer and can do simple voltage readings.
Now, he flew around and out 150 feet waiting on the failsafe, to show his buddy. Maybe he full throttled it a few times and that pulls a lot of current, this is where voltage sag comes in. Those quick fast full throttle bursts cause the battery to immediately dip, sometimes drastically. His battery dipped below the required current/voltage to run all four motors and keep the quad in the air. So they cut out and drastically slowed down...no motors spinning fast = no lift = crash.
Now, on the ground, with no load the battery will bounce back to say...20+%. Then you are confused as to why it crashed with 20% battery left and the failsafe did not kick in.
You can test this with a lipo alarm or lipo meter with digital display.
You can plug the lipo meter into a lipo battery (one with a balance plug), start the motors and read the voltage 12.97 volts, hold the quad down and full throttle (load) you can watch the lipo meter voltage start to drop instantly, if it's a low "C" battery, it could dip as low as 10v.
So if you start with 11v and full throttle it or fast maneuver it = voltage sag= not enough power to run four motors and props = gravity = crash.
Okay, we are done here.

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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.

 

[msinger]

Has anyone checked to see if the ops been active recently?

He was on yesterday morning. Perhaps he was too overwhelmed by all of the feedback here

 

[Rynocity]

Are you aware this is a Phantom 3 forum? If you are,...then you have really shown your ignorance in the quoted post above.

Also as you may know it's just not good to use multiple accounts to disagree and argue with members. Basically if you don't have any intention on contributing some positive things to the community, then there's really not much reason for you to stick around, is there?

Paranoid much?

 

[Rynocity]

No its not "wag"

its history and been there done that for the most part.

go back about 6 -9 months back and google the forums about battery and phantom, much discussed and all these questions have been gone over and over.

good luck and have fun flying!

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.

 

[Rynocity]

This board is ridiculous. Everyone loves using old firmware, while there is some good reasons to use new firmwares. Use a battery at 90% and people will blame you for any crash, even when there is 0 evidence that it was caused by that. Nobody can point to any scientific reason why that would be a problem only with this one device(or really any facts about anything, anecdote trumps logic here). There's a hive-mind mentality, where previously formed BS becomes fact over time until the group think is so entrenched that nothing will disrupt it.

Back to your previously scheduled circle-jerk.

 

[msinger]

This board is ridiculous. Everyone loves using old firmware, while there is some good reasons to use new firmwares. Use a battery at 90% and people will blame you for any crash, even when there is 0 evidence that it was caused by that.

Welcome to the Internet. Don't believe everything you see.

 

[SimonH78]

Sorry but these P3's will fly on less than 10% even down to 0% - they don't just STOP - something else must be causing the total shutdown in flight ?...

 

[JamesG2571]

Too many opinions not enough facts. Hold off on the accusations. We need to see data so we can really see what caused this crash and we can then see if it's something that might effect us.

Till then, fly the same you way you have done for months/years. Have fun and safe flying


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[m0j0]

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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[Rommel]

I think the issue about battery charge and flying is when the FIRST flight of the day is started with a less than fully charged battery.

If one is flying and simply lands , for short time and re takes off the issue is not so much..

The reason is the first case (battery sitting and maybe into self discharge mode) the actual charge level is a GUESS.
the second case the charge has been calculated and known by the system is much more accurate.

good luck and have fun flying!

Thank you. That explained a lot

 

[flyNfrank]

Sorry but these P3's will fly on less than 10% even down to 0% - they don't just STOP - something else must be causing the total shutdown in flight ?...

In the history of the battery issue. and prior to a firmware update1, several P3's were dropping out of the sky. The pilots at the time that were flying full throttle for a length of time were reaching unsafe loads on internals. So dji set the batteries to shut down. After it cost dji hundreds of thousands in warranty claims they finally revised the firmware. Since cold weather is known to reduce the smart battery performance, dji in turn took performance away from the P3's once the air temp drops below around 65-70 degree.

Too many opinions not enough facts. Hold off on the accusations. We need to see data so we can really see what caused this crash and we can then see if it's something that might effect us.

Till then, fly the same you way you have done for months/years. Have fun and safe flying
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I'm beginning to think the OP doesn't have actual flight data.

 

[Billisminimus]

Have data, had to wait for computer to upload it though and have work will post when I get home but here is pic of right when it went down....

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[Billisminimus]

Also the firmware is up to date on both the bird and the remote


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[Trackman1]

The Flight Log.txt file is only about 1 Megabyte in size. Upload is fast.

 

[Billisminimus]

I got the .Dat file but with it zipped it was 100mb thought it was the right file


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[Billisminimus]

How do I upload the txt from my phone?


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[Meta4]

How do I upload the txt from my phone?

Forget the .dat file.
Go to https://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight record.
It will only take a minute.

 

[Billisminimus]

Ok, I will have to do that once I get home from work in another 5 hours....


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[Fifty7]

newbie here - sitting at my desk waiting for UPS and my Phantom 3 Advanced. I have a quick question regarding the responses to the OP question. I have been reading and watching videos to educate myself before flying for the first time. I have seen posts stating that you shouldn't charge a battery unless it is dead (so don't recharge say a battery that is at 60%). So what do you do to discharge the battery if it is unsafe to fly? Don't mean to start back up the conversation about whether you should fly with a battery thats fully charged or not and Sorry for the thread hijack but thought it was ok since it was based on advice given here.