Is this normal?

[chessman]

So the UK weather finally cleared up, lovely sunny dry with low wind.
I had been planning a trip to a nearby castle for a week but the weather prevented me.
I got there this morning fully charged (in every way possible) and launched from a nearby park.
After a little skipping over the castle grounds, I was throttling forward when I realised she wasn't doing the same. This was 11 minutes into the flight. Almost seemed to just hover. Then I get a forward propulsion warning claiming to be limiting my propulsion to conserve battery. I still had well above 50% remaining at this point. I have had her flying in the past as low as 15% and never seen this warning before.
Worrying that my throttle stick was virtually disabled I hit RTH and she headed back, albeit slowly.

I am a bit concerned now.

What would have caused this?

 

[msinger]

It sounds like you installed firmware 1.6. This is a new "feature" DJI added to prevent the battery from shutting off mid-flight. If you post your flight log (the TXT file), we can take a look a see. I'm assuming we'll see the battery voltage spike right around that point.

 

[CCDD]

Was it possibly an NFZ you were trying to enter?

 

[4wd]

At 11 minutes in the battery should have been warm enough to be supplying enough power.
Upload the flight to healthy drones you may find one cell is showing issues.
If the batteries have been unused for several weeks a full discharge and recharge will probably be helpful even if you aren't at the scheduled 20 flights.

It's wise to have the voltage show on screen, you might be a bit surprised how much it drops during more aggressive movements even when well above 50%

 

[msinger]

Upload the flight to healthy drones

After you're done, please post the TXT file here too if you'd like us to take a look.

 

[chessman]

Sorry I did mean to add my flight log. I copied it but in my haste didn't paste it in the post.
HealthyDrones.com - Innovative flight data analysis that matters

 

[chessman]

After you're done, please post the TXT file here too if you'd like us to take a look.

Where do I get the txt file from? A link to instructions would be great.
Thanks

 

[msinger]

You can find instructions for Android devices here. And, I guess the best you can do is upload the CSV file if you're using Litchi.

 

[chessman]

Ok... My phone won't open the txt file clearly so I've uploaded the file here :
Dropbox - DJIFlightRecord_2015-12-31_[14-22-07].txt

 

[chessman]

No sorry that's the wrong one lol, hold on

 

[chessman]

Ok this is the correct link, my apologies I was reading the file list in reverse
Dropbox - DJIFlightRecord_2016-01-08_[21-15-57].txt

 

[msinger]

That's not the correct log either.

 

[chessman]

Ahhh crap. Right I'll go right through these. Sorry

 

[msinger]

The filename should start with "DJIFlightRecord_2016-02-07" since it's from February 7th.

 

[Sinisalo]

is it possible that this was caused by a strong wind? The healthydrones log doesn't have any wind data

 

[chessman]

This one is definitely correct.
What should I be using to convert this in order to make sense of it?
Dropbox - DJIFlightRecord_2016-02-07_[09-34-12].txt

 

[ryanmanchester]

The exact same thing happened to me this morning, approx 11,000 into a flight and voltage system fails and rth system kicks in, landed with 2%


Sent from my iPhone using PhantomPilots mobile app

 

[Sinisalo]

there is a strong wind warning in that area for February 8th but I don't know if there was wind on the day of your flight. It certainly could have been more windy at 300+ feet AGL though.

 

[chessman]

I was out yesterday flying in an average wind speed of 15mph with 30mph gusts... My *** was twitching but she was fine. Kept upwind to assist getting back and didn't get a single warning. Today was a slight wind but nothing compared to yesterday.

 

[msinger]

That warning was triggered when your battery voltage was at 3.47V (46% battery), 3.47V (41% battery), and then once more at 3.46V (40% battery). That's an average cell voltage since the log does not show each individual battery cell. Assuming your battery is fairly balanced, those numbers should be close. Your battery was below 50% -- not well above it as you mentioned above.

I don't see any unusual spikes in the battery voltage. It looks like you were trying to fly the battery down too low. You should consider landing when the DJI GO app is showing the battery is at 3.5V (see more details here). Since you continued to fly at that point, the battery was trying to spike below that level. The firmware counteracted that by reducing the throttle.