Today I got critically low battery - landing,  and he aircraft landed right where it was at 54%., lucky not over water ortoo far away Any suggestions. battery was about 17 degrees C.   

Check the flight log for a bad cell - the log should show each cell and the deviation range .... if a cell goes down seriously - the total voltage will be low and trigger auto-land. Once landed and load is off - the cell rebounds and you see reasonable charge as you say 54%. But under load that cell fails to deliver.


Next you could : Fire up the lot and have motor started on the ground but not take-off ... see what battery cells show. One cell should show lower ... as a small load is on ... if you take-off and keep very low ready to land again ... you should see that cell drop even more ...

If that is case ... cells had it and I advise get a replacement battery for flight ...

You can keep this faulty one for bench use ... ie Updating / simulator etc. instead of using a good flight battery.

Nigel

Battery temp is worrisome.

Please upload your log here:  http://www.phantomhelp.com/LogViewer/Upload/

...and paste the link.  The membership may be able to provide additional help.  

site credit:  msinger

Lucky you weren't way out somewhere. Chuck battery!

Is there any warning message in APP? How about discharging the battery and fully charging?

Sounds like your battery needs recalibrated; critical battery should usually occur at 10% +/-  Procedures for recalibrating a battery are numerous on this forum. These intelligent flight batteries can get out of calibration fairly easily especially if not used in a good while and after auto- discharge has occurred.

DJI Susan Posted at 2017-9-18 01:56
Is there any warning message in APP? How about discharging the battery and fully charging?

Thanks everyone, I already recallbrated it,, no warnings or bad cells...I am watching it closely .. I suspect it is a combination of flying with half empty battery on a cold day from now on will fully charge before take off

Good .... Full charge !

Let us know what is outcome ...

On the subject of 'calibration of battery' - that's BS myth !!

Charge up and test by take off but stay VERY close to ground ... see results.

Nigel

GeeDee Posted at 2017-9-24 07:31
Thanks everyone, I already recallbrated it,, no warnings or bad cells...I am watching it closely .. I suspect it is a combination of flying with half empty battery on a cold day from now on will fully charge before take off

I suspect it is a combination of flying with half empty battery on a cold day from now on will fully charge before take off .

If you look at your recorded flight data as recommended in post #3, you'll see the voltage for each cell in your battery for every 1/10th of a second during the flight.
From what you've said, it sounds like you were running a very low battery and the cell voltages must have dropped perilously close to 3.3V which will trigger a critically low battery condition and force your drone to land.

NEVER launch with a partially discharged battery, particularly in cold conditions.
The battery % indicator will give you a false reading.
That's just asking for trouble.
Only fly with a fully charged battery.

Labroides Posted at 2017-9-24 12:06
I suspect it is a combination of flying with half empty battery on a cold day from now on will fully charge before take off .

If you look at your recorded flight data as recommended in post #3, you'll see the voltage for each cell in your battery for every 1/10th of a second during the flight.

Labroides,
Need some instruction on checking battery state in flight log, specifically how is that done?
I can see what the batt was at takeoff and what it is at shutdown, but I cannot tell how to find all this additional data all of you are referring too.  Can you please explain how I can find that info and anything else that might be useful in analyzing my flights?
Thank you

Genghis9 Posted at 2017-9-24 12:54
Labroides,
Need some instruction on checking battery state in flight log, specifically how is that done?
I can see what the batt was at takeoff and what it is at shutdown, but I cannot tell how to find all this additional data all of you are referring too.  Can you please explain how I can find that info and anything else that might be useful in analyzing my flights?

The recorded flight data solves many mysteries and answers many questions.
To read your flight data you upload the relevant txt file from your phone or tablet.
Here's where you upload it and you'll find instructions there:  http://www.phantomhelp.com/LogViewer/Upload/
It provides a very helpful report that includes full battery data and much more.

Here's an example from one I was looking into earlier:  http://www.phantomhelp.com/LogViewer/2ZR9YSZUXAKYXHJLI78D/
You can see that when Olivier flew his Phantom into the lake at high speed, his battery was quite healthy.

GeeDee Posted at 2017-9-24 07:31
Thanks everyone, I already recallbrated it,, no warnings or bad cells...I am watching it closely .. I suspect it is a combination of flying with half empty battery on a cold day from now on will fully charge before take off

Battery is one of the most important factors of flight. Please keep us posted if there is any update.

Labroides Posted at 2017-9-24 13:06
The recorded flight data solves many mysteries and answers many questions.
To read your flight data you upload the relevant txt file from your phone or tablet.
Here's where you upload it and you'll find instructions there:  http://www.phantomhelp.com/LogViewer/Upload/

Thanks for the tip on getting the log
Here is the file
http://www.phantomhelp.com/logviewer/OHZ7LA7TJTTXK0RK5PGC/

GeeDee Posted at 2017-9-27 05:52
Thanks for the tip on getting the log
Here is the file
http://www.phantomhelp.com/logviewer/OHZ7LA7TJTTXK0RK5PGC/

The critical problem with that flight is that you launched with a battery that had been sitting around for a week or more discharging and it showed 58% before you flew.
The % indicator is only accurate if you start with a fully charged battery.
What the Phantom cares about is the voltage the battery can deliver.
Before flying, yours was showing 15V with no load but as you climbed and put it under load, it rapidly dropped to 13.1V at 38 seconds with some individual cells below the critical 3.3 volts.
You continued to drain the battery by climbing and at 41 seconds all cells were now below 3.3V and it's all over.
The Phantom has to autoland because if you pushed it any further, it would have fallen from the sky.

Labroides Posted at 2017-9-27 06:31
The critical problem with that flight is that you launched with a battery that had been sitting around for a week or more discharging and it showed 58% before you flew.
The % indicator is only accurate if you start with a fully charged battery.
What the Phantom cares about is the voltage the battery can deliver.

Yep... fully charge is the lesson here

Strange.......

I had the same error with a battery.....specially with this new 1.11fw...

Just saying....nothing this happen before with old 1.4fw.....