Unexpected Failsafe landing - Battery issue?

[Jesse_M]

Hello all.

Can you offer some things I can check after a flight yesterday when the bird went into a normal low battery RTH but then went into failsafe landing?

I was high up but not far away so flying into the wind should not have been an issue. Luckily I was able to land it on a road nearby to my home point. No damage thankfully. I am concerned that this happened and want to know why it happened?

Will a flight log show battery data?

Thank you for your help!
-Jesse

 

[msinger]

Will a flight log show battery data?

Yes. You can upload and view your TXT flight log online here.

 

[Jesse_M]

Ok, I will do that this evening. To clarify, I will plug my Samsung tablet into my computer to locate the flight log? I have never pulled a flight log before.

Thank you.

 

[msinger]

To clarify, I will plug my Samsung tablet into my computer to locate the flight log?

Yes. Look for it in "DJI/dji.pilot/FlightRecord".

 

[Jesse_M]

Thanks Msinger! Your help on this forum is always appreciated!

 

[Jesse_M]

OK, here is the flight log.

Phantom Log Viewer - PhantomHelp.com

Lots of red and yellow battery info. In the middle of RTH it went to failsafe @ 38% which seems odd. Can you guys help me determine the issue? Is this battery toast? I flew with it again yesterday but didn't push it far as to be careful of a repeat. I did get a warning that propulsion output was limited to ensure battery health.

 

[msinger]

Your Phantom started auto landing when the battery reached the critically low level. While the automated features are pretty good, they aren't fool-proof. Next time, start returning home before the battery reaches such a low level. It's a good idea to try to be on the ground when or before the first battery cell reaches 3.4V. Your Phantom was quite a distance away from the home point at 3.5V.

 

[Jesse_M]

So 38% is normal for 'critically low'? Or was it strictly voltage that brought it down?

I ask because I have had lots of flights were I fly until RTH kicks in and she comes back home with no problems.

 

[msinger]

So 38% is normal for 'critically low'?

The battery can reach the critically low level at various percentages. Ignore the battery percentage and watch the battery voltage instead.

 

[Jesse_M]

Ok, I appreciate the help. One more question, looking at the log I see lots of red and yellow voltage numbers. Is that part of the problem? Are you seeing that this battery is acting 'off'?

 

[msinger]

Your battery shows a lot of deviations and was at 50% after only 8 minutes. It looks like it might have been pretty windy though, so that could explain the rapidly depleted battery. Try another flight at a lower altitude (e.g. 200 feet) in calm conditions and see if the battery is rapidly depleted again. If so, it's probably time to get rid of it.

 

[Jesse_M]

Will do! I appreciate the help.