In just this last week I have upgraded my old Flame Wheel f450 quad to an f550 hex with new e310 motors, ESCs, and props. Everything else I simply moved from the quad.
The parts on board are:
  - DJI e310 motors, ESCs, and props
  - NAZA M V2 flight controller
  - Zenmuse H4-3D gimbal + GoPro Hero 4
  - Zenmuse GCU for the gimbal
  - iOSD mini
  - ImmersionRC 5.8Ghz transmitter
  - Taranis x8r receiver
  - Turnigy 5000mah 4s 25c lipoly
All of these sum up to about 4.4 lbs or 1.996 kg.

Now, my problem is the battery only lasts ~1:30 in the air before the voltage is too low to fly. When I go to charge it afterwards, the charger only puts ~700mah back into it. I thought maybe it was too heavy at first but according to DJI, the e310 motor/esc/prop set is able to lift 2.5kg without any problems. That being said, I don't see how weight would be an issue here. I have a Turnigy 5000mah 3s 25 lipo that I have tested this on also and it lasted the same amount of time as the 4s. I've done some research and the only idea I have is that the c-rating of the batteries aren't high enough to prevent the voltage from sagging.

If anybody could help me with this issue that would be great!

EDIT: Forgot to mention that the two batteries I tested this on were stored at 40% charge for one month beforehand.

The E310 ESC can take up a decent amount of energy compared to the E300s or the E305s. Have you tried adjusting your voltage warnings? Did you ensure that you changed the cell level from 3s to 4s in the Naza Assistant? Having a higher C rating may help if you have a battery to test.

I have been changing the NAZA's settings every time I switch batteries but I haven't tried changing the default voltage warnings. I'll try that and see if I can get it to run longer.

BlueVista7000 Posted at 2016-10-7 07:28
I have been changing the NAZA's settings every time I switch batteries but I haven't tried changing  ...

Please keep me posted.

DJI-Jamie Posted at 2016-10-6 20:20
Please keep me posted.

I did a test flight with the voltage safety settings on the NAZA adjusted downwards by one volt. This didn't seem to affect it at all. The voltage moved down at a steady rate from ~15.6 to 14.7 for 2 minutes before it started to wobble and I had to land it. When I charged the battery, the charger only put 1065mah back into it. This seems to mean that the battery didn't even come close to being drained. Any other ideas?

BlueVista7000 Posted at 2016-10-8 10:44
I did a test flight with the voltage safety settings on the NAZA adjusted downwards by one volt. T ...

Could you happen to provide a screenshot of your voltage settings from the Naza Assistant Software?

DJI-Jamie Posted at 2016-10-8 21:29
Could you happen to provide a screenshot of your voltage settings from the Naza Assistant Software ...

I have recorded the data from my iOSD mini during a test flight and posted it in this video:
You'll be able to tell in the video that the voltage moves down at a fairly steady rate.
Also, here is the screenshot of my NAZA config: http://i.imgur.com/qboxcJT.png
The configuration should be at it's default settings in the picture and they are the settings I used in my last test flight

BlueVista7000 Posted at 2016-10-10 01:02
I have recorded the data from my iOSD mini during a test flight and posted it in this video: https ...

Do you have any other components in line with the main battery.?

The reason I ask is that with my F550 powered from 10,400mAh pack I noticed my fly time had reduced from an average of 17mins ( AUW of 2.5kg )  down to just over 6 mins after inserting a current sensor in the power train. It was obvious that there was an unacceptable voltage drop across the current sensor which increased as it warmed up as the current draw increased. This translated back to the PMU as a near depleted battery. I decided I could live without the current sensor.

Regards

Nidge

Nidge Posted at 2016-10-9 14:58
Do you have any other components in line with the main battery.?

The reason I ask is that with m ...

I don't have anything inline between the battery and the built in PDB but I have became suspicious of the wire that I used. The wire is 12 AWG and has a very stiff copper inside. Not sure if I'm supposed to be using a wire more like the one on my battery or not.

Neither 5000mah 3s lipo battery or 4s lipo battery, I think you should sure your battery is full chargers, 5000mah 4s 25c lipoly c-rating should in a full charger.

BlueVista7000 Posted at 2016-10-11 00:49
I don't have anything inline between the battery and the built in PDB but I have became suspicious ...

Hey BlueVista7000 - the default wire for the battery on this kit is probably 14 AWG and the components (iOSD, GCU, etc.) are using 18 AWG...  wondering if introducing 12 AWG is a problem.  I've added 18 AWG wire to my F450 build) and everything works fine.  You may also want to double check any soldering that you've done.

If you haven't already, I would check the integrity of the cells on your battery.  I use the EOS Sentry battery checker and it works pretty well...

You want the Max-Min value to be small (delta between cell with max voltage and cell with min voltage).  When batteries start to go bad you'll see this number increase.  I check before/after every charge just to be safe.

On the video you posted, I didn't see the voltage drop below 15.0 v.  Your second level warning is set to 14.4 so why are you landing at 15?  Is the performance / handling that bad that it forces you?  If you could post a video of what you're seeing it would be helpful.

I am also having similar problem with my DJI F550. I am also using Elogger to log the voltages and amperes. My DJI F550 also flies for around 2 minutes max and then warns for battery drain and lands. I was wondering if you were able to find a solution?