I have had this P2 for about 6 months and everything was working fine until about 2 months ago

My P2 h3-3d is flying fine then for no resaon just starts descending even with full throttle.  I have several videos of a 7-8 min flight at 200-300' and start descending back to land at about 20 to 30 feet it just drops out of the sky.  Lights never indicate low battery and I am giving it full throttle and the motors never respond.  it just keeps descending rapidly until it crashes.  I have been able to repeat this problem but not all the time.  It is an intermitent problem which has rendered this aircraft useless until can find a fix.

I have upgraded all firmware as of 12-15-2014
I have replaced batteries in both the TX and the P2
I have changed blades

Any suggestions? Or just throw it away and buy something else?

I would send it to a DJI Service Center for repair.

I have had the exact same problem.  I can be flying the drone and with a freshly charged battery have it lose enough power so that it cannot maintain level flight.  It descends rapidly 30-60 feet, bounces off the ground (thank goodness) and then slowly goes back up.  The entire time I have they joystick full up to get as much power as possible.

I have searched other forums to find we are not alone in this.  Sadly, however, DJI employees responding to your concern in the threads have either not understood what you are saying or not wanting to admit there is a problem.

Let me add useful information that might help you or DJI.  I am an instrument rated pilot of many years and have hundreds of hours in UAV as well.  I haven't written in on this yet because when others did, they were scoffed at indicating "pilot error."  That's bogus.  I have repeated the issue enough to have some thoughts on what "might" be happening and would love to heard from DJI and be given a "reasonable" response before just writing it off as operator error.

First, the brown out (I'm calling it that because I don't want DJI to think the rotors simply stopped) for me has consistently occurred under several conditions.  Density altitude (not altitude), weather, and power in the smart battery.

One thing I have noticed about technical specifications on these drones as they don't report a service limit.  In other words, unlike a manned aircraft, they do not report what the maximum altitude is the UAV can fly to with a full charge.  Weather will offset that.  High altitude and hot weather can really jack an aircraft's flight performance.  It is possible your altitude and weather may have factored into the momentary loss of flight attitude.  However, that shouldn't be enough to cause loss of power.  I believe there is an inherent design flaw with the smart battery that might need addressing.

In every instance I had a momentary loss of controlled flight, the battery was right at the 50% mark.  I am making a hypothesis here.  Could it be that the battery switched cells causing a very brief momentary drop in power delivery?  Maybe.  If that situation was combined with climatological problems like high density altitude, the combination might bring the UAV down.

The times I have had loss of power were in the plains states on a hot day and in the mountains at high altitude.  In the mountains, I hit a pocket of cold air and the UAV dropped, bounced, then  regained power.  

Again, every time I have had the issue repeat itself, the battery has been right at the 50% mark so I come back to smart battery, not operator error.

I am not trying to be antagonistic but I do think more thought should be put into this issue.  I am certainly willing as a scientist to concede my theory may be wrong; however I also think it is wrong in other blog sites to just blame the pilot on this.  I do not believe this is a factor.

My thoughts.  I hope DJI is willing to consider my words and possibly consider looking into this.  It is an important matter.  As the United States is wrestling with laws to restrict UAV use, if drones fall out of the sky, people will cite that as an excuse to restrict them.

Take care and Happy New Year.

Arvada

I have been having this same issue.  I am also a fix win pilot so I understand density altitude and other things you spoke about.  My P2 flew just fine for about a month.  Then out of nowhere I was flying across a field level flight and it just slowly fell to the ground despite full upward thrust on the remote.  My battery was at about 55%.  Since then it has never acted right.  Every flight since it will fly fine for the first couple minutes then its nearly impossible to keep it in the air.  Yesterday I was videoing a job that we are doing at probably 80-100ft and I stopped forward motion.  It fell all the way to the ground.  When I seen it descending I input full up on the controls and it acted as if i had done nothing.  It softly bounced off the ground and then went up slowly.  As soon as I tried to hover it fell again.  This was with an 80% battery.  So this morning with nice cool air no wind and just at sunrise, I pulled a battery off the charger and took the video equipment off it to save weight and took off.  It flew like new for about 30 seconds and then started to loose performance.  Before the battery got to 85% it was flying very slowly.  I landed and switched batteries, put new props on and tried again.  It would barely take off.  With full vertical power it would just barely go up.  I landed and and took off again and it flew right for a few moments before it fell slowly to my lawn.  I am not happy at all.  I got this thing and spend about a grand on fpv equipment so I could film work projects for advertisement.  But I can't do that if I can't trust it to not crash on top of someones house of car.