Hello

I was flying my phantom3 advanced around halifax. It was a clear day no wind. I played with the drone and used about 10/20% of the battery around my friends house then i flew around the valley and went a good distance. The battery was 50% and it said returning to home. I thought this was strange but let the drone return. Around half way home the drones fpv flickered and i could no longer see where it was from my dji app a message appeared saying activate alternate flight modeipressed cancel.I was not worried as the drone had 40% battery and thought it would easily regain signal as it hadnt had any issues earlier in my flight. I waited around 10 minutes and it didn return.I looked at the location it was last connected and it was not to be seen. I have uploaded my flight to the following site:

https://healthydrones.com/main?f ... _id=GENERALOverview

Please upload here:  www.phantomhelp.com/LogViewer/Upload/

Then paste the link.

It's generally not a good idea to launch with anything less than a fully charged battery.  

Sorry for your loss.  Hope you find it.  

You didn't mention if you started with a fully charged battery. That is important. If your battery was not in use for a few days/week, but showed decent charge, the phantom might have not calculated the percentage correctly and it just flat ran out of power. You should pay attention to battery voltage instead of totally relying on the percentage. Not trying to be harsh, but it is strongly advised not to take off with a partially charged battery, even if it shows 70%-80%. I may be way off base here, but wanted to throw it out there. You may have a totally different issue. The data will help diagnose what happened.

I was able to download and analyse your flight record from AirData.  The first part of your flight is unremarkable and does not show anything out of the ordinary.

At 444 seconds into the flight (7min24sec) the aircraft initiated a Low Power RTH (with 54% battery!).  Your aircraft turned due north and commenced returning home at 300ft altitude, with no stick inputs recorded.  At 518 seconds (8min38sec), the flight record shows a full left-stick-down until the record runs out of data.  Your aircraft was descending quickly to 126ft, and probably lower.  You were heading for the field just north of the indicated house A.  You then flew behind the hillside indicated B further north and interrupted the connection between you and your controller.  It is likely that the aircraft failed to respond to your controller commands any more, and continued to descend at about 9ft/sec for about 5 seconds.  As it was in a low-power RTH already, it continued the course home at whatever altitude it was at.  It is likely that it hit the side of the hill in the area indicated C at an estimated altitude of 80ft.  Try looking in the field east of Thorney Ln and Delph Hill Ln.

Sorry for your loss.

RicardoGray Posted at 2017-8-29 07:45
You didn't mention if you started with a fully charged battery. That is important. If your battery was not in use for a few days/week, but showed decent charge, the phantom might have not calculated the percentage correctly and it just flat ran out of power. You should pay attention to battery voltage instead of totally relying on the percentage. Not trying to be harsh, but it is strongly advised not to take off with a partially charged battery, even if it shows 70%-80%. I may be way off base here, but wanted to throw it out there. You may have a totally different issue. The data will help diagnose what happened.

In the old days of ESC's and LiPo's .... they had a hang-over from the NiXX days of not relating to actual voltage of the LiPo when connected.

The Low Voltage Cutoff was related to a set point ... instead of actually reading voltage and acting accordingly. That meant if you started with a partially discharged LiPo - you could run it seriously low and crash.

Later manufacturers realised the error and corrected it - so the ESC now reads the voltage at start and uses that to arrive at correct % value. Funny though - they have left NiXX with the old format !
So you should see and I know from my own Phantoms and GO ... that it does show the correct values of the state of the battery.

Therefore if OP is stating what he read on screen - then that is what he had.

What is strange is the Warning to change mode ...

The suggestion that it may have struck the hillside is quite possible if it disappeared behind.

Nigel

It's strange that it commenced a low power RTH at 54%.  The RTH speed was 22mph and the roll and pitch was only -5°, which is consistent with the (slower than maximum) speed of a RTH in little to no wind.  We've seen cases on here that have started with a partially discharged battery, and the flight estimates are updated and change while in flight, giving a shorter time or quicker discharge than expected.

solentlife Posted at 2017-8-29 08:45
In the old days of ESC's and LiPo's .... they had a hang-over from the NiXX days of not relating to actual voltage of the LiPo when connected.

The Low Voltage Cutoff was related to a set point ... instead of actually reading voltage and acting accordingly. That meant if you started with a partially discharged LiPo - you could run it seriously low and crash.

Well, thanks for the explanation on the batteries. I did think the voltage displayed was probably correct, but isn't  it possible for the GO app to show percentage of what it thinks is correct, but could be off? Just asking, it seems I read on this forum about those percentages maybe being not 100% accurate. Anyway, I wasn't trying to give bad advise here. I for one, have always looked at the voltages more than percentages.

GO will display what the battery board sends by telemetry ... then the standard LiPo HV table of voltage to capacity is used to display %. Nothing fancy about it all ... regardless of what some think.

The one that is inaccurate - is the Battery LED's themselves as they have a variation of +/- 12.5% ..... so full 4 LED's can in fact be less than 90% ................

Nigel

Have you contacted our Support Team via support.eu@dji.com to report this case? Please tell me your case number, I'd like to look into it.