Please select Into the mobile phone version | Continue to access the computer ver.
P3A automatic low voltage landing at 44% battery
669 12 2016-2-23
Uploading and Loding Picture ...(0/1)
o(^-^)o
Lil' Outdoo
lvl.3
Flight distance : 294777 ft
United States
Offline

Hey guys so i took my p3a out last night in my front yard to get some pics of the full moon and ecountered a strange issue. Starting off, i always get 17 satillites in my front yard and here my quad was struggling to get 8. Since i was just doing a short flight, straight up, take some pics, and straight down, i didt think there was a need for a fully charged battery. My battery was at 48%. I took the quad pretty much straight up, staying over my yard (luckily). Then i get a warning at 44% battery saying "low voltage automatic landing." And just like that it came down and landed, thankfully i stayed over my front yard and the quad landed safely in the grass. I've heard a lot of people saying to never take off without a fully charged battery, and maybe i learned my lesson. After the flight though i checked the cells and each cell was at a heathy 3.7 volts. Im going to do the same flight tonight, with a fully charged battery, staying over my yard, just to be safe. Any tips please help.

Thanks

Lil outdoorsman
2016-2-23
Use props
IMI193
lvl.4

United States
Offline

Your lucky, usually taking off with a battery at 48% results in it shutting off and falling out of the sky  like a brick.
2016-2-23
Use props
dji-p3p1
Second Officer
Flight distance : 534970 ft
Australia
Offline

I have described this "Known" issue in a post: http://forum.dji.com/thread-41951-1-1.html

Do Not Use Partially Charged Packs if at all possible.

If you use partially charged packs, a discrepancy may exist, whereby the voltage of a pack may drop dangerously low, whilst the Percentage indicator still shows sufficient capacity.
  
I believe this has been the issue that many Pilots who have used partially charged packs have suffered from.
  
So the lesson learnt is:
  
  • Charge packs fully before flying.. - Try not to use partially charged packs, especially if they have been left for a few days.
  • If you do use a partially charged pack, then hover for around a minute, and keep a Hawks Eye on each battery Voltage. - if any battery quickly drops to under 3.60v in around 1.5 minutes or less then stop flying and change the battery.
  • Do not use the Percentage as the only indicator to determine the state of the battery. - Turn On "Show the voltage on the main screen" and keep an eye on it. - if it goes yellow and stays yellow, then start to prepare to come back home or land somewhere safe.

2016-2-23
Use props
AG0N-Gary
Captain
Flight distance : 700846 ft
United States
Offline

Also, when flying with less than freshly charged battery, do not use full throttle for anything, unless it is an emergency.  Failure is almost guaranteed at full throttle, as that is when the most load is put on the battery.  Climb slowly, traverse slowly, and be ready for it to land with little or no notice.
2016-2-23
Use props
Dr. Acula
lvl.3

United States
Offline

We really need a fix on this DJI, 50% battery should be just as stable as 100% battery.

Also we'd much rather protect our Phantoms than the batteries.  Let us run them dry to save the aircraft if need be.
2016-2-23
Use props
Geebax
Captain
Australia
Offline

Dr. Acula Posted at 2016-2-24 15:32
We really need a fix on this DJI, 50% battery should be just as stable as 100% battery.

Also we'd m ...

I think this is a popular misconception, nothing it being done to protect the battery in preference to the aircraft. It lands because it thinks there is not enough power in the battery to continue safely, and that is the safety of the aircraft, not the battery.
2016-2-23
Use props
kirk2579
First Officer
Flight distance : 37415 ft
United States
Offline

Dr. Acula Posted at 2016-2-23 23:32
We really need a fix on this DJI, 50% battery should be just as stable as 100% battery.

Also we'd m ...


it probably is ok at 50% battery. if the battery is truly 50%

I believe the issue is that the reading you see--

50%-or as OP 48%--  is only a momentary INACURATE voltage measurement.
think about old flashlight battery that light up bright for a minute then dims out fast......

it is not truly indicative of available battery power needed to fly safely.

ONLY SAFE WAY TO KNOW is always charge full prior to use.....

argue , say it should not be so all you want , it is what it is...
2016-2-23
Use props
Geebax
Captain
Australia
Offline

kirk2579@aol.co Posted at 2016-2-24 16:22
it probably is ok at 50% battery. if the battery is truly 50%

I believe the issue is that the rea ...

Actually it is not a voltage measurement, it is a calculated capacity of the battery. You cannot determine the capacity of a battery by measuring its terminal voltage because that voltage stays at one level almost until the battery is depleted. The only was to measure a battery's capacity is to know how much charge it has been given. That means you need to know the amount of current delivered to the battery, and for how long. This is the value that is displayed as battery capacity. A better parameter to watch is the battery voltage, but you need to know that it can be quite constant right up until the battery is flat.
2016-2-24
Use props
dji-p3p1
Second Officer
Flight distance : 534970 ft
Australia
Offline

Geebax Posted at 2016-2-24 16:35
Actually it is not a voltage measurement, it is a calculated capacity of the battery. You cannot d ...

Geebax..., You Hit The Nail On The Head  Buddy!!!!
Absolutely Correct!

The % Capicity measurements have nothing to do with voltage, it's calculated by the smart circuit in the battery on the basis of what charge goes in must come out, taking into account ineffency which is a standard constant derived by the manufacturer.

So if a partially depleted battery is kept for some time, the smart circuitry remembers the charge state, however there may be some self discharge, or other factors over time, so that the memorised state is NOT the True state, hence a discrepancy may exist, when the battery is reused without fully charging, whereby voltage drops to critical even though the battery "thinks" it's got enough charge!

The only way to remedy the situation is to fully charge, or in some cases, cycle the pack so that the smart circuitry is brought back up-to-date to the actual true state of the battery pack..
2016-2-24
Use props
Geebax
Captain
Australia
Offline

dji-p3p1 Posted at 2016-2-24 21:30
Geebax..., You Hit The Nail On The Head  Buddy!!!!
Absolutely Correct!

"The only way to remedy the situation is to fully charge, or in some cases, cycle the pack so they the smart circuitry is brought back up-to-date to the actual true state of the battery pack.."

Exactly, spot on!
2016-2-24
Use props
Dr. Acula
lvl.3

United States
Offline

That makes sense Geebax, thanks.  I still would like to see an override where I can keep the engines spinning even if the software "thinks" it has no battery left.
2016-2-24
Use props
kirk2579
First Officer
Flight distance : 37415 ft
United States
Offline

Geebax Posted at 2016-2-24 03:35
Actually it is not a voltage measurement, it is a calculated capacity of the battery. You cannot d ...

I think end result is we are saying the same thing, in the end.

misleading measurement of .....
unsafe to fly due to that mislealeading info....

and need to charge to full state prior to flying.

I  simply used the term " volt " due to most users know that term and that is what they read on app. the underlying tech is , well, you know , most don't bother...

take care and good luck flying!

with that battery fully charged always at first take off anyhow.
2016-2-24
Use props
Lil' Outdoo
lvl.3
Flight distance : 294777 ft
United States
Offline

Thanks everyone for the tips! I'll always fly with fully charged battery's from now on.
2016-2-25
Use props
Advanced
You need to log in before you can reply Login | Register now

Credit Rules