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Pucker factor of 20 on long distance flight!!
1049 15 2015-8-8
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jimcloud74
Second Officer
Flight distance : 1298317 ft
United States
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Ok. So I did the hack this morning for the extra channels and had a minute of oh heck while testing!!! I was at about 90% battery when I decided to put the range to the test. I set out. climbed to around 350 feet and went towards the highway. I switched to "atti" for some extra speed (was showing 45mph with carbon fiber reinorced DJI pprops which I thought was quite a bit faster than normal. May have had a tailwind) and got out to around 6300 feet in 3 minutes or so when I heard an audible "low battery" alert, "return to home in 10 secs". Needless to say, I almost soiled my drawers. I immediately switched to P/GPS", hit RTH then looked more closely at the battery. (I wasn't waiting ten seconds for it to turn around) It was at 70%. I have no proof as the flight log doesn't reflect battery level at time the warning pops up on screen. The return flight was uneventful and I finished out a 13-14 minute flight before landing at 22%. On a positive note, the video was awesome and flawless. Any ideas as to what threw out the low battery warning with plenty of battery left? I am at a loss. Keep in mind that I have flown almost 3 times that distance and never had this happen and the battery is at around 9 discharges. Thanks for your help guys!

Here is where the warning popped up.....
flight 2.JPG
2015-8-8
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gregg1r
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First off, 350 meters elevation?  The fed gods would love you.

Secondly, if using IOS you can monitor each battery cell for voltage, can't remember if if shows capacity.

I suspect that by your spirited flying that you had the battery at it's maximum discharge rate of 20 amps continuous. If that's the case, your lucky that the protection PCB didn't kick in and shut the battery down.

I use some high drain batteries for some hot rodded flashlights. Once the 20 amp rating on those batteries are reached, the PCB pops and the light stops functioning.
2015-8-8
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FlappyBird
lvl.2

United States
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350 meter ??! Hmmm, tell me you meant feet, not meter.

I wonder how the value for 'low battery' warning gets calculated. It might be not the battery status at the time the warning shows up. May be, the controller looks ahead and calculates in the distance from point of take off and the speed you're going at. It might conclude that going at this rate away from home, it will be impossible to return to home with the charge left and send you the warning.
Just a thought...

You landed with 22% charge left because you took immediate action and initiated return. If you not have done that, you probably would have landed with zero % left. Remember you said you might have had tail wind because of the incredible speed. Going back, into the wind, cost you much more energy. You would have run out of juice before you had a chance to get back home. The controller somehow figured that.

But, that's just my own speculation... I could be wrong.
2015-8-8
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jimcloud74
Second Officer
Flight distance : 1298317 ft
United States
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FlappyBird Posted at 2015-8-9 01:13
350 meter ??! Hmmm, tell me you meant feet, not meter.

I wonder how the value for 'low battery' war ...

Sorry that was confusing as I stated it. I live way out in the country and I usually fly a little higher than most to get over the trees. After the return to my location I had 40% left still. I flew around a few more minutes to deplete the battery down to 20%. It was obviously a glitch in the system as I can go 30,000 feet round trip on a 100% charged battery and still have right at 20% left on a relatively calm day. (15k both ways) I was flying atti to get a little more speed for distance. That was short lived however. LOL .
2015-8-8
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jimcloud74
Second Officer
Flight distance : 1298317 ft
United States
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gregg1r Posted at 2015-8-9 00:39
First off, 350 meters elevation?  The fed gods would love you.

Secondly, if using IOS you can monit ...

I have gone the distance several times with this modded with the FPLRV setup but nerves give in at about 15000 feet as the yellow h and green bar kiss. Today I was using 2 9db Omni's and was out 6300 feet without issue with loss of video or lag. I guess my test was successful. I have always just pushed the stick hard forward and let it fly. I have never seen any issues with wide open forward flight. But today, maybe up and forward wide open is too demanding? Maybe that was the difference as I was climbing and forward when this occurred.
2015-8-8
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Willie Wonka
First Officer

United States
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Can you please show us a screenshot of the detailed battery screen on the dji app of that battery you used.
2015-8-8
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Rigworker
First Officer
Flight distance : 52303 ft
Canada
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FlappyBird Posted at 2015-8-9 01:13
350 meter ??! Hmmm, tell me you meant feet, not meter.

I wonder how the value for 'low battery' war ...



Max height says 1334 feet. Is that accurate? That seems a little high to "get over the trees".
2015-8-8
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Willie Wonka
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Rigworker Posted at 2015-8-9 02:14
Max height says 1340 feet.

OH shit jim take that picture down FAST.
2015-8-8
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jbcenterprise
lvl.2

United States
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How did you run your settings on the channel menu?
Auto or custom
2015-8-8
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david.p.mann
First Officer
Flight distance : 17759432 ft
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I fly long distance flights frequently.  Flew several 9000-12000 feet max distance from home point flights today and up to 13,810 feet max distance in the past couple weeks.  I can tell your from experience that on my iOS camera screen there is a remaining battery life indicator bar. On the bar is also an "H" symbol that is constantly being recalculated by the battery software.  This is the "point of no return" i.e., the point at which the software calculates based on distance from home point and remaining battery voltage (percent battery power left) that you need to start returning to home.  If at any point the remaining battery life bar reaches the "H", you will immediately get the low battery warning and the Return to Home will be initiated in 10 second warning.  Of course, you can click on cancel if you wish to keep flying the P3 yourself.  So, on long distance flights, for example the one where I flew out 13,810 feet (2.6 miles), I got this warning at about 12,500 feet out when the battery level was 52% (the software errs on the conservative side when calculating the "point of return", which I think is a good idea.  However, I continued flying further until battery level was 47% because I had flown a non-straight path out to that distance.  I canceled the warning and auto RTH to accomplish this.  Then I flew a straight path directly home and landed with 12% battery.  The low battery warning on long-distance flights when battery level is near 50% point is not a bug or a glitch, it is a SAFETY feature for your protection.  You can fly much longer Total Distance flights of up to 35,000 feet without ever getting this warning until the battery hits the programmed low-battery warning level if your P3 is already approaching or flying within several thousand feet of home point during the last 60% of the flight. In these cases the H point always remains below the remaining battery level bar end point.
2015-8-8
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aburkefl
First Officer
Flight distance : 78612 ft
United States
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gregg1r Posted at 2015-8-9 00:39
First off, 350 meters elevation?  The fed gods would love you.

Secondly, if using IOS you can monit ...

In his version of the post I'm looking at, he *does* use feet - says he went to 350 feet.

To the OP (can't see the post now that I'm in edit mode) you can go to one of those utility sites that produces a comma-delimited file (CSV) and you should be able to see battery status and compare it to your physical position for every portion of the log.

Big relief to come back safe, huh?
2015-8-9
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aburkefl
First Officer
Flight distance : 78612 ft
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david.p.mann@ea Posted at 2015-8-9 15:38
I fly long distance flights frequently.  Flew several 9000-12000 feet max distance from home point f ...

I've tried to play with a number of those calculations - the ones relating to how much battery life remaining relative to how far you are away from your home point.

The built-in calculations for that line take everything it possibly can into account, except one thing - the wind! If you have to fly upwind to get back to your home point, that line will lie to you! Since the wind can be a variable at any point in time, it does not enter into the calculations. Needless to say, it's not always possible/practical to fly upwind on the "outbound" leg.
2015-8-9
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jimcloud74
Second Officer
Flight distance : 1298317 ft
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david.p.mann@ea Posted at 2015-8-9 15:38
I fly long distance flights frequently.  Flew several 9000-12000 feet max distance from home point f ...

Yeah, I am not a virgin to flying like this either. That meter was fine when my pucker moment happened. I always watch that pretty close. As the h moves to the right I become steadily more anxious. When this happened, there was plenty of battery and range left on that meter. I have flown several times since then and not had the warning return. I can only assume that it "errored" due to demanding too much out of the battery all at once. It was probably a fluke. I have flown 17,500k feet 1 way and the h was right on top of the end of the bar. I immediately turned around. I have seen guys keep going but that isn't going to be me. I really like RTH and being lazy letting it fly itself. I especially like how you can speed it up coming home and aim the camera as you like.
2015-8-9
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jimcloud74
Second Officer
Flight distance : 1298317 ft
United States
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Willie Wonka Posted at 2015-8-9 02:16
OH shit jim take that picture down FAST.

What pic Willie?
2015-8-9
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jimcloud74
Second Officer
Flight distance : 1298317 ft
United States
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jbcenterprise@a Posted at 2015-8-9 12:07
How did you run your settings on the channel menu?
Auto or custom

Usually custom works better.
2015-8-9
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jbcenterprise
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jimcloud74@yaho Posted at 2015-8-10 06:03
Usually custom works better.

Thank You for the info
2015-8-9
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