RTH altitude vs low battery
1945 20 2018-3-8
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Bikingdawg
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[size=14.666666984558105px]Flying Phantom 3SE now 2-3 months. Site fishing is the goal so I'm testing limits in an open field. I'm trying to learn all these little nuances so I'm not caught off guard.
[size=14.666666984558105px]I have RTH altitude set at 50 meters and get the 30% battery warning. I hit RTH, it goes to 50 meters, RTH like it should. I take off again, battery 20%. At 10% it automagically RTH but at a reduced altitude, is this right? Makes sense, don't want it to fly high and run outta juice. In the manual it says if low battery warning triggers Failsafe/RTH, 20 meters is the altitude. Is this correct?
2018-3-8
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ALABAMA
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At 10% it's going to land period.  I wouldn't tempt fate.
2018-3-8
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Hellsgate
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Why on earth would you ever want to take off again with only 20% battery left thats just asking for trouble.
At the 10% battery mark it should go into emergency landing mode ie it will automaticly land were it is regardless of wether you are over water or land.
Well thats what my p4p does the p3se maybe different.
But still i would not try testing the limits of low battery situations in theory you should never let your battery get that low.
2018-3-8
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Bikingdawg
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No doubt, just courious, caught me by suprise. Plan is fly till 50%, bring it in. I wonder if boat GPS will interfere with AC signal. Could be several boats in the area.
2018-3-8
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Bikingdawg
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hey i'm with you, I was 3-4 feet of the ground, 60 feet from home. I wanted to know if it would straight out land, or try RTH altitude with 10%. And it did ascend to 20ish feet and flew about half way back before landing.
2018-3-8
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Hellsgate
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I would never risk such an expensive piece of equipment to test out a theory the risk of something going wrong is far too great.
Depending on your circumstances 50% battery is a good return home point but if your drone is close to you going down to 25 -30% should be fine.
Never let your drone go down to the 10% battery limit its not worth loosing your drone over.
2018-3-8
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Texas-Mark
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The OPer said he was just testing these functions in an open field. I see no issue with doing that under controlled conditions.
2018-3-8
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Bashy
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I see no issues here, if he wants to test then thats up to him, plus, its not like he'd just taken it out the car at 20%. He did a flight, he gets a RTH at 30%, once at homepoint he sends it up again starting from 20%, i would class that as the same flight and under the circumstances, open field, a few feet from home (house) testing the drone at a few feet in the air, i dare say no more than a broken prop if it goes boobs up, but thats not likely seen as it would auto land at 10% anyway.

Question here should be, why does he think it did a RTH at 10% and not an auto land, i think my friend, because it was that close to you, that you thought it did a RTH but in fact it just landed where it was? does that sound about right or, did it actually return back to its homepoint and land?
2018-3-8
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Geebax
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Bikingdawg Posted at 2018-3-8 17:05
No doubt, just courious, caught me by suprise. Plan is fly till 50%, bring it in. I wonder if boat GPS will interfere with AC signal. Could be several boats in the area.

' I wonder if boat GPS will interfere with AC signal. Could be several boats in the area.'

GPS is a receive-only device, it does not transmit, so it will not affect anything else.
2018-3-8
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Labroides
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Bikingdawg Posted at 2018-3-8 17:05
No doubt, just courious, caught me by suprise. Plan is fly till 50%, bring it in. I wonder if boat GPS will interfere with AC signal. Could be several boats in the area.

If you are flying from a boat, why would you set RTH to 50 metres?
Are there a lot of high waves there?
Set your RTH height to something appropriate to the location where you are flying.
If you don't want the Phantom burning battery needlessly climbing to 50 metres and requiring a slow descent from up there, set a better RTH height.

Flying until 50% before coming home might not be a good idea, depending on how far you fly from home.
You need to factor in winds and if you are at sea, you also need a comfortable safety margin.
You don't want to be fumbling around when the battery hits 10% because you ran into a situation you didn't anticipate.
2018-3-9
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Bikingdawg
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Hey Bashy, after I got the 10% message it did fly toward home for 10-20 feet before landing. Manual says something about flying within 20 meters of home and landing. So I think that was a successful test. At least according to the manual. I like to see things for myself, real time.  And yes I have discovered, higher and faster equates to less flight time. Especially at 30%.
2018-3-9
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solentlife
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All I can say - is don't go below 25% battery if you can help it ...

My P3S was lost at 13% battery ... at 15% - it went into autoland and nothing I could do altered its loss into the river ...

It made no difference shouting at it that Manual said I could alter it and that it should fly till 10%  ... it ignored that !

Nigel
2018-3-9
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ALABAMA
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solentlife Posted at 2018-3-9 11:39
All I can say - is don't go below 25% battery if you can help it ...

My P3S was lost at 13% battery ... at 15% - it went into autoland and nothing I could do altered its loss into the river ...

Then you didn't have a true  15%.
2018-3-9
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Hellsgate
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Ive read far too many threads about people doing multiple flights on the one battery only to have their drones fall from the sky.
Then they come on here and ask why did it happen.
The answer was nearly always an issue with low power.
That is why i would never try and push my luck to test it but its the op's drone he can do as he likes.
2018-3-9
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Labroides
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Bikingdawg Posted at 2018-3-9 11:00
Hey Bashy, after I got the 10% message it did fly toward home for 10-20 feet before landing. Manual says something about flying within 20 meters of home and landing. So I think that was a successful test. At least according to the manual. I like to see things for myself, real time.  And yes I have discovered, higher and faster equates to less flight time. Especially at 30%.

Manual says something about flying within 20 meters of home and landing.
What the manual says is that if you initiate RTH while your Phantom is within 20 metres of the launch spot, the Phantom will simply land where it is and not fly towards you.
This is unrelated to what you describe.
2018-3-9
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Rodger8
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Labroides Posted at 2018-3-9 00:34
If you are flying from a boat, why would you set RTH to 50 metres?
Are there a lot of high waves there?
Set your RTH height to something appropriate to the location where you are flying.

It is better to be thought a fool than open your mouth and remove all doubt
2018-3-9
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Labroides
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Rodger8 Posted at 2018-3-9 18:07
It is better to be thought a fool than open your mouth and remove all doubt

Umm ... how is that at all related to anything in this thread?

It is better to be thought a fool than open your mouth and remove all doubt

I guess you've learned that the hard way?
2018-3-9
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Rodger8
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Labroides Posted at 2018-3-9 18:32
Umm ... how is that at all related to anything in this thread?

It is better to be thought a fool than open your mouth and remove all doubt

Just my obversation
2018-3-9
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Labroides
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Here's some advice Roger
Posting when drunk isn't very smart.
Turn the computer off and come back when you're sober.
2018-3-9
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Jeff Millard
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Hellsgate Posted at 2018-3-9 12:37
Ive read far too many threads about people doing multiple flights on the one battery only to have their drones fall from the sky.
Then they come on here and ask why did it happen.
The answer was nearly always an issue with low power.

I've been reading this forum for four months, and I agree. Time after time, "I took off with 50%(+ or - 20%) battery, should have been enough." Wasn't.
Personally, all this has caused me to launch with 100% or wait until I can recharge the batteries.

Jeff
2018-3-10
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Bikingdawg
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Should have known this would get outta hand. But, thanks for all your input.
2018-3-12
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