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After flight time low warning RTLactivated and H520 crashed

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Hi members be extremely careful with low battery warnning, after that activated RTL, I lost any commands with dron. Dron flight away from my home position and position of remote control about 250 meters and crashed. Here some pictures.In safety option parameter "return to GCS" set, on altitude 35 m.
 

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h-elsner

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Can you see in logged messages if and what home point was set at the beginning of the flight? Could it be you started at bad GPS conditions near the buildings?

br HE
 
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@mdavud have you wait a couple of minutes from the "welcome pilot" before taking off?
It's important, to give more time to satellites to be hooked, especially to the transmitter...
You can check, before taking off, that the distance from TX and drone is correctly reported.
You should be at least 8 Mt far from drone at take off.
 
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Can you see in logged messages if and what home point was set at the beginning of the flight? Could it be you started at bad GPS conditions near the buildings?

br HE
iI did"t change position all the time, so home position was same as position of remote control.
 
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@mdavud have you wait a couple of minutes from the "welcome pilot" before taking off?
It's important, to give more time to satellites to be hooked, especially to the transmitter...
You can check, before taking off, that the distance from TX and drone is correctly reported.
You should be at least 8 Mt far from drone at take off.
Honestly I don"t know, but dron flight away almost 300 m as you can se on pic (purple line), I can understand 20,30 or 50 m but 300 m it is unbelievable.
 
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Is that one of your normal flying locations or was it a new one? If it is a new location how far is it from where you last flew?
 
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Normal flying location.I have never been in a place that is in the direction where the dron crashed.
UAV: Yuneec H520
Data pilot version: 1.6.92
RC version. 0.39.0
Flight controller version 1.7.116
 
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DoomMeister

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Were you on the first or second low battery warning when this occurred?

What level are your settings for the low battery warnings?
 
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that was a extremely short timeframe between low battery recommend return to land then switching to emergency low battery activating return to launch mode then power loss. what was the condition of the battery before that flight?
 
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theory battery drained fast lost gps due to lack of power the wind took over and took the h520 with it then power so low motors stop. when the aircraft went down was it in a arch or all vertical down to the ground..
 
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20% low battery level
After first low level warning I tried to land, and I almost managed to do it, dron was on maybe 5-6 meters above me, lending gear was on down position, in that position 3-4 seconds I did not touch any commands on RC. After second warning "Flight time low! Activating RTL" dron suddenly lift landing gear, flight up on 35 m altitude. In first moment it seems all ok for me, and I did not touch anything on RC, but then dron flight away from me. I tried to control dron, but I completely lost command on my RC. Dron crashed about 300 m from home position.
 
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More questions.
What was the status of the ST16, both for satellites and power.

As I understand it the when the 520 goes into RTL mode and your system is set for an RTL at the controller's position the 520 goes to where the ST16 said it was. If there are any issues re GPS acquisition by the ST16 (power related or GPS signal) and the 520 has to do an RTL to the controller's reported position the drone may go somewhere totally unexpected.

That scenario fits your flight but without knowing what the status of the controller was it is just a guess and could be totally off the mark.
 
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DoomMeister

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20% low battery level
After first low level warning I tried to land, and I almost managed to do it, dron was on maybe 5-6 meters above me, lending gear was on down position, in that position 3-4 seconds I did not touch any commands on RC. After second warning "Flight time low! Activating RTL" dron suddenly lift landing gear, flight up on 35 m altitude. In first moment it seems all ok for me, and I did not touch anything on RC, but then dron flight away from me. I tried to control dron, but I completely lost command on my RC. Dron crashed about 300 m from home position.
The scenario you are describing is really giving indication that the GPS location of the ST16S was not known to the aircraft and it was going to the last known location of the ST16S that was stored in its onboard memory.

Is it possible you live in that direction and had the system on and bound at your home sometime between your last flight and this one.

Another thing to consider is the time elapsed from the first low battery warning at 20% and the second low battery warning and the auto RTL that went awry. What was the ambient temperature you were flying in? Cold has a very drastic effect on LiPo/LiHV batteries, especially at lower remaining capacity levels.
 
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In mid-January, Yuneec released an update for the H520.
Afterwards, there were some reports that the H520 was developing a strange life of its own.... no longer knew where it was.
Then at the end of January came another update... After that everything was normal again.
Unfortunately, I do not have the version numbers of the firmware in my head.
When did you make the last firmware update? It's been a while... between mid and end of January or end of January, beginning of February?

Gruss Enrico
 
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More questions.
What was the status of the ST16, both for satellites and power.

As I understand it the when the 520 goes into RTL mode and your system is set for an RTL at the controller's position the 520 goes to where the ST16 said it was. If there are any issues re GPS acquisition by the ST16 (power related or GPS signal) and the 520 has to do an RTL to the controller's reported position the drone may go somewhere totally unexpected.

That scenario fits your flight but without knowing what the status of the controller was it is just a guess and could be totally off the mark.
Yea, I also think so.
Tomorrow I will put here last screenshot from ST16S conntroler.
 

Ty Pilot

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If the 520 reacts like the Plus (and I believe it does), upon the 3rd, 'Low Battery' warning - the aircraft automatically switches into 'RTL' mode and will first climb to the prescribed altitude and then will set off towards the last recorded 'Home' point. In the event you wish to deny this; you must flip the mode switch to another mode then back. Assuming you are in 'Angle' mode when this happens you would simply flip to 'Sport' mode then back to Angle - this will cancel the auto RTH.

The other question in this case is: did the 520 record a Home point and if not - why?
 
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3rd, 'Low Battery' warning - the aircraft automatically switches into 'RTL' mode and will first climb to the prescribed altitude and then will set off towards the last recorded 'Home' point. In the event you wish to deny this; you must flip the mode switch to another mode then back. Assuming you are in 'Angle' mode when this happens you would simply flip to 'Sport' mode then back to Angle - this will cancel the auto RTH.
Totally agree with your comments. Also I think the battery could have a faulty sell?
Cheers.
Mike
 

Ty Pilot

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Totally agree with your comments. Also I think the battery could have a faulty sell?
Cheers.
Mike
Perhaps yes, but it would help to know the temperature during that flight and how the battery was prepared. If it was cold, and the battery did not start off with a full charge, then this would be a recipe for thermal runaway. I posted a piece on LiPo's and cold weather flying HERE.

In addition (and again if it was cold), the aircrafts' switching to RTH while at the same time the battery is very low is also a costly penalty - right when the battery can be taxed the least - the aircraft's desire to climb quickly puts a tremendous load on an already depleted battery.

If the OP wishes to post the logs we can take a look and get a better idea as to what happened.
 
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Perhaps yes, but it would help to know the temperature during that flight and how the battery was prepared. If it was cold, and the battery did not start off with a full charge, then this would be a recipe for thermal runaway. I posted a piece on LiPo's and cold weather flying HERE.

In addition (and again if it was cold), the aircrafts' switching to RTH while at the same time the battery is very low is also a costly penalty - right when the battery can be taxed the least - the aircraft's desire to climb quickly puts a tremendous load on an already depleted battery.

If the OP wishes to post the logs we can take a look and get a better idea as to what happened.
Yes in a situation where you have low power reserve, the last thing you want is to allow the drone to hit and continue on RTH. I set my H Plus to 90f as it is unlikely that I will hit any buildings trees etc at that height. Set and forget so to speak. As you said in your last post cancel RTH and land asp 🥵.
Cheers.
Mike
 
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DoomMeister

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I can see that the ulog file was uploaded to the PX4Viewer so if he would just post the link we can see the data on our own and be able to see more of the MAVLink messages. This gives a better picture of what happened.
 

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