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1739 40 1-7 07:22
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marc70
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So after 1 year ownership/flying with 1 very slight glitch a long time ago, my Mini2 started climbing and flying basically out of my control.
RTH had little effect, and kept climbing despite my going down on the stick.
Samsung SM-A520W,  FlyApp v1.4.8(1185)
I've been using this flyapp for a long time as previous updates were unreliable.
-22C outside (l know, colder than should be using, but never been an issue and flying for 1 year in Canada).
I'd like to upload my flight log and maybe somebody knowledgeable can help me.
Should I send this in? I do have carerefresh for 2 years (1 year left).
1-7 07:22
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yogi053
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Minus 22C and you wonder why it does not operate 100%. C'mon Marc! You may have flown in colder temps but I reckon you are pushing it a bit too far. Up to you of course how you fly your drone, but..........
1-7 07:29
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JJB*
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hi,

good idea to upload your flightlog.

Use this > https://www.phantomhelp.com/LogViewer/Upload/

Post the uploaded link on here or just put a cloud link to the log here.

cheers
JJB
1-7 07:29
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marc70
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JJB* Posted at 1-7 07:29
hi,

good idea to upload your flightlog.

Thanks for the prompt reply.
Now how do I find the proper flight log?
1-7 07:31
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JJB*
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marc70 Posted at 1-7 07:31
Thanks for the prompt reply.
Now how do I find the proper flight log?

it is on your mobile device...
in the phantomhelp you can read how to find the log

or use a file explorer on your device, // root/android/data/dji.go.v5/files/Flightrecord

cheers
JJB
1-7 07:35
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Bashy
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From the info provided,  the sounds of it, i dont think its the cold temps, sound like a classic case of magnetic interference, i don't think prop icing would cause it to do this
But yeah, follow the instructions on the link provided above, we will take a look, if you cannot find that folder, its cause its been hidden, you will either need to download an app called X Plore or use a computer/laptop to find the files... then either JJB* or Labroides will give you a detailed analysis
1-7 07:49
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marc70
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https://www.phantomhelp.com/LogViewer/4IVM1B47ZTPB01OYLQCQ
1-7 09:06
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marc70
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finally got it to work
1-7 09:07
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JJB*
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Hi,

Interesting log...

Batt current and voltages fluctuating like crazy.
One part of your flight in ATTI mode

Need better look into the log (now first to cook dinner here...)

cheers
JJB
analysis1.png
1-7 09:24
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marc70
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Yes, was (first time) looking at log, and lots of irregularities going on there. Batteries just out of 1 year warranty. Figures.
Thanks for looking, let me know what you think: should I send it in, try again same/different battery?
1-7 09:31
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dpeagle
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i wonder what the temperature and wind speed was at the point you lost control. the wind chill temperature might have been much lower then -22c. do the logs give any indication?
1-7 12:52
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marc70
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Wind wasn’t bad, wind chill only affects skin, not materials like plastic and steel.
1-7 13:21
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Sean-bumble-bee
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some points
1) as far as I can see the height limit was/is set to 1640ft, the drone climbed to 1605ft.
   I recollect playing with height limits and if a new height limit was set that was below the drone's height at that time then the drone descended to or below, the new height limit.
2) It seems to have ignored the RTH height, 164ft?
3) The VPS height ( the height recorded by the downward looking sensors) is 42.3ft from 26sec to 705 seconds whilst the drone climbed above that. I have had a look at a couple of logs from my Mini 2 and when the VPS is out of range the relevant entries in the log are blank. It might be worth other folks checking their logs to see what the norm is. I have just had a look at the log from my Mavic Mini and it shows the same behaviour as yours i.e. the maximum recorded  VPS height is displayed in the logs whilst the drone it out of VPS range.4) Look at the climb rates, e.g.
@501 sec 1405.2ft
.                    
.
@505 sec 1511.5ft =26ft/s?

then
@521 sec 1490.2ft

.
.
@526 sec 1604ft =22.8ft/s  and this flight seems to have been flown in P mode or RTH mode where the maximum ascent speed is, I believe, 3m/s ~ 10ft/s

CsvView isnt working on this computer otherwise I'd post  graph.

1-7 13:58
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Pleomax
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marc70 Posted at 1-7 13:21
Wind wasn’t bad, wind chill only affects skin, not materials like plastic and steel.
****************
1-7 14:03
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Labroides
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marc70 Posted at 1-7 09:31
Yes, was (first time) looking at log, and lots of irregularities going on there. Batteries just out of 1 year warranty. Figures.
Thanks for looking, let me know what you think: should I send it in, try again same/different battery?

Your drone was behaving very erratically with respect to altitude.
At times it would climb or descend without corresponding joystick input, or even opposite to joystick input.
At other times during the flight it would hold altitude and descend to match the throttle input.
The uncommanded climbing and descending would change suddenly without any obvious reason.
The rate of climb or descent also changed without any obvious cause.

I can't find a pattern to show what the cause might have been.
It's not related to the heading of the drone , which would have indicated obstacle avoidance as the cause.
I can't see any relationship to height either.
The loss of GPS signals for a while and subsequent recovery later is also mysterious.


The drone only appears to have responded erratically in the vertical axis.
Response to rudder, elevator and aileron inputs seems normal during the flight.

This behaviour isn't something that I've ever observed in flight data.
I would suggest referring it to DJI to see what they say.
1-7 14:31
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Labroides
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Sean-bumble-bee Posted at 1-7 13:58
some points
1) as far as I can see the height limit was/is set to 1640ft, the drone climbed to 1605ft.
   I recollect playing with height limits and if a new height limit was set that was below the drone's height at that time then the drone descended to or below, the new height limit.

2) It seems to have ignored the RTH height, 164ft?
RTH height is not a limit.
It can be exceeded or the drone can descend with appropriate control input during RTH.

3) The VPS height ( the height recorded by the downward looking sensors)
There was no problem with the VPS data.
It appears to be normal and working properly during the flight.
It would only be a problem if it showed a low height during the flight when well above the ground.

1-7 14:38
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Sean-bumble-bee
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Would you agree that the drone was above the RTH height when the RTH was initiated and that it climbed whilst in that RTH? .........If so, should it have done so?
Just as a matter of interest how would you then describe the effect of RTH height when a drone is below the RTH height when the RTH is initiated?
1-7 15:25
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marc70
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Yes, my rth was set to a lower height when I initiated it.
When the drone is lower than the rth, it climbs to the set rth height. If it higher it continues to destination, lowers to rth, pauses, then continues to descend. From my experiences.
1-7 16:04
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marc70
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Contacted DJI online chat, initiated a return of drone and battery. They didn’t ask for flight log, unfortunately.
Was hoping it’s just a bad battery issue, but better safe and check the drone too.
1-7 16:08
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Sean-bumble-bee
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For safety's sake back up the entire flight records folder from the phone to computer I'd check to see that the DAT's are backed up to, they should be as the MCDatFlightRecords folder should be copied across in the backup. The relevant dat will have a name that contains the number 039.
1-7 16:28
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Bashy
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Yeah, back it all up, also, you really do not want this to be covered by your Refresh package, this should be covered by warranty, hopefully, Ya may need to argue that point because going by the comments, its not normal behaviour, i cant see the cold causing a vertical issue like this.

I have not even bothered looking at the log myself, the replies from other more knowledgeable members tells me that i couldn't do any better here, good luck for a favourable outcome
1-7 17:19
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Labroides
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Sean-bumble-bee Posted at 1-7 15:25
Would you agree that the drone was above the RTH height when the RTH was initiated and that it climbed whilst in that RTH? .........If so, should it have done so?
Just as a matter of interest how would you then describe the effect of RTH height when a drone is below the RTH height when the RTH is initiated?

Just as a matter of interest how would you then describe the effect of RTH height when a drone is below the RTH height when the RTH is initiated?
RTH will climb to the set height if the drone is lower, but RTH doesn't limit the height.
You can go furtherup or down with joystick while in RTH.
This drone had something unknown that was causing uncommanded climbing and descending, which affected the height of the drone just as joystick input would have.
1-7 18:06
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Labroides
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marc70 Posted at 1-7 16:08
Contacted DJI online chat, initiated a return of drone and battery. They didn’t ask for flight log, unfortunately.
Was hoping it’s just a bad battery issue, but better safe and check the drone too.

They didn’t ask for flight log, unfortunately.
That's pretty slack of them .. it's hard to look into unusual flight behaviour without data.

Was hoping it’s just a bad battery issue, but better safe and check the drone too.
A bad battery won't ever cause uncommanded climbing.


A second flight in warmer conditions would have been interesting to see if the issue persisted or went away.

1-7 18:11
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marc70
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Labroides Posted at 1-7 18:11
They didn’t ask for flight log, unfortunately.
That's pretty slack of them .. it's hard to look into unusual flight behaviour without data.

I still have time to try that, and I’m thinking I might.  
But Bashy mentioned that I should push this as a warranty rather than a Refresh claim, and I agree.
1-7 18:16
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DAYTONA392
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marc70 Posted at 1-7 16:04
Yes, my rth was set to a lower height when I initiated it.
When the drone is lower than the rth, it climbs to the set rth height. If it higher it continues to destination, lowers to rth, pauses, then continues to descend. From my experiences.

No, thats not correct. When the drone is above RTH height, and RTH is initiated, the drone will remain at that height and stay there while returning. The only pause is when it stops having arrived at home and then begins to descend.
1-7 20:33
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Labroides
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marc70 Posted at 1-7 18:16
I still have time to try that, and I’m thinking I might.  
But Bashy mentioned that I should push this as a warranty rather than a Refresh claim, and I agree.

It could be that there's nothing wrong with the drone and the issue was a result of flying in colder conditions than the specs allow for.
Or maybe not.

Without a test flight in different conditions we might never know.
I'd just be curious to see if it exhibits the same behaviour in warmer conditions or if it flies normally.
1-7 23:58
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JJB*
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marc70 Posted at 1-7 09:31
Yes, was (first time) looking at log, and lots of irregularities going on there. Batteries just out of 1 year warranty. Figures.
Thanks for looking, let me know what you think: should I send it in, try again same/different battery?

Hi,

Had a better look, see if i could find some data connections between all values....

First your battery temperature, at start 20 degree Centigrade, last value 40.
But flying in -22 ; craft and motors getting real cold ofcourse....

Just before the RTH down input but your MINI2 started to climb, well indications of baro height values hows that. BUT vertical speed value a minus value!Normal behaviour is : RC stick down, craft height decreases and vert speed shows a minus value. (this minus value within specs as in the manual)

In RTH multiple RC down inputs, height increases and vertical speed shows large numbers down!! (out of my chart y-axis)
Rate of descend up to 42 m/s !  wich ofcourse is incorrect, this belongs to a brick falling down....
I have seen this before in few flights, but not in very cold temp flights though. A warrant case that was, but as you flew your MINI2 in minus -22....

With conflicting data values going beyond a certain threshold drone goes into ATTI mode.
This must be the reason for going into ATTI, as the GPS data isn`t used anymore by the drones FC/IMU ; thus into ATTI.

Amazing to see that ATTI changes into Normal mode again (see chart at Record # 5300), and your MINI2 gets normal values for descend,
craft is loosing height on down stick,  batt volts normal and not fluctuating, same for amps.
Only at record 6482 a high rate of descend in the log, this for short moment. This with a batt voltage drop at the same time.

Lowest batt cell 3.28 volts, wich is not below the critical value of 3 volts.

Would be intersting to see your next flight in 'normal' temperatures with this battery, wich imo is a oke battery.

cheers
JJB




analysis1.png
analysis2.png
1-8 02:39
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Sakari Kaulaote
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I had similar voltage fluctuations when i had my drone gaining altitude by itself, in freezing temperatures also.
Voltage fluctuations were more radical in cell2.
1-8 03:48
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marc70
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https://www.phantomhelp.com/LogViewer/YMPSVFXETXIIU4H5FU6W/
This is another flight log from this year on a cold day, just not as cold (-12C)
I see there were cell deviations, but there were no problems flying.
I'm going to go out on the ice and try my drone again today, with the same battery, and if everything works ok, I'll try another battery.
I'm going to forego sending the drone out to DJI for now.
I'll keep you good and helpful people posted.Thé weather will be rising from -21 to -10C later today.
1-8 04:56
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JJB*
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marc70 Posted at 1-8 04:56
https://www.phantomhelp.com/LogViewer/YMPSVFXETXIIU4H5FU6W/
This is another flight log from this year on a cold day, just not as cold (-12C)
I see there were cell deviations, but there were no problems flying.

Hi marc,

well, not really a flight without issues....

See my chart of your data, fluctuating volts...and baro height also fluctuating.
Baro height line = red coloured where going up / down without RC commands on height.

Same battery in use, battery temp bit colder, now 15 to 30 degrees C.
cheers
JJB
analysis4.png
1-8 05:22
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marc70
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JJB* Posted at 1-8 05:22
Hi marc,

well, not really a flight without issues....

Wow, thanks again JJB, for your time and input.
Wasn’t sure if this was the same battery.
So what do you make of this? Could it be battery related?
I’m thinking the cold weather does have lots to do with this. I just hope it’s not the drone itself as I’ve not crashed it or anything, and it’s been so reliable I trusted it fully (till now) to go way out and always come back.
1-8 05:44
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JJB*
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marc70 Posted at 1-8 05:44
Wow, thanks again JJB, for your time and input.
Wasn’t sure if this was the same battery.
So what do you make of this? Could it be battery related?

Hi Marc,

As the MINI2 is a great reliable drone, lots of power in it if you know how the MINI1 was...

Must be the cold, in this flight after 5 minutes the height was unstable.
So takes about 5 minutes for the craft to get really cold.

My guess is just cold, waiting for higher temps to see what happens than.

cheers
JJB



1-8 05:59
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Labroides
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marc70 Posted at 1-8 05:44
Wow, thanks again JJB, for your time and input.
Wasn’t sure if this was the same battery.
So what do you make of this? Could it be battery related?

So what do you make of this? Could it be battery related?
No the battery can't make things like this happen.
1-8 06:50
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Sakari Kaulaote
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Labroides Posted at 1-8 06:50
So what do you make of this? Could it be battery related?
No the battery can't make things like this happen.

If there is irregular output from the battery is it impossible for the electronics to have some glitches?
1-8 07:00
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Labroides
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Sakari Kaulaote Posted at 1-8 07:00
If there is irregular output from the battery is it impossible for the electronics to have some glitches?

The only way that a battery problem could cause altitude instability would be for a very bad battery to cause the drone to fall from the sky.

It couldn't cause the drone to climb and descend against joystick inputs.
1-8 15:43
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No Original Thought
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Sakari Kaulaote Posted at 1-8 07:00
If there is irregular output from the battery is it impossible for the electronics to have some glitches?

Far from impossible.

In fact an unstable power supply can cause totally unpredictable behaviour in electronic systems.

In something running code this can be anything from erroneous results, freezes or total system crashes/reboots.

This is why manufacturers invest so much in stable power supplies for critical systems.

In something the size and weight of the Mini 2 I suspect that there is little regulation of the power from the batteries and so when operating outside of the environmental limits of the battery you are in dangerous territory - those erroneous results, if not caught by software, could cause erratic behaviour.

Add to that the fact that temperature causes significant changes in electrical conductivity and you could potentially be getting sensor errors as well.

Add these together (or multiply) and the results are anyone's guess!
1-8 15:47
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marc70
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https://www.phantomhelp.com/LogViewer/U5NBRYVXPGH1PNGNBD4F

https://www.phantomhelp.com/LogViewer/A9UZ732K5LOP5SMBRIB3

So these are two flights I did this morning. One with the battery that I thought gave me trouble, and another just to be sure.
-2C, ~46kmh winds @ 100m.

Everything went well, will keep testing so I dont have to send the Mini2 to DJI.
And of course I wont be flying in extremely cold weather for awhile anyways.
1-9 06:18
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JJB*
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Hi Marc,

2 good flights!  so now we know what really cold temperatures does to a MINI2.

cheers
JJB
1-9 06:32
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Sean-bumble-bee
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Marc, the battery serial numbers are or should be, recorded in the log. Download and open the csv's then look in columns EN, 144 and EZ, 156
e.g. 3QFPH9WCA30400 in DJIFlightRecord_2022-01-09_[07-54-38]
1-9 09:04
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digibud
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marc70 Posted at 1-7 13:21
Wind wasn’t bad, wind chill only affects skin, not materials like plastic and steel.

That's generally true and completely true for an item sitting outside that has no heat source but for something that is generating heat, like a battery, wind can have an effect. Wind chill would not be an appropriate term but if you picture something that is warm outdoors in no wind, it will create a area next to the surface that is warmer than the ambient temp. There will be a gradient of heat from the surface to the air outdoor. If you then add some wind that gradient will be blown away (literally) so wind does in fact impact an item that is warmer then the ambient air. Once the item is the same temp as the air the wind will have no effect. I doubt wind has much effect on drones in terms of cooling the batteries down but it might have some. I also fly in cold temps - today it was -20F or so but the temp has surprisingly little effect on battery life - certainly some, but not as dramatic as I would have expected.
1-9 13:51
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