Hi I was flying the other day, and after a couple of minutes this message appears Max motor speed reached, the spark was only howering and there were almost no wind, a bit later it just started descending by it self, and I could not control it anymore, so it landed.
Now I’m curious about what May have caused this, I have tried fly empty 3 batteries today and it all seems to be okay now, I was thinking to analyze  the black box to see what went wrong, but I don’t know how to do this?
I have analyzed the flightrecord from Go4 via Assistent 2, and from this it seems like one cell in the battery had to high deviation, it also say “battery power limit will automatically reduce the aircraft’s mobility to ensure flight safety”

Anyone who knows?

Maybe the max motor speed was reduced because of the faulty cell in the battery.

Hi,

My first thought is cold weather cold battery, flying in Norway this time of the year...  brrrrr  cold

But mayby your flightlog will tell it all, so if you like upload your log using this link: https://www.phantomhelp.com/LogViewer/Upload/

Cheers
JJB

JJBspark Posted at 1-19 09:50
Hi,

My first thought is cold weather cold battery, flying in Norway this time of the year...  brrrrr  cold

Hi, I have used this link, and that is where I found out that the batterycell was deviant, but in the DJI Assistent I transferred the black box files, but I don’t know how to read this file, or where to send them for analysis?

But my thoughts where that I maybe was to cold perhaps, but when I flew today it was just 2 degrees warmer in the air, and the battery temp seemed okey, it was between 23-32*C

Looks like everything works fine right now, but it was abit unpleasant when I could not manage to control it with the RC anymore

JohanSpark Posted at 1-19 12:12
Hi, I have used this link, and that is where I found out that the batterycell was deviant, but in the DJI Assistent I transferred the black box files, but I don’t know how to read this file, or where to send them for analysis?

But my thoughts where that I maybe was to cold perhaps, but when I flew today it was just 2 degrees warmer in the air, and the battery temp seemed okey, it was between 23-32*C

it seems like you have a faulty propeller. Please check the air worthiness of your props

i got a warning when flying in cold windy day

check props have battery warm in pocket and drone let it sit for min before flying to warm up

JohanSpark Posted at 1-19 12:12
Hi, I have used this link, and that is where I found out that the batterycell was deviant, but in the DJI Assistent I transferred the black box files, but I don’t know how to read this file, or where to send them for analysis?

But my thoughts where that I maybe was to cold perhaps, but when I flew today it was just 2 degrees warmer in the air, and the battery temp seemed okey, it was between 23-32*C

ok, only if you like do post your flightlog link on this forum others can make up their opinion.

JJBspark Posted at 1-20 04:35
ok, only if you like do post your flightlog link on this forum others can make up their opinion.

I have not tried before, but you mean like this?

https://www.phantomhelp.com/LogViewer/NWXYJP5JI7QOIFPA34E2/

JohanSpark Posted at 1-20 09:15
I have not tried before, but you mean like this?

https://www.phantomhelp.com/LogViewer/NWXYJP5JI7QOIFPA34E2/

Hi Johan,

You did it correctly. You see that your Spark only had 3 minutes of flight before cell #3 got into yellow area.
Either your battery is dead, or it was too cold. Lithium batteries don't like temperatures below +10°C too much. Their internal resistance increases dramatically and that limits the current they can provide, hence the warning you got.
Let the battery warm up to room temp, only then recharge it. When you go flying in winter, put the batteries in a pocket so they stay warm. Put them into the Spark only right before flight. Once the bird is flying, the current flow keeps the battery warm itself, at least for temperature as low as 0 °C.

Cheers,
Wolferl

Wolferl Posted at 1-20 09:43
Hi Johan,

You did it correctly. You see that your Spark only had 3 minutes of flight before cell #3 got into yellow area.

Okey, good.
But yesterday I tried fly with a few batteries from max to empty just to try to see if it happened again, but nothing bad happened then, I only flew a few feet high just in case, so I’m still curious only thing in difference was that it came a little snow that night it fell down, so as far as I know that maybe made the battery absorb cold faster maybe?
Have also inspected the props, and can’t find any cracks or abnormalities on them,
Curiouser and curiouser

JohanSpark Posted at 1-20 09:15
I have not tried before, but you mean like this?

https://www.phantomhelp.com/LogViewer/NWXYJP5JI7QOIFPA34E2/

Hi Johan,

At 64% batt level the total voltage was 10.6, normally its about 11.3-  11.4 volt.

at 77% batt level there was already lack off power, your Spark could not hold its GPS - position.
Never seen this before, but indeed your Spark could not hold its height and slowly descended to zero height.

Mayby the temperature, but in the record is the batt temp written from 18 to 36 celcius at the end of the flight.

better keep an eye on this battery next flight...Max cell deviation 108 mV, i have seen worse deviation without causing problems, so total output Volts just too low.
(blue line = cell #3)
cheers
JJB

JJBspark Posted at 1-20 11:12
Hi Johan,

At 64% batt level the total voltage was 10.6, normally its about 11.3-  11.4 volt.

wow, thank you so much, great work. I better keep my eyes on that battery, can I ask what program you use for analysis?

JohanSpark Posted at 1-20 14:14
wow, thank you so much, great work. I better keep my eyes on that battery, can I ask what program you use for analysis?

And is there anyone who have ever decoded the black box data? bet its alot of interesting info in those files

JohanSpark Posted at 1-20 14:14
wow, thank you so much, great work. I better keep my eyes on that battery, can I ask what program you use for analysis?

this one > https://forum.dji.com/thread-145649-1-1.html

JohanSpark Posted at 1-20 14:18
And is there anyone who have ever decoded the black box data? bet its alot of interesting info in those files

Google for > DATcon  and  CSVview.

Converts DAT files to large CSV files, 'problem' is that you have to know what all values stand for....

cheers
JJB

JJBspark Posted at 1-20 23:00
Google for > DATcon  and  CSVview.

Converts DAT files to large CSV files, 'problem' is that you have to know what all values stand for....

Okey, thank you very much, Ill try this