Low voltage landing

[martinetti]

Hi everybody:

Today I had an undesired landing due to battery critical low voltage. I started the flight with somethng like 70% remaining battery....after several days since my last flight with te same battery. I know: I was wrong, you should never start to fly with less than 100% freshly charged battery.

OK, I learned the lesson because I was very, very close to loose my P3A.

But I would like to share the Litchi flight log just to be sure. You will see a sudden change in Battery Cell values about 6 seconds after takeoff and the aircraft entering landing mode about 32 seconds later (40 seconds after takeoff). I would like to confirm the "not full battery takeoff" issue (my fault) and know if possible, whý it took 32 seconds to start landing mode after an obvious battery problem.

I attach an .txt file, but the original Litchi log file is in .csv format (csv was not accepted at upload time) I hope it works.

Thanks!

 

[Fly Dawg]

I attach an .txt file, but the original Litchi log file is in .csv format (csv was not accepted at upload time) I hope it works.

That file appears to be unusable. Try this link, follow the instructions and upload your log file there, then place a link to that back here. Alternatively, upload your Litchi .csv file to a sharable location such as Drop Box, Google Drive etc...and share that link.

DJI Flight Log Viewer

 

[Oso]

That file appears to be unusable. Try this link, follow the instructions and upload your log file there, then place a link to that back here. Alternatively, upload your Litchi .csv file to a sharable location such as Drop Box, Google Drive etc...and share that link.

DJI Flight Log Viewer

The viewer should accept a Litchi csv file directly.

 

[Fly Dawg]

Finally got it to decode correctly.....Here are your battery levels. This is not necessarily an "Obvious" Battery issue.

 

[Fly Dawg]

From what you mentioned, this may not be the correct flight in question. This flight is over 3 min in duration. Not sure where you are seeing the "40 Second" landing mode. There is nothing in the log referencing that. It appears to be a normal flight.

 

[martinetti]

Fly Dawg, thanks for your help. I followed instructions and this is the link to the log:

DJI Flight Log Viewer - PhantomHelp.com

As you can see, the P3A started Auto Landing Mode 40 seconds after takeoff. I can't understand why, but it seems to recover at 1m 2s reentering P-GPS Mode. But then, at 1m 20s it restarted Auto Landing.I could catch it with my hands while descending, and avoided a crash at 2m 52s, after some random maneuvers trying to understand what was going on. At that point, I stoped motors.

 

[Fly Dawg]

It seems quite odd that you never received any sort of message from the App, regarding autoland. At least there is nothing in the logs to indicate that. That large votage drop you see immediately after takeoff is normal. However, due to the fact that you took off with only 62% battery, that drop appears more drastic. 3.2v is the absolute cutoff point for the battery cells. They were very very close. Had they reached that point the battery would simply shut down. Consider yourself lucky this time. I would suggest that you do not attempt to fly any sort of distance with this battery as of now. What I would try, would be to fully recharge it and do a very close in low altitude test run. Then look at the battery data again. If any of these cells are way off, consider disposing of that battery. Just in my opinion.

Secondly, as I mentioned, it is quite odd that you did not recieve an "autolanding" message. All the manuevering you were doing made that basically a mute point as you were basically overiding it without even knowing it was occurring. I am curious as to either a "Possible" battery issue, or a miscalculation in the FC. You might try pulling the .dat file from the aircraft and share that. If you are interested in that, see this link for instructions: How to retrieve a .DAT

 

[martinetti]

Thanks again for your advice. As you can see, I started Home Lock mode and after a while, I observed a weird behaviour in my P3A. It started to descend, and I couldn't bring it back, just make it climb a little. At some point, I heard the beep tone related with autoland, but I was trying to see where it was going. From my position, I was near to loose visual, so I started to run to the position where it was going to land and arrived there just in time to move the bird in order to avoid some trees. Then, I literally catched it in the air...
I will try to retrieve the .dat file and let you know. Thanks!

 

[martinetti]

Ok

It seems quite odd that you never received any sort of message from the App, regarding autoland. At least there is nothing in the logs to indicate that. That large votage drop you see immediately after takeoff is normal. However, due to the fact that you took off with only 62% battery, that drop appears more drastic. 3.2v is the absolute cutoff point for the battery cells. They were very very close. Had they reached that point the battery would simply shut down. Consider yourself lucky this time. I would suggest that you do not attempt to fly any sort of distance with this battery as of now. What I would try, would be to fully recharge it and do a very close in low altitude test run. Then look at the battery data again. If any of these cells are way off, consider disposing of that battery. Just in my opinion.

Secondly, as I mentioned, it is quite odd that you did not recieve an "autolanding" message. All the manuevering you were doing made that basically a mute point as you were basically overiding it without even knowing it was occurring. I am curious as to either a "Possible" battery issue, or a miscalculation in the FC. You might try pulling the .dat file from the aircraft and share that. If you are interested in that, see this link for instructions: How to retrieve a .DAT

I've got the .DAT file from my drone. I also got a .csv from it using DatCon. I would like to share those files but I can't upload any of these. I will try Google Drive and let you know. Regards.

 

[martinetti]

Ok

I've got the .DAT file from my drone. I also got a .csv from it using DatCon. I would like to share those files but I can't upload any of these. I will try Google Drive and let you know. Regards.

Ok, this is the Google Drive lint to the .DAT file related with this event:

FLY342.DAT

Best Regards

 

[Fly Dawg]

@sar104 , @BudWalker , Am I over anaylizing a battery issue alone? Or is there something that I am missing here. I see no app warnings for auto land, although the OP does state that the "Auto Land" tone was issued. I realize the battery levels were extremely low here and a bad battery is a distinct possibility. My curiosity is no notice or warnings of such in the logs.......Your thoughts?

 

[martinetti]

@sar104 , @BudWalker , Am I over anaylizing a battery issue alone? Or is there something that I am missing here. I see no app warnings for auto land, although the OP does state that the "Auto Land" tone was issued. I realize the battery levels were extremely low here and a bad battery is a distinct possibility. My curiosity is no notice or warnings of such in the logs.......Your thoughts?

Being triggerd by low voltage, Autoland should be a one way event. In other words, should not be an Autoland followed by "normal mode", followed by another Autoland. It seems to happen here. The problem is that once I detected an abnormal behaviour, I concentrated in looking at the drone. I can't be sure about app warnings, but at some point I realized the Autoland being started, due to the beep and (I'm not sure) some screen warning message....

 

[Fly Dawg]

The problem is that once I detected an abnormal behaviour, I concentrated in looking at the drone. I can't be sure about app warnings, but at some point I realized the Autoland being started, due to the beep and (I'm not sure) some screen warning message....

Completely understandable. The fact that there were no indications in the log of any such warnings is unusual. This is why I copied a couple of others that may take a closer look at the data. Especially so, since the AC seemed to cancel it's own autoland and as you mentioned, "Recover" from that event, which is also very unusual. This I have not seen before.

 

[martinetti]

Completely understandable. The fact that there were no indications in the log of any such warnings is unusual. This is why I copied a couple of others that may take a closer look at the data. Especially so, since the AC seemed to cancel it's own autoland and as you mentioned, "Recover" from that event, which is also very unusual. This I have not seen before.

Thanks a lot!

 

[Meta4]

Today I had an undesired landing due to battery critical low voltage. I started the flight with somethng like 70% remaining battery....after several days since my last flight with te same battery. I know: I was wrong, you should never start to fly with less than 100% freshly charged battery.

The % indicator is only accurate if you launch with a full battery.
The voltage is what matters - not the % shown and your voltage dropped to 3.3V within 6 seconds of startup.
Your battery level was much less than you imagined

 

[Fly Dawg]

Your battery level was much less than you imagined

I agree, but it wasn't the % I was looking at. It was the cell values. One would have expected errors or warnings. There were none according to the logs. That is what was and is a bit odd......

 

[martinetti]

The % indicator is only accurate if you launch with a full battery.
The voltage is what matters - not the % shown and your voltage dropped to 3.3V within 6 seconds of startup.
Your battery level was much less than you imagined

Thanks for your help

 

[sar104]

@sar104 , @BudWalker , Am I over anaylizing a battery issue alone? Or is there something that I am missing here. I see no app warnings for auto land, although the OP does state that the "Auto Land" tone was issued. I realize the battery levels were extremely low here and a bad battery is a distinct possibility. My curiosity is no notice or warnings of such in the logs.......Your thoughts?

This was caused by a battery error. The smart battery voltage % dropped precipitously to zero at around 24 seconds and at 45 seconds the smart battery status went to "VoltageLowNeedLand" with associated log entries:

45.958 : 10302 [Ctrl<11>] REQ_BATTERY AUTO_LANDING_HOLD ctrl_auto_landing
45.998 : 10304 [LED] changed: battery error!​

That looks like a faulty battery or battery monitoring system, so I'd be cautious using that battery again.

 

[martinetti]

This was caused by a battery error. The smart battery voltage % dropped precipitously to zero at around 24 seconds and at 45 seconds the smart battery status went to "VoltageLowNeedLand" with associated log entries:

45.958 : 10302 [Ctrl<11>] REQ_BATTERY AUTO_LANDING_HOLD ctrl_auto_landing
45.998 : 10304 [LED] changed: battery error!​

That looks like a faulty battery or battery monitoring system, so I'd be cautious using that battery again.

Thanks sar104. Yesterday I fully charged my 3 batteries and tested them without troubles so far. Anyway, I will be cautious and NEVER try again to fly with a non fully charged battery.

 

[Angry Antelope]

Hi everybody:

Today I had an undesired landing due to battery critical low voltage. I started the flight with somethng like 70% remaining battery....after several days since my last flight with te same battery. I know: I was wrong, you should never start to fly with less than 100% freshly charged battery.

OK, I learned the lesson because I was very, very close to loose my P3A.

But I would like to share the Litchi flight log just to be sure. You will see a sudden change in Battery Cell values about 6 seconds after takeoff and the aircraft entering landing mode about 32 seconds later (40 seconds after takeoff). I would like to confirm the "not full battery takeoff" issue (my fault) and know if possible, whý it took 32 seconds to start landing mode after an obvious battery problem.

I attach an .txt file, but the original Litchi log file is in .csv format (csv was not accepted at upload time) I hope it works.

Thanks!

The exact same thing happened to me! I was flying my P3S over sea and I got the same “low voltage, landing and my drone slowly started to descend towards the sea. I’m sure you can imagine my heart attack. Luckily when the drone was about 10 meters away from the sea I regained control and was able to fly back to land and land safely. Since then I’ve had no probalms with the battery or drone?...