"Critically Low Voltage. Aircraft will land" with 42% battery left?

[kodiak1120]

I was flying today and I got that message, along with the drone starting to lose altitude. Luckily, I could still control it on its way down, so I aimed it for an open clearing. Right about the point where the video started to break up, the issue must have cleared up and I got control of the altitude again. I brought it up to about 200 feet and flew it home with no problems.

I did a few short flights close by right after and everything seemed fine.

Any idea what's up with the warning message and forced landing?

 

[kodiak1120]

Here's my healthy drones report:

HealthyDrones.com - Innovative flight data analysis that matters

 

[Cyberpower678]

The battery may have a bad cell and intermittently failed during flight. With the voltage too low, it becomes near impossible for the drone to maintain flight altitude and will land to avoid an accident.

 

[Robbyg]

Just taking a guess:
19 seconds into the flight and 106ft away It says you entered Class B airspace and when you went further in and higher up I think it initiated a landing.

Rob

 

[kodiak1120]

No, I get that message all the time and it never autolands. It's also completely wrong because I am not in class b airspace at that altitude.

 

[Cyberpower678]

Just taking a guess:
19 seconds into the flight and 106ft away It says you entered Class B airspace and when you went further in and higher up I think it initiated a landing.

Rob

I somehow doubt that.

 

[Robbyg]

No, I get that message all the time and it never autolands. It's also completely wrong because I am not in class b airspace at that altitude.

I don't know what to tell you other than all bets are off after the last firmware update. If it thinks your in Class B it will do whatever it supposed to do. They did mention something about updating the NFZ in the last update.

That's the annoying thing about DJI, they don't have any clear guidelines as to what a Mavic will and will not do for any given situation. Their is 1000% more info in this forum and in YouTube videos than what DJI tells the customers.

Flying in class B airspace as a recreational pilot
http://www.phantompilots.com/threads/flying-in-class-b-airspace-as-a-recreational-pilot.94507/page-1
Rob

 

[Robbyg]

I somehow doubt that.

I am just reading back what I see:

HealthyDrones.com - Innovative flight data analysis that matters

I have no idea what it does after it determines it's in Class B airspace.

 

[Mavicsailor]

I was flying today and I got that message, along with the drone starting to lose altitude. Luckily, I could still control it on its way down, so I aimed it for an open clearing. Right about the point where the video started to break up, the issue must have cleared up and I got control of the altitude again. I brought it up to about 200 feet and flew it home with no problems.

I did a few short flights close by right after and everything seemed fine.

Any idea what's up with the warning message and forced landing?

It will be helpful to take a look at the .dat file downloaded from the Mavic, if you could post that using Dropbox. Healthy drones doesn't give useful info on the state of the individual cells of the battery, or voltage difference.

 

[kodiak1120]

I am just reading back what I see:

HealthyDrones.com - Innovative flight data analysis that matters

I have no idea what it does after it determines it's in Class B airspace.

If it was that, you'd see A LOT more people complaining because that message pops up ALL THE TIME if you fly within 30 miles of any major airport. Also, the app specifically stated it was landing due to the battery issue.

 

[kodiak1120]

It will be helpful to take a look at the .dat file downloaded from the Mavic, if you could post that using Dropbox. Healthy drones doesn't give useful info on the state of the individual cells of the battery, or voltage difference.

Thanks, I'll post them when I get home later.

 

[Robbyg]

If it was that, you'd see A LOT more people complaining because that message pops up ALL THE TIME if you fly within 30 miles of any major airport. Also, the app specifically stated it was landing due to the battery issue.

So if you knew what the problem was why make a post?

Next time I will know to avoid answering these kinds of questions. I have noticed that most of the senior guys no longer seem to be interested in helping people with these kinds of problems. Now I know why!

 

[kodiak1120]

So if you knew what the problem was why make a post?

Next time I will know to avoid answering these kinds of questions. I have noticed that most of the senior guys no longer seem to be interested in helping people with these kinds of problems. Now I know why!

Don't get all butt hurt bud. I appreciate the suggestion, but that possibility seems to be ruled out. Also, I've flown since then, gotten the Class B warning, and it didn't autoland. I don't know what the issue is, whick is why I posted, but I'm fairly certain it has nothing to do with the airspace issue.

 

[CyberNate]

The only issue I see is that the temperature is a bit low. Flying in temperatures of 32 degrees or lower will drastically affect the battery performance. You started with 42% so the battery was already on the low side. If you are going to fly in colder temperatures, start with a full battery. The craft will warm the battery due to the heat of discharge, but starting too low doesn't give it a chance. Additionally, start with the batteries already warmed up,coming from a warm environment. If they have been sitting in the cold, you'll get poor performance.

 

[Xcel]

You only started with a battery at 42% which might explain the issue, but the voltage drop to 9.989v in the beginning still seems pretty low, especially since the current draw is only under 10A according to Healthy drones. I don't know how accurate that 10A reading is though.

I went through my own logs to try and find a comparable result when I have around 40% battery left and at full whack drawing over 20Amps my voltage still stayed at 10.171v.

Just take a look at the different cell voltages in the battery info screen next time you fly and see if any cell is dropping too much compared to the other.

EDIT/ I did not take cold batteries into consideration. That might have been an issue like CyberNate said.

The battery may have a bad cell and intermittently failed during flight. With the voltage too low, it becomes near impossible for the drone to maintain flight altitude and will land to avoid an accident.

I concur, that sounds plausible.

 

[CyberNate]

You only started with a battery at 42% which might explain the issue, but the voltage drop to 9.989v in the beginning still seems pretty low, especially since the current draw is only under 10A according to Healthy drones. I don't know how accurate that 10A reading is though.

I went through my own logs to try and find a comparable result when I have around 40% battery left and at full whack drawing over 20Amps my voltage still stayed at 10.171v.

Just take a look at the different cell voltages in the battery info screen next time you fly and see if any cell is dropping too much compared to the other.

EDIT/ I did not take cold batteries into consideration. That might have been an issue like CyberNate said.



I concur, that sounds plausible.

Yes, the batteries were likely cold when he started. The process of discharging them will warm them up and they will perform better.

 

[Mavicsailor]

Yes, the batteries were likely cold when he started. The process of discharging them will warm them up and they will perform better.

I forgot to mention in my first post that Healthy Drones also doesn't measure the temperature of the battery or current correctly, at least not for the Mavic. It always says 32f for temp, and 10 amps or under for current.

The max speed on this flight was about 32mph. At that speed the Mavic was probably drawing about 15 amps give or take from the battery. Just cruising fairly slow, it's typically is about 7-10 amps. Full elevator to hit 40 mph is about 22 amps or so.