Mavic 2 EA losing altitude

[jfo]

Hi guys, I know this is not the first thread on altitude issues with Mavic 2, but as far as I know, this one is a bit different. I have owned the Mavic 2 Enterprise Advanced for a little over 7 months. The first time I noticed the problem was approximately a month ago. The bird takes off without any issues. I fly it to 15-20 meter (45-60 ft) height and then it starts losing altitude. Slowly, but surely. It is fully controllable, so I am able to either land it, fly it higher or do anything else. Today I flew it to 15 meters (45 ft) and waited to see what happens. The drone actually slowly came down to 1 meter (3 ft). I then took control and landed.
A few points:
- The problem first occured in December and still persists. This makes me think it may have something to do with the battery warming up
- The issue happens at the begnning of the flight, afterwards the drone behaves normally. After swapping the battery, the problem is back
- When the drone loses altitude, the altitude reading is not working properly. Say I take it 20 meters up and then it loses 10 meters. I would bring it 10 meters higher (back to 20) and the altitude displayed is 30 meters (give or take)
- So far I did not have the guts to try this in the mapping mode

Is this a normal feature and is this simply because I am impatient and take off immedtaley after starting up/swapping the battery? Would waiting after the start-up help?

 

[old man mavic]

@jfo the best way to confirm your theory about battery temperature would be to have a battery in your vehicle and allow the warm air from the heater to give it an initial warm up then put it in the drone and repeat your test ,if it doesnt descend then you will have at least eliminated that as the cause are you using the genuine DJI batteries as these are supposed to have built in heating as part of their spec ,check the manual to see what it says about this feature and how it is activated

 

[jfo]

@jfo the best way to confirm your theory about battery temperature would be to have a battery in your vehicle and allow the warm air from the heater to give it an initial warm up then put it in the drone and repeat your test ,if it doesnt descend then you will have at least eliminated that as the cause are you using the genuine DJI batteries as these are supposed to have built in heating as part of their spec ,check the manual to see what it says about this feature and how it is activated

Hi, yes, I am using the original DJI batteries. Actually, when I fly (say, today) I had the batteries in my office, they barely had the time to cool off significantly. It was just 2 degrees below Celsius and they only have been out f my office (in the trunk of my car) for about 10 minutes.

 

[old man mavic]

Try transporting them inside the car instead

 

[slup]

The best way to figure out what's going on is to check the flight log ... go here and upload your log & come then back here & share the link they provide (description where to find it in your mobile device on the same page) --> DJI Flight Log Viewer | Phantom Help

 

[jfo]

Try transporting them inside the car instead

Thanks, will try.
I was transporting them in the original DJI hard case, so I am not sure if it would work, as they really did not have much of a chance to cool off significantly, but I will give it a shot anyway.

 

[jfo]

The best way to figure out what's going on is to check the flight log ... go here and upload your log & come then back here & share the link they provide (description where to find it in your mobile device on the same page) --> DJI Flight Log Viewer | Phantom Help

Thanks, but I am not sure how this works with the smart controller

 

[slup]

Thanks, but I am not sure how this works with the smart controller

The SC is android based ... plug it into your computer & go to DJI\dji.go.v4\FlightRecord

 

[Not A Speck Of Cereal]

I have flown in very cold weather where the battery temp was below spec, but DJI Go always reports the temp with an error and tells you not to fly. If you are not getting that error, your battery is not out of temp spec.

To get the battery to temp, you can let it sit running, which will warm it up fairly quick but will take eat power.

(Not recommended) I have also on a couple of flights let the bird hover in the air to warm up, but only at a couple of meters. The bird would hover without losing altitude.

Because of that last experience, I'm not convinced that the problem is simply that the battery is too cold. I would definitely post the logs.

PS: I did learn to anticipate cold batteries in winter weather and warm them up in the car beforehand when I could, and keep a spare in an inner jacket pocket.

Chris

 

[brett8883]

Hi guys, I know this is not the first thread on altitude issues with Mavic 2, but as far as I know, this one is a bit different. I have owned the Mavic 2 Enterprise Advanced for a little over 7 months. The first time I noticed the problem was approximately a month ago. The bird takes off without any issues. I fly it to 15-20 meter (45-60 ft) height and then it starts losing altitude. Slowly, but surely. It is fully controllable, so I am able to either land it, fly it higher or do anything else. Today I flew it to 15 meters (45 ft) and waited to see what happens. The drone actually slowly came down to 1 meter (3 ft). I then took control and landed.
A few points:
- The problem first occured in December and still persists. This makes me think it may have something to do with the battery warming up
- The issue happens at the begnning of the flight, afterwards the drone behaves normally. After swapping the battery, the problem is back
- When the drone loses altitude, the altitude reading is not working properly. Say I take it 20 meters up and then it loses 10 meters. I would bring it 10 meters higher (back to 20) and the altitude displayed is 30 meters (give or take)
- So far I did not have the guts to try this in the mapping mode

Is this a normal feature and is this simply because I am impatient and take off immedtaley after starting up/swapping the battery? Would waiting after the start-up help?

How many satellites do you have locked when this happens and how many do you have when it doesn’t do it? Do you have the RTK module on when this happens?

 

[Meta4]

How many satellites do you have locked when this happens and how many do you have when it doesn’t do it? Do you have the RTK module on when this happens?

Even with no satellites, the drone should be able to maintain altitude.

 

[brett8883]

Even with no satellites, the drone should be able to maintain altitude.

I was trying to figure out if this is happening with RTK or not but you are right either way the OP should send it in for repair

 

[brett8883]

BTW the M2EA batteries have a self heating feature. You can have them warm themselves up on the way to where you want to fly.

 

[slup]

All speculations about batteries & GPS is totally irrelevant when it comes to a erratic altitude hold ... not a single mechanism from these have any influence & give a erratic behavior.

-If the battery can't provide requested amperage the voltage will drop ... low enough & a forced auto landing will start, not a gradually descend which can be stopped with a throttle command.

-The GPS height isn't in the equation at all when it comes to altitude hold ... the barometric sensor have full command.

If the OP share the logs (& most likely the DAT log is needed also) we will most probably see an uncommanded ascent from the barometric sensor value & a constant VPS height in that low height hover ... that would make the FC command a descent to fight the (wrongly) indicated ascent coming from the sensor... and as the ascent isn't real, the craft will descend in reality. This behavior have been here on the forum earlier.

 

[jfo]

All speculations about batteries & GPS is totally irrelevant when it comes to a erratic altitude hold ... not a single mechanism from these have any influence & give a erratic behavior.

-If the battery can't provide requested amperage the voltage will drop ... low enough & a forced auto landing will start, not a gradually descend which can be stopped with a throttle command.

-The GPS height isn't in the equation at all when it comes to altitude hold ... the barometric sensor have full command.

If the OP share the logs (& most likely the DAT log is needed also) we will most probably see an uncommanded ascent from the barometric sensor value & a constant VPS height in that low height hover ... that would make the FC command a descent to fight the (wrongly) indicated ascent coming from the sensor... and as the ascent isn't real, the craft will descend in reality. This behavior have been here on the forum earlier.

I agree. The temperature thing only came to my mind as I first saw the issue when it got colder.
A while ago I took it out. It is a few degrees below zero Celsius. The batteries were warm (20°C). The drone worked well, no issues, it hovered at approximately 20 meters, no altitude drop.
Now comes the fun part - I did get to the flight logs in the DJI Pilot app in the SC, but I have no idea how to upload these to the computer/internet
When I use the USB - USBC cable (USB to the computer, USBC to the Smart Controller), it does nothing. I thought I will see the SC in my computer as I would an USB stick, but no. Could you please advice me how to upload them?

 

[slup]

Don't have any detailed knowledge regarding the actual use of an SC, but it should go up as a detachable drive unit if plugged into your computer if you have all necessary drivers installed properly. Don't know if you have any wireless possibilities to transfer files, WiFi or Bluetooth ..?

 

[brett8883]

-The GPS height isn't in the equation at all when it comes to altitude hold ... the barometric sensor have full command.

I think with RTK it’s different. At any rate it should be better with RTK certainly not worse so the drone should be sent in.

 

[CaseyK]

Pardon my ignorance. RTK?

 

[Arnold LeVine]

IMU sluggish when cold vs after warming up? Or possibly altitude barometric sensor ?

 

[brett8883]

Pardon my ignorance. RTK?

Real Time Kinetics. The M2EA is the only Mavic model that has this capability. In a really simplified explanation it uses advanced methods to correct GPS data so you get centimeter level accurate GPS positioning data. It’s particularly useful when doing mapping missions or you need the drone to hover really still.