Mavic 2 EA losing altitude

[BudWalker]

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?

Another possibility is related to the IMU heater. At power on the IMU temperature is raised from ambient until it reaches 65 C. I suspect that during the ramp up a correction has to be applied to the barometric pressure sensor. The error occurs during the ramp up but once it reaches 65C no correction is required. Subsequent flights or batteries don’t show the error because they operate on an IMU that has already warmed up.

Have you tried recalibrating the IMU? Start the recalibration when the M2 is as cold as you can get it.

 

[slup]

Another possibility is related to the IMU heater...

Certainly a possibility, but that usually throw up a screen message about IMU pre-heating.

 

[CaseyK]

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.

Thank you! I spend a lot of time looking up acronyms and couldn't find this one.

 

[BudWalker]

Certainly a possibility, but that usually throw up a screen message about IMU pre-heating.

I’m not familiar with that message - at least I’ve never seen it. But a “pre-heat“ or warm up is always necessary to get the IMU to 65C.

 

[slup]

I’m not familiar with that message - at least I’ve never seen it. But a “pre-heat“ or warm up is always necessary to get the IMU to 65C.

It's there, in GO4 at least ... common if a IMU calibration have been performed in hotter ambients. Got it sometimes for my craft in my early days before learning to calibrate in cooler ambient temps ... & something in the back of my mind tells me that arming can't be done until the message disappears ... but I'm not sure about that.

 

[BudWalker]

It's there, in GO4 at least ... common if a IMU calibration have been performed in hotter ambients. Got it sometimes for my craft in my early days before learning to calibrate in cooler ambient temps ... & something in the back of my mind tells me that arming can't be done until the message disappears ... but I'm not sure about that.

Pre-heat must refer to heating the IMU to the temperature that was the starting temperature when the IMU calibration was done. Between that low end and 65C a correction obtained from the IMU calibration is applied to the barometric sensor data. I was supposing that correction was not right and that an IMU calibration may fix that.

 

[Soaring Hawk]

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?

When attaching SC to computer using Windows do not turn on the controller until connected. After it is connected turn on the controller. It's normal for me to have to wait a minute or two before it connects. It will then let you know it charging at slow speed and you would press ok. Next you will get three options. Charging controller, Transferring Files, and Transferring Photos. Select Transferring Files. You will find the folders on internal storage. You should be able to figure the rest out since you found them on the SC before but if not let us know