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RTH Altitude Ascent and Battery Overcurrent Discharge Warning

rydoleary

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Hey all -

I'm new to flying, but I've been cautious in beginner mode getting a handle on the settings and controls. Today I decided to play around a little more practicing manual landing and take offs and playing around with camera settings at relatively low alts outside of beginner mode. I've been a bit nervous to really use any 'autonomous' features because I'd rather be in control of my mavic instead of software, but I figured the space was large enough to try out Active Tracking and an RTH landing. So, I tried it - reached the height of 30 m that I set beforehand and then I got a Battery Overcurrent Discharge Warning - at which point it then rocketed up 850 feet out of sight. Tried stopping the RTH and I also tried bringing it down manually but nothing worked until it got to the max altitude, at which point I then had to manually land it which was fine, but freaked me out because I couldn't see it beyond the video / GPS.

I tried reading into it, but the only threads I found were related to sports mode and temperature related issues. From what I understand, the warning shouldn't trigger an increase in ascent velocity (from a point of 0 velocity to begin with). Also, watching the flight log on the app, the vertical speed is 0 while the mavic swiftly launches to 850 ft in the air.

The weather was ideal too for playing around.

Any help understanding this more would be appreciated. I synched my flight info with Airdata to try to get more info out of the flight, but I'm not entirely sure how to look further into the issue.
 
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Reactions: radman
Check out your TXT flight log to see if it explains what happened. You can upload and view it online here. If you'd like other people to review and comment on your flight log, then please post a link back here after you upload it.
 
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Reactions: Timbo~SYD
So I checked it out.. same info I got viewing the CSV. Here's a link DJI Flight Log Viewer - PhantomHelp.com

I'm thinking that obstacle avoidance had something to do with the sunlight on the sensor? So it thought, hey I'm going to launch myself up away from it... 700 feet higher than set to. It switched modes a few times too - RTH initiated at ~ 32 ft to ~ 85 feet where it switched from Go Home to Positioning... which ended at 105 feet, and then switched to Forced Landing noting Obstacle Avoidance turned off... at which point it continued to ascend and then the Battery Overcurrent Discharge Warning happened at 110 feet and then climbed 2 - 5 fps until it reached max height ~850 - despite the message highlighting max flight altitude reached at 450 ft. Forced Landing still noted as it came down after reaching that height until it finally landed. All these changes in modes never a consequence of interacting with controls.
 
Your Mavic auto switched into Forced Landing mode a few times because the downward sensors were detecting the ground was near (even though it wasn't) while you were holding the left stick (throttle) in the full down position. When the Landing Protection setting is enabled, the Mavic will also auto ascend to get away from the ground when it thinks it's hovering too low. If the downard sensors continue to detect the ground is near, the Mavic will continue to ascend.

Here are the usual cases where the downward sensors incorrectly detect the ground is near:
  • Something is dangling beneath the Mavic (e.g. a GPS tracker antenna)
  • A 3rd party accessory is installed beneath the Mavic (e.g. extended landing gear)
  • The sensors needs to be calibrated like this
  • The sensors are dirty and need to be cleaned
  • The sensors are damaged and need to be replaced (not a common problem)
FYI, if this ever happens again in the future, you can remedy it mid-flight by disabling the "Landing Protection" setting in DJI GO. That'll at least allow you to get your Mavic back down to the ground safely.

DJI-GO-Landing-Protection.jpg
 
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Reactions: Timbo~SYD
Got it. So - other fact: I made sure all the sensors were clean before takeoff / nothing was attached to the device or obstructing them. I'm going to try calibrating the sensors and attempt a RTH in a less restricted airspace in the event that it does rocket beyond 400 ft again. Thanks for your help. I would assume if it happens again the sensors were damaged out of the box.
 
I would assume if it happens again the sensors were damaged out of the box.
It's possible, but make sure you carefully check everything listed above that item in the list above before going through the repair/replacement route.
 
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Reactions: rydoleary
FYI, if this ever happens again in the future, you can remedy it mid-flight by disabling the "Landing Protection" setting in DJI GO. That'll at least allow you to get your Mavic back down to the ground safely.

Thanks that’s a great tip! [emoji1303]
 

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