46% remaining battery , only 175ft away and suddenly "The remaining battery is only enough for RTH. Return home now." What happened?

[saxotenor]

Hello guys,

Last week, I used my MA for a quick & short flight. Just after take off, while MA was only 175ft (53m) from Home position and remaining battery capacity was at 46%, I got the alert message: "The remaining battery is only enough for RTH. Return home now".
It is the first time I had such a bad experience. I have checked the logs and found nothing strange.
Did I do something wrong? Could someone explain me what has happened? Very first time for me to get such an unexpected warning? Have you had such a experience as well?

Thanks a lot!

 

[dawgpilot]

I took a look at the log and didn't see anything to explain that message either. Maybe one of our resident experts has a better idea why that message occured?

DJI Flight Log Viewer | Phantom Help

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[ZX14-R]

You didnt change change settings ??

 

[saxotenor]

No I haven't changed any settings. I made 2 other flights on the same morning without any issues.
Very strange to me indeed. And I do not know which settings may have justified such a notice.
Please note, the notice occurred only once in the flight log. Could it be a bug? Have anyone experienced the same before?

 

[bobscheel53]

Hello guys,

Last week, I used my MA for a quick & short flight. Just after take off, while MA was only 175ft (53m) from Home position and remaining battery capacity was at 46%, I got the alert message: "The remaining battery is only enough for RTH. Return home now".
It is the first time I had such a bad experience. I have checked the logs and found nothing strange.
Did I do something wrong? Could someone explain me what has happened? Very first time for me to get such an unexpected warning? Have you had such a experience as well?

Thanks a lot!

One of the cells might have been sinking faster than the others. I've heard that the battery self discharge can drain them unevenly and if you launched without a full charge this can happen.

 

[saxotenor]

Hello
Based on the flights' log, all 3 battery cells were at the same % of charge. The battery was fully charged the day before, I simply had short flights before starting this one...

 

[Keule]

I simply had short flights before starting this one...

This what Airdata.com reveals from your log related to the last flight battery cells:

 

[saxotenor]

Thanks Keule,
So when the pop up showed up, at 10m46s, there were no strange behavior from the cells. Deviations between cells < 0.02v and no significant drop of voltage (quite stable around 3,73V).
Still a mystery...

 

[MikeC]

What is your RTH altitude? I had the same problem and noticed I fat fingered the altitude to 500m instead of 50m.

 

[Deleted member 94047]

What is your RTH altitude? I had the same problem and noticed I fat fingered the altitude to 500m instead of 50m.

Ouch!

 

[saxotenor]

Oh I think you've got it Mike! You're right, my RTH altitude was 500m...
Thanks a lot!!

 

[Deleted member 94047]

Oh I think you've got it Mike! You're right, my RTH altitude was 500m...
Thanks a lot!!

Yup! It's right there in the log. Wonder how everyone missed that. You are lucky it was near. Imagine the AC was a significant distance away, you lost signal, and it started climbing to the set RTH height. It would never make it back to home.

 

[DanMan32]

I hadn't thought about RTH height affecting battery threshold to RTH. That does make sense since it has to consider the energy to go up to 500m and then back down.

 

[bobscheel53]

Learned another new one. The best advice I can give a newbie is read this forum for all the ways to lose or destroy your drone and don't do that. Lol

 

[Deleted member 94047]

Learned another new one. The best advice I can give a newbie is read this forum for all the ways to lose or destroy your drone and don't do that. Lol

This! I don't quite remember how I stumbled on to this forum. But I dread to think what kind of a flyer I would have been had I not. Or if I would still have a drone to fly ...

 

[MikeC]

Oh I think you've got it Mike! You're right, my RTH altitude was 500m...
Thanks a lot!!

When I first saw the issue I asked in another forum and some guy told me to Read the Manual. Figured it out on my own, glad I could help someone else.

 

[Tyani7505]

Thanks Keule,
So when the pop up showed up, at 10m46s, there were no strange behavior from the cells. Deviations between cells < 0.02v and no significant drop of voltage (quite stable around 3,73V).
Still a mystery...

Had this happen, myself, when flying a few months back. Was at about 50% then almost nothing. Had to do an emergency landing in the middle of street about a quarter mile from my home point.

DJI couldn't explain it. Had me send the battery in, and just replaced it under warranty.