Has anybody ever had this happen to them?

[conchman]

I was flying my M2P with a battery that showed about 3/4 full on the green LED lights on the battery, it may have discharged some power automatically over the previous day, when all of a sudden, right after take off but I was already about 200 yards away, the phone display showed me 0% battery and the alarm went off. Needless to say I almost panicked since I had a river to cross and there were buildings in the area, I thought it was going to go into auto-land. I made it over the river and basically emergency landed it between a park bench and the river, almost landing diagonally. The battery still shows 3/4 full with the green lights, but on the phone display it shows 0%.

Are you not supposed to fly batteries after they have discharged to being idle, without re-charging them first? I am assuming the automatic discharge must have had something to do with this incident, even though I have flown discharged batteries without problems before.

I still don't know if the battery is actually 3/4 full or empty. I haven't tried to fly again with this battery, but will probably do a test soon. I did fly with another battery, and it worked fine.

Can somebody shed some light on this?

 

[StantonZ]

A couple of comments and then a question:
1) I tend to always charge my batteries (to full) the day of flying (with some "cooling off" time in between)
2) You should definitely "top off" the offending battery before using again

My question is: do you have any data on that battery...or proof that it was ~75% full per the lights (like an AirData report on a previous flight)? I would keep my eye on that battery; I keep my batteries labeled for that reason.

 

[Phantomrain.org]

I was flying my M2P with a battery that showed about 3/4 full on the green LED lights on the battery, it may have discharged some power automatically over the previous day, when all of a sudden, right after take off but I was already about 200 yards away, the phone display showed me 0% battery and the alarm went off. Needless to say I almost panicked since I had a river to cross and there were buildings in the area, I thought it was going to go into auto-land. I made it over the river and basically emergency landed it between a park bench and the river, almost landing diagonally. The battery still shows 3/4 full with the green lights, but on the phone display it shows 0%.

Are you not supposed to fly batteries after they have discharged to being idle, without re-charging them first? I am assuming the automatic discharge must have had something to do with this incident, even though I have flown discharged batteries without problems before.

I still don't know if the battery is actually 3/4 full or empty. I haven't tried to fly again with this battery, but will probably do a test soon. I did fly with another battery, and it worked fine.

Can somebody shed some light on this?

You did pretty well for being in a panic. What was the actual Phone battery at ?

Phantomrain.org
Gear to fly your Mavic 2 in the Rain and Land on Water.

 

[Deleted member 103366]

Thinking about is I am sure I have seen "Battery in self discharge" or similar warnings with a P3Adv but I do not remember any such warnings with my M2P.
That said the P3adv does not seem to like an 'old' charge and fairly quickly gives low battery warnings but I haven't seen the same behaviour with the M2P. Though I have not pushed the M2P as hard as I did the P3Adv and I haven't flown the M2P out any distance on an 'old charge' battery, less than 100m

 

[kendrex]

A couple of comments and then a question:
1) I tend to always charge my batteries (to full) the day of flying (with some "cooling off" time in between)
2) You should definitely "top off" the offending battery before using again

My question is: do you have any data on that battery...or proof that it was ~75% full per the lights (like an AirData report on a previous flight)? I would keep my eye on that battery; I keep my batteries labeled for that reason.

Is it good to leave the batteries uncharged for days? I live by the ocean and when it's not raining, it's too windy to fly. If I charge the batteries after I fly they're usually down to 60% by the time I can fly again. I usually stop around 20% and I thought leaving them in that state was also bad.

 

[Starz]

Push and hold the battery button (not in aircraft) until lights come on.
If you have four lights, you have 100% battery life. If you have three lights, you have a battery that is only 75% life left. This sequence is indicating battery life, not charge state.

 

[StantonZ]

Is it good to leave the batteries uncharged for days? I live by the ocean and when it's not raining, it's too windy to fly. If I charge the batteries after I fly they're usually down to 60% by the time I can fly again. I usually stop around 20% and I thought leaving them in that state was also bad.

Lithium based batteries (like LiOn and LiPo) like to be cycled between 30-80%; doesn't mean you can't go beyond that, but it's not a good idea to let them sit/store for extended periods (days) beyond that range. It's fine to let them "sit" for a few days, but I would keep them closer ~50% (2 dots) for longer life. I usually charge my drone batteries up the day I fly, allowing some time for "cool down" before I fly (which heats them up quickly).
I have done the same thing with my EV for years with good results.

 

[hiflyer201]

if it said "critically low battery landing" or something close to that, you probably had a huge cell deviation. The drone will land. If that was the case the battery may seem normal and behave normally for a few flights but it will do the same thing again...trust me on this! Airdata will show all the past battery cell deviations if you have the gold level.

 

[Dobmatt]

Push and hold the battery button (not in aircraft) until lights come on.
If you have four lights, you have 100% battery life. If you have three lights, you have a battery that is only 75% life left. This sequence is indicating battery life, not charge state.

Not true at all.

 

[BigAl07]

Not true at all.

Please enlighten us as to what the LED on the battery DO indicate . . .

 

[Dobmatt]

Please enlighten us as to what the LED on the battery DO indicate . . .

The Manual will do much better explaining the features of battery LED indicator ...

 

[Starz]

Not true at all.

I have been wrong before and will probably be in that position again.
Your source of information please?

 

[Dobmatt]

I have been wrong before and will probably be in that position again.
Your source of information please?

Everybody can be wrong, some more often than others .

1. Mavic 2 Pro User Manual, page 35-36. No mention of such feature.
2. Physical confirmation. Button push displays the charge level as expected, nothing else. Holding the button down doesn't reveal any other information, lights dies out after a while.

 

[Starz]

This information has been around for some time. Certainly a difference between the m1 series and the m2 series batteries. I believe the difference is the button hold sequence was changed on the m2 series batteries. Power on the m2 battery, then hold the button down.
I don’t have any m2 batteries that are old enough to provide any light sequence variation to verify this. Possibly someone has an old one that they could check?

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[DanMan32]

P3 batteries show remaining life by holding down power button for more than 5 seconds.

My M2 will show all 4 LEDs blink if powered on and power button is held for more than 1 second.
And thats with July 2018 batteries that have swollen last year. (But not swollen enough that I can't use them at all).

 

[conchman]

so nobody has ever had 2 or more green lights on the battery but then had 0% battery life shown on the remote display/phone display?

 

[Starz]

so nobody has ever had 2 or more green lights on the battery but then had 0% battery life shown on the remote display/phone display?

Probably a possibility, but I’ve not seen that issue. I do have several DJI products besides the m2 and not seen what you describe on any of the other aircraft that I fly. Maybe I’m just lucky?

 

[Emanáku]

I would upload the flight data of this flight and maybe the one before to airdata and see, what the battery tab tells you. Especially, if the internal state of battery was correctly reflected by the app.
I had problems with a near flyaway (and a dead battery afterwards). The Airdata thing showed that one of the cells in the battery had problems the last 3 or 4 flights (but I did not notice that).

 

[Thomas B]

I was flying my M2P with a battery that showed about 3/4 full on the green LED lights on the battery, it may have discharged some power automatically over the previous day, when all of a sudden, right after take off but I was already about 200 yards away, the phone display showed me 0% battery and the alarm went off. Needless to say I almost panicked since I had a river to cross and there were buildings in the area, I thought it was going to go into auto-land. I made it over the river and basically emergency landed it between a park bench and the river, almost landing diagonally. The battery still shows 3/4 full with the green lights, but on the phone display it shows 0%.

Are you not supposed to fly batteries after they have discharged to being idle, without re-charging them first? I am assuming the automatic discharge must have had something to do with this incident, even though I have flown discharged batteries without problems before.

I still don't know if the battery is actually 3/4 full or empty. I haven't tried to fly again with this battery, but will probably do a test soon. I did fly with another battery, and it worked fine.

Can somebody shed some light on this?

I had a battery, which appeared normal and was charged within a hour to 100%, indicate four lights full charge. Then when I took off I had a warning like yours of low battery level and autolanding starting.... managed to get the bird back. Found the battery bulged, apparently during early flight.
So it could have been a battery failure like the one I describe above. Fortunately this type of event is very uncommon, but does occur.

 

[tribar]

Push and hold the battery button (not in aircraft) until lights come on.
If you have four lights, you have 100% battery life. If you have three lights, you have a battery that is only 75% life left. This sequence is indicating battery life, not charge state.

I can confirm this for the batteries from P3, P4 and MP.
The batteries from the MA & MM do NOT have this feature.
I don't know for other DJI batteries.