P3A slowed down to 15mph and got battery discharge warning

[S5S5G6]

New one for me...flying at night, no sun or high temps. Picked up the bird 250-400' and flew it at top speed for about 3 min. in a straight line. Panned around a lit up church then turned to bring it back. I noticed it wouldn't go above 15-16mph (and kept having RC link failure displayed) but I had video and seemed to be in control.

Then everything stopped for a .5 second, the voltage display went to 0.00v and I got a red message indicating "Overcurrent during discharge" which also appears in the "history" of my battery in the DJI app.

Thinking it was going to fall like a rock I put throttle down and video came back, and seemed like I was in control the whole time since the bird was now descending. I limped it along at 15mph and as it got closer it started picking up speed again.


I searched for similar and only saw people bitching about firmware stuff. I am on latest FW btw.

Do you guys think that:

A. Some sort of environmental glitch , maybe due to high humidity? (Was not hot but was humid).
B. Possible battery issue..
C. Something else common that I'm just not finding results on yet.

Thanks for any input...

 

[duse500]

did you check to see what all the cells in the battery are reading?
run the bird with props off , battery voltage displayed, see if your dropping a cell.
Then give it a charge and do it again

 

[bobmyers]

New one for me...flying at night, no sun or high temps. Picked up the bird 250-400' and flew it at top speed for about 3 min. in a straight line. Panned around a lit up church then turned to bring it back. I noticed it wouldn't go above 15-16mph (and kept having RC link failure displayed) but I had video and seemed to be in control.

Then everything stopped for a .5 second, the voltage display went to 0.00v and I got a red message about over current discharge.

Thinking it was going to fall like a rock I put throttle down and video came back, and seemed like I was in control the whole time since the bird was now descending. I limped it along at 15mph and as it got closer it started picking up speed again.


I searched for similar and only saw people bitching about firmware stuff. I am on latest FW btw.

Do you guys think that:

A. Some sort of environmental glitch , maybe due to high humidity? (Was not hot but was humid).
B. Possible battery issue..
C. Something else common that I'm just not finding results on yet.

Thanks for any input...

you need to check the battery cells-- Charge the battery that you were using, take the props off, and fire the Phantom up. Look at the all the cells and see how close they are-- any cell over .03 could be a problem. Run the battery on the Phantom until it gets down to about 50 % all the while keeping an eye on cell balance. If you have one cell lower than the others then that is your problem. Once a bad cell reaches a certain voltage, it will start to bleed off rapidly, cutting down drastically the total power the motors need to maintain a speed.

 

[S5S5G6]

Terrific info, thanks guys! Will try this in am.

 

[S5S5G6]

Just to be clear, I'm looking for a -/+.03 delta?

So far only seeing -/+ .02 under load.

Going to put the props on and do some punch outs in my yard and see how it does...

 

[bobmyers]

Just to be clear, I'm looking for a -/+.03 delta?

So far only seeing -/+ .02 under load.

Going to put the props on and do some punch outs in my yard and see how it does...

.02 is not bad-- What does it look like fully charged?, if you have .03 difference when running, that is borderline and is a potential issue.

 

[S5S5G6]

Sorry...fully charged nothing was further than .01 delta. I'm going to top it off again now.

 

[bobmyers]

Sorry...fully charged nothing was further than .01 delta. I'm going to top it off again now.

Sounds like the cell balance is good. You might also run the motors on the bench with the props off and see if you can detect any dragging or strange noise that might cause one motor to draw more current on load or heat up excessively. Ever now and then the magnets in the motor can attract metal, that can catch on the magnet and wind up inside the motor. Part of my checklist is to check all the motors and make sure they are turning free. I did catch one that had a very tiny screw in on the magnet and it was causing drag. Don't know how long it had been there-- but did get it out with not consequences.

 

[S5S5G6]

Ironically, that's what I did while checking batt load this AM. Checked motors out since I had props off, nothing in there. Then ran them in various (stick) positions to see if any had a differing or adverse impact on the battery.

No dice. But as the battery is new, I'm thinking switch it out while I can. I am going to make the exact same trip tonight with my "most used" pack and see if the same use case generates similar results.

The one thing I did notice is in the history for the battery , the "history 01" has the specific error. Not interactive though and nothing I can glean from any sort of log that covers this.

(I'll copy the exact message in here once the battery is topped off again).

 

[S5S5G6]

Message is Overcurrent During Discharge by the way. It is what shows in the "history" of the battery and is the same thing displayed top dead center on my app that evening.

Just charged to 100% and cells are :

1-4.31v
2-4.32v
3-4.32v
4-4.33v

That is very similar to how some of my other batteries are as well.

 

[S5S5G6]

Contacted DJI support...will see what they say.
As of this time, I suspect the battery has a failing cell. I could swap it out where I bought it easily enough, but I have (4) batts so I can live until I get this fixed. Want to see what (if) DJI says anything.

 

[AlmostTan]

Load your flight records into healthydrones.com - it will analyze the battery for you.

 

[Dronebow]

Wondering if the battery had problems after running hard for so long and heating up?

 

[acherman]

I have seen the same message right at the beginning of a flight - take off, hover around 30' for half a minute, then take off full speed forward and up towards a target or flight path, and after about 5-10 seconds it popped up. I think I have actually seen this twice (made me pucker up both times). I let off the sticks and a few seconds later all is normal, continue the flight as usual. I don't recall if it was with the same battery for both flights as I think they were weeks apart (possibly). I think I will upload my logs to healthydrones.com tonight and see what comes up. Seems worth the time and effort.