http://www.phantomhelp.com/LogViewer/GKR0CDZMBVKQB2JDWS84/

Can someone review this. A few funky things happen to my drone in this log, including accelerating to 37mph once the auto-landing feature takes over. The acceleration causes the motor to overload. The overload message says the aircraft will decelerate but it doesn't actually decelerate until I pull off the throttle. Keep in mind I am continuously pushing up on the left stick to prevent auto-land. After I pull off the throttle to turn around my battery drops instantly from 18% to 0% and drops from about 30 feet in the sky.

As far as I can tell this is entirely a malfunction of something in the firmware that I had recently updated. This was extremely dangerous and I hope DJI can figure out how something like this could have happened so it doesn't happen to anyone else in the future. I am afraid DJI could be sued in my home state.
Under Florida Law, “Culpable Negligence” is a serious criminal offense that may be classified as a misdemeanor or felony. Culpable negligence is a charge that assigns criminal liability for gross acts of negligence that expose others to harm or the threat of harm.

Looks like your new battery misjudged how much power was stored inside it.

Did you recharge to full on the day of the flight, or had it been sitting around for a while before flying.


Your lucky that actually landed, should have let it land rather than override it, although you wouldn't have known that at the time.

I had it fully charged about an hour before flight.

Danielfonseca64 Posted at 2017-6-1 11:25
I had it fully charged about an hour before flight.

In that case I would be very careful if using that battery again.

I suggest you get DJI Support to analyse the log and tell them to look at the battery power, see if they want to replace it under warrantee or have some other advice.

It looks to me like the battery simply ran out of power while it thought it still had a reasonable amount left, not seen that before on a freshly charged to full battery, I think there is a fault in it.

Is it a new aircraft as well?  
Have you another battery that works OK?

Hope you landed on something soft? ... it came down the last few meters rather fast!

It was a new aircraft. I bought it with 3 batteries and the other two batteries worked fine... It actually landed in water... So I guess you could call that "soft"

You might be best off returning it to the store you bought it from then, it would probably be a lot faster than getting DJI support to sort it out.

Nigel_ Posted at 2017-6-1 11:55
You might be best off returning it to the store you bought it from then, it would probably be a lot faster than getting DJI support to sort it out.

Good idea. The DJI case is underway but it is at snail speed.

Also refer to my reply to your question on this incident you posted in another thread here.

My understanding is the battery is designed to force an auto land at 3.3 volts and that's to save the AC because the battery is at extreme risk of turning itself off at 3.0 volts.  That's for any cell.  With the p2 series, when it auto landed it auto landed.  With the P3 series, DJI allowed the pilot to force the AC to stay aloft in order to get it out of a dangerous situation such as landing in the ocean, but the risk is that the battery could turn itself off without warning at any time.  

http://www.phantompilots.com/thr ... s-of-failure.43313/

endotherm Posted at 2017-6-1 13:20
Also refer to my reply to your question on this incident you posted in another thread here.

WOW, I missed your comment!!! OK, so can you explain to me how my drone got to 35 mph when I was in P-mode before switching to Auto-landing.. I put the throttle to a MAXIMUM of 70% in NEAR 0 wind.  Once it switched to forced landing I was given only ONE second before the drone went to 0% battery and went into a free-fall, not a forced landing. I will also say once the motor overload occurred it did not decelerate on its' own, I decelerated manually.  I didn't intend on discharging the battery that fast, I have no clue how my drone would reach that speed unless it was in sports mode, which was not the case. With 2.5V of battery would I not be able to fly for another 5 seconds at least??

After reviewing further I still had 2.876 Volts of battery and 18% battery and an  estimated 1:46 remaining of flight time.. Had the remote been close to accurate my crash would not have had devastating results.. I really hope DJI honors their warranty for me, especially because the battery wouldn't have drained so fast if it weren't for the malfunction occurring with the acceleration of the drone. Had the drone not gone so fast (up to 37 MPH) I would never have been over water, my motors would have never overloaded, and my drone's battery probably wouldn't have instantly dropped from 18% to 0%..

One more question, IF 3 Volts is a dangerous level to fly a drone, Then why on God's green earth did it tell me I had 18% battery, If 3 was dangerous then it should have said 5% battery, or less. If it said 5% I would have been happy to take my drone down.

It's my understanding that the percentage comes from the mAh reading and does not necessarily have anything to do with the voltage.  The exhalted msinger has posted more than once that it's a good idea to keep an eye on both the percentage and the voltage when flying.  You can't just watch the percentage alone, he says.  

Danielfonseca64 Posted at 2017-6-1 13:53
WOW, I missed your comment!!! OK, so can you explain to me how my drone got to 35 mph when I was in P-mode before switching to Auto-landing.. I put the throttle to a MAXIMUM of 70% in NEAR 0 wind.  Once it switched to forced landing I was given only ONE second before the drone went to 0% battery and went into a free-fall, not a forced landing. I will also say once the motor overload occurred it did not decelerate on its' own, I decelerated manually.  I didn't intend on discharging the battery that fast, I have no clue how my drone would reach that speed unless it was in sports mode, which was not the case. With 2.5V of battery would I not be able to fly for another 5 seconds at least??

Given the amount of power that was in the battery, it should not have let you take off.  For some reason the batteries estimate of the remaining power was inaccurate, this was a battery fault not an aircraft fault.

The reason for the high speed I suspect was lack of power from the battery resulting in the aircraft not being able to correct it's attitude due to lack of power to the propellers, so the speed was not intentional.

Check battery logs in dji go, looks like one cell in the battery gone bad.

Yuri_au Posted at 2017-6-1 16:27
Check battery logs in dji go, looks like one cell in the battery gone bad.

Once under 3 volts one cell did empty first and one lasted a little longer but they all reached 2.8 volts within 2 seconds of each other which is remarkably good after a 24 minute flight.  

The only problem I see is that it didn't auto land and refuse to take off again before the battery was completely empty, and that was partly because the critical landing was being over ridden with a throttle up command from the pilot and partly because the battery was reporting that it still had significant power in it until two seconds before the end.

It simply ran out of fuel.

Danielfonseca64 Posted at 2017-6-1 14:21
One more question, IF 3 Volts is a dangerous level to fly a drone, Then why on God's green earth did it tell me I had 18% battery, If 3 was dangerous then it should have said 5% battery, or less. If it said 5% I would have been happy to take my drone down.

There's a good write up Here on Lithium Polymer batteries, enough to understand perhaps why your battery behaved as it did.

Aardvark Posted at 2017-6-2 02:48
There's a good write up Here on Lithium Polymer batteries, enough to understand perhaps why your battery behaved as it did.

Thanks for posting that article on Lipo batteries.  Obviously it's to our advantage to fully understand how our power source works.

Jeffyk Posted at 2017-6-2 05:06
Thanks for posting that article on Lipo batteries.  Obviously it's to our advantage to fully understand how our power source works.

It's always good to understand how things work, however P4 batteries are "smart batteries".  They are supposed to do the difficult work for us and make our flying simple, and in most cases they do, we very rarely see a P4 fall out of the sky because the battery is empty.  On the P3 it seems far more common.

Something that hasn't been said so far on this thread - be careful on your test flights.  This battery had only been charged once.   General advice on lipo batteries is to not completely empty them on the first few flights since they normally need a little exercise to reach full capacity, also best not to override the critical landing on the first few flights.

I never let my batteries get that low in flight.  I set "Low Battery Warning" at 30%, and "Critical Battery Warning" at 10%.  The instant the low battery warning appears, I head for home and land.

Danielfonseca64 Posted at 2017-6-1 14:21
One more question, IF 3 Volts is a dangerous level to fly a drone, Then why on God's green earth did it tell me I had 18% battery, If 3 was dangerous then it should have said 5% battery, or less. If it said 5% I would have been happy to take my drone down.

After reviewing further I still had 2.876 Volts of battery and 18% battery and an  estimated 1:46 remaining of flight time.

That's just it, it's an esitmate.  Why did it say you had 18% battery left?  From what I understand it was a new battery and hadn't been charged up and discharged  a couple of times yet.  That's when the Intelligent battery can calibrate and fine-tune its capacity and learn how far it can discharge.  If you think about it, it was sitting on the ground and not being taxed at all, and the discharge is minimal, merely powering some low current circuits.  The battery measures how many mAh it has left and makes a calculation and says, "if everything remains the same and the power requirement remains constant, with this many mAh it should represent 18%" and reports that to the aircraft and the app.  However when you power up the high current motors and fly fast (for whatever reason) those current measurements drop really fast.  The next time the calculation is done, it says "with this really low mAh reading the battery should be reading 0% and I'm getting ready to shut down" and it updated the app accordingly.  For some reason (new pilots especially), people think they can and should fly it to zero every time.  Conservative pilots set a critical battery warning between 10-30% and come home, land it and swap the battery once the alert goes off, even if that means the battery still has quarter charge.  This is the safe and responsible thing to do.  You don't want to be >400ft or over the water when it clicks over to zero, I have seen it reported all too often on the forums.

djordan2 Posted at 2017-6-2 05:42
I never let my batteries get that low in flight.  I set "Low Battery Warning" at 30%, and "Critical Battery Warning" at 10%.  The instant the low battery warning appears, I head for home and land.

Especially on the first use of the battery.  smh

I having the same problem with 1 battery also,p4p+ autolands with 50% power showing...afraid to take it out of my yard....

Marley1 Posted at 2017-12-24 10:11
I having the same problem with 1 battery also,p4p+ autolands with 50% power showing...afraid to take it out of my yard....

Can you upload the floight logs for people to look at http://www.phantomhelp.com/logviewer/upload/

Alanhd, took the bad battery back to Best Buy for a replacement, charged it up , installed it, immediate update firmware alert, downloaded firmware, problem solved. Best Buy rechecked battery and found a bad cell.

Marley1 Posted at 2017-12-25 03:18
Alanhd, took the bad battery back to Best Buy for a replacement, charged it up , installed it, immediate update firmware alert, downloaded firmware, problem solved. Best Buy rechecked battery and found a bad cell.

I’m glad you got it sorted and it didn’t cause a crash.