Advanced Drops from SKY

[Oso]

I agree! Seems the GPS was working because of distance and altitude readings, but total voltage and every cell never changed from start to finish.

Sorry to here of the crash, but you, my friend, are lucky it was so low and in such an isolated place and NOT in the ocean!

There has GOT to be something wrong with the voltage sensing circuitry.

Yeah, the other telemetry seemed fine, but no voltage changes. When I first opened the log, the first red flag I saw was a take off at 43%. I thought to myself right away that this would be yet another case of the voltage quickly dropping to critical as we've seen so often. That's when I kept scrolling down to see how soon it happened, only to find no voltage change at all in any cell.

Clearly the data shown in the log was not accurately reflecting the voltage dropping during flight. It appears the AC was just flying around happily with no cares in the world thinking it had enough power when it did not. If the app was also showing a static percentage / voltage, that could have been an indicator of pending trouble had it been noticed during flight.

I tend to agree with you that there may be something wrong with the sensing circuitry.

 

[Sasquad]

I don't quite agree that it's pilot error. I have landed and restarted aircraft over 350 flights now and have never had this occur, why now? The A/C should not just drop from the sky with 7.20 minutes of battery remaining, if the aircraft was to disconnect from signal loss, low battery, it would complete its RTH function.
Thanks for your help, ill follow up with DJI

350 flights, starting, and stopping the battery? This equals pilot error, and a heavly taxed battery. Wonder it lasted that long.

 

[UpLift Aerial]

Could you maybe send the flight log to DJI? Maybe they could figure out what happened.

Strange how the battery voltages do not drop at all during the flight. Even with a short 2 minute flight like the one you posted, I would expect to see voltages going down in the cells.

Agree. I looked at it and see nothing wrong as far as I'm concurred. it jus stops at 61 feet as if the motors were shut off.

Starting a flight with a battery at 43% is, frankly, never a good idea. I fear that may've been your problem?

Agree but wouldn't that cause the battery percentage to drop rapidly?

 

[Crack The Sky]

While taking off with a battery reading 43% may not be best practice, I'm not sure that this was entirely pilot error. The log data clearly show that the battery was reporting incorrectly. It never changed from 43%, and so the 43% value itself was quite possibly incorrect at takeoff, and the aircraft quite likely flew until the battery was exhausted and unexpectedly shut down. Either way, battery reporting failure is hardware failure, and so DJI may well cover it.

I agree, 100%. The fact that the logs never show any battery drop for the entire flight is an indicator of the origin of the problem. I think it just flew until the faulty battery died.

 

[Solly747400]

350 flights, starting, and stopping the battery? This equals pilot error,

Umm, How is it pilot error when he's intentionally taken off (as many other times) without a problem? Pilot error is when the pilot accidently does something that he/she did not mean to do, or was not aware he/she was doing.

The fact that the battery was not changing to reflect the actual remaining charge, I'd say it's a hardware issue. Secondly, if there was nothing wrong with the battery, as soon as it reached 10%, it would auto land, but it didn't. Obviously the drone thought the battery was always at 47%, and therefore kept flying until there was no juice left so it fell from the sky. If the battery had no issues, it would've reported the battery charge was declining and therefore the drone wou've auto landed at 10% or even given the pilot a warning at 30% or whatever this is set by the operator.

I also agree it is not a good idea to take off with less than a full battery. I have done it myself a couple of times just to test certain things around the house.

I'd say to the OP, go full steam ahead with putting a case to DJI about the battery issue.

 

[Loz]

I too do NOT see this as pilot error, as Solly stated so constructively, REGARDLESS of whether pilot should have lifted off with non fully charged battery, the Hardware and log indicate a failure resulting in a crash which NO pilot could have anticipated - the display and aircraft behaviour (ie: not auto landing) indicated there still was power to fly.

Yes perhaps noticing voltage / time remaining were not dropping could have been noticed, the fact that they were not does NOT override the apparent hardware failure.

 

[kerrylaw7307]

It was pilot error. DJI will state that; it's not a hardware failure, so don't waste your time with that. You'll need to fix it yourself or get a Oz based repair service on the case. And buy a few more batteries!

Was NOT pilot error. Logs indicate NO voltage change on the batteries. MAYBE poor judgement to fly with 43%, but his software/hardware failed him by not indicating correct voltage. MOST of us would be flying at 43% IF we thought the voltage readings was correct.

 

[captainmilehigh]

Interesting conclusions above concerning battery issues. I keep wondering though, since the OP was using the GoApp, did the screen on his device show the battery level as correct or incorrect? I scan my GoApp screen frequently to monitor signal strength (GPS) and battery level.

Can't help but wonder if battery level was hung up at 43% on the app too.

 

[Solly747400]

Well anyone feel free to correct me if I'm wrong but the Go app gets its info from the bird and controller, thus the app would've been showing 43% the whole time

 

[sar104]

Interesting conclusions above concerning battery issues. I keep wondering though, since the OP was using the GoApp, did the screen on his device show the battery level as correct or incorrect? I scan my GoApp screen frequently to monitor signal strength (GPS) and battery level.

Can't help but wonder if battery level was hung up at 43% on the app too.

I'd be surprised if the log entries and the screen status were different, since the log is created from the same streamed telemetry that feeds the app screen.

 

[captainmilehigh]

Well anyone feel free to correct me if I'm wrong but the Go app gets its info from the bird and controller, thus the app would've been showing 43% the whole time

Ok. I was just wondering how that worked. Seems like a correct answer to me. Thanks.

 

[Numone]

Was NOT pilot error. Logs indicate NO voltage change on the batteries. MAYBE poor judgement to fly with 43%, but his software/hardware failed him by not indicating correct voltage. MOST of us would be flying at 43% IF we thought the voltage readings was correct.

I agree, think everyone would be flying at 43%; I would not t/o at 43%. It'd be interesting to see the previous flight log and and what, if anything, that flight threw-up. Ok, so this my not be pilot error, but IMO anyone that uses the publicised flight times as fact, and flies to this number to calculate remaining flight minutes to the second isn't showing great judgement on either counts.
Also, does anyone actually know and not just speculate, where the data of the remaining battery percentage is derived - in the battery, the app or within other hardware?

 

[Loz]

...IMO anyone that uses the publicised flight times as fact, and flies to this number to calculate remaining flight minutes to the second isn't showing great judgement on either counts.

Numone that's true but not sure why you raise it, this OP pilots instruments (the screen app) where showing him 43% and an estimated ~7minutes flying time remaining - that's plenty flying time left and not poor judgement at all, particularly as AC was close by, unless I miss your point?

 

[Numone]

Numone that's true but not sure why you raise it, this OP pilots instruments (the screen app) where showing him 43% and an estimated ~7minutes flying time remaining - that's plenty flying time left and not poor judgement at all, particularly as AC was close by, unless I miss your point?

They admit to >350 start/stop/start flights - we all seem to be agreed that this is a poor decision. They think 43% equals > 1/3 (7.20) of remaining flight time (?) and due to their experience, sounds like they won't be moved on that opinion? Its just my opinion. I have no axe to grind here and I really hope that DJI repair the AC FOC.

 

[BudWalker]

@alexdalley If there was something wrong with the battery reporting it's data that would likely show up in the .DAT file as a batteryComm error. This could be confirmed if you retrieve the .DAT file. Look here to see how to do that.

 

[RockinRog]

Love the technical side of this forum! I just learned valuable lessons here about taking off at battery percentages! Me I take off from these percentages but will err on caution now!

 

[Vexed]

43% is more than a third of the 24 minute flying time, what's wrong with that?

You don't do it, that's what's wrong with it.

 

[RammerJammer]

To continue... never ever start a new flight without a fresh battery at 100%. They are designed for continuous use, not stopping and restarting. The DJI quoted 23 minute flight time (which I've never reached btw!) is a continuous not cumulative number. The result of this was probably the failure of the battery and 43% remaining was an erroneous figure.

From whence does your claim "designed for continuous use, not stopping and restarting" originate?

Batteries are, well, batteries. And, if anything, actually perform better after a short recovery period - with the exception of batteries that self-discharge over days or weeks. At least, that's been my experience with everything from carbon-zinc to lithium batteries.

Now, DJI might have designed the circuitry and software as you claim. But, if so, in my opinion, that would be shortsighted due to the obvious absence of consideration for real-world use! On the other hand, it would allow them to sell more batteries!

 

[Solly747400]

You don't do it, that's what's wrong with it.

It depends on what you're doing. If my battery is at 43% (we seem to use this number now) and I wanted to just go up and test something for a couple minutes (within 50 metres), or take one pic that I needed to, then I would do it. Basically you need to be in a position where if your battery tells you you have 20% left, then it will take you no more than a minute to have the bird on the ground. You just need to be very aware of how far to push the envelope.

 

[Numone]

From whence does your claim "designed for continuous use, not stopping and restarting" originate?

Batteries are, well, batteries. And, if anything, actually perform better after a short recovery period - with the exception of batteries that self-discharge over days or weeks. At least, that's been my experience with everything from carbon-zinc to lithium batteries.

Now, DJI might have designed the circuitry and software as you claim. But, if so, in my opinion, that would be shortsighted due to the obvious absence of consideration for real-world use! On the other hand, it would allow them to sell more batteries!

With respect, these are not like any other type of battery so before you chime-in, I suggest you investigate the chemistry, construction and operation of lipo batteries. Stopping and restarting, or in reallality partially discharging, stopping and partially discharging it again, can cause cell voltage deviation imbalances which, in turn, can result in power loss or failure.