Genghis9 Posted at 2017-8-28 19:09
TN Lone Wolf
I guess Labroides took a pass on those questions.
However, if you read through this thread https://forum.dji.com/thread-51147-1-1.html you will become fairly well informed on the topic and find several if not all the answers to the questions I asked.  This link actually comes from post #37 here.  Either way it leads to some good stuff, also in this other thread there is yet another link to another thread that has some additional info, suggest you read that one too.  If you read them both I believe you will learn what you want on this subject.

It initiated the RTH at a little over 2000 feet Distance and 364 ft vertical when it disconnected, but once i got it back i manually controlled it home. At 680 feet distance, i was bringing it down and back and that's when it cut out. It would seem really silly that the drone would do that during this flight when i had flown it twice moments before and that didn't happen.

wormz30 Posted at 2017-8-29 07:57
It initiated the RTH at a little over 2000 feet Distance and 364 ft vertical when it disconnected, but once i got it back i manually controlled it home. At 680 feet distance, i was bringing it down and back and that's when it cut out. It would seem really silly that the drone would do that during this flight when i had flown it twice moments before and that didn't happen.

Wormz
I'll have to take your word for it, I am by no means an expert on this stuff.  I hope you get it all straight and back up flying soonest.
Good Luck to You!

wormz30 Posted at 2017-8-29 07:21
@Nigel_ from what i've assessed of the the damage, the gimbal needs to be replaced for sure. one of the ccw motors needs to be replaced, landing gear, and shell need to be replaced. Also, I've had the gimbal guard for a long while so I don't think the gimbal guard would have anything to do with it. Even just holding down the throttle from up high lol, otherwise I wouldn't have ever been able to land. However, a few months ago, i did send my P4 into DJI and (after several weeks) they sent me one back so who knows? Maybe that is the culprit?

P4 parts are not very expensive if it is just gimbal, case and landing gear, might be worth getting a quote from DJI for repair before deciding which way to go.  Not sure a DIY repair would be sensible, with all that damage there is a significant chance of something going wrong and then it costing even more.

Nigel_ Posted at 2017-8-29 08:47
P4 parts are not very expensive if it is just gimbal, case and landing gear, might be worth getting a quote from DJI for repair before deciding which way to go.  Not sure a DIY repair would be sensible, with all that damage there is a significant chance of something going wrong and then it costing even more.

Yeah, I ended up contacting customer support and i sent it in. Cost-wise for the components, i'd end up spending almost the same if i ended up just buying a refurb unit. Which in my experience with DJI when you send something in, they often just send you a refurb unit instead

300 ft up its using the barometer for altitude so gimbal guard should not have effected it. The logical conclusion is that a bug in firmware is using downward sensors instead of barometer to work out when it's landed. That or a major malfunction. so back to square one.

Yeah, sent it in. DJI said it's not their fault and I had to pay them $220 to fix it (replace it). They didn't explain how it's not their fault.

sooo and whats the difference in flying a battery from 100-40% to flying it from 60-40%?
what is the reason for higher failure rate, making it 'silly flying' to do so?
thanks

Sebb Posted at 2017-9-1 07:28
sooo and whats the difference in flying a battery from 100-40% to flying it from 60-40%?
what is the reason for higher failure rate, making it 'silly flying' to do so?
thanks

I think if you read the whole thread you would have the answer.   The only REAL time the battery % is accurate is usually after charging the battery to 100%.  If you use the fully charged battery, come in land at 60% and go back out 10-15 minutes etc later.....the percentages should be relatively accurate.....BUT if you run your battery percentage down to 60% and then don't use it again for a few days, the battery may still show close to 60% capacity but the voltage may be a lot lower and more critical.   Voltage IS,  if not MORE important, as important as capacity......I have two examples that might help.

A week ago had a P4 battery that I had charged up on the P4 charger to storage capacity, at least 4 weeks earlier......still showed to two solid green and one blinking green when pressed indicating a charge of at least 51%.  Put the battery on the charger to do a full charge and just after it started charging the status lights rolled back to only the first light on the battery blinking green.........meaning less then 10% of the battery remained .    I realized the battery WAS at 51% until the charger put a load on the battery checking the status as the smart charger does, and BOOM, in reality it was really less then 10%.  The battery charged normally......but it doesn't take much to realize what would have happened had I put that in my P4 and got to 100 feet high.........BOOM.
2 days ago I charged a P3 that had drained to one light over a period of time.....I then charged the battery to @ 60% just to check out a compass calibration I did......started the P3 went up to 25 feet slowly......happened to have the battery screen up,  and saw the battery cells drop into the orange almost immediately....@ 3.6 Volts.  I realized I had made a mistake thinking that if I charged the battery up to 60%......it was really 60%.  I also did some digging before I read this thread and ascertained that LiPo batteries do not charge uniformly over the whole charging cycle.......the capacity goes up faster then the voltage.  If you watch a battery charging carfully it seems to get up to 75%+ pretty fast and then seems to take a very long time to finish up the full charge.
Geebax, Nigel and Labroides have ponied up some great info.....people should listen.

You might get away with using a depleted, days old battery.......under the right circumstances......but is it really worth it!

wormz30 Posted at 2017-9-1 06:39
Yeah, sent it in. DJI said it's not their fault and I had to pay them $220 to fix it (replace it). They didn't explain how it's not their fault.

That seems a very good deal, especially if they are Canadian $!

I am still fairly sure that it was the gimbal guard that caused the issue, I'm a bit surprised they didn't tell you that but the service centres on your continent don't seem to be that good.  The data in the log clearly shows the ultrasonic sensors seeing something immediately below the aircraft during the time you pulled the throttle full down and it powered down a few seconds later as is supposed to happen.

Sebb Posted at 2017-9-1 07:28
sooo and whats the difference in flying a battery from 100-40% to flying it from 60-40%?
what is the reason for higher failure rate, making it 'silly flying' to do so?
thanks

That is not the issue.

The issue is that after a period of non-use, the % figure is incorrect, you can't even trust a 100% figure if it is a week since it was charged.

If you fully charge the battery on the morning of the day you are going to use it then the % will be correct for the rest of the day, doesn't matter if you take off with it at 100% or 60%, it will work fine.

Nigel_ Posted at 2017-9-1 12:41
That is not the issue.

The issue is that after a period of non-use, the % figure is incorrect, you can't even trust a 100% figure if it is a week since it was charged.

ok thanks for clarification. geebax declared it is general rule to NEVER start a flight on anything other than 100% charged.  

i frequently fly 2 sessions per batteries on same day... however, i consciously do a 100-60% / 60-30% split, not anything more lobsided.

Sebb Posted at 2017-9-6 00:54
ok thanks for clarification. geebax declared it is general rule to NEVER start a flight on anything other than 100% charged.  

i frequently fly 2 sessions per batteries on same day... however, i consciously do a 100-60% / 60-30% split, not anything more lobsided.

The geebax rule is a rule that works very well and is very simple to explain

It is also the best way to reduce the risk of accidently running out of power due to strong winds, bad planning or unexpected events.

For a pilot with some experience flying in a familiar location there is no need to stick to it, but do make sure you are using freshly charged batteries, not week old batteries, and if you have a choice of flying on a half used battery or a full battery then there will always be less risk of running out of power due to unexpected events if you use the full one.

Nigel_ Posted at 2017-8-27 13:58
Although you were running very low on battery, and the battery % figure was very inaccurate, the actual reason it fell out of the sky was that your ultrasonic sensors thought that it had landed on something, you then pulled the throttle full down as you do when you land to cut the motors and a few seconds later it cut the power to the motors since it thought they were no longer needed.

Do you have a gimbal guard or something mounted under the aircraft that it could mistake for the ground?

Wow some good stuff on here

I'm not sure why are you getting issues. At first, I was hesitant to update due to some issues i've read online but one day when I fly my un updated drone, dji says you are limited to this range blah blah. Log out and log back in didn't help so I decided to update my p4 in this sequence:

1.update dji go app on ipad air (i use ipad air)
2. update the remote in dji go app
3. update aircraft thru DJI Assistant 2 on computer (i use mac). (download firmware then restart the computer. If you don't, you will stuck on transmitting 0%)
4. try to update the aircraft with DJI Assistant 2 again and it will continue to update until 100%. Note: take out your sd card from your aircraft before updating.
5. Calibrate your aircraft obstacle sensors.6. Reset Factory Settings of your aircraft.
7. open dji go app, connect your aircraft and calibrate your IMU, then Compass and lastly, your camera gimbal.

No issues at all except that wind velocity is popping but i just ignore it.

Glad it worked for you. We did try everything, but issue still the same. Now, just waiting DJI to release a fix.

UPDATE: I sent in my P4, paid $220 for them to "repair it" but instead as expected I got a refurbished unit. No big deal. Except it came with the latest firmware and I got pretty much the same warnings as before and I put a freshly charged battery too. Just as wobbly as ever so even though I've pretty much ruled out that the firmware was the sole cause of my crash (thanks to geebax and the other veterans) I've learned to have my voltage in display from now on.

I also didn't realize that there was so much more that is explained in the forums that DJI doesn't seem to make known to rookie pilots like myself. Didn't know about DJI Assistant until the forums, didn't know about downloading flight logs until the forums, didn't know about checking voltage until the forums, etc etc etc. thanks so much to you guys for educating me and the rest of us on this matter. I put my P4 in the air today and I can tell it's still not flying well. Oh well, back in the case it goes until then