Phantom 3P falls out of sky

it seems to me that dji has at least tried to address this in the latest fw. whether it is a definitive fix or not we will need to wait and see.

i have a lot of experience with lipos and pushing lipos to their limits (within reason of course) because i use them on my multiple electric bikes building battery packs that are 18s 30ah and beyond.

using the voltage to determine how much battery life is remaining is suspect at best. and as we all know, voltage sag is real and can cause problems like this. voltage on lipo batteries isn't linear and it really drops off when cells hit around 3.5v so within a matter of seconds, when you combine discharge + high Cs for discharge, you can find yourself <3.0v.

this is probably obvious to most of you (i'm rather new with the phantom 3) but my understanding of the latest fw is to limit throttle when the voltage gets lower to prevent this. this is better than nothing but my recommendation would be for dji to do the following (maybe they already do some of these?):

1) build a rudimentary watt meter into their hardware of the battery to measure amp usage. since you know the starting amps, you should keep tracks of amps used to determine whether you are at 10%/30%/etc. stop trying to guess with voltage.

2) remove any type of hard limit at any voltage (3.0v). this does help protect the battery from damage but falling out of the sky doesn't seem like a reasonable alternative.

3) power will naturally reduce with the same throttle position as the battery depletes due to lower watts as the voltage goes down. don't let users compensate by throttling more aggressively. adjust throttle limits via amp usage.

4) be more conservative with battery power - currently they charge to 4.3v/cell and discharge down to close to 3.0v/cell. charge up to 4.2v and down to 3.4v and you won't see that much loss in range but the battery will last much longer.

until dji makes these types of changes, as users we can do the following (mostly what dji already recommends):

1) standard stuff like update to the latest fw, charge to >90% for each flight, don't go below 30%, etc.

2) prevent drastic voltage sag by not going max throttle if the battery is lower than 70%
 
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was this ever an issue with the phantom vision or vision +? I don't ever remember reading instances like this with the older models so how in the hell could they mess this up.....
 
Dude, call it laughable if you want. But it's the reality of liPo batteries and the P3. You can, of course, ignore the manufacturer who clearly states to only initiate flight with freshly charged, fully charged batteries. If you don't, you clearly risk the same fate as many others have already experienced. Or, you can learn from others hard learned lessons and not follow in their unfortunate footsteps.


Sent from my iPhone using PhantomPilots mobile app
 
this is quite possibly the dumbest thing I've ever heard....you can't use the quadcopter for it's intended use under 70% battery....that's laughable!

have you been reading this thread? assuming that the logs aren't lying, he started at 63% battery remaining (i know he says he was at 95%) and the current theory is that voltage sag at max throttle brought him down to less than 3.0v/cell causing motor shutdown.

at 63%, the cells should be at around 3.9v/cell or so. there should be no way that voltage sag/drop brings this down to <3.0v/cell (even in cold weather). my only conclusion is that 63% wasn't 63% but was more like 3.5v/cell or 3.6v/cell or even less. the problem is much worse in cold weather though right when takeoff (which is when the battery is at its coldest).

i actually agree that it should not be this way and we shouldn't have to baby these things but this isn't the first person who had his phantom 3 drop from the sky.
 
this is quite possibly the dumbest thing I've ever heard....you can't use the quadcopter for it's intended use under 70% battery....that's laughable!
What's laughable is that you've had a p3 for a couple weeks and you think you're an expert because you had a p2. They are nothing at all alike.
 
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No, I know where it landed though. Its in about 7 foot of salt water. I have a buddy that scuba dives, might have him come over and look for it. What is it worth?
SEND IN THE DIVER.... you can get the phantom off of the bottom and that memory card will likely still be good also. SanDisk memory cards have often been fine even after lengthy underwater periods... can't wait to learn more. One question I have is, why do you keep asking others what YOUR logs say? it's a puzzle...
 
I was flying my phantom on vacation. I was 300 feet up about 100 feet out. No big deal but i lost signal instantly. It didn't get weak like it normally does when your too far away. It just cut out. Moved my controller to try to get signal. I hear it buzzing out of the sky and into the water. What happened? Will DJI refund me as flyaway if i send my flight log? I have recording up until I lost signal.
Don't know what happened in your case but losing signal would have put it in the return to home mode and it would've paused and then the return to home mode would kick in and it should have come back home and landed. This has happened to me several times and home it came.
 
I was flying my phantom on vacation. I was 300 feet up about 100 feet out. No big deal but i lost signal instantly. It didn't get weak like it normally does when your too far away. It just cut out. Moved my controller to try to get signal. I hear it buzzing out of the sky and into the water. What happened? Will DJI refund me as flyaway if i send my flight log? I have recording up until I lost signal.
In the cases of lately where the battery cuts off and you get total power outage signal is lost immediately. But did you say you ask he heard the motors were still running on the way down that would eliminate that possibility
 
I've just bought a p3p NDNA tried it for the first time....Great, but this is worrying.


Sent from my iPhone using PhantomPilots mobile app
 
it seems to me that dji has at least tried to address this in the latest fw. whether it is a definitive fix or not we will need to wait and see.

i have a lot of experience with lipos and pushing lipos to their limits (within reason of course) because i use them on my multiple electric bikes building battery packs that are 18s 30ah and beyond.

using the voltage to determine how much battery life is remaining is suspect at best. and as we all know, voltage sag is real and can cause problems like this. voltage on lipo batteries isn't linear and it really drops off when cells hit around 3.5v so within a matter of seconds, when you combine discharge + high Cs for discharge, you can find yourself <3.0v.

this is probably obvious to most of you (i'm rather new with the phantom 3) but my understanding of the latest fw is to limit throttle when the voltage gets lower to prevent this. this is better than nothing but my recommendation would be for dji to do the following (maybe they already do some of these?):

1) build a rudimentary watt meter into their hardware of the battery to measure amp usage. since you know the starting amps, you should keep tracks of amps used to determine whether you are at 10%/30%/etc. stop trying to guess with voltage.

2) remove any type of hard limit at any voltage (3.0v). this does help protect the battery from damage but falling out of the sky doesn't seem like a reasonable alternative.

3) power will naturally reduce with the same throttle position as the battery depletes due to lower watts as the voltage goes down. don't let users compensate by throttling more aggressively. adjust throttle limits via amp usage.

4) be more conservative with battery power - currently they charge to 4.3v/cell and discharge down to close to 3.0v/cell. charge up to 4.2v and down to 3.4v and you won't see that much loss in range but the battery will last much longer.

until dji makes these types of changes, as users we can do the following (mostly what dji already recommends):

1) standard stuff like update to the latest fw, charge to >90% for each flight, don't go below 30%, etc.

2) prevent drastic voltage sag by not going max throttle if the battery is lower than 70%
You're right, DJI has some work to do, this isn't over unless they have absolutely REMOVED the routine that will shut off the battery DURING FLIGHT. I suppose DJI's intention for the shut off scheme was to prevent battery damage in the case where you leave the drone on and accidentally store away for days in your case. That kind of a mistake could damage a battery, so they may have been trying to prevent that from happening. However they forgot the fundamental logic of the inclusion of shutting off the battery ONLY when it's NOT FLYING. Dah!

Nobody at DJI has stated the shut off routine has been removed in 1.6, they have only stated things were "optimized" with no explanation. Maybe they were too embarrassed. It's interesting the OP said he was using the original firmware from 6mos ago. I'm thinking that could be 1.9 up to about 3.2. This implies the shut off routine may have been part of the firmware since the beginning. So why are these catastrophes only showing up now? Some say it's the temperature, but the OP had a reasonable ambient temperature I think.

JHammy, did you fetch the bird out of the drink? If yes, is the memory card good? Let us know what DJI says. In my book they should give you 50% off, and you should only have to buy the bird, not another RC, I'm thinking $400. However you share some liability. You should have been on the latest 1.6 firmware (some may say otherwise), and you should also have topped off the battery if it had been sitting for more than a couple days (turn on the battery when connected to the charger). If you had done either of these you may have had a different result. So a shared liability seems logical, too bad though, sorry for your loss.

Keep in mind, the battery protection scheme may be setup to shut down the power when one of the 4 cells gets below 3V. As batteries reach their end of their useful life, and one of the 4 batteries fails to hold a charge, the craft may still have the shut off occur (I'm thinking), unless DJI fesses up and tell us they have removed the shut off routine, or include a requirement to shut off only when not flying (preferred).

I really hope DJI eventually corrects this flaw in a more logical way.
 
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After reading all this, I have few questions:

1) Does the DJI app record the logs automatically (on Android) or do I have to do something to make sure the logs exist if anything serious happen?

2) Someone advised to not to fly on full throttle when the battery power is under 70%. Well, it's quite easy to accidentally to turn full throttle on for a while before you realize that "hey, I wasn't suppose to fly this fast". So, how relevant this advice is in warm weather? Is it something I should keep in mind only in cold? Can I prevent myself from using full throttle ever by adjusting settings? I mean, I usually have no hurry on my aerial photography or video missions.

3) If the voltage goes below 3,5V in a cold weather, how much time do I actually have to bring the drone down? Let's say I have still 40-50% left on battery.

4) If the battery would get damaged, could it cause a fire?
 
Does the DJI app record the logs automatically
Yes. It stores logs on your mobile device and on a non-removable memory card inside of your Phantom too.

Someone advised to not to fly on full throttle when the battery power is under 70%.
You can fly full throttle. Just keep an eye on the battery voltage.

If the voltage goes below 3,5V in a cold weather, how much time do I actually have to bring the drone down?
It's a good idea to consider landing when the battery is at about 30% or 3.4V. You should certainly watch the battery voltage though to ensure it does not dip below 3.0V. Even if the battery is at 3.5V while hovering, it could dip below 3.0V if you put it under a lot of stress (e.g. a full throttle steep climb).

If the battery would get damaged, could it cause a fire?
It could, but it's not likely. If you damage a battery, you should definitely dispose it.
 
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