I fly a full battery to about 60% capacity and a few days later fly the same battery again only to receive a warning after a minute or so of flight that the battery is critically low voltage. What's wrong? Same for all three batteries. When they are fully charged everything works fine.

If everything works fine when you fly with fully charged batteries, then maybe you should fly with fully charged batteries.  This seems logical to me.

What you are describing is talked about all the time around here.  Usually the poor fellow has just lost his drone to a fatal crash when he finds this out.  Sounds like you have been lucky so far.

How long are you waiting between flights and how many days do have selected before battery starts discharging?

If you are saying you flew the battery down to 60% and flew again a few days later without recharging the battery, then your assumtion that it had ample charge is incorrect.
The % indicator gives you a false reading when you start with a partially discharged battery.
What matters to the Phantom is actual voltage the battery can provide and when that gets close to 3.3V the Phantom will autoland to prevent damaging the battery and/or crashing.
To see what voltage you were getting from your battery go to http://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions there to upload your flight record from your phone or tablet.
Come back and post a link to the report it provides

Go to http://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions there to upload your flight record from your phone or tablet.
Come back and post a link to the report it provides

Which aircraft are you flying? Is it possible that the battery  discharged during that period of time?

never takeoff with a battery that has not been charged fully prior to use.the percent reading is not acurate. otherwise

P3A/P Intelligent Flilght Battery Safety Guidelines:

Top of page 3:  Make sure the battery is fully charged before each flight.

http://dl.djicdn.com/downloads/p ... _Guidelines__en.pdf

Labroides is dead on about the battery percentage.....and after several days you in fact DID NOT have an ample charge.  

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.

5 weeks ago had a P4 battery that I had charged up on the P4 charger to storage capacity (51%), at least 4 weeks earlier, probably longer......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...the voltage dropped, and 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 weeks 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 red 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.

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

Irate Retro and Labroides and Tmygun are all correct...
This is a well worn and discussed topic here, and there are literally volumes of info about it, everything from simple stuff found on this thread to some quite in-depth electrical & battery explanations.  Keep in mind these batteries are not your typical household Duracells, they each have a small computer circuit board - thus "smart battery."

The simplest answer is what the manual says, only fly with a fully charged battery.  If you attempt to fly with anything else you are taking a risk you will end up regretting.
Good Luck

yeah - if my battery hasn't been used in a week or so, it shows 62%. I found out about while over a large lawn area, so no damage. Flight lasted about 20 seconds, but it landed safely. Now, when my battery shows 62%, I'll allow it to lift off the ground a few feet, until it yells at me (about 20 seconds later), and I've successfully drained my battery.

Bartone Posted at 2017-10-1 11:58
yeah - if my battery hasn't been used in a week or so, it shows 62%. I found out about while over a large lawn area, so no damage. Flight lasted about 20 seconds, but it landed safely. Now, when my battery shows 62%, I'll allow it to lift off the ground a few feet, until it yells at me (about 20 seconds later), and I've successfully drained my battery.

There's no need to "drain your battery".

I figured that, but hey, it's my opportunity to get in an extra 20 seconds of flight time. ;-)

Irate Retro Posted at 2017-9-30 13:53
If everything works fine when you fly with fully charged batteries, then maybe you should fly with fully charged batteries.  This seems logical to me.

What you are describing is talked about all the time around here.  Usually the poor fellow has just lost his drone to a fatal crash when he finds this out.  Sounds like you have been lucky so far.

Did it occur to you that after 5 minutes of flying with a fully charged battery, the battery is no longer fully charged?  The best advice you could give... is to stop giving advice.

Irate Retro Posted at 2017-9-30 13:53
If everything works fine when you fly with fully charged batteries, then maybe you should fly with fully charged batteries.  This seems logical to me.

What you are describing is talked about all the time around here.  Usually the poor fellow has just lost his drone to a fatal crash when he finds this out.  Sounds like you have been lucky so far.

Hey Archie, did it occur to you that after 5 minutes of flying with a fully charged battery, the battery is no longer fully charged?  The best advice you could give... is to stop giving advice.

Dji ever answers to any questions???? Same thing happened to me yesterday. Took of and after few seconds got the low voltage msg. The aircraft started landing but as it was over the sea i hit the left stick all the way up and it lifted just a bit as so to manage to get it over land. If you dont touch the stick, the drone will come down on its own. Just telling you so maybe next time this happens to anyone he manages to save from crashing.

fansfec6d998 Posted at 5-26 10:45
Dji ever answers to any questions???? Same thing happened to me yesterday. Took of and after few seconds got the low voltage msg. The aircraft started landing but as it was over the sea i hit the left stick all the way up and it lifted just a bit as so to manage to get it over land. If you dont touch the stick, the drone will come down on its own. Just telling you so maybe next time this happens to anyone he manages to save from crashing.

Not sure what your questions are, but post #9 has some very important info in it.

fansfec6d998 Posted at 5-26 10:45
Dji ever answers to any questions???? Same thing happened to me yesterday. Took of and after few seconds got the low voltage msg. The aircraft started landing but as it was over the sea i hit the left stick all the way up and it lifted just a bit as so to manage to get it over land. If you dont touch the stick, the drone will come down on its own. Just telling you so maybe next time this happens to anyone he manages to save from crashing.

This is a public forum for owners of DJI products to discuss issues.  It is not really intended to get a specific official answer from DJI, even though a DJI rep/administrator frequents it.  They are likely to give a pre-packaged answer and not particular in-depth.  The other users on the forum range from complete novices up to extremely seasoned and experienced pilots.  Very valuable information can be gathered by reading all the responses.

The capabilities of the aircraft often exceed the intelligence of the person flying it.  It is pre-programmed to perform certain functions for self-preservation and public safety despite being instructed to do something to the contrary by the pilot.  In your example, you are flying in a situation where you have a depleted battery (either you flew it partially charged or until flat, or it developed a fault).  Instead of landing sooner with a reserve of power, you continued flying it to empty.  The fact you are over water/trees/other hazardous or difficult terrain is not a consideration for the aircraft -- that is a risk you take every time you fly.  It knows it is imminently about to run out of power and crash.  It will now auto-land to keep the aircraft, battery and people on the ground safe (better to touch down under power than fall out of the sky onto someone's head).  DJI have built in a capacity to steer the aircraft while it is auto-landing so you can avoid obstacles on the way down, exactly as you discovered.  Most people that read the manual know that but you seem to have fortunately discovered this during this landing.  While it gives you limited capacity to maintain altitude or climb, the aircraft's primary purpose is to land.  Should the battery deplete further to critical levels (a crash is pending in the next minute), it will land immediately and discard any inputs.  The greater good is to get it on the ground in powered flight for the potential safety of humans, and the safety of the aircraft is no longer paramount.  You should never have to experience these fail-safes in normal operation as you really should not be flying with such low battery levels.  A safe pilot would land much sooner.  A real aircraft will land with a large reserve of fuel with potentially hours of capacity for flight, to do otherwise is dangerous.  Military aircraft during war time might push the envelope and have minimal reserves, but one thing is clear -- no fuel means no flight.

I flew a P3A with a fully-charged battery just pulled off the charger.  After a few minutes I got a critically low voltage warning and had a forced landing. Luckily the aircraft was still nearby!  After landing, I looked at the Go app display and it said the battery was at 88%!  So I took off again without recharging the battery and the P3A flew fine for many more minutes. After a while I looked at the voltage per cell and it was around 3.96V.  So I’m convinced we have a software or firmware or maybe even hardware (connection?) problem somewhere!  I have a Ph.D. In EECS (more CS than EE) and have been teaching at universities for well over 30 years, and that includes embedded systems lab classes. I can pretty confidently say that it’s not pilot error we’re talking about here. There’s an error in the system somewhere and may cause drones to be lost or may even cause danger.  By the way, I lost a Mavic 2 Pro and a P4P up on a mountain through forced landing, though I have by now retrieved the P4P.  I believe those forced landings were also due to system errors, though I am slightly less sure of the cause than in the case of the P3A.

fans9b81c9f5 Posted at 10-1 00:39
I flew a P3A with a fully-charged battery just pulled off the charger.  After a few minutes I got a critically low voltage warning and had a forced landing. Luckily the aircraft was still nearby!  After landing, I looked at the Go app display and it said the battery was at 88%!  So I took off again without recharging the battery and the P3A flew fine for many more minutes. After a while I looked at the voltage per cell and it was around 3.96V.  So I’m convinced we have a software or firmware or maybe even hardware (connection?) problem somewhere!  I have a Ph.D. In EECS (more CS than EE) and have been teaching at universities for well over 30 years, and that includes embedded systems lab classes. I can pretty confidently say that it’s not pilot error we’re talking about here. There’s an error in the system somewhere and may cause drones to be lost or may even cause danger.  By the way, I lost a Mavic 2 Pro and a P4P up on a mountain through forced landing, though I have by now retrieved the P4P.  I believe those forced landings were also due to system errors, though I am slightly less sure of the cause than in the case of the P3A.

It is not necessarily an error. If you are flying a P3A, then very likely the battery is now quite old. The displayed capacity is a calculated figure, and the value is arrived at by monitor the quantity of charge (current X time, for a fixed voltage), whereas the aircraft is constantly monitoring the voltage of each cell during the flight. If the voltage goes down to a critical level, it will trigger the low voltage warning, even though the display may indicate a higher charge. This is most often due to one or more cells in the pack developing a higher internal resistance.

Geebax Posted at 10-1 15:43
It is not necessarily an error. If you are flying a P3A, then very likely the battery is now quite old. The displayed capacity is a calculated figure, and the value is arrived at by monitor the quantity of charge (current X time, for a fixed voltage), whereas the aircraft is constantly monitoring the voltage of each cell during the flight. If the voltage goes down to a critical level, it will trigger the low voltage warning, even though the display may indicate a higher charge. This is most often due to one or more cells in the pack developing a higher internal resistance.

But in that case, the calculation must have been off by a huge amount.  Also, how would you explain the ability to fly a lot after the forced landing without charging the battery? I haven’t looked at the flight log yet, but it seemed to me that the flight after the forced landing was much longer than the flight before the forced landing.

fans9b81c9f5 Posted at 10-2 02:56
But in that case, the calculation must have been off by a huge amount.  Also, how would you explain the ability to fly a lot after the forced landing without charging the battery? I haven’t looked at the flight log yet, but it seemed to me that the flight after the forced landing was much longer than the flight before the forced landing.

I haven’t looked at the flight log yet, but ...
Guessing without seeing recorded flight data is a waste of effort.

Mark The Droner Posted at 2017-10-1 03:02
P3A/P Intelligent Flilght Battery Safety Guidelines:

Top of page 3:  Make sure the battery is fully charged before each flight.

Has people’s IQ’s dropped sharply?  I am having the exact same problem with my p3p with all my batteries being fully charged and I can’t takeoff for more than a minute and it gives me the same warning and does an emergency landing.  Almost landed on top of a moving UPS truck.  This is not a matter of human irresponsibility but an obvious mechanical or hardware malfunction.  Someone please help us here.

fans069ddc01 Posted at 12-7 13:49
Has people’s IQ’s dropped sharply?  I am having the exact same problem with my p3p with all my batteries being fully charged and I can’t takeoff for more than a minute and it gives me the same warning and does an emergency landing.  Almost landed on top of a moving UPS truck.  This is not a matter of human irresponsibility but an obvious mechanical or hardware malfunction.  Someone please help us here.

It sounds like you have a bad battery.  If you would post your log info, we might be able to figure this out for you.  Upload, paste link.  https://www.phantomhelp.com/LogViewer/Upload/#

Edit:  I'll just add some more info here.  If you have a individual cell that drops too low, the AC will autoland.  Doesn't matter how much voltage you have because it's not a battery voltage test that causes the autoland, it's a cell voltage test, so if one cell drops too low, it will autoland.  This would indicate a battery that's out of balance which is another way of saying it's a bad battery.  Another possibility is you're in some kind of strange NFZ area but that seems unlikely.  Showing us the log via the above link might clarify.  

In reply to the OP, As it says in the manual, always fly with a full battery, simple!

fans069ddc01 Posted at 2020-12-7 13:49
Has people’s IQ’s dropped sharply?  I am having the exact same problem with my p3p with all my batteries being fully charged and I can’t takeoff for more than a minute and it gives me the same warning and does an emergency landing.  Almost landed on top of a moving UPS truck.  This is not a matter of human irresponsibility but an obvious mechanical or hardware malfunction.  Someone please help us here.

True
I have exactly the same problem fully charged 30s in the flight... battery critically low landing and i manage to glide it in not landing in the see twice today with 2 batteries

Lost a P3A into the sea on the 5th flight of the day taking out a fishing line. The first 2 flights went about 300m out, I changed the battery for the 3rd and 4th where I took the line out to 500m and 350m. I then decided to change back to the first battery for a last short run because the second battery was down to 45% and the first was 55%. It got about 80m out then warning came up "critically low voltage, emergency landing" and started descending towards the sea. I quickly released the line and stupidly spent more time trying to cancel the "emergency landing" than trying to lift and fly back. If I had have tried to fly it back do you rekon it could have made the 80-100m?
Obviously I shouldn't have taken the risk but thought I had the safety net of it warning me about the battery getting low and returning home like it had done other times. BUt this time it gave no warning and about 10 seconds later was in a watery grave!

Sorry for your loss.  You must launch with a fully charged battery every flight.  If you want to do five flights, bring five fully charged batteries.  And yeah, you can't cancel emergency landing, but you might be able to guide it back by carefully and gently feathering the throttle.  Sorry again

djiuser_U8h99BcGVC3a Posted at 12-31 18:33
Lost a P3A into the sea on the 5th flight of the day taking out a fishing line. The first 2 flights went about 300m out, I changed the battery for the 3rd and 4th where I took the line out to 500m and 350m. I then decided to change back to the first battery for a last short run because the second battery was down to 45% and the first was 55%. It got about 80m out then warning came up "critically low voltage, emergency landing" and started descending towards the sea. I quickly released the line and stupidly spent more time trying to cancel the "emergency landing" than trying to lift and fly back. If I had have tried to fly it back do you rekon it could have made the 80-100m?
Obviously I shouldn't have taken the risk but thought I had the safety net of it warning me about the battery getting low and returning home like it had done other times. BUt this time it gave no warning and about 10 seconds later was in a watery grave!

I then decided to change back to the first battery for a last short run because the second battery was down to 45% and the first was 55%.
You can't rely on the % indicator as a perfect guide to battery charge level.
What the motors need and what triggers critical low voltage is the cell voltage.
Post your flight data and we'll see a better picture of how good/bad the battery was.

Mark The Droner Posted at 12-31 19:08
Sorry for your loss.  You must launch with a fully charged battery every flight.  If you want to do five flights, bring five fully charged batteries.  And yeah, you can't cancel emergency landing, but you might be able to guide it back by carefully and gently feathering the throttle.  Sorry again

Thanks Mark
That definitely makes sense. Just wish i had reacted quicker. Unfortunately was only flying the drone around 10m high, so bait didnt have too far to fall so didnt get a lot of time..

I've seen this happen.. even with a fully charged battery, on the Inspire 1 I had critical low voltage with 60%+ battery charge in the air.  With the Spark, this happens even with 40%+ indoors but with prop guards on.  I was flying it though after and it was no problem.  Sold the whole set to someone which was the person I bought the FLIR XT from.

Apparently there is nothing you can do about the "hiccup".  Everyone is overcomplicating it way too much.

Labroides Posted at 12-31 19:30
I then decided to change back to the first battery for a last short run because the second battery was down to 45% and the first was 55%.
You can't rely on the % indicator as a perfect guide to battery charge level.
What the motors need and what triggers critical low voltage is the cell voltage.

Ive learnt a lot in the last week. It was my dads old drone and he had got another one because the camera was broken. I removed the camera completely to take some weight off. And had only just learnt about flying it on maps etc, and since posting,  about looking at past flight data! I will try and post it on. Very interesting, it was actually 150m out but battery had only dropped to 51% and there was no pror warnings

AntDX316 Posted at 12-31 23:16
I've seen this happen.. even with a fully charged battery, on the Inspire 1 I had critical low voltage with 60%+ battery charge in the air.  With the Spark, this happens even with 40%+ indoors but with prop guards on.  I was flying it though after and it was no problem.  Sold the whole set to someone which was the person I bought the FLIR XT from.

Apparently there is nothing you can do about the "hiccup".  Everyone is overcomplicating it way too much.

I've seen this happen.. even with a fully charged battery, on the Inspire 1 I had critical low voltage with 60%+ battery charge in the air.
But if you didn't read the flight data, you'd never know what caused the incident

Labroides Posted at 2021-12-31 23:36
I've seen this happen.. even with a fully charged battery, on the Inspire 1 I had critical low voltage with 60%+ battery charge in the air.
But if you didn't read the flight data, you'd never know what caused the incident

I did, but I didn't use airdata..  The flights didn't upload to airdata.. I cleared out the flights before uploading so a lot was lost Unfortunately. : (

I did as in, I've checked the basic logs and everything looked good (green) with no major faults or fauls like MIL codes.

AntDX316 Posted at 1-1 02:09
I did, but I didn't use airdata..  The flights didn't upload to airdata.. I cleared out the flights before uploading so a lot was lost Unfortunately. : (

I did as in, I've checked the basic logs and everything looked good (green) with no major faults or fauls like MIL codes.

But you didn't get someone who can read the data to interpret it for you, so nothing was learned.
There is much more in the data than you'll ever see with Airdata.

AntDX316 Posted at 2021-12-31 23:16
I've seen this happen.. even with a fully charged battery, on the Inspire 1 I had critical low voltage with 60%+ battery charge in the air.  With the Spark, this happens even with 40%+ indoors but with prop guards on.  I was flying it though after and it was no problem.  Sold the whole set to someone which was the person I bought the FLIR XT from.

Apparently there is nothing you can do about the "hiccup".  Everyone is overcomplicating it way too much.

I've flown thousands of flights and in my experience, 0% of the flights have "hiccup" problems as you are describing.  In the rare case I have an unexpected drop, there's always a good reason such as a swollen battery or a cold battery or an aftermarket battery or cells out of balance or damaged cells.  However, I never fly with a battery that's not fully charged.  Every once in a blue moon I'll come outside to test a drone "just for a minute or two" at a height of five feet with a 50% charged battery because that's what I have on hand, and it flies fine for maybe a minute before it starts flashing red and dropping.  There are hundreds of threads on this site and others from people who lost their drone because they flew with a battery that wasn't fully charged.

Here's a battery that was unknown to me and slightly swollen which I wanted to test:

Labroides Posted at 1-1 03:56
But you didn't get someone who can read the data to interpret it for you, so nothing was learned.
There is much more in the data than you'll ever see with Airdata.

How can we get access to the tools for better interp?

Mark The Droner Posted at 1-1 04:08
I've flown thousands of flights and in my experience, 0% of the flights have "hiccup" problems as you are describing.  In the rare case I have an unexpected drop, there's always a good reason such as a swollen battery or a cold battery or an aftermarket battery or cells out of balance or damaged cells.  However, I never fly with a battery that's not fully charged.  Every once in a blue moon I'll come outside to test a drone "just for a minute or two" at a height of five feet with a 50% charged battery because that's what I have on hand, and it flies fine for maybe a minute before it starts flashing red and dropping.  There are hundreds of threads on this site and others from people who lost their drone because they flew with a battery that wasn't fully charged.

Here's a battery that was unknown to me and slightly swollen which I wanted to test:

Your drone just fall like that out of the sky?

AntDX316 Posted at 1-1 05:46
How can we get access to the tools for better interp?

You could learn how to read flight data, or have someone who is good at it do it for you.

AntDX316 Posted at 1-1 05:47
Your drone just fall like that out of the sky?

I had one that dropped dead from the sky into some woods - that was an aftermarket battery.  A couple others auto-landed a little prematurely, but they landed safely at or near the home point.  The battery both times was a little swollen.  That's it.  

I consider all of my drops pilot errors.

Mark The Droner Posted at 1-1 06:30
I had one that dropped dead from the sky into some woods - that was an aftermarket battery.  A couple others auto-landed a little prematurely, but they landed safely at or near the home point.  The battery both times was a little swollen.  That's it.  

I consider all of my drops pilot errors.

never use non-DJI products unless it's a cover for the packing