I've been seeing a lot of discussion lately related to flying with partially charged batteries.  Primarily, they've been blamed for several drones falling out of the sky.  That worries me, since I have on multiple occasions flown with a less than fully charged battery.  While I'll certainly be far more careful from now on, I wanted to know what kind of scenarios would be considered acceptable.  For starters, we can all agree that:

Scenario 1:  Taking off with a battery at 100%.

. . . is the recommended, safe way to go about it.  However, what about these other hypothetical scenarios?

Scenario 2:  Taking off with a battery at 100%, landing at 60%, keeping the drone ON, then taking off again in five minutes with a ~60% charge.

Scenario 3:  Taking off with a battery at 100%, landing at 60%, turning the drone OFF, then turning it back ON in five minutes and taking off with a 60% charge.

Scenario 4:  Taking off with a battery at 60% charge that has been stored at that level for one day.

Scenario 5:  Taking off with a battery at 60% charge that has been stored at that level for one week.

well drones falling out of the sky could literally be anything, it's so random i seriously doubting it is battery charge level issue.

it is totally ok to fly with partially charged batteries as long as they are fresh still, not be sitting idle for days.. however keep in mind that the batteries have a built in smart self discharge this you can tweak in the app under battery and advanced configuration options..  i have read in some places that once the battery self discharge and sits a while it can sometimes report invalid amounts of power, for this i seen recommendations of plugging the batteries in and letting then charge so the meter kicks back in correctly.  

You should always top off your flight packs, if they have been idle for any length of time.

It don't take long, and you can be more sure about actual voltages.



RedHotPoker

If you are doing a touch and go, landing and taking off again soon after, that's fine.
Taking off with a battery that's been sitting around for a week is never a good idea and can significantly increase the probability of a fall-from-the-sky incident.

If everything is working correctly with no bad cells in the battery then I think the only scenario that is a real problem is if it has had a chance to self discharge since the last charge.

The self discharge is very slow so that it doesn't overheat if stored inside the aircraft inside the carry case inside a storage box inside a warm car,  as a result it fails to accurately measure how much power is removed and the % figure can then be very inaccurate.

From what I have seen posted it appears very sensible to charge the battery to 100% no more than a day before it will be used, then you know that it is starting off at a true 100% and you can make as many flights as you like.  You can even part charge it during use, I quite often take it down to 30% then top it up to eg 70% with the car charger and then fly again, but only if it is done the same day.

If it has had a chance to self discharge then it is essential that you keep a close watch on all the cell voltages during the flight, if any get down to 3.3v then it will either land or fall out of the sky very soon after.

Aloha Wolf,

     It is really good that you ask questions and frame them so well.  Those who read your threads get a fairly clear picture of the problem.

    Scenario 4 and 5 are a no go, period.  The first three scenarios are fairly safe but need to be monitored since you have specific pieces of equipment that may see variation of some sort due to manufacturing or source material (quality control variation).

     I have been flying DJI products for 2 years and just learned that charging half to nearly full batteries should be done with the battery on.  The battery will shut off after it is fully charged.  Never knew that before.

     The other day, I topped off a battery (80% or so) without turning it on and had some real strange performance issues.  The battery performed like it was never charged but the reporting on the DJI GO app indicated was fully charged and loosing charge accordingly.  My bird got all the warnings and they were dutifully reported through the app, but the numbers were 15-20% higher in the display.  

     Eventually, the bird went into a forced landing as I was trying to land it anyway.  About 18 inches off the ground the battery shut off and she fell into the thick grass (lucky me) and bounced.  The battery indicated a swelling until cooled and after an hour I charged it fully and properly.  When analysed in the DJI GO program, everything was prim and proper.  I have flown it since with no problems and no swelling but I kept it real close and low.

     Because this is cutting edge technology, we need to be as observant as we can and try our best to figure out any problems we encounter.  This Forum is our way to let the DJI engineers and other fliers know of interesting developments.  Great questions!

Aloha and Drone On!

Can you if you use your battery from 100% down to say 50% finish what you were doing , go home  then recharge it back up again.

dayviduk Posted at 2017-9-3 01:36
Can you if you use your battery from 100% down to say 50% finish what you were doing , go home  then recharge it back up again.

You can recharge at any time, it doesn't need to be empty.  

For storage it is best to have it around 50%, then charge it to 100% before going out to fly.  Don't leave it completely empty for long periods.

WOOOOOO, charging batteries with them switched on (when 50%-near full)...... Is this actually documented anywhere?

I can imagine taking some flights on the same day with one battery having started at 100%, but otherwise I would try and start with 100% always.
Not sure if that is best for the battery, but that seems best to me.

if it isn't 100% it isn't going flying Just the way I do things. so even if I put a bird in the air fly for 5 min land and am at 80% or so it goes back on charge before I put it back in the bird. I recharge hours before going flying so I know my batteries are as fresh as possible. Here is my reasoning, with so many unknowns with these things I want all the battery I can get so if I have to land be it emergency or crash and I need to search for it, I want the bird to remain powered up for as long as possible. In wooded areas the lights alone flashing can be a help in locating the bird. if I go for a flight and loose control I want battery time to try and regain that control. I know RTH should kick in right? well I can name one incident with a buddies drone when it didn't, it just sat there hovering for 15 min and never initiated RTH even though he was toggling the switch and using the go app button, we started running towards the drone which was out at 2500feet at 1100feet the bird reconnected and he got control of it again. That incident almost caused me to not buy one of these drones. he assured me that's never happened before and probably wont happen again. I took a chance and Bought a DJI drone I'm not willing to risk loosing it when its so easy to just make sure you have the best chance of recovery.

Keep in mind, your DJI Go/4 app gives an estimated time to tell you how long you have left with the battery.  If you're just aiming to do a few manuvers or film a few quick shots, it should be more than fine.  If you're going for long distance in Sport Mode, that might speed up the use of the battery.  It all depends on your plans and how well you monitor your battery.

HomePoint Posted at 2017-9-3 02:02
WOOOOOO, charging batteries with them switched on (when 50%-near full)...... Is this actually documented anywhere?

Don't know how you could do that, as the same connector is used for charging and discharging.

Capt Whitefoot Posted at 2017-9-3 17:44
Keep in mind, your DJI Go/4 app gives an estimated time to tell you how long you have left with the battery.  If you're just aiming to do a few manuvers or film a few quick shots, it should be more than fine.  If you're going for long distance in Sport Mode, that might speed up the use of the battery.  It all depends on your plans and how well you monitor your battery.

I look at it this way, the aircraft is about a $2.5K investment and I am going to put it up several hundred feet in the air. I want everything working for me to keep it up there, and carefully managing batteries is a simple part of the process.

You can take off with a 60% battery, but sooner or later you are probably going to turn up here with a "Drone fell out of the sky WTF?" posting.

When you learn to fly a full size aircraft, only about 20% of the training is on how to actually fly the aircraft, the other 80% is hammering into your head the concept of safety and removal of avoidable risk.

Geebax Posted at 2017-9-3 19:44
I look at it this way, the aircraft is about a $2.5K investment and I am going to put it up several hundred feet in the air. I want everything working for me to keep it up there, and carefully managing batteries is a simple part of the process.

You can take off with a 60% battery, but sooner or later you are probably going to turn up here with a "Drone fell out of the sky WTF?" posting.

I know what you mean.

Thats why I set my alarms at 25% for warning and 10% for "she's coming down whether you like it or not".  There will be those times when you're driving home and see that "I can't miss this" moment.  If you listen to and obey your warning paramaters on the battery, dropping out of the sky shouldn't be an issue.

Knowing your equipment, knowing your time limits, and knowing if you have the time are the keys to the equation to "Is it ok. to fly".  

Geebax Posted at 2017-9-3 19:44
I look at it this way, the aircraft is about a $2.5K investment and I am going to put it up several hundred feet in the air. I want everything working for me to keep it up there, and carefully managing batteries is a simple part of the process.

You can take off with a 60% battery, but sooner or later you are probably going to turn up here with a "Drone fell out of the sky WTF?" posting.

P.S.  I spent 20 years taking multi million dollar yachts out for cruises for their owners.  I do understand the concept of "risk" as their lives were legally in my hand every time the lines came off the docks.

Capt Whitefoot Posted at 2017-9-3 17:44
Keep in mind, your DJI Go/4 app gives an estimated time to tell you how long you have left with the battery.  If you're just aiming to do a few manuvers or film a few quick shots, it should be more than fine.  If you're going for long distance in Sport Mode, that might speed up the use of the battery.  It all depends on your plans and how well you monitor your battery.

As has been said here dozens of times, the battery % indicator only works properly when you launch with a fully charged battery.
If you launch with a battery that's been lying around for a week and has partially discharged, although it might be indicating 50%, this will be very different from flying a 100% battery down to 50%.
You'll find that the voltage (which is what matters) falls down towards the critical 3.3V per cell very quickly.
There have been lots of fall-from-the-sky incidents  caused by flying with partially discharged batteries.
Only fly with a fully charged battery.

At the price of a new drone, basic care must always and all ways, be observed, for best results.
Charging a battery that had begun its act of self depletion, is mandatory.

Getting to fly another day, is success...





RedHotPoker

When is it ok to fly with any depleted flight packs?

Probably while piloting with the flight SIM...


RedHotPoker

Labroides Posted at 2017-9-3 20:22
As has been said here dozens of times, the battery % indicator only works properly when you launch with a fully charged battery.
If you launch with a battery that's been lying around for a week and has partially discharged, although it might be indicating 50%, this will be very different from flying a 100% battery down to 50%.
You'll find that the voltage (which is what matters) falls down towards the critical 3.3V per cell very quickly.

You mean that the self discharged battery has a lower voltage even if they are both showing 50%?

Fruxen Posted at 2017-9-3 21:05
You mean that the self discharged battery has a lower voltage even if they are both showing 50%?

You just can't be sure of true voltage once auto discharge has been started.
So charging a flight pack to full capacity, will be an actual reading.



RedHotPoker

Here's a guy who thought it would be a good idea to fly with a battery he had flown with the day before.  Why bother to charge it?  It showed a 50% charge which should be fine.  Right?  Keep in mind, your DJI Go/4 app gives an estimated time to tell you how long you have left with the battery.  Right?  If you're just aiming to do a few manuvers or film a few quick shots, it should be more than fine.  Right?  

He was lucky.  It could have landed in a tree, a lake, or simply dropped from the sky without warning.  This has been documented hundreds of times over the years.

Scenario #2  I have done this a lot I always do soft landings on a square piece of plywood so I practice soft landings in verifying wind conditions, about every two weeks I use one battery just to practice landings and takeoffs, when wind conditions are at there worst at ground level. However, I always start back for my landings when my 28% low voltage warning sounds.  

Mark The Droner Posted at 2017-9-4 05:19
Here's a guy who thought it would be a good idea to fly with a battery he had flown with the day before.  Why bother to charge it?  It showed a 50% charge which should be fine.  Right?  Keep in mind, your DJI Go/4 app gives an estimated time to tell you how long you have left with the battery.  Right?  If you're just aiming to do a few manuvers or film a few quick shots, it should be more than fine.  Right?  

He was lucky.  It could have landed in a tree, a lake, or simply dropped from the sky without warning.  This has been documented hundreds of times over the years.

Great video.  Over time batteries do fall from 100% full charge.. that goes for all videos.  The older your batteries are, the faster they will deplete their power.

Cetacean Posted at 2017-9-3 01:24
Aloha Wolf,

     It is really good that you ask questions and frame them so well.  Those who read your threads get a fairly clear picture of the problem.

How does "turning the battery on" while charging change the voltage level coming in to the battery?  Does powering it on cause it to "trickle charge" as opposed to the battery being off?  Is this related to the slower you charge any kind of battery, the better?
I love that there is programming so you can see the full strength of the battery.  
I understand that batteries have an "upper", "middle" and "lower" level of the cells, and over time some parts of the cell erode or weaken faster than the other parts of the cells.  This is what causes batteries to lose their voltage over time if not regularly charged at a proper rate.

Capt Whitefoot Posted at 2017-9-4 08:48
How does "turning the battery on" while charging change the voltage level coming in to the battery?  Does powering it on cause it to "trickle charge" as opposed to the battery being off?  Is this related to the slower you charge any kind of battery, the better?
I love that there is programming so you can see the full strength of the battery.  
I understand that batteries have an "upper", "middle" and "lower" level of the cells, and over time some parts of the cell erode or weaken faster than the other parts of the cells.  This is what causes batteries to lose their voltage over time if not regularly charged at a proper rate.

Aloha Cap,

     This is at least the second time that this issue has been brought up on the Forum and I believe it is endorsed by DJI (turn the battery on).  In the beginning there were a number of theories about charging but it is clear that LiPo batteries have their own quirks regarding charging.

     But, to tell the truth, I have seen no rationale for why we should turn on the battery under these circumstances.  I do know that my P3P battery had serious issues when I topped it off without turning it on but the actions my bird made were well known to me from reading the manuals.  I just did not think it would override the current battery level on the display.  Good thing I was only 18 inches off the soft grass!  My P3P is my baby!

     So, I for one, will be testing the  theory to see if there is a performance issue.  I sure hope not.  I really like learning new tricks to the trade!

Aloha and Drone On!

Cetacean Posted at 2017-9-4 16:50
Aloha Cap,

     This is at least the second time that this issue has been brought up on the Forum and I believe it is endorsed by DJI (turn the battery on).  In the beginning there were a number of theories about charging but it is clear that LiPo batteries have their own quirks regarding charging.

Yes, that was new to me as well, but perhaps there might be a reason why DJI themselves don't discuss it.  I understand the three different ways of charging batteries, but wasn't sure if it applied to this kind of low voltage battery.

Capt Whitefoot Posted at 2017-9-4 17:36
Yes, that was new to me as well, but perhaps there might be a reason why DJI themselves don't discuss it.  I understand the three different ways of charging batteries, but wasn't sure if it applied to this kind of low voltage battery.

Aloha Cap,

     I am pretty sure that the first time I heard about this it was from a DJI Team Member.  So they do discuss these types of issues on the Forum.

Aloha and Drone On!

p3p manual says if battery is 90% or more turn battery on before charging. i have not started a charge at that high %yet.i activated volt reading .i think its more important than % reading but i would start day with every thing at 100%  thanks everyone for such good info.

Geebax Posted at 2017-9-3 19:44
I look at it this way, the aircraft is about a $2.5K investment and I am going to put it up several hundred feet in the air. I want everything working for me to keep it up there, and carefully managing batteries is a simple part of the process.

You can take off with a 60% battery, but sooner or later you are probably going to turn up here with a "Drone fell out of the sky WTF?" posting.

While I would not necessarily disagree with your break down, I would state it better this way.    

Flying is inherently risky, therefore removing risk is not realistic, rather it is more about risk mitigation.  

  

This means a tremendous amount of training goes in to emergency procedures to allow the pilot the ability to deal with those risks.  

  

In this case, operating a UAV is a different circumstance as the risk posed is primarily to the UAV directly.  Since it is not a cheap item and there are other risks involved, it only makes sense to operate a UAV in the safest way possible.

P.S. I'd much more prefer civilian pilots get more than 20% flight training

Genghis9 Posted at 2017-9-7 16:14
While I would not necessarily disagree with your break down, I would state it better this way.    Flying is inherently risky, therefore removing risk is not realistic, rather it is more about risk mitigation.    This means a tremendous amount of training goes in to emergency procedures to allow the pilot the ability to deal with those risks.    In this case, operating a UAV is a different circumstance as the risk posed is primarily to the UAV directly.  Since it is not a cheap item and there are other risks involved, it only makes sense to operate a UAV in the safest way possible.P.S. I'd much more prefer civilian pilots get more than 20% flight training

'P.S. I'd much more prefer civilian pilots get more than 20% flight training.'

Learning emergency procedures is still part of the training. My point was that actually flying the aircraft is pretty simple, but learning how to deal with emergencies takes up far more of the actual flight training than the basic flying training does.