Whats going on here? Has me puzzled need an expert opinion.

[mikeyoda]

Hi Guys,
Air2s , all three batteries today did the same thing, not sure why or whats going on, so thought I would find an expert.

Quick rundown:

Drone last used a month ago.
Did get a first battery warning ever with one battery last month but went away mid flight.
Charged all batteries before their use today
All had about 50% power on flight as they drain themsleves over that month of no use.
All batteries went from around 50% to nothing in less than a minute.

Could all three batteries have a problem at the same time?

See log of one of the flights, 3 flights all the same basically. lasted about a minute or less
Had the drone do an emergency landing in each case. Lucky I was not over water.
.

Thanks suppose I will head over to DJI as well to see what to do now as cant fly the bird..

 

[Yorkshire_Pud]

It is my experience that using on 'old charge ' one needs to be careful i.e. keep the drone close and low. That's with other DJI models. I would suggest that you retest using recently fully charged batteries. I.e. use that charge within a day or so of the charging.

 

[slup]

...Did get a first battery warning ever with one battery last month but went away mid flight.

Yeah, you got below messages...


But I'm not following you in your rundown... first you say

Charged all batteries before their use today

Then you say...

All had about 50% power on flight as they drain themsleves over that month of no use.

So which was it... did you charge them to 100% immediately before the flight or did you use them in a discharged state laying around for a long time suffering a self discharge?

Looking at the log it seems to have been the later... laying around discharged & you flew them without having them fully charged.

Initially in the flight the BMS (battery management system) reports that the battery have 52%... but that is totally wrong if looking at the individual cell voltages. Immediately after motor start the voltage fell down to around 3,5V/cell which is mainly a empty battery... 0%.

About 13sec into the flight the cell voltage was down below the permanently damaging 3V limit... the cells fell to 2,95, 2,96 & 2,94V.

Shortly after the BMS realized that the percentage calculation was totally off & started to show 0%... & then the forced low battery auto landing started in order to prevent the drone to free fall as a rock.

 

[Meta4]

All had about 50% power on flight as they drain themsleves over that month of no use.
All batteries went from around 50% to nothing in less than a minute.

Here's the thing.
Your batteries did not have 50% charge when you started.
It just looked like that, because the % indicator gives a false indication when you are looking at batteries that have been sitting around discharging for some time.

Rather than the false % indication, look at the battery cell voltages (that's what really matters) here:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

Within seconds, when you put the battery under load by launching, the battery cells were into critical low voltage levels (3.2 volts).
If the battery was freshly charged, the cell voltages would have been around 4 volts.
When you fly, always makes sure that you are using a freshly charged battery, not one that's been sitting around discharging.

 

[Yorkshire_Pud]

So, at a guess, PH has had that log uploaded at least three times lol.

 

[mikeyoda]

Oh Thanks so much Slup, , I think I have got this right , correct me if I am wrong. By allowing the batteries to have not been charged by about 4 weeks from a full charge , My bad I may having not explained this properly given my poor english skills, even if I push the button on top of the battery and it shows 2 green lights out of the four hard on and one gree light blinking , which would indicate around a 50% charge they are not it a state to fly? So moving forward the lesson is dont fly unless your batteries are fully charged regardless of what the batteries are telling you and the software...

I did get that warning, but it went from warning to landing very quickly as I tried from the warning to bring the bird closer for a controlled landing by grabing it, while trying to make sure the farm dog did not eat the drone I was able to grab the dog just in time but it was a hetic scene.

This is where I got confused, and I what I couldnt work out after the flight landed , batteries showed over 40% charge, so full batteries from now on everyone, Thanks for taking the time, and I know your information will be of use to others as I was surprised, knowing that even though the batteries self drain , if they show a 50% charge, which indicated to me, ok to fly for a short while, dont trust that information.

Thank you for also to all the other replies they also helped and I apprecaite you all taking the time and showing me some patience in the matter.

 

[mikeyoda]

Here's the thing.
Your batteries did not have 50% charge when you started.
It just looked like that, because the % indicator gives a false indication when you are looking at batteries that have been sitting around discharging for some time.

Rather than the false % indication, look at the battery cell voltages (that's what really matters) here:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

Within seconds, when you put the battery under load by launching, the battery cells were into critical low voltage levels (3.2 volts).
If the battery was freshly charged, the cell voltages would have been around 4 volts.
When you fly, always makes sure that you are using a freshly charged battery, not one that's been sitting around discharging.

Thankyou , I will be flying with full batteries from now on. I did not understand the whole concept so I am very happy you guys helped me understand what was going on.