Critically Low Voltage Warning__Aircraft will be forced to land

[di4b0liko]

Hi there

This is my first post so please excuse if i dont follow the norms.

I have a Mavic 2 Pro. I put it in the air over the weekend and for the first time had a Critically Low Power/Voltage error displayed and it automatically started to land my drone.


I have attached the flight logs, can you help me?
thanks

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[SkyeHigh]

Hi there

This is my first post so please excuse if i dont follow the norms.

I have a Mavic 2 Pro. I put it in the air over the weekend and for the first time had a Critically Low Power/Voltage error displayed and it automatically started to land my drone.


I have attached the flight logs, can you help me?
thanks

DJI Flight Log Viewer | Phantom Help

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www.phantomhelp.com

It looks like you have a bad battery showing some abrupt changes in voltage during the flight. Cell 4 within the battery looks suspect.

How old is the battery?
How many charges had this battery had?
Has it been maintained and not allowed to go completely flat?

 

[di4b0liko]

I forgot to mention that the weather was cold, around -2 degrees centigrade.
the battery was fully charged, I had charged it in the morning and had flown 1 hour earlier, and everything was fine.

I think the battery is 2 years old.
the drone is not new

I don't know how many charges he has, where can I see that?

the guy who sold me the drone gave me three batteries, two are a bit swollen, this one I used instead seems OK, but at this point I think this too has defects.

 

[Meta4]

I have a Mavic 2 Pro. I put it in the air over the weekend and for the first time had a Critically Low Power/Voltage error displayed and it automatically started to land my drone.

It's important to only launch with fully charged batteries.
The battery you used had been lying around unused for some time and they self-discharge to avoid damaging the battery.
Leaving a battery sitting with a full charge would damage it.

But if the battery has partially discharged, the % indication will not be correct.
Look down the columns marked Cell 1, cell 2 etc and see what the voltages look like at 22.5 sec under the effort of climbing.
They have already reached critical low voltage (3.3 volts).

The battery could well be OK ... but it should be fully charged shortly before you launch it next time.

In case you haven't found the manual yet, you can get a copy here:

https://dl.djicdn.com/downloads/Mavic_2/Mavic_2_Pro_Zoom_User_Manual_v2.2_en.pdf

 

[Meta4]

I don't know how many charges he has, where can I see that?

In the app settings, look at the battery section (with the drone connected) and you'll see a display like this:

 

[Deleted member 103366]

In addition to Meta4's screen capture I have the attached another useful screen.
It might also be advisable to set the self discharger delay to 1 or 2 days.
If you open the csv you posted as a spreadsheet and look in the column ( DG or 111) containing "loop" in the title you will see the charge count, if you open the column (DQ or 121) containing "prod" in the title you will see the battery's production date.

 

[slup]

...I had charged it in the morning and had flown 1 hour earlier, and everything was fine.

I think the battery is 2 years old.
...gave me three batteries, two are a bit swollen, this one I used instead seems OK, but at this point I think this too has defects.

It's important to only launch with fully charged batteries.
The battery you used had been lying around unused for some time and they self-discharge...

From what's described this doesn't seem to be a case of a self-discharged battery being laying around ... This battery was fully charged the same day as the flight & was used for a previous flight flying it down to 70%.

Instead this is what will happen to all LiPo batteries eventually if they aren't periodically monitored regarding their performance & degradation over time.

This battery was manufactured in Oct-2018 & was probably together with the other swollen 2 included in a kit together with the drone. You bought it second hand & have no clue how the batteries have been cared for regarding storage or usage ... & it seems like you doesn't have full knowledge about battery care either, instead you probably have continued to mistreating them.

When batteries ages (which all will do ... quickly or slowly depending on care), the chemistry in them will break down & that create gases which make them swell ... furthermore the internal resistance increases & makes the battery prone for voltage drops when put under higher amp draw. So flying with a bad battery in cold weather & push it is to beg for thing's like this to happen.

Advice you to ditch those 3 old batteries & invest in a couple new ones instead.

The 2 swollen is very clearly over due ... don't use them at all ... not even for desk duties, bad thing's can happen during discharge & charging.

The battery from this flight ... all 4 cells went well below 3V & had major cell deviations. This meant that you again increased the internal resistance so it will now be even more prone to drop the voltage & it may start to swell also shortly.

 

[di4b0liko]

It's important to only launch with fully charged batteries.
The battery you used had been lying around unused for some time and they self-discharge to avoid damaging the battery.
Leaving a battery sitting with a full charge would damage it.

But if the battery has partially discharged, the % indication will not be correct.
Look down the columns marked Cell 1, cell 2 etc and see what the voltages look like at 22.5 sec under the effort of climbing.
They have already reached critical low voltage (3.3 volts).

The battery could well be OK ... but it should be fully charged shortly before you launch it next time.

In case you haven't found the manual yet, you can get a copy here:

https://dl.djicdn.com/downloads/Mavic_2/Mavic_2_Pro_Zoom_User_Manual_v2.2_en.pdf

I had charged the battery the same morning.

I had made a flight just before which brought the battery from 100 to 70%.

this was the second flight, a few minutes later.

 

[Meta4]

I forgot to mention that the weather was cold, around -2 degrees centigrade.
the battery was fully charged, I had charged it in the morning and had flown 1 hour earlier, and everything was fine.

I missed this detail.
But a healthy battery, freshly charged and flown down to 70% an hour earlier would have been fine.
That battery was far from healthy if it was at critical low voltage around 20 seconds after launching.

 

[di4b0liko]

From what's described this doesn't seem to be a case of a self-discharged battery being laying around ... This battery was fully charged the same day as the flight & was used for a previous flight flying it down to 70%.

Instead this is what will happen to all LiPo batteries eventually if they aren't periodically monitored regarding their performance & degradation over time.

This battery was manufactured in Oct-2018 & was probably together with the other swollen 2 included in a kit together with the drone. You bought it second hand & have no clue how the batteries have been cared for regarding storage or usage ... & it seems like you doesn't have full knowledge about battery care either, instead you probably have continued to mistreating them.

When batteries ages (which all will do ... quickly or slowly depending on care), the chemistry in them will break down & that create gases which make them swell ... furthermore the internal resistance increases & makes the battery prone for voltage drops when put under higher amp draw. So flying with a bad battery in cold weather & push it is to beg for thing's like this to happen.

Advice you to ditch those 3 old batteries & invest in a couple new ones instead.

The 2 swollen is very clearly over due ... don't use them at all ... not even for desk duties, bad thing's can happen during discharge & charging.

The battery from this flight ... all 4 cells went well below 3V & had major cell deviations. This meant that you again increased the internal resistance so it will now be even more prone to drop the voltage & it may start to swell also shortly.

View attachment 123878

this is a perfect analysis.
but I have never mistreated the batteries. I have about 5 active flights with this drone

 

[di4b0liko]

I missed this detail.
But a healthy battery, freshly charged and flown down to 70% an hour earlier would have been fine.
That battery was far from healthy if it was at critical low voltage around 20 seconds after launching.

no, I had flown before, here is the log:

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[Meta4]

no, I had flown before, here is the log:

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That flight data confirms that the battery was in poor condition.
When under load, it was reaching low cell voltages only a minute into the flight.
A healthy battery doesn't do that.

 

[slup]

this is a perfect analysis.
but I have never mistreated the batteries. I have about 5 active flights with this drone

That's all good ... judged your battery knowledge from you posting & you wondering what happened & using 2 swollen ones.

Now ditch those 3 & buy new ones & consider yourself lucky that you still have the drone in shape.

Then never keep batteries outside storage voltage (3,7-3.8V/cell) longer than 48h ... don't discharge them periodically below 15% & respect the operational temperatures from the manual. Store them in room temps. If this is followed they will last.

 

[Meta4]

no, I had flown before, here is the log:

For comparison, I just checked data from a recent flight on a healthy battery.
After 17 minutes of hard flight, the battery cells were all showing >3.6 volts when under full load.

 

[di4b0liko]

my old mavic 1 guaranteed 3 years of honorable service, never a problem.
i believe the old owner mistreated this mavic 2.
Thanks for your suggestions.
I will buy new batteries (they are very expensive).
Are you telling me that I will never be able to use the drone in the snow?
in the manual, it's indicated that below 15 degrees, it's dangerous to fly.

is there a test to check if the battery parameters are ok? maybe with dji assistant 2 or something similar?

 

[Meta4]

is there a test to check if the battery parameters are ok? maybe with dji assistant 2 or something similar?

Batteries gradually lose capacity over their life.
The battery display shown in post #5 shows how what the capacity has dropped to from the original capacity in milli amp hours

 

[di4b0liko]

For comparison, I just checked data from a recent flight on a healthy battery.
After 17 minutes of hard flight, the battery cells were all showing >3.6 volts when under full load.

thanks.

what do you think about this LOG?

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any problems?

same place.

 

[slup]

my old mavic 1 guaranteed 3 years of honorable service, never a problem.
i believe the old owner mistreated this mavic 2.
Thanks for your suggestions.
I will buy new batteries (they are very expensive).
Are you telling me that I will never be able to use the drone in the snow?
in the manual, it's indicated that below 15 degrees, it's dangerous to fly.

is there a test to check if the battery parameters are ok? maybe with dji assistant 2 or something similar?

The operational temp for a M2 according to the spec.



If you want to foresee thing's like this before it happens ... you need to monitor the battery over a longer period ... look at the trends regarding max possible flight times, max charged capacity vs. designed capacity, cell deviations & voltage drops.

Looking at a single flight isn't enough to judge if a battery needs to be taken off flight duties ... a battery can show a normal behavior in warmer temps & lighter load, but totally fail pressed in sub freezing temps.

Airdata.com have paid alternatives where you can watch the trends for the batteries over all logs you have there ... those subscriptions can be a cheap insurance?

 

[di4b0liko]

The operational temp for a M2 according to the spec.

View attachment 123879

If you want to foresee thing's like this before it happens ... you need to monitor the battery over a longer period ... look at the trends regarding max possible flight times, max charged capacity vs. designed capacity, cell deviations & voltage drops.

Looking at a single flight isn't enough to judge if a battery needs to be taken off flight duties ... a battery can show a normal behavior in warmer temps & lighter load, but totally fail pressed in sub freezing temps.

Airdata.com have paid alternatives where you can watch the trends for the batteries over all logs you have there ... those subscriptions can be a cheap insurance?

thanks for the details.
I imagined that it took a longer period to have a correct view of things.
The difficult thing is knowing how to interpret the data that is formed.
reading the instruction manual doesn't always make you educated to understand some things.
Airdata.com is a good insurance

do you think that DJI can recognize the defect of swollen batteries or is this always attributable to the misuse of the owner?

 

[slup]

thanks.

what do you think about this LOG?

DJI Flight Log Viewer | Phantom Help

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www.phantomhelp.com

any problems?

same place.

Crappy ... throw it away.

Imagine that is a flight with one of the swollen ones (manufactured July-2018) ... also have a major voltage drop down to 3.19V when you used it with max stick inputs.

...do you think that DJI can recognize the defect of swollen batteries or is this always attributable to the misuse of the owner?

They have 6 month warranty on batteries ... after that you're on your own.