I have a DJI Mavic Pro 2o n the latest firmware versions for all.

Recently was trying to get some close up surveys of wall panels / caulking issues by getting within 8-6ft of the building. While getting close to the building, the message of 'Critically low power. Aircraft Landing. Thorttle up and reduce the speed of descent and use sticks to avoid obstacles.'

Few moments later "Critically low voltage warning. Aircraft Landing".

I've sinced charged the batteries back to 100% but haven't attempted a flight yet. More-so curious if anyone else has seen this. I did happen with two different batteries, similar timeframe and symptoms.

https://www.phantomhelp.com/LogViewer/6KXYJ13SIJPWIRNJ3GCA/

Look at the warnings and voltages. Not even close to 100% charge.

I get that but doesn’t explain why. I’ve flown with batteries at the 60% discharge and took off below 60% at times when needed without issues. And for all my batteries to do this?

Hi,

At start your battery cells shows already low values, see my chart of your flightlog.
In normal flight cell values always > 3.3 volt.

As you can see in the chart, cells dropped quickly to very low values.

When 1 or more cells really get low ( at 39.5s in flight  cell at 2.717 !)  than the sofware calls for an critical low autolanding.
Hopefully to land the craft before dropping down while in flight.

Battery wich are not used for some time can show this....
Best practise is to check batt cell values before a flight.

So check this before the next flight(s), and stay close to HP, check regular in this test flight the cell values.

Normal is 100% = approx 4.2 volts.

If your batterry does not show a linear drop from apprix 4.2 - 3.4, 100% to 20% ; battery life is over....

In the small chart  typical cell values for a MAVIC2

cheers
JJB     [ Chart by FRAP ; the 'best' software for flightlog analysis ]

Out of interest, is it a genuine DJI battery and was it cold that day?

Also, if it was cold, did you keep the battery in the car overnight or something?

CloudVisual Posted at 4-12 11:24
Out of interest, is it a genuine DJI battery and was it cold that day?

Also, if it was cold, did you keep the battery in the car overnight or something?

Yup all of them genuine dji - original from the purchase so going on five years now?

It was below freezing at takeoff. Drone was kept indoor overnight.

brfr2005 Posted at 4-12 11:32
Yup all of them genuine dji - original from the purchase so going on five years now?

It was below freezing at takeoff. Drone was kept indoor overnight.

What was the run up to the batteries being used that day? Were they left in the cold for an extended amout of time, or kept warm to at least room temp?

This kind of sudden drop really looks like a very cold battery, which wasn't fully charged, being flown. No different to when a mobile phone switches off early when it's freezing cold.

Looking at the voltages it seems as if one cell makes a comeback just as you're landing, showing that it's started to warm up a bit. The fact the voltages were so low at takeoff really points to the batteries being too cold to fly. If I'm working in cold weather, the batteries always stay in a car with the heating on or in a warm building.

Just like JJB says, it happened because the batteries were put to use after storing in discharge state around 50-60%.
This is not unusual, the cell voltage is much lower than the percentage indicates, no matter the temperature.
Solution: Always fully charge batteries before flying!

brfr2005 Posted at 4-12 11:32
Yup all of them genuine dji - original from the purchase so going on five years now?

It was below freezing at takeoff. Drone was kept indoor overnight.

Look at the cell voltages in the Phantomhelp report.
At just 3 seconds when you started to climb, the cell voltages sank below critical low voltage level (3.3 volts).
You cannot rely on the % indicator when the battery has been lying around discharging.
Only fly with a battery that has recently been fully charged.

Hi there. Thank you for reaching out. We highly recommend flying the aircraft with a fully charged battery to avoid this issue. You may refer to the response of JJB about his analysis based on the flight logs provided. Kindly please have a test flight using your fully charged batteries and check whether the issue persists. Please keep us posted. Thank you.