What destroyed these two Mavic Air batteries? Logs attached.

[Kupe]

Hey gang-

With humble thanks to this forum, I've just enjoyed 18 months of accident and damage free flying of my Mavic Air- my first drone ever. But last night left me scratching my head. I appear to have destroyed two batteries and I don't know how or why.

Background: I was flying around sunset in hopes of capturing some fireworks, hence the low-light warnings. I started with two fully charged batteries with 4-LED charge. On both flights, I initiated auto-RTH at around 30% battery. Everything seems to go fine, but in both cases battery voltage plummeted suddenly and my Mavic Air went into Forced Landing mode. (Fortunately in both cases basically at my feet). So my Mavic is fine, but neither battery will charge any longer. My charger displays Green briefly, then goes to Red and stays there.

Here is the first flight:

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Battery voltage plummets from 22% to 0% at 10minutes, 54.6seconds of flight. Forced landing mode activated at approximately same timestamp.

Here is the second flight:

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Battery voltage plummets from 20% to 0% at 11minutes, 4.4seconds of flight. Forced landing mode activated at approximately same timestamp.

What happened here? And are these batteries recoverable?

Thanks gang!

 

[Starz]

Looks like the batteries have an issue. Both show a problem on cell 3.
May be time to replace them both.
Without knowing how they were being used, hard to determine why they have failed. Could be a number of factors that put them in that position.
Any warnings in the first few minutes on the first flight?

 

[Kupe]

Looks like the batteries have an issue. Both show a problem on cell 3.
May be time to replace them both.
Without knowing how they were being used, hard to determine why they have failed. Could be a number of factors that put them in that position.
Any warnings in the first few minutes on the first flight?

Thanks Starz. All the warnings that I got are there in my logs- none battery related until the charge plummeted to zero.

My Mavic has been pretty lightly flown in the time I've had it, and the batteries are the originals that came with the Fly More package. They have for the most part lived in my Mavic 4-battery smart charging hub. Given the intelligent charge/discharge properties of the Intelligent Flight Batteries, I saw no potential harm in this. Was I mistaken on this? i.e. must the batteries be left out of the charger? I initially tried that when I first got my Mavic, but invariably I wanted to go fly and had uncharged batteries, so I ultimately went with leaving them in the charger.

 

[Starz]

Not the best thing to do as far as leaving them fully charged for long periods of time with no use.
Buy some new ones and hit the research button.

 

[Kupe]

Not the best thing to do as far as leaving them fully charged for long periods of time with no use.
Buy some new ones and hit the research button.

Thanks again Starz. My experience though was that they don't stay fully charged- even when left in the charger. I checked on this frequently when I first got my Mavic until I was confident of the Intelligent Charge/Discharge features. From the Mavic Air manual:

1. Auto-Discharging Function: To prevent swelling, the battery automatically discharges to below
   65% of the maximum charge when it is idle for more than 10 days. It takes approximately one day to discharge the battery to 65%. It is normal to feel moderate heat being emitted from the batteryduring the discharging process.

I found that this was true even when the batteries were left in the charger. i.e. the batteries would discharge to two-to-three LEDs (out of 4) even when left in the charger. Only removing the batteries from the charger, then re-inserting them, would initiate charge to full or 100%.

So this is why I'm surprised at the failure and why I felt it was okay to leave them in the charger.

Maybe they're just old and too many cycles? That at least would make sense.

 

[old man mavic]

you say they are 18 months old how many charges have they had ,and what is your self discharge number of days set at ,all batteries loose some of their ability to hold a charge over time due to how the chemical process in the cell works and it is unable to provide enough voltage as the percentage of remaining battery power drops and then one cell will fail and can cause the drone to loose power and fall from the sky,for your safety and the safety of others ,retire those batts and get some new ones and with the remaining ones you have just check battery health in the app before you fly

 

[E90RAW]

Hey gang-

With humble thanks to this forum, I've just enjoyed 18 months of accident and damage free flying of my Mavic Air- my first drone ever. But last night left me scratching my head. I appear to have destroyed two batteries and I don't know how or why.

Background: I was flying around sunset in hopes of capturing some fireworks, hence the low-light warnings. I started with two fully charged batteries with 4-LED charge. On both flights, I initiated auto-RTH at around 30% battery. Everything seems to go fine, but in both cases battery voltage plummeted suddenly and my Mavic Air went into Forced Landing mode. (Fortunately in both cases basically at my feet). So my Mavic is fine, but neither battery will charge any longer. My charger displays Green briefly, then goes to Red and stays there.

Here is the first flight:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

Battery voltage plummets from 22% to 0% at 10minutes, 54.6seconds of flight. Forced landing mode activated at approximately same timestamp.

Here is the second flight:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

Battery voltage plummets from 20% to 0% at 11minutes, 4.4seconds of flight. Forced landing mode activated at approximately same timestamp.

What happened here? And are these batteries recoverable?

Thanks gang!

LiPo batteries are usually good for 150-250 cycles of charging. They are finicky animals. You cant leave them at full charge for too long( 1 week at full charge can degenerate a batt), and you do not want them at low charge (<3.0 volts) or that can kill them. Discharge will cause heat production. Running below 12 volts total (virtually impossible with DJI automation) during a flight will kill them. Unfortunately with DJI automation drone pilots do not need(and most dont) any knowledge about LiPo batteries. Its probably better that we do as they are tricky. I have run my batteries to 0%(obviously not recommended) but the volts were 14 total. Its best to always be checking your battery meters during flight, no different than a pilot checking the full gauge. I have found that the temp of the batteries is a more relevant indice during flight than volts.(% batt is not relevant in my small opinion-I'd rather see the volts). When the temp is >50 Celsius I bring her/him home. Remember LiPo's can catch fire so best to keep in fireproof container or bags.

 

[E90RAW]

Thanks again Starz. My experience though was that they don't stay fully charged- even when left in the charger. I checked on this frequently when I first got my Mavic until I was confident of the Intelligent Charge/Discharge features. From the Mavic Air manual:

1. Auto-Discharging Function: To prevent swelling, the battery automatically discharges to below
   65% of the maximum charge when it is idle for more than 10 days. It takes approximately one day to discharge the battery to 65%. It is normal to feel moderate heat being emitted from the batteryduring the discharging process.

I found that this was true even when the batteries were left in the charger. i.e. the batteries would discharge to two-to-three LEDs (out of 4) even when left in the charger. Only removing the batteries from the charger, then re-inserting them, would initiate charge to full or 100%.

So this is why I'm surprised at the failure and why I felt it was okay to leave them in the charger.

Maybe they're just old and too many cycles? That at least would make sense.

Looking at your data you were screwed once your total volts were near or below 9. You do NOT want your batteries below 3 volts per cell or you kill them. Oxidation dramatically increases when any LiPo cell goes below 3 volts.(lithium oxide formation). Your % is at 22% but who cares because the damage is done. I am surprised because DJI has a very conservative algorithm with their batteries and they usually dont let you run that low(on the volts). Never count on % but instead volts. I would replace the batteries as you dont want a fire. Oxide formation causes increase risk of spontaneous combustion.

 

[Starz]

I‘m leaning towards the low usage and age being the most contributing factors on these batteries.

 

[E90RAW]

Sorry to break up this response. On your second flight your total volts are 10 which is usually OK but the #3 cell is approaching the 3.0 cutoff. I would have brought her home once cell #3 was at 3.3 to be conservative. The temp must have been very high at this point I would think. Scrolling up, at 33% your cell #3 is at 3.3. One would think your OK looking at the %. Plenty of time, right. But no, time to come home. If you notice DJI's cutoff is 3.5 volts. Once a cell is under 3.5 the color changes on your flight plan to yellow. Remember you may get the bird home but you are irrevocably damaging the battery through oxidative damage when you approach that 3.0 volt/cell level(9 volt/total). Hope that helps.

 

[virtualphotographers]

I‘m leaning towards the low usage and age being the most contributing factors on these batteries.

Agree cycling (regularly using) your batteries will keep them working optimally. I’ve had a bunch of lipos die through inactivity over long periods. The fly more combo is aptly named. Best of luck and happy flying!

 

[Ridgeback]

Thanks Starz. All the warnings that I got are there in my logs- none battery related until the charge plummeted to zero.

My Mavic has been pretty lightly flown in the time I've had it, and the batteries are the originals that came with the Fly More package. They have for the most part lived in my Mavic 4-battery smart charging hub. Given the intelligent charge/discharge properties of the Intelligent Flight Batteries, I saw no potential harm in this. Was I mistaken on this? i.e. must the batteries be left out of the charger? I initially tried that when I first got my Mavic, but invariably I wanted to go fly and had uncharged batteries, so I ultimately went with leaving them in the charger.

I have always removed my MA batteries from the charger after fully charging them, as my way of thinking is thru failure of the charger the batteries may trickle discharge fully thus destroying 4 batteries.

 

[Kupe]

you say they are 18 months old how many charges have they had ,and what is your self discharge number of days set at ,all batteries loose some of their ability to hold a charge over time due to how the chemical process in the cell works and it is unable to provide enough voltage as the percentage of remaining battery power drops and then one cell will fail and can cause the drone to loose power and fall from the sky,for your safety and the safety of others ,retire those batts and get some new ones and with the remaining ones you have just check battery health in the app before you fly

Thanks gang- awesome info and discussion!

My Mavic Air was purchased 18 months ago in February 2019, but apparently the batteries were about a year old at that time. I am unable to pull up any data on the two batteries that died since they won't power up my Mavic for DJI Go to look at them. But my third battery which came as part of the same Fly More Combo seems to look okay (attached below). I'm surprised at how few charging cycles it shows.

In any case I've ordered two new batteries and I am marking this remaining one as "walking wounded- light duty only"

 

[Ridgeback]

I also number my batteries 1 to 4 in the case of the MA1 and use them in that order 1 to 4 so keep them evenly used within reason helps keep track of them.
Just purchased a new Mavic Mini fly more combo first job was fit numbers on batteries
These are from UK Seller on ebay sticky Vinyl Numbers stickers Decals weather proof RED & Blue door office home | eBay

 

[Starz]

Local office supply. Numbered and another tag for tracking charge cycles.

 

[Kupe]

This thread has got me wishing there was a way to change the the Battery Level display from % to volts. And to change the Low Battery warning from % to volts as well. But I'll make it a point now during flight to periodically toggle that display to volts. Thanks again gang!

 

[everBit]

You could select "Show voltage on main screen" in the DJI GO 4 app and you will have possibility to monitor the weakest cell around battery icon near percentage display. So no need to spent time to go in the batt menu.

 

[Kupe]

You could select "Show voltage on main screen" in the DJI GO 4 app and you will have possibility to monitor the weakest cell around battery icon near percentage display. So no need to spent time to go in the batt menu.

Great idea- but that option does not appear in Battery preferences for my original Mavic Air. I'm running on an iPhone XS with the latest DJI Go 4 version 4.3.37. Software update on my phone shows no newer version available. Screenshot of my preferences appear above in post #13.

 

[dawgpilot]

You could select "Show voltage on main screen" in the DJI GO 4 app and you will have possibility to monitor the weakest cell around battery icon near percentage display. So no need to spent time to go in the batt menu.

View attachment 107689
View attachment 107690

I can confirm that those options aren't available for the Mavic Air. (neither DJI Go for iOS or Android)

 

[everBit]

Have you looked this video from well-known blogger?
Here shown exactly Mavic Air.