Mavic Air battery went from 92% to 0%

[RobotBee]

I have searched on here and seen this happen to other people, but from what I've read the cause can't be determined without the flight logs.

Mine are attached.

I had a successful flight with no issues. I landed, put a fresh battery in, and started a second flight.

I took off as normal, and headed away and up. I seem to remember putting it into sports mode. Soon after that, I got a notification that the battery was at 0% (dropped instantly from 92%) and the aircraft was landing. I turned it around and tried to fly it back to me as far as possible (a mistake in hindsight as it meant it landed going forwards rather than just straight down). It was in a grassy field though and seems pretty unharmed. The gimbal is slightly off centre but looks fine so I'm hoping a recalibration sorts that.

If anyone would be kind enough to tell me what they think happened I'd be very grateful.

Thanks a lot

 

[slup]

That battery is now history ... at most usable for desk duties, no more flying.

At 59sec into the flight cell 3 was way under 3V which means that DJI drones will force auto land to avoid free fall. The only odd here is that cell 3 already at 30sec was under 3v ... but no autolanding there?

Already at 11 sec into the flight the total cell deviations is huge ... all coming from cell 3. But the other cells isn't good either.

That the battery percentage just goes to zero is due to that it's only a approximation made by the battery management system ... basing the percentage on the amp draw, but when cell 3 falls like a rock the BMS doesn't trust the approximation anymore & instead just say 0%.

The pink & green field to the left is motor start & take off ... the blue is Sport mode & the green field to the right is autolanding. Have placed the marker in the chart where the autolanding starts. The graph explanations is under the chart.

(Click on the chart to make it larger)

 

[RobotBee]

Thank you so much for the quick reply.

So not the "battery 0% firmware bug" I've ready about? It's clearly a physical problem with the battery?

I have always looked after my batteries well. This one is prob about 18-24 months old and has 62 cycles. I always land with my batteries at 20% or more (usually much more).

Does this just happen randomly at this sort of battery age?

Many thanks again

 

[slup]

...It's clearly a physical problem with the battery?

Yes ... cell 3 failed major & the voltage fell way below 3V (down to 2,55V)

Does this just happen randomly at this sort of battery age?

No batteries will last forever, they are man made ... they all will come to this sooner or later. The only way to somewhat foresee this coming is to monitor the performance trends of the battery ... cell deviations, full charge mAh compared to designed capacity, theoretical max total flight times & voltage drops. If this is followed you can be able to spot misbehavior's & degradation's in the performance in time & take them off flight duty before they fail.

 

[RobotBee]

Yes ... cell 3 failed major & the voltage fell way below 3V (down to 2,55V)



No batteries will last forever, they are man made ... they all will come to this sooner or later. The only way to somewhat foresee this coming is to monitor the performance trends of the battery ... cell deviations, full charge mAh compared to designed capacity, theoretical max total flight times & voltage drops. If this is followed you can be able to spot misbehavior's & degradation's in the performance in time & take them off flight duty before they fail.

Thanks again.

Just had a look at airdata. So a good idea to stick flight logs in there every now and again to check battery cell deviations etc?

 

[slup]

Thanks again.

Just had a look at airdata. So a good idea to stick flight logs in there every now and again to check battery cell deviations etc?

With Airdata's paid subscriptions you will get access to trend calculations over all logs you have there ... an easy way of following the battery performance & perhaps also a cheap insurance to avoid what happened to you.

 

[RobotBee]

With Airdata's paid subscriptions you will get access to trend calculations over all logs you have there ... an easy way of following the battery performance & perhaps also a cheap insurance to avoid what happened to you.

Very interesting.

I've done a PfCO and an A2 CofC and nowhere was this issue mentioned. Seems pretty important to me.

Also wishing I didn't sell the spare brand new batteries I had last summer....

Thanks again

 

[RobotBee]

Ju

With Airdata's paid subscriptions you will get access to trend calculations over all logs you have there ... an easy way of following the battery performance & perhaps also a cheap insurance to avoid what happened to you.

Just checked my other batteries. Strangely the oldest ones are in the best condition.

I will no longer fly with the one discussed in this thread, but I've noticed another one of mine looks like this:




And a recent flight with it looks like this:


Maybe it's time to stop using that battery too? It's not even that old - only 3 hours of flying over 9 months.

The best two batteries each have around 12 hours of flying over 2 years!

 

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[Thomas B]

Happened to me with one battery flying my M2P. All looked well as I checked then mounted the fully charged (4leds) battery, started up and lifted off... suddenly got a low battery warning and landing warning after about 20 seconds... barely got a controlled landing.
Found the battery, which was normal to preflight inspection, was now significantly bulged.

 

[slup]

Maybe it's time to stop using that battery too? It's not even that old - only 3 hours of flying over 9 months.
...have around 12 hours of flying over 2 years!

The Airdata charts from a single flight you show don't look OK at all ... now, I don't see the indicated BMS battery percentage there so can't relate the voltage to that ... & don't know if the charts show the total flight or if it's zoomed in ... or how that flight was flown, full sticks in Sport, calm cruising, hot or cold weather.

LiPo batteries don't like to be left without use ... how have you handled them in between those few flight hours, on which cell voltage have they been stored? Have you charge cycled them each 3 month? Have the batteries been over heated in the past or during storage (Laying around in a hot car, been left in direct sunlight or recharged still warm)? Any signs of swelling?

Also have a MA1 & none of the batteries have ever shown anything similar to this ... even if I've pushed them. Always follow their performance trend from a payed Airdata subscription ... so know pretty well which will be the closest candidate to go for only desk duties ...

Have 8 batteries in total ...

-3 that came in the Fly More kit dated Jan-19, definitely show wear when it comes to flight times & occasionally show very short lived major deviations especially if it's colder ambient temps & using Sport. Have taken one of them out from air duty due to too large voltage drops when pushed.

-2 newer, bought extra (dated mid & end -19) perform as they should.

-And 3 new, still in hibernation ... waiting to go in & replace the next that will be taken off flight duty.

 

[RobotBee]

The Airdata charts from a single flight you show don't look OK at all ... now, I don't see the indicated BMS battery percentage there so can't relate the voltage to that ... & don't know if the charts show the total flight or if it's zoomed in ... or how that flight was flown, full sticks in Sport, calm cruising, hot or cold weather.

LiPo batteries don't like to be left without use ... how have you handled them in between those few flight hours, on which cell voltage have they been stored? Have you charge cycled them each 3 month? Have the batteries been over heated in the past or during storage? (Laying around in a hot car, been left in direct sunlight or recharged still warm)

Also have a MA1 & none of the batteries have ever shown anything similar to this ... even if I've pushed them. Always follow their performance trend from a payed Airdata subscription ... so know pretty well which will be the closest candidate to go for only desk duties ...

Have 8 batteries in total ...

-3 that came in the Fly More kit dated Jan-19, definitely show wear when it comes to flight times & occasionally show very short lived major deviations especially if it's colder ambient temps & using Sport. Have taken one of them out from air duty due to too large voltage drops when pushed.

-2 newer, bought extra (dated mid & end -19) perform as they should.

-And 3 new, still in hibernation ... waiting to go in & replace the next that will be taken off flight duty.

In that particular flight there was no indication that there was anything wrong. Displayed battery percentage looked as expected during the flight. From memory it was largely in sport mode.

I have never run them below about 20%, and charged straight away to full after use, allowing the auto discharge system to discharge them down to storage level after a few days. I have never stored them discharged.

They've never been overheated in storage.

What I have done though is to often recharge them straight after flying. I have relied on their internal system to avoid charging when warm - I noticed that if I tried to charge them straight away after a flight, I am not able to. But I have charged them as soon as I was able to. Was this a mistake? Can it be the case that their internal protection does allow them to be charged, but they are still too warm to be charged without damaging them?

The thing is I've always done this, and my oldest batteries are in very good condition. Either 1 or zero isolated major discrepancies.

The newer batteries are the ones that show these continuous major discrepancies.

I wish I knew all this a couple of years ago! Glad I know it now though.

 

[slup]

...there was no indication that there was anything wrong.

Yep ... that's the usual, if the batteries aren't monitored performance wise this will always come as a surprise. The only visible battery degradation is swelling ... & that doesn't always occur.

...allowing the auto discharge system to discharge them
...I have relied on their internal system to avoid charging when warm

Yep ... relying in DJI's battery auto protection is also a common factor if going through similar cases here at the forum. They auto discharge during 10 days for the MA1 ... & the guideline says not to keep them outside 3,7-3,8V/cell (that's roughly 30-50%) more than 48h. Furthermore the auto discharge leave them at 60% & generate a lot of heat, so if having them in a bag the auto discharge can overheat them ... Perhaps the temp protection is similar bad designed?

...my oldest batteries are in very good condition. The newer batteries are the ones that show these continuous major discrepancies.

Yep ... the batteries will definitely be different when it comes to the cell quality ... DJI have used different sub-suppliers over the months so it's possible that certain batches are worse than others ... especially if comparing batteries from the same manufacturing year... the difference in age isn't that large yet, how they have been handled means more.

 

[RobotBee]

Yep ... that's the usual, if the batteries aren't monitored performance wise this will always come as a surprise. The only visible battery degradation is swelling ... & that doesn't always occur.


Yep ... relying in DJI's battery auto protection is also a common factor if going through similar cases here at the forum. They auto discharge during 10 days for the MA1 ... & the guideline says not to keep them outside 3,7-3,8V/cell (that's roughly 30-50%) more than 48h. Furthermore the auto discharge leave them at 60% & generate a lot of heat, so if having them in a bag the auto discharge can overheat them ... Perhaps the temp protection is similar bad designed?


Yep ... the batteries will definitely be different when it comes to the cell quality ... DJI have used different sub-suppliers over the months so it's possible that certain batches are worse than others ... especially if comparing batteries from the same manufacturing year... the difference in age isn't that large yet, how they have been handled means more.

Thanks - more useful info.

So what do you do with your batteries after a flight, if you don't plan to use them again for a few days? Manually recharge them to about 50%?

 

[slup]

...So what do you do with your batteries after a flight...

With the original charger I took the batteries off when the LED's where blinking from 1 firm+1 blinking - 2 firm+1 blinking ... that equals to approx 30- a tad above 50%.

Nowadays I use this charger --> https://www.amazon.com/Hanatora-Battery-Controller-Charging-Discharging/dp/B07ZV44415 it either disharge or charge to 50% automatically. Place all batteries on 50% after each flight session ... & as this charger parallel charge 4 batts+RC I'm up & running with all batteries & RC at full charge in approx an hour.

 

[JoelP]

I have searched on here and seen this happen to other people, but from what I've read the cause can't be determined without the flight logs.

Mine are attached.

I had a successful flight with no issues. I landed, put a fresh battery in, and started a second flight.

I took off as normal, and headed away and up. I seem to remember putting it into sports mode. Soon after that, I got a notification that the battery was at 0% (dropped instantly from 92%) and the aircraft was landing. I turned it around and tried to fly it back to me as far as possible (a mistake in hindsight as it meant it landed going forwards rather than just straight down). It was in a grassy field though and seems pretty unharmed. The gimbal is slightly off centre but looks fine so I'm hoping a recalibration sorts that.

If anyone would be kind enough to tell me what they think happened I'd be very grateful.

Thanks a lot

 

[cgmaxed]

The Airdata charts from a single flight you show don't look OK at all ... now, I don't see the indicated BMS battery percentage there so can't relate the voltage to that ... & don't know if the charts show the total flight or if it's zoomed in ... or how that flight was flown, full sticks in Sport, calm cruising, hot or cold weather.

LiPo batteries don't like to be left without use ... how have you handled them in between those few flight hours, on which cell voltage have they been stored? Have you charge cycled them each 3 month? Have the batteries been over heated in the past or during storage (Laying around in a hot car, been left in direct sunlight or recharged still warm)? Any signs of swelling?

Also have a MA1 & none of the batteries have ever shown anything similar to this ... even if I've pushed them. Always follow their performance trend from a payed Airdata subscription ... so know pretty well which will be the closest candidate to go for only desk duties ...

Have 8 batteries in total ...

-3 that came in the Fly More kit dated Jan-19, definitely show wear when it comes to flight times & occasionally show very short lived major deviations especially if it's colder ambient temps & using Sport. Have taken one of them out from air duty due to too large voltage drops when pushed.

-2 newer, bought extra (dated mid & end -19) perform as they should.

-And 3 new, still in hibernation ... waiting to go in & replace the next that will be taken off flight duty.

Slup, I have a question for you. I have had my Mavic Air 2 and Mavic 2 Pro for about a year now, I cycle the three batteries I have for each. I have noticed they don't give me the flight times I had when new. I'm losing 5-7 minutes from new condition. Should I just replace them. No signs of bulging, but who knows, DJI encases the entire battery in a plastic shell. Or, should I invest in the AirData app and see what it shows?

 

[RobotBee]

Slup, I have a question for you. I have had my Mavic Air 2 and Mavic 2 Pro for about a year now, I cycle the three batteries I have for each. I have noticed they don't give me the flight times I had when new. I'm losing 5-7 minutes from new condition. Should I just replace them. No signs of bulging, but who knows, DJI encases the entire battery in a plastic shell. Or, should I invest in the AirData app and see what it shows?

None of mine had the bulging either. AirData was a complete revelation to me. I paid $6 for a month's membership to try it out and stayed up half the night going through all my data - I'm a geek though and love a graph!

I'd highly recommend it. As a result of the Airdata analysis, I have now labelled my batteries -

- don't use (the one that caused the drone to auto land) for anything other than flying in my garden
- be careful (don't fly far away or over buildings/people)
- good condition - use for anything!

 

[cgmaxed]

None of mine had the bulging either. AirData was a complete revelation to me. I paid $6 for a month's membership to try it out and stayed up half the night going through all my data - I'm a geek though and love a graph!

I'd highly recommend it. As a result of the Airdata analysis, I have now labelled my batteries -

- don't use (the one that caused the drone to auto land) for anything other than flying in my garden
- be careful (don't fly far away or over buildings/people)
- good condition - use for anything!

I'll try it. I would hate for a sudden power drop and auto land over a body of water, which I usually am doing, since I live on the Florida coast. I have had issues where I simply flew too long and my Aircrafts tried autoloading themselves. I just pushed the altitude stick up and maintained a steady altitude and direct path to my home point. I have actually flown for 3 minutes with 0% battery. Talking about a frightening experience. I thought the drones just might fall out of the sky, but they kept flying as long as I pushed up the altitude stick, forcing it from trying to land. It worked, but I never put myself in those situations anymore. I make sure I have at least 15-20 percent battery by the time I land.

 

[RobotBee]

I'll try it. I would hate for a sudden power drop and auto land over a body of water, which I usually am doing, since I live on the Florida coast. I have had issues where I simply flew too long and my Aircrafts tried autoloading themselves. I just pushed the altitude stick up and maintained a steady altitude and direct path to my home point. I have actually flown for 3 minutes with 0% battery. Talking about a frightening experience. I thought the drones just might fall out of the sky, but they kept flying as long as I pushed up the altitude stick, forcing it from trying to land. It worked, but I never put myself in those situations anymore. I make sure I have at least 15-20 percent battery by the time I land.

Yeah I'd def try it. Well worth it.

I flew my drone towards me when it was trying to land itself, but with hinsight I should have just let it land to lessen the impact. It was only about 200m away in a grass field, luckily. I often do fly far over water though!

At least now I know which batteries not to do that with.