Swelling Battery caused Crash

[GadgetGuy]

DJI are seemingly replacing swollen batteries for free, recognizing they could cause crashes, I even know of at least a youtube video about a DJI endorser reporting that.

Within the 6 month warranty, yes. Otherwise, no!

 

[GadgetGuy]

Myself and others just got a blunt "its outside 6 months so nothing" response off them. One person appears to have been offered 20%.
In some cases they've asked for the batteries to be sent back (illegal in most countries to ship damaged Lithium batteries!).

How many months after the Production Date did yours start swelling? From my understanding, it started just after 6 months, so we should have had reports from March on with later Production Dates, if it was simply age related.

 

[gnirtS]

How many months after the Production Date did yours start swelling? From my understanding, it started just after 6 months, so we should have had reports from March on with later Production Dates, if it was simply age related.

They probably started slightly inside the 6 months. But became unusable 7 months after purchase. Which was August 18.

I think my posts were the first on here about it (and just resulted in its my fault for mistreating them. user error etc etc). Thats why i think its possible there is a temperature element here as well. I live in the tropics so every battery was used in 30c ish temperatures and high relative humidity so possibly why mine aged faster than others.
Now we're getting more failures and it does follow a northern hemisphere summer where ambient temperatures are going to be higher than when it first came out so more people might be getting the same.

If i had to bet, id say some manufacturing issue with the chemistry that is making them less tolerable to a higher operating temperature which DJI identified and fixed mid August.

 

[GadgetGuy]

They probably started slightly inside the 6 months. But became unusable 7 months after purchase. Which was August 18.

I think my posts were the first on here about it (and just resulted in its my fault for mistreating them. user error etc etc). Thats why i think its possible there is a temperature element here as well. I live in the tropics so every battery was used in 30c ish temperatures and high relative humidity so possibly why mine aged faster than others.
Now we're getting more failures and it does follow a northern hemisphere summer where ambient temperatures are going to be higher than when it first came out so more people might be getting the same.

If i had to bet, id say some manufacturing issue with the chemistry that is making them less tolerable to a higher operating temperature which DJI identified and fixed mid August.

The unusable just 7 months after 2018.08 clearly is unique to the earlier Production Dates. We had one current slight swelling mentioned by Thomas B on a 2018.12 battery with 150 cycles on it, and we have been through another summer, with no other swelling on post 2018.08 Production Dates, which contradicts that heat alone or "battery abuse" is causing the problem.

 

[gnirtS]

I dont think heat alone.
I think its a chemistry defect whose effects *may* be accelerated with higher ambient temperatures. But the defect still exists in those batches regardless but is slower to manifest.
To me this seems to be a specific failure mode - its small cycle batteries (ive seen 15 - 40 mentioned a lot) which is (i) significantly under the quoted endurance and (ii) seems remarkably consistent). It also seems to be the case that electrically the battery appears fine in terms of voltages, current drain, deviations etc.

To be honest 150 or so cycles id kind of expect some swelling due to normal wear and tear. Thats about the level my mavic 1 batteries started suffering.

 

[7thstring]

To be honest 150 or so cycles id kind of expect some swelling due to normal wear and tear. Thats about the level my mavic 1 batteries started suffering.

That's the point. The problem is not about the swelling itself, the aircraft design should take care of that gracefully. And we shouldn't be concerned about using external tools to fix the weak clamping method adopted by DJI.

I understand some people love a brand's product and some might even feel that without DJI there wouldn't be advanced drone tech, but this looks like a Stockholm syndrome. DJI is to be held accountable for their design mistake. They should have a recall, as carmakers do when a fault is spotted.

 

[Mike4884]

Were these genuine DJI batteries, or clones?

I have just gone through this, so I feel somewhat knowledgeable on the subject.

I had four batteries for my MPP. I would generally keep them all charged (you never know when you'll need to go flying, right?), and I would store them in my MPP backpack in the back of my car. Over the last two months, we've had MANY 100+ degree days here in Sacramento. This means 120+ degrees inside the locked car, esp. if parking in the sun. I've come to find out (from this forum) that heat is really bad for these batteries, and causes them to swell, esp. when stored with a full charge.

So now I have two batteries that are swelled beyond my comfort zone. They will barely plug into the Mavic. Since I don't trust them, I have disposed of them (not worth my investment to chance flying with them), and bought two new batteries, which are completely flat on the bottom, like they should be.

Lesson learned: 1) Do not carry charged batteries in hot weather in the car, and 2) Take the drone case out of the car and bring it inside with me when I go to work or home.

This has solved my swelling issues so far.

Well i was gonna tell u to not keep charged lipis for "when " u go flying next....but u acknowledged that so thats good? learned your lesson (expensive one?) and if u take care of future lipos shouldnt have any swelling issues or crappy lipo performance. I always charge the day im going out and when done keep at 30% charge for sitting around. Never ever have problems with dji lipos and i have many dji aircraft

 

[Mike4884]

Don't do that. I've read tons of forum posts and watched lots of videos about this. The consistent message is to store them within the recommended tenperature range (which I cannot remember off the top of my head, except to recall that with my A/C I keep my apartment at about 24C, and that's perfect for these batteries), and always discharge them to below 50%, but don't let them discharge completely either (running your batteries down to 0%, for example, is a great way to severely shorten their lifespan).

They are intelligent batteries, and will self-discharge (to protect themselves) after several days if you store them fully charged, but this generates heat, so if your storage area isn't nice and cool, you may also exceed their storage temperature.

Now, I don't personally know if this is true, but it seems to be the official position, therefore if you ignore it, DJI has a strong position from which to refuse replacement if it is found they were stored fully charged, or outside of recommended temperatures. Your call.

Althouth u are right lets keep in mind that the mavic 2 has a 10 day discharge.....i dont know why dji chose on mavic 2 to not have this adjustable (other dji ac allow this) so 10 days is just wayyyy long to have a fully charged lipo sitting around.. I always after flying for day get them to one light and another light blinking so 30% and thats a good storage level.

 

[gnirtS]

That's the point. The problem is not about the swelling itself, the aircraft design should take care of that gracefully. And we shouldn't be concerned about using external tools to fix the weak clamping method adopted by DJI.

Well to me its not the drone design as such - its sufficient for working batteries.
The batteries themselves rendering themselves useless after very little use is the main problem.

 

[gnirtS]

Althouth u are right lets keep in mind that the mavic 2 has a 10 day discharge.....i dont know why dji chose on mavic 2 to not have this adjustable (other dji ac allow this) so 10 days is just wayyyy long to have a fully charged lipo sitting around.. I always after flying for day get them to one light and another light blinking so 30% and thats a good storage level.

Mavic 1 defaulted to a 10 day discharge and i doubt very many people ever bothered changing it. Yet their batteries were fine...

 

[7thstring]

There's another point to consider. Who takes the battery off every time before a flight?
Often you reach takeoff point and the battery with may have already started swelling inside the (original DJI) handbag while you are simply walking, thinking about summer. You power up, start flying and here you go, you have a flying omelette falling down the sky.

 

[7thstring]

Well to me its not the drone design as such - its sufficient for working batteries.
The batteries themselves rendering themselves useless after very little use is the main problem.

What I'm saying is that battery swelling could occur while flying, so the battery compartment should allow some tolerance.

 

[gnirtS]

There's another point to consider. Who takes the battery off every time before a flight?

I do and always have done going back to mavic 1. Amongst other things it allows me to ensure its properly latched and hasnt been bumped in transit and become loose.

 

[gnirtS]

What I'm saying is that battery swelling could occur while flying, so the battery compartment should allow some tolerance.

There is some tolerance. But it has limits.

 

[7thstring]

There is some tolerance. But it has limits.

I don't have a Mavic here now but I recall a flat surface. Should there be more tolerance, however, wouldn't there be less drones falling off the sky? Or have all seasoned pilots gone nuts all of a sudden?

 

[gnirtS]

There are some mavics falling out of the sky but doesn't seem to be too high a number compared to M1 and other drones. Possibly a small number caused by batteries but its not huge.
They cant engineer the drone to cope with what is clearly a very unexpected shape battery too much. It does cope with small swelling. What it cant do is cope with huge bulging which is often present before flight and worse afterwards.

The batteries are the issue here. The drone itself works as advertised.

 

[DanMan32]

I live in Florida, and showed swelling on my M2 2018-7 batteries a couple months ago but not evident before that. I almost didn't notice it for battery 2, but battery 3 had difficulty latching because it had greater swelling. I cautiously flew it close to ground in a soccer field with no issues.
The two batteries deviated in their swelling by 1mm. I can't recall if #2 was 1 or 2mm hot from use. They both went down by 1mm once cooled to room temperature.
Now they are both 1mm. I've powered them up idle motors but had not flown them since I first came across the swelling.

 

[DanMan32]

We really should minimize the number of threads dealing specifically with the M2 battery. I already subscribed to one, now subscribing to this one.

 

[BossBob]

M1 batteries are designed so that any swelling pushes against the latch mechanism, this leads to pressure on the latches and failure during rapid changes of speed or direction.. The battery case has a soft area on the bottom which allows expansion. My batteries swelled and also distorted the lower front and rear rails of the batteries. Luckily I noticed and the swollen batteries were removed from the flight duty.
I think that Mavic batteries need to be redesigned so that any expansion that takes place is directed away from the latch. They’d have to move the power button and lights and there wouldn’t be a nice smooth top skin to the drone but better to expand upwards and outwards than downwards and pushing against the latch.

 

[Mike4884]

Mavic 1 defaulted to a 10 day discharge and i doubt very many people ever bothered changing it. Yet their batteries were fine...

How do u know people didnt change it? I did! Come on seriously with that one?‍?‍