Is ever so slightly swollen battery no good?

[WithTheBirds]

Okay I have been dealing with this whole battery swelling situation particularly with my mavic 2 pro. I have come to the conclusion that it is actually the casing that is the problem and not so much the battery. I take very good care of my batteries but yet three of them have become what is now considered swollen and possibly defective. So I decided to take a closer look. And what I found was pretty interesting. It turns out that my three batteries that has swelling on the bottom side which created a situation of possible this lodging in flight that there was space within the encasement of the battery and it seems that it is the external case rather than the battery that is the issue.
I decided to do an experiment and I took a slit out of the bottom of the battery and amazingly it totally took away the swelling and the battery still had space. So at the moment I am trying experimenting with that batteries make sure no adverse effects were present.
so at the moment I have done this to two batteries that I would have had to just throw away but the surprising thing is both batteries are working totally normally.
I have mentioned this in previous comments in the forms and I was shot down saying if there's any swelling you should always throw away the battery to that I say anybody that does that is crazy I just loves to waste money.
My actual point to this whole thing is that this is more of a DJI defect in the process and apparently heating and cooling makes the outside case distort and it is not a matter of the battery being defective.
I have most of the DJI line and this is the only one that I see this happening. so if you want to avoid paying that $138 wherever these batteries go for these days try my experiment just put a slit in the bottom plastic and I guarantee you will get a lot more life out of that but he warned you need to be very careful to not cut into the actual battery behind it but again there is a gap so just be careful.

Good for you. All lipo can, and usually do, swell to some extent during use and generally throughout their usable service life. The fact cell manufacturers often publish reasonable expansion limits supports that fact.

Many, myself included, have suspected it might be insufficient internal space in the enclosure that was the issue. Your recent findings seem to support that.

I don’t have issues with my M2 batteries however would not be adverse to modifying the enclosure as a potential solution. Especially in circumstances where they seemed to have no performance issues.

 

[WithTheBirds]

I can assure you that these are not effective batteries rather it's effective battery case. I have been experimenting with them and I found that the bottom side has an actual gap between battery and the housing.
However I found that this swelling of the case is occurring and it is not the battery pushing on that bottom side. so I have experimented and I have taken a notch out along the center of the bottom side it is fine it is working for two of my three batteries that were swelling. I am going to do number 3 next. When I look at the the app it shows no problems with the battery. DJI definite defect on their battery casing.

My money is on your take on this being the right one. Fire is an unlikely outcome, particularly when the electrical parameters and performance are within expectations.

 

[Oconnb910]

My money is on your take on this being the right one. Fire is an unlikely outcome, particularly when the electrical parameters and performance are within expectations.

Thank you and I I think we have stumbled on the actual situation rather than everybody throwing out these expensive batteries. I was pissed off because one of them only had like 10 charges on it. So it kind of prompted me to look deeper into this especially since this was not going to be covered under warranty apparently.

 

[Oconnb910]

I have now done this operation on three batteries and all of them are working perfectly normal.

 

[Oconnb910]

I figured I lost these three batteries but now I know they do work so I have way more batteries because I ordered replacements

 

[Oconnb910]

It is my guess that DJI found a new loophole to make more money off of us. I'm glad I was able to debunk this problem.

 

[DanMan32]

There's hardly any space between the cells and the bottom. The battery is practically glued onto the bottom with thin, very sticky double stick tape. The battery I took apart found the cells to be "squishy" which doesn't seem bad out of the case, but when packed into that tiny case, you can see there's hardly any extra room.

If there's any room, it would be at the top of the battery, not the bottom.

I think what you did by the cut is to relieve some of the pressure on the case that the cell was exhibiting against it.
I hope what you didn't actually do is cut into the bag enveloping the cell, thus releasing the captured gas, but also exposing the battery to ambient moisture which will deteriorate the cell over time, if not worse. There's a reason lipos are hermetically sealed in polymer bags rather than having a vent like other battery types have.

 

[Oconnb910]

There's hardly any space between the cells and the bottom. The battery is practically glued onto the bottom with thin, very sticky double stick tape. The battery I took apart found the cells to be "squishy" which doesn't seem bad out of the case, but when packed into that tiny case, you can see there's hardly any extra room.

If there's any room, it would be at the top of the battery, not the bottom.

I think what you did by the cut is to relieve some of the pressure on the case that the cell was exhibiting against it.
I hope what you didn't actually do is cut into the bag enveloping the cell, thus releasing the captured gas, but also exposing the battery to ambient moisture which will deteriorate the cell over time, if not worse. There's a reason lipos are hermetically sealed in polymer bags rather than having a vent like other battery types have.

I guess we shall see so far so good! And once again it's interesting to see that every possible scenario reversal can be completely reversed again. My original battery that I did the surgery to has been nothing less than a stable and there is no leakage or any of that. And unlike what you stated there is a gap between the surface of the battery and the surface of the casing. Quite frankly I don't care if anybody wants to listen to this possible scenario that fixes spending money on a battery that's perfectly fine. I am telling you my experience so far so good my mavic 2 pro is flying around with these batteries and no crashes no flames know anything.
and I want to make one more point that every time somebody comes up with some scenario to hopefully correct what we see in this hobby as a problem, there'll always be somebody shooting down that alternative.

So hopefully you all enjoy spending all that money to replace batteries that are perfectly fine! Have a happy and wonderful holiday season!

 

[Oconnb910]

All I know is that I now have three extra batteries that are working perfectly fine!

 

[WithTheBirds]

It is my guess that DJI found a new loophole to make more money off of us. I'm glad I was able to debunk this problem.

I suspect that isn’t true. That is it was a deliberate money making attempt. Bad engineering with the usual and persistent reluctance to admit to the problem is more likely.

 

[WithTheBirds]

There's hardly any space between the cells and the bottom. The battery is practically glued onto the bottom with thin, very sticky double stick tape. The battery I took apart found the cells to be "squishy" which doesn't seem bad out of the case, but when packed into that tiny case, you can see there's hardly any extra room.

If there's any room, it would be at the top of the battery, not the bottom.

I think what you did by the cut is to relieve some of the pressure on the case that the cell was exhibiting against it.
I hope what you didn't actually do is cut into the bag enveloping the cell, thus releasing the captured gas, but also exposing the battery to ambient moisture which will deteriorate the cell over time, if not worse. There's a reason lipos are hermetically sealed in polymer bags rather than having a vent like other battery types have.

Just thinking about this- if cutting the cells relieved pressure it would have bulged further outwards. The reason Lipo Cells don't need a vent is because there is room for expansion without mechanical restriction.

 

[DanMan32]

The case is the restriction.
Consider this: take a brick, vacuumed seal it in a bag but the available volume of the bag is bigger than the brick. Those vacuum sealed bricks of coffee would be a good visualization. Ambient air pressure squeezes the bag tightly against the solid, even though the volume capacity of the bag is greater than the solid.

Now the brick or coffee somehow generates some gas but not enough to balloon the bag, only enough that the bag is now squishy.

Now consider the shrouded brick or coffee is in a container that just fits the size of the brick or container when the brick or coffee had a vacuum seal. With the bit of gas trapped in the bag, it is just squishy when not in the container, but in the container it exhibits pressure. If you manage to accidentally break that seal, the bag no longer exhibits pressure on the case.

I assure you, the bottom of the case is completely flat. The only gap is maybe less than 1mm from the sticky tape that adheres the bottom cell to the bottom half of the case.
The top cell is adhered to the top half of the case with sticky tape, but not quite as much.

 

[WithTheBirds]

The case is the restriction.
Consider this: take a brick, vacuumed seal it in a bag but the available volume of the bag is bigger than the brick. Those vacuum sealed bricks of coffee would be a good visualization. Ambient air pressure squeezes the bag tightly against the solid, even though the volume capacity of the bag is greater than the solid.

Now the brick or coffee somehow generates some gas but not enough to balloon the bag, only enough that the bag is now squishy.

Now consider the shrouded brick or coffee is in a container that just fits the size of the brick or container when the brick or coffee had a vacuum seal. With the bit of gas trapped in the bag, it is just squishy when not in the container, but in the container it exhibits pressure. If you manage to accidentally break that seal, the bag no longer exhibits pressure on the case.

I assure you, the bottom of the case is completely flat. The only gap is maybe less than 1mm from the sticky tape that adheres the bottom cell to the bottom half of the case.
The top cell is adhered to the top half of the case with sticky tape, but not quite as much.

I’m with you- I haven’t taken a M2 battery apart (mine are good so far) and don’t doubt your direct observation as to the internal construction. I do note an error in my post however, I didn’t mean to say cut the cell. I am saying if the cell was pressing against the bottom of the enclose casing cutting it, as depicted in the posted image, would allow it to bulge further.

 

[DanMan32]

Not if you managed to punch a small hole in the polymer seal.

 

[WithTheBirds]

Not if you managed to punch a small hole in the polymer seal.

Do you think he punctured the pouch? There is nothing to suggest he did. You have created a distracting irrelevance.

People should be excited- potentially we could have a lot not needing to discard otherwise good packs.

 

[DanMan32]

I already knew they were electrically sound. LiPos generally do swell a little but still work. The problem is the case doesn't allow any room to accommodate moderate swelling.

There are no ribs at the bottom of the case to leave any gap, it is completely flat with thin sticky tape adhering the cell to the bottom of the case, and less sticky tape to adhere the top cell of the 4 pack to the top half of the case.

 

[WithTheBirds]

I already knew they were electrically sound. LiPos generally do swell a little but still work. The problem is the case doesn't allow any room to accommodate moderate swelling.

There are no ribs at the bottom of the case to leave any gap, it is completely flat with thin sticky tape adhering the cell to the bottom of the case, and less sticky tape to adhere the top cell of the 4 pack to the top half of the case.

So you disassembled a puffed battery. It’s still fine electrically. There must be some simple mod you could do to continue using it. Or you have already?

 

[DanMan32]

After being pulled apart, I won't fly with it, besides I broke the leads to the latch switches so app won't let me fly with it, but I can use it for ground work. Because of the bloat, the case won't go tightly back together again.

I also accidently broke the leads to the temperature sensor which then wouldn't let it turn on at all, but I resoldered it and it started working again.

There's one or two topics somewhere about a couple of us describing pulling it apart. I think my comments about it may be in the thread you may have started with your theory a few months back.

Unlike the M1 battery, besides clips, they did put a thin bead of CA along the seams.

DJI may be lightening up and realizing the extent of the problem as one or two members were able to get replacements even after 6 months. They needed to submit a video showing it rocked when placed on a flat surface, and then later show the battery was destroyed somehow, such as soaking in a salt water solution.

 

[WithTheBirds]

After being pulled apart, I won't fly with it, besides I broke the leads to the latch switches so app won't let me fly with it, but I can use it for ground work. Because of the bloat, the case won't go tightly back together again.

I also accidently broke the leads to the temperature sensor which then wouldn't let it turn on at all, but I resoldered it and it started working again.

There's one or two topics somewhere about a couple of us describing pulling it apart. I think my comments about it may be in the thread you may have started with your theory a few months back.

Unlike the M1 battery, besides clips, they did put a thin bead of CA along the seams.

DJI may be lightening up and realizing the extent of the problem as one or two members were able to get replacements even after 6 months. They needed to submit a video showing it rocked when placed on a flat surface, and then later show the battery was destroyed somehow, such as soaking in a salt water solution.

Getting replaced- even better. I don’t think I started a thread on batteries?

 

[DanMan32]

Here's a topic where two of us took our batteries apart:

open mavic 2 battery

I haven't found any tutorials on this anywhere... I (stupidly) crashed my Mavic 2 in a river a couple of weeks ago. I have the refresh thing from DJI and received a replacement drone and battery within a week. This leaves me with the battery that got wet. It charges just fine. I even put it...

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