# TS's a bit swollen



## spdas (Nov 28, 2009)

Aloha, I have clamped my 160ah used TS's on the bench because they were a wee bit swollen on the sides. With two all-thread rods I made a clamp and clamped 18 cell together and used enough torque by just using a deep socket by hand to tighten it up and the cells are pretty much flat. (I did not use a rachet, just my hand on the socket to explain I did not have to tighten very much to get 'um flat). Question is, "now what". I take the clamp off and the cells pretty much go 50% back to swelled. Do I just put them into the car and clamp them and forget it ? Voltage is still right on at 3.35v each since i top balanced them.


thanks
francis


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## Coulomb (Apr 22, 2009)

spdas said:


> Do I just put them into the car and clamp them and forget it ?


Yes, that's my understanding. It frightens the willies out of me what must be happening inside a cell to cause swelling, but the manufacturers seem to be quite relaxed about it.


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## Guest (Feb 26, 2011)

Gassing and squeezing them won't fix the problem. What's happening is either your overcharging or over discharging.

If you top balance your cells and drive them until they start to drop like a rock you could be driving a cell or more into the zero level and at that point the cells are heating up real fast and hot. You basically boil them to death. If allowed to go to far you loose your cell. If you over charge them the same happens. 

The cells swelling are telling the story. You can't hide that you either overcharged them or were driving them into the ground by the batteries ending the charge before the rest and being driven into the zero point. 

Can't fix swelling. Sorry. Properly charge them to 3.6 or so and don't let them go below 2.9 static voltage. At that point the drop is fast. It has been proven. don't disregard the issue. 

Bottom balance your cells to like 2.8 then charge them until you get to 3.6 volts per cell. You may have a few up in the upper end but all cells have a different capacity. No cells have the same capacity. 


Watch this video. http://media.ev-tv.me/news111309-1280.mov


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## Coulomb (Apr 22, 2009)

gottdi said:


> What's happening is either your overcharging or over discharging. ... Can't fix swelling. Sorry.


Well, I guess one of us is wrong. I'm just going by the fact that the manufacturers say that swelling is inevitable if the cells aren't clamped, and that no permanent harm is done.

Also, I've observed swelling with what I consider to be normal (well within specifications) treatment. If I'm wrong, I'd sure like to know about it.


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## peggus (Feb 18, 2008)

Swelling happens with the cell just sitting on the shelf for a couple of years. I've got 8 of them slowly ballooning, still at 3.3V, no over discharge or charge.


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## Guest (Feb 26, 2011)

peggus said:


> Swelling happens with the cell just sitting on the shelf for a couple of years. I've got 8 of them slowly ballooning, still at 3.3V, no over discharge or charge.


That is an interesting thing to note. How much have they swollen? Have they swollen like this?


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## icec0o1 (Sep 3, 2009)

Coulomb said:


> Well, I guess one of us is wrong. I'm just going by the fact that the manufacturers say that swelling is inevitable if the cells aren't clamped, and that no permanent harm is done.
> 
> Also, I've observed swelling with what I consider to be normal (well within specifications) treatment. If I'm wrong, I'd sure like to know about it.


Where did you read manufacturers saying this? In lithium batteries, you have electrolyte which shuttles Li+ ions between the cathode and the anode. The electrolyte can undergo electrolysis and be split into gasses if the voltage exceeds 4.2V just like water can be split into hydrogen and oxygen. The electrolyte will undergo natural degredation but that reaction is very slow so your cells shouldn't swell by themselves for at least 5 years. Once you create those gasses, there's no coming back. Although your capacity might remain about the same, the internal resistance of those cells shoots through the roof as Lithium ions can't move very easilly and the batteries become very easy to overheat. Clamping them will help some as you decrease the distance between the cathodes and the anodes but your cells are on their way out.


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## ascomm74 (Feb 16, 2011)

gottdi said:


> That is an interesting thing to note. How much have they swollen? Have they swollen like this?


Is this a result of overcharge or overdischarge? And what cell is that?


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## Guest (Feb 26, 2011)

This is a result of over discharge due to one battery being driven to the ground because my pack was not properly bottom balanced. It was more like mid balanced. The one cell reached the knee long before the others and the others drove it into the ground. The cell however is not dead. But it was extremely hot and bloated when I got back to check the batteries. It happened before I balanced the cells better. Now none get hot towards the end of the drive and all are very close in voltage too. 

This is what happens when you have a top balanced pack and you have a cell that has a lower capacity than the rest and it reaches that level long before the others. The others will drive it to the ground. 


It is a Hi-Power Cell. 

The cell still holds power. I am thinking of pressing the cell and then melt a small hole in the cell to relieve pressure then reseal the cell and see how that works. I will do a discharge test to see if it has the same capacity or if it has lost a bunch or none.


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## icec0o1 (Sep 3, 2009)

gottdi said:


> The cell still holds power. I am thinking of pressing the cell and then melt a small hole in the cell to relieve pressure then reseal the cell and see how that works. I will do a discharge test to see if it has the same capacity or if it has lost a bunch or none.


Ooh, I'd recommend against it. Next time you cause even a tiny bit of gassification, your seal will break and the electrolyte will leak out. You can cause quite a bit of pressure inside these cells. Props on the bottom balance though.


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## Ingot (Feb 25, 2011)

Thank you, gottdi for the video! Was great, haha. Lots of good knowledge, definitely going to be checking out that site a lot from here on out.

*SIMPLE QUESTION*
I've heard of liquid cooled LiIon battery packs, but what about lead acid battery packs. Do they get hot as well? Can't find too much about lead acid battery packs as far as cooling goes, so I'm even unsure if they need cooling.


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## Guest (Feb 26, 2011)

Yes lead acid batteries can get hot too. But if you drive them or charge them properly they won't. They will get warm. Warm is fine. Melting hot is not. 

Every one should be watching Jacks videos. You don't have to agree with all he says but he backs up his claims with real information. Better than many around these forums.


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## Guest (Feb 26, 2011)

icec0o1 said:


> Ooh, I'd recommend against it. Next time you cause even a tiny bit of gassification, your seal will break and the electrolyte will leak out. You can cause quite a bit of pressure inside these cells. Props on the bottom balance though.


For testing and I can seal it up tight. I plan on using heat not drilling out plastic. I have done this before on other things. Some times it works sometimes not. Just going to try. Can't hurt because the battery won't ever be used in an on the road EV. Maybe in a lawn mower but not on the street.


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## Ingot (Feb 25, 2011)

gottdi said:


> Yes lead acid batteries can get hot too. But if you drive them or charge them properly they won't. They will get warm. Warm is fine. Melting hot is not.
> 
> Every one should be watching Jacks videos. You don't have to agree with all he says but he backs up his claims with real information. Better than many around these forums.


Tank ya', mate. Yeah, he somewhat reminds me of Alex Jones, heh, which could be bad, but I do enjoy his demonstrations that then back up his knowledge. That and he has a nice taste in cars.


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## spdas (Nov 28, 2009)

gottdi said:


> That is an interesting thing to note. How much have they swollen? Have they swollen like this?


Whoa, no way near that much. If you put two of your HP swollen cells side by side, I guess they probably would measure 1 inch apart. With mine, two cells together, they would measure 1/4 inch. I bought my 160ah cells that were used and came from a testing facility (so the seller says), so I do not really know the history, but I am treating them properly now. We will see I guess.

Francis


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## Guest (Feb 26, 2011)

Well that answers that question.


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## peggus (Feb 18, 2008)

gottdi said:


> That is an interesting thing to note. How much have they swollen? Have they swollen like this?


Not that much, but there is a visible bulge in the middle.


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## Guest (Feb 26, 2011)

Got some interesting news. The swelling is not from gassing within the cell. It is a physical change that causes the swelling. I will be taking video and photos of my Hi-Power I dismantled that was at 0 volts and totally swollen like the one in the above photo. I chose this one to open because it had no chance of shocking me during the opening of the cell. Again, swelling like I suspected is not from gas but from a physical change that causes swelling.

Pete


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## spdas (Nov 28, 2009)

gottdi said:


> Got some interesting news. The swelling is not from gassing within the cell. It is a physical change that causes the swelling. I will be taking video and photos of my Hi-Power I dismantled that was at 0 volts and totally swollen like the one in the above photo. I chose this one to open because it had no chance of shocking me during the opening of the cell. Again, swelling like I suspected is not from gas but from a physical change that causes swelling.
> 
> Pete


Hi Pete. and do you think this change is detrimental with ANY Swelling or do cells swell for whatever reason and progressively become less efficient until they are 0volts? TS does mention the clamping device, (but then again they mention charging at 4.2 volts too.)


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## Guest (Feb 27, 2011)

Cells do not swell for no reason. Swollen cells are not good. Not that they loose all capacity but you won't get them flat again. At least not that I am aware of anyway. Maybe a full charge and discharge under pressure will help lessen the swollen battery issue but damage is done when batteries swell as they have been either overcharged or over discharged. Neither of which is good. Actually the over discharge is more like when you drive a cell into the ground and it also overheats. If you slowly discharged a cell to zero I'd almost bet it wont swell. But overcharging which goes along with overheating will cause swelling and over discharge (drive to the ground) includes overheating also. Swelling will occur. But its not gas that causes the swelling. 

Pete 

I will have the movie in HD on youtube tomorrow but until then I have one you can look at with your phone or browser. Works with quicktime too. It is smaller but my server is kinda slow for large format movies. Until it has completely uploaded this one will have to do. Once loaded you can save it too until I have the youtube one available. 

http://greenev.zapto.org/GreenEV/GreenEV/GreenEV_Productions_Albums/Pages/Hi-Power_Movie.html

Photos too are up. 
http://greenev.zapto.org/GreenEV/GreenEV/GreenEV_Productions_Albums/Pages/Hi-Power_Photos.html


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## Coulomb (Apr 22, 2009)

icec0o1 said:


> Where did you read manufacturers saying this?


I can't find it now. I thought it was in the Thundersky Instruction Manual (2007030222 seems to be in the name of the PDF file). But when I read page 37 of that document, it seems to say that swelling should not happen in normal use.

I'm talking about slight swelling, a few millimeters of extra width, which gentle clamping will fix. A post that seems to agree that gentle clamping is good for cells:

http://www.aeva.asn.au/forums/forum_posts.asp?TID=1903&PID=23996#23996


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## Wiredsim (Jul 4, 2008)

I don't agree that is what it is saying. It looks more like a device they have to apply a large amount of pressure to correct casing distortion issues. It is repeating exactly as previously said in this thread that swelling is due to damage to the cells.


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## Guest (Mar 1, 2011)

My cases are distorted for sure from the heat generated but the pack within is also swollen and will not go back flat. Now that the cells have been sitting awhile the fattest one will be cut open too and the pack within will be checked. I think I will do a load test first because it is still holding a charge. The case would need to be heated up again and held under pressure until it cooled to get the case back to a more normal size if the internal packs are still flat. But squeezing the cell results in no change in swelling. I will check once again but use a much stronger form for squeezing. I think the fat one is just that. FAT.

Correct. No cells swell under normal use of charge and discharge. Period.


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## Coulomb (Apr 22, 2009)

Wiredsim said:


> It looks more like a device they have to apply a large amount of pressure to correct casing distortion issues. It is repeating exactly as previously said in this thread that swelling is due to damage to the cells.


Well, I can't disagree with you there. What I was trying to say is that my recollection is that "the manufacturers" (I can't remember if it was TS only or SE only or both of them) indicated that swelling is common, not serious, however mild pressure is recommended to prevent this anyway. I thought that this document is one of the places that I formed this opinion. I agree that after all, this document does not support my recollection.

Two quick observations:
Why do both Thunder Sky / Winston and Sky Energy / CALB supply clamping hardware if it should not be necessary in normal use?

Why would TS make a device for clamping swelled cells, if swelling implies that the cells are damaged? Well, I suppose it makes sense in a laboratory situation, where they would presumably push cells to their limits and beyond, and attempt to quantify the amount of damage done, and whether that damage is reversed with clamping.


The other thing is that we did observe some of our cells swelling enough to be visible to the naked eye. (See below for details.) We had probably done things like 6C continuous tests down to about 2.5 VPC, which at the time we thought of as acceptable treatment. I'm now coming to the conclusion that perhaps 6C continuous discharge is bad for the cells; even though we recorded a maximum temperature of 52°C (126°F), they may have gotten a lot hotter inside.

Possibly, charging at over 3C is also bad for cells. After all, the manufacturers do specify that limit. I guess we were hoping to get away with higher peak regen than 3C (at least for short bursts), although in our case that would be some 90 kW. I note that in the link below, Tesla argue that charging at higher than C/2 is detrimental. However, they are using a different chemistry in their cells.

Ok, I finally did a proper search (searching the images, in fact, using images.google.com), and I think this thread is what started the clamping habit:

Clamping is for real after all?

It all seems to be based on one comment on a photo, and that was about a cell that had ballooned like a blimp from overcharging. I don't suggest that everyone read all of the above thread, it's just for reference in case someone wants to delve deeply into this. The take-home message seems to be: high current charging is bad for cells, and makes them swell. Our Thunder Sky test cell seems to have taken this rather badly; it's not clear to me whether any of the Sky Energy cells (which we need for our MX-5 conversion) received the same treatment. I hope and suspect not.

In conclusion, I have to withdraw my assertion (that manufacturers consider swelling to be normal). My memory of why we routinely clamp our cells seems to have been faulty (unfortunately, not an unheard-of circumstance). My apologies.


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## Guest (Mar 1, 2011)

If I am not mistaken TS comes with end clamps with like 5 cells already clamped. I more assumed that the clamping is to hold them and not for keeping them from swelling. If they swell they swell clamped or not. But if they are clamped you just don't see it or they vent sooner. I can see that a case might sag a bit due to heating and just weight and time. But I highly doubt it. That is some tough plastic. But it will sag under excess heat. I think they should use different plastic. I will open my super fat cell to confirm that that pack within the cell is bloated too. If I find it is not then I will eat my words about that and try to squeeze my other one back to normal. But once the plastic is distorted I am quite sure you need heat and pressure the let it cool before it will return to normal. I don't think just squeezing it would do the trick. Swelling a cell results in lots of heat. That heat will distort the plastic without a doubt. When I removed that side piece the plastic is obviously distorted and no longer flat. 

Pete


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## Guest (Mar 1, 2011)

I see no reason not to clamp nor a reason to clamp. If you are one of those that uses a BMS and takes the cells to the outer limits each and ever charge and discharge then I'd be in the camp of clamping the cells. It won't prevent damage but may keep hot cells from having the cases sag. 

Pete


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## DIYguy (Sep 18, 2008)

gottdi said:


> I see no reason not to clamp nor a reason to clamp.


One very important reason to clamp is to prevent movement between cells that can put undue load on terminals... a nasty thing that you don't want to do, that is, if you are not using braided/flex interconnects.


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## Guest (Mar 1, 2011)

True, you do want them secure from load shift but a good fitting box can do just fine.


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## DIYguy (Sep 18, 2008)

gottdi said:


> True, you do want them secure from load shift but a good fitting box can do just fine.


I dunno Pete, I'm not so sure that a good fitting box can offer the same tight, unitized battery that clamping can??. . . unless perhaps if the box was made to clamp???


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## Guest (Mar 1, 2011)

Clamping would be best but if you take care of your cells then a good stiff bok and good fit in the box should be fine.


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## tomofreno (Mar 3, 2009)

> Why do both Thunder Sky / Winston and Sky Energy / CALB supply clamping hardware if it should not be necessary in normal use?


 In case you overheat the cells due to high currents (3C) in hot summer temperatures, or due to severe overcharge? They can't assume everyone will use them within the prescribed limits.
I think someone here posted that Jack Rickard is no longer clamping cells, and is using the flexible webbing interconnects to avoid strain on the terminals. I know Jack has swelled some and used a clamp to compress them with some regain of capacity, but they are never the same. There would have to be voids where there is no solvent and electrolyte since the volume increased with swelling, and some solvent may have vented. My cells are only clamped with one of the small CALB clamps centered on the cells and they show no visible sign of swelling. All edges are tightly together. A couple were overcharged once to about 3.95V, but at low current. I would guess they don't swell under normal conditions unclamped, but sure wouldn't try it. They say clamp, I clamp with the hardware I was sent.


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