Compression force on LifePO4 200Ah Help

[stepus]

Hi,
I bought some Lifepo4 200Ah batteries for my FVE project. They will be 16s1p combination.
My question is: I have seen some information about compressing pouch cells for higher cycle life and not allow to swelling cell.
I also seen this in datasheet for my cell:

循环寿命 25℃0.5C/0.5C 80% ≥2500Cycle 100% DOD，300±20Kgf 压力下， 容量保持率基于标称计算
Cycle life 25℃0.5C/0.5C 70%≥3000Cycle 100% DOD, under 300±20Kgf preload，based on typical capacity

There mentioning 300+-20Kgf compression. I dont know is it a 300Kgf on sqare centimeter, or a whole battery cell ? or what its ?
Can someone please show me how to compress cells - photos, how to set right tight etc?
Thanks

 

[Hillhater]

It difficult to comment accurately without knowing which cells you are using.
..but thinking rationally,..what are the dimentions of your cells ?....likely at least 25cm square ?
That would mean 625 sqr cms to compress.
At 300 kgf per sq cm ,..you would be needing to apply nearly 200 TONs of compression ! :?
So i might think that it means 300kgf total on the face of the cells. ,! :wink:

 

[john61ct]

You do not really need precision.

Non conductive sheet materials between pouches with a minimal give helps if you have no precise framing / box to fit.

Allow 2-4% expansion no more.

Aluminum plates at each end with threaded rods

hand tighten nice and snug

https://www.cruisersforum.com/forums/attachment.php?attachmentid=206010&d=1577899393

 

[SafeDiscDancing]

I have seen some information about compressing pouch cells for higher cycle life and not allow to swelling cell.

I have a very DIY trick.

What I do is wrap each pouch with a layer of fiberglass cloth and then work in the resin and let it cure.

Now do it to all of them.

When they are done you can now stack them and add more fiberglass around the whole thing.

Of course do all the clamping and balance wire stuff before you seal it up. (keep the tabs clean)

Now you have the lightest possible battery pack with pouches that are reluctant to swell.

Fiberglass has some incredible strength but it is also flexible to some degree.

And the fiberglass shell is strong enough to make that your final container... just add mounting hardware.

Sand, sand, sand until it's perfectly smooth or just leave it rough.

It's possible to achieve perfection if you work at it long enough.

 

[stepus]

Hi, I put the datasheet in the attachment.
Suprisingly these teway cells bought on alibaba looks like grade A cells. I have measured capacity at 100A continous discharge and it was 190Ah - cells are 200Ah rated. Also internal resistance of cell is about 0.5mOhm. Pretty good for a price.

Ok, so 300kgf is pressure for whole battery side. Do you recommend do compression with for exaple 4 rods with springs, that will be tightned and pressed to 75kg? Or do a rigid metal frame and tight it only with hand as mentioned above?
Thanks

 

[john61ct]

purchase link please

yes great cap test result

Where are you, how long to arrive, how long ago ?