640ah liitokala build, 2p4s, is this case/compression ok ?

[GavCol]

Hi,
I recently received my 8 x 320ah cells from the liitokala store on AliExpress.
So far capacity tests (2p4s for a total of 640ah) have been very promising (but not finished yet ) with capacity meter reporting 615ah.

I just had a question about the method I'm using for compression to prevent the cells bulging.
I have the cells in square with some thin vinyl sheets separating them to prevent friction wearing/contacting the cell walls.

Looking at the pic below, is this setup ok to compress the cells ?
- Can there be too much pressure ? (I can definitely tighten even more but I'm not sure if too much will damage the cells.)
- Does there need to be walls on all sides or just the wider walls ?

Cheers and thanks in advance
Gav

 

[snoobler]

Hi,
I recently received my 8 x 320ah cells from the liitokala store on AliExpress.
So far capacity tests (2p4s for a total of 640ah) have been very promising (but not finished yet ) with capacity meter reporting 615ah.

I just had a question about the method I'm using for compression to prevent the cells bulging.
I have the cells in square with some thin vinyl sheets separating them to prevent friction wearing/contacting the cell walls.

Looking at the pic below, is this setup ok to compress the cells ?

Better than nothing, but would be better if it covered the entire face.

- Can there be too much pressure ? (I can definitely tighten even more but I'm not sure if too much will damage the cells.)

Yes. Most cells specify a pressure on their datasheet. If they don't, tighten only sufficiently as to ensure that the cells are fixed in place.

- Does there need to be walls on all sides or just the wider walls ?

No, wider only as you have it.

 

[Bob B]

I would separate the batteries enough to put another pair of threaded rods in the middle. I think that frame will warp and you will mostly get pressure on the outside of the cells.
That may make it harder to mount the BMS unless you can find a wider composite board .... or just use plywood.

 

[GavCol]

I would separate the batteries enough to put another pair of threaded rods in the middle. I think that frame will warp and you will mostly get pressure on the outside of the cells.
That may make it harder to mount the BMS unless you can find a wider composite board .... or just use plywood.

Thanks. I don't think the wood will warp. It's Merbau hardwood that I have left over from a recent decking project. It should be stronger than plywood but it's good advice and something I wasn't sure of. I hadn't considered centre rods...... I'll keep an eye on it and will do as you say with centre rods if I notice any warping.