Another Cell Compression Thread, this time about foam

Zwy

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Hi everyone, been lurking in the shadows and finally decided to put up my first thread and post. I've read thru many of compression threads and can say there is much discussion about this subject. My background is automotive, I'll just leave it at that. This is how the EV manufacturers are handling cell compression with prismatic cells. https://www.tapesolutions.saint-gob...icles/foams-are-driving-ev-battery-innovation As you can read here, compression is important and how it is done is equally important.

One more article on this subject from the same manufacturer, although it is primarily direct toward pouch type packs but I feel it equally applies to prismatic cells also. https://www.tapesolutions.saint-gob...ssembly-robust-efficient-batteries-norseal-pf
 

Critter350

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Interesting... I’ve been thinking about using neoprene from an old wetsuit, to provide some give and electrical isolation from end plates. It would crush over time and want to be re-torqued.
the PF100 sounds like it’s made for the job. Can’t find a price for it anywhere- any ideas on cost?
 

Zwy

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BiduleOhm

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How about encapsulate the cells in a battery box at a low SOC with 6lb stuff.

Good luck if you need to do any maintenance on the battery...
 

Ironman

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the PF100 sounds like it’s made for the job. Can’t find a price for it anywhere- any ideas on cost?
No cost ideas at the moment.
I am talking to them now, and it is such a new product that they don't know much, will get back to me. The two sales men I have talked to keep their promises and are clear on the phone to my crapped out hearing. They do call back.
When I have anything to report on this, I will do so on this thread. It is a closed cell foam and they have several products, PF20, PF40, and PF100.
The 100 has the least compression set. I am assuming that is the rebound after pressure release, so 5% set would mean it returns to 95% of it's former thickness.
He is going to email me on all this.
 

Burke

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How about encapsulate the cells in a battery box at a low SOC with 6lb stuff.
I have used the expanding polyurethane for other purposes, it expands to many times its liquid volume. The pads mentioned earlier seem like a much better alternative and that expanding foam is pretty much permanent so you wont be able to do much with the pack once it happens.
 

Ironman

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I got a call today from my contact at St Gobain regarding the PF100.
His name is Richmond Powers and he has given permission to post his name and help the community.
He can be reached at 949-238-0482. We discussed thicknesses and he is getting back to me on this in a couple days. He said the big manufacturers St Gobain sell to use 2mm thickness, which is good because it won't inflate the battery pack size very much. He will also want to know the sq ft amount when you talk to him. A group buy may be a good thing too.
When I know more I'll post more.
 

zzyzx

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@Ironman THANKS for your efforts. I am very interested in hearing more about this foam.
 

Critter350

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What is peoples views on installing between each cell or only on outsides of a pack?
 

Maast

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I dunno.... heat is the #1 cause premature aging of LFP cells. Unless its in Alaska I'd be hesitant to place foam around my batteries.

Unless you're talking about an arrangement where you have a aluminum plate with some excess poking out as a heat elimination surface area with smaller sheets of foam pressing the aluminum plates to the cells.
 

Ironman

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What is peoples views on installing between each cell or only on outsides of a pack?
As I live in a colder climate, heat is less of a concern, but I think it would be best to have an end plate of 3/8" aluminum with draw bolts done finger tight, and foam between each cell, but on every second cell if you slipped in a sheet of aluminum about 1/16" thick which extended out 1 inch on all sides, this would act as a cooling or heating fin to bring the pack to ambient temps.This would put one cooling fin on one side of every battery this way.
If you had 16 cells in a long string the charge swell of 1mm (280ah) per cell would equal a total swell of 16mm or roughly 5/8" so constraining this seems important to me.

I have AGM and LA experience, but not in this so don't assume this is the only way. Add salt. Some may have better ideas.
 
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Hedges

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The following Saint-Gobain "Norseal® PF-series Compression Pads" document clearly shows a foam pad between each cell on an EV battery assembly:

https://www.tapesolutions.saint-gob...pf-compression-pads-for-ev-battery-o-1512.pdf

From a vendor of foam pads, not of cells.

The higher performing EV have liquid cooling of the battery.

I could imagine an aluminum sheet per cell and foam one one side if desired. Might need enhanced insulation between aluminum and cell, if case can be electrically hot.
 

Acho_303

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I'm using homedepots xps foam board (pink board) it has 15psi.... so hopefully it will stand up to the pressure

Basically my setup will be 1/2 baltic birch, 1/2 xps, Cell, 1/2 xps, etc compressed with all thread
 

Critter350

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On low C rate application I’m not expecting much heat generated from the battery (from what I’ve read).
I do want enough room for expansion, so wonder if 2 sheets of 2mm foam will have enough give for 4S expansion. Probably better to place between each cell (for my application).
 

Hedges

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I wonder if those silicone baking sheets would do, they're pretty rubbery.
I don't think they have much give. They won't flow, but the battery's filling will.
 

ramiws

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So are you guys talking about giving way to the batteries to expand ? I thought that we compress them so they won't expand, to prolong life..
 
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