What's the latest opinions on cell compression.

[bds70]

In the RV situation what is the latest opinions on compression? I am building 4 x 12v 280AH batteries, each of which will be enclosed in its own box, to minimise dust Ingress etc. But the boxes would not necessarily be compressing the cells, unless I design them that way. Most of the stuff I have read is 2 plus years old, so things may have changed.
Any thoughts anyone?

 

[robby]

I don’t think anything has changed.
Discharge the cells down to about 10% SOC then fixate them in place with your clamping system. Don’t compress them just snug them in with a slight bit of pressure.
This will prevent them from bulging when you charge them back up.

 

[Brucey]

Seems like compliant foam is the way to go these days. Compensates for the non uniformity of the cell faces, versus say fr4 insulating sheet which may create hotspots of pressure under compression? I’m planning on using poron

Compression material thoughts...

While waiting for my Lishen 272ah that will be in a 16s configuration, I’ve been thinking about all the “fixture” information and materials. Going through material to place in between cells, I came across this and wanted to get your guys’ thoughts...

diysolarforum.com

 

[hrchonda]

still the same info.

eve to my knowledge still state 280kgf.

after months of going down the rabbit hole i settled on tightening them LITERALLY just enough to hold the cells. cells arrive 30/40 percent charged this is when i done it.

 

[Brucey]

still the same info.

eve to my knowledge still state 280kgf.

after months of going down the rabbit hole i settled on tightening them LITERALLY just enough to hold the cells. cells arrive 30/40 percent charged this is when i done it.

I would compress them at the level they were shipped with. Dropping them down to 10% then compressing could cause an over compression situation at full charge?

 

[Brucey]

PORON 4701-40 Foam W/Adhesive Backing - 0.125" is what I'm planning on ​

 

[bds70]

Thanks everyone. Just sent for some Poron foam. Cheers for the desc Brucey

 

[Brucey]

Thanks everyone. Just sent for some Poron foam. Cheers for the desc Brucey

Here's what I got:

PORON 4701-40 Foam W/Adhesive Backing - 12.375" x 9.375" x 0.125" - Box of 10 | eBay

PORON Black 4701-40 Polyurethane Foam With 1173B Acrylic Pressure Sensitive Adhesive. Compression Set, % max @ 23°C (73°F): 5. Quantity: 10 sheets per box. Maintains integrity in lengthy temperature fluctuations.

www.ebay.com

 

[bds70]

Reading the Cell specifications and test data, this was mentioned for clamping "initial
clamping force of 3000N
(± 200N), 15mm
aluminium sheet"

How does one convert Newton's to to pound/foot?

 

[Brucey]

Reading the Cell specifications and test data, this was mentioned for clamping "initial
clamping force of 3000N
(± 200N), 15mm
aluminium sheet"

How does one convert Newton's to to pound/foot?

 

[bds70]

View attachment 223955

Wow, that's like a lot of force isn't it. My car suspension parts aren't torqued to that much.

 

[Brucey]

Wow, that's like a lot of force isn't it. My car suspension parts aren't torqued to that much.

Well keep in mind that's the force applied across the entire cell face, not a single spot.

 

[Suijkerbuijk]

Wy ??
If i see this i ask my self wy ?

And

 

[bds70]

Wy ??
If i see this i ask my self wy ?

And

Just finished watching one of those, I think I have my answer. I shall build a "support" fixture because my batteries are stored in an external locker under the floor of my bus, so they need to be restrained from movement, and they will simply be contained rather than compressed per sa.
My next issue is deciding how to protect the BMS from dust without running the risk of overheating it.

Any suggestions?