Don't forget about: If you don't know what it is, but everyone else seems to have one, maybe some research is in order.
Cell compression: zip ties and lexan?
- Thread starter Batvette
- Start date
Don't forget about: If you don't know what it is, but everyone else seems to have one, maybe some research is in order.
I can't see why those big as% zip ties wouldn't hold the pressure. I would think a person would need to waste a couple, however, getting a feel for "when tight is tight enough". The lexan might need to be thick, however, for it not to distort when you crank down on the zip ties.
As the philosophy pertains to coming across one in a store, I think if everyone else has one I know what it is.
Do you go to surplus or thrift stores? I see a lot of weird stuff there, and I keep reminding myself of the truism to avoid wasting time, thats all.
It's been a while since I've been to a surplus store, but I have shopped the thrift store within the past year. When I go there I'm looking for something very specific. The last time it was rollerblades. I needed rollerblade wheels and wasn't willing to buy new ones.
The past few years I've been doing my best to avoid making other people's crap, my crap.
Yep.
i think 1/2" lexan would be more than stiff enough. Even 3/8, though since Id rather not find out it isnt and do it twice, will go with the thicker stuff.
Hopefully the demand from covid has subsided, last summer clear lexan was unobtanium.
I'm big on the "but if everyone else seems to have one....order two" which tends to keep me in trouble and broke because you guys have a LOT of stuff.Don't forget about: If you don't know what it is, but everyone else seems to have one, maybe some research is in order.
Woody
Solar Enthusiast
Here’s an alternative low tech approach for keeping the cells compressed when charged that I call the Milk Crate Compression approach for 280Ah LiFePo4 cells.
Four 280Ah cells (side by side) fill a milk crate with about 1/2” of extra space. Slide in 4 cutting boards (2 each end) and thin cutting sheets (between the cells) from the Dollar Store and your cells fit snugly. Cells are taped together with thin cutting sheets between them and centered in the milk crate on the sides with 2x3s. There’s a 3/4” plywood lining the bottom to provide a flat surface for the cells. The plastic crate will restrain the cells and yet allows for some flexibility when they expand. Plus if the cells need a bit more space because the bloat is more than expected when charged, then one can remove a cutting board spacer. This simple approach, not as nice as those 3D or metal compression builds, does allows the cells to ”breath“ and keeps them constrained proportionally to their charge. I’d expect better cell life cycle from having some level of constraint than if no constraints were used. Here’s some photos of what I‘m assembling.
Four 280Ah cells (side by side) fill a milk crate with about 1/2” of extra space. Slide in 4 cutting boards (2 each end) and thin cutting sheets (between the cells) from the Dollar Store and your cells fit snugly. Cells are taped together with thin cutting sheets between them and centered in the milk crate on the sides with 2x3s. There’s a 3/4” plywood lining the bottom to provide a flat surface for the cells. The plastic crate will restrain the cells and yet allows for some flexibility when they expand. Plus if the cells need a bit more space because the bloat is more than expected when charged, then one can remove a cutting board spacer. This simple approach, not as nice as those 3D or metal compression builds, does allows the cells to ”breath“ and keeps them constrained proportionally to their charge. I’d expect better cell life cycle from having some level of constraint than if no constraints were used. Here’s some photos of what I‘m assembling.
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From 24 years of owning an airplane I built - zip ties become brittle over time. And then break. (And most people aren't using aircraft quality ties - the ones with a metal tang for the rachet mechanism.) Okay to use them - just be aware that every few years you need to inspect them. (And possibly replace some.)
You know some states have this milk association police that come and arrest you for misappropriating their equipment... LOL.
Im committed to 2 of these seahorse cases already, but thanks for the input.
https://diysolarforum.com/threads/4s-272-280ah-enclosure-suggestion.16652/#post-223794
Woody
Solar Enthusiast
You know some states have this milk association police that come and arrest you for misappropriating their equipment... LOL.
At one time that was true but today even Lowe’s and Home Depot sell them. But the older one were made better than todays crates! ?
At one time that was true but today even Lowe’s and Home Depot sell them. But the older one were made better than todays crates! ?
TexasFan
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I tried to understand the compression thread, but just decided to keep it simple like some have said. Ordered 1.5"x 24"reusable velcro wire wraps to apply light compression on .5" wood end plates. 4 272 cells should be about 36" so 2 24" wire wraps should do it so 4 straps per battery pack.
Heyjimmy911
Let's keep it simple.
No, you need to go totally overboard, like me. You will thank yourself in 8 years when you squeeze extra cycles out of your old batteries and all your friends on here upgrading to the latest and greatest. 
Buy a welder from harbor freight, a spool gun, scrap angle from Arlo metals, teach your self to weld ugly (but strong) and make one of these. Cover the threaded rods with an aluminum tubes. Complete the project with removable rigid foam insulation.
Buy a welder from harbor freight, a spool gun, scrap angle from Arlo metals, teach your self to weld ugly (but strong) and make one of these. Cover the threaded rods with an aluminum tubes. Complete the project with removable rigid foam insulation.Attachments
It is properly spelled CDO. has to be alphabetized...
If the compression adjustment is entirely from the bottom it doesnt seem to me that the pressure would be uniform?No, you need to go totally overboard, like me. You will thank yourself in 8 years when you squeeze extra cycles out of your old batteries and all your friends on here upgrading to the latest and greatest.
Heyjimmy911
Let's keep it simple.
The compression is achieved only in the center 2.5" strip of the 4 end cells as set up in the photos I shared. In the first photo you can see the holes the threaded rods run through. In the second photo you can see the covered threaded rod providing the tension. The vertical supports that hold the compressing angle aluminum in place allows for back and forth movement when acted upon by the tightening and loosening of the threaded rod. The addition of a plate, matching the face size of the battery, would help the compression uniformity. It can simply be placed between the compressing angle aluminum and the battery, on each end.
ArthurEld
Solar Wizard
Compression Dis Order
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