Compression vs restriction

[Skypower]

Effing love those top crossbars!!!!!

I see a wrench in the works

 

[Skypower]

I don't have to paint it and it looks so cool. No corrosion, stronger per pound.

Aluminum can be easier to work with than steel. My first cell fixture was for my truck camper, 1/2" thick aluminum and I tapped threads in it to hold the BMS.

View attachment 255512

I work with just about any material and for some things aluminum makes the most sense. It costs more but the labor involved with painting it and the paint costs money too. I want to assemble it and not have to repaint it down the road. I can weld aluminum, stainless, steel and braze/silver braze. Stainless is hard to work with but for some applications like my shower stall pan in my truck camper it is totally functional and looks great.

View attachment 255515

Yes, I fabricated the 2 piece shower pan and even coined the drain hole in the shop press. I purchased the power brush for the brushed look and passivated after welding using electrical current and phosphoric acid.

Back to your original question, it is a matter of choice but I liked using aluminum and the 8" wide flat bar is perfect for battery cells. Steel will work.

One of the hardest things to do is weld thin stainless and not make it look like a sick bird walked by. Nice.

 

[AntronX]

Done for now. Gaff tape in the middle and 7 layers of clear scotch tape on top and bottom. Need to get a roll of fiber reinforced packing tape. Used a caliper to match amount of compression on all sides. Cells were already a little swollen so I did not compress much. This is more like fixing in place rather than compression to spec.

 

[fatjay]

Done for now. Gaff tape in the middle and 7 layers of clear scotch tape on top and bottom. Need to get a roll of fiber reinforced packing tape. Used a caliper to match amount of compression on all sides. Cells were already little swollen so I did not compress much. This is more like fixing in place rather than compression to spec.
View attachment 255535

I wonder if they will appear not bloated because the bloat will go into the foam, if they actually bloat.

 

[AntronX]

I wonder if they will appear not bloated because the bloat will go into the foam, if they actually bloat.

That's the idea. Let them have room to bloat to prevent excessive pressures on the cell while maintaining constant pressure to slow down whatever destructive mechanical effects bloating causes that lead to reduced cycle life in the long run. I don't recall exactly why pressure on cell surface extends cycle life but that's the message from manufacturers and researchers.

 

[Hedges]

Since I blathered on about stiffness, steel is nearly 3X stiffer than Aluminum.

The approach to stiffness should not be more meat, but getting a better geometry.

The differences between stiffness and strength in metal

Many in the metals industry think that stiffness and strength are the same thing. That's not the case, especially when you are talking about metals used in automotive designs.

www.thefabricator.com

"Ribs are added to truck bed designs to help increase overall stiffness."



Of course, this can also be accomplished by an additive process, rather than forming.

 

[DPC]

The approach to stiffness should not be more meat, but getting a better geometry.

Of course, this can also be accomplished by an additive process, rather than forming.

Huge snicker
I’m mean come on man
Someone had to say it

 

[Hedges]

That's OK.
I play the straight man.

 

[DPC]

For a straight thread it sure had a lot of talk about bondage rigidity stiffness

I could go on….

I don’t judge
But wow this is the gayest thread not in the off topic section

 

[Re-Volt-Oz]

Did it this way on a small 24v pack I put together using strapping material and fr4 board

Hi, Good idea on using the strap, How did you tension the strap and what locking clips did you use?

 

[fatjay]

I guess this thread comes back and i never updated with what I did.

Behold.

 

[sunshine_eggo]

clear tubing is a nice touch!

 

[robbob2112]

I like it, I decided to use blue PEX tubing... matches the battery color and should give the eggo a shwing

 

[Drunkin Solar]

Hi, Good idea on using the strap, How did you tension the strap and what locking clips did you use?

The clips came with the strapping material. It also came with a tension tool as a kit. Could not use the tool because I was concerned on damaging the side of the cells. Instead I put vise grips on the ends of the strapping and pulled it tight. That took some strength but worked nicely.

 

[Drunkin Solar]

Real nice build there Jay

 

[Aridom82]

I guess this thread comes back and i never updated with what I did.

Behold.

Very nice build!
Be careful though with those black and red dc switches. I had the same type (or very similar) for 160Amps and one of them failed and burned at around 100Amps. Since then i changed them for something a bit better, the Dihool ones for Aliexpress. Still chinese stuff, but a bit better i believe.

 

[Brucey]

Saw this on Facebook this morning, insufficient strength in the end plates:

 

[Aridom82]

Saw this on Facebook this morning, insufficient strength in the end plates:

View attachment 281044

Maybe this is just the plywood

 

[Brucey]

Maybe this is just the plywood

Yeah steel plate could have kept them in order
Alternatively, another set of rods down the center