Little blue brick, or cylinders

[Fingers]

I just don't get it........ Maybe you could shed some light?
Why would so many people be fixed on pouches in little blue bricks, instead of cylindrical cells?

Cylindrical cells are wrapped in metal and so to an extent avoid expanding, and I'm guessing easily changed when they go bad.
But when a pouch goes bad in a blue brick you have to A) crack the brick open and see if the expanded pouch has damaged the other pouches, or B) throw the blue brick away.

So what gives? It it just down to purchasing price or have I totally missed something?

 

[sunshine_eggo]

I just don't get it........ Maybe you could shed some light?
Why would so many people be fixed on pouches in little blue bricks, instead of cylindrical cells?

Cylindrical cells are wrapped in metal and so to an extent avoid expanding, and I'm guessing easily changed when they go bad.
But when a pouch goes bad in a blue brick you have to A) crack the brick open and see if the expanded pouch has damaged the other pouches, or B) throw the blue brick away.

So what gives? It it just down to purchasing price or have I totally missed something?

At a loss as to what you're talking about. Few folks on here use cylindrical and fewer folks use "blue brick" full of pouch cells. I'm allowing for that possibility, but I've never seen one on here.

The vast majority use single prismatic cells in aluminum "bricks" wrapped in blue shrink wrap. Are you possibly confusing the two?

 

[Fingers]

prismatic cells in aluminum "bricks" wrapped in blue shrink wrap

Blue bricks.
In side the blue brick (alloy or plastic case) are prismatic cells (pouches).

Few folks on here use cylindrical

That's what I'm on about. Why?

 

[sunshine_eggo]

Blue bricks.
In side the blue brick (alloy or plastic case) are prismatic cells (pouches).


That's what I'm on about. Why?

Very sorry. You are mistaken. There are no pouches inside the aluminum cans in prismatic cells. There is no opening them, and there is no repairing them. The reasons they are often chosen is they are among the cheapest per kilowatt hour, they have extremely low internal resistance, and they can be used to very quickly build a battery rather than spend hours days and weeks assembling cylindrical cells.

They are also less prone to failure than a single "cell" comprised of multiple parallel cylindrical cells.

 

[WYtreasure]

I think I get what Fingers is asking. Terminology may not be totally accurate but I have wondered the same thing (maybe).
Why use the blue rectangular VS the cells which are cylindrical (they look like the D batteries in a flashlight)? I guess Sunshine answered the question.
Cylindrical cells, swiped from @Stucco

Uh oh. lost the magic smoke

So finally got the electric cycle to a position where I could test it out. Low "gear" worked great, slow wind up to about 30 mph. Flipped it to high and gunned it. Power cut out. I was thinking I was pulling too many amps through my transfer switch between my 2 batteries, so I removed it...

diysolarforum.com

Blue Bricks, swiped from @mrzed001
https://diysolarforum.com/threads/epever-mppt-killed-mpp-solar-inverter-and-lfp-pack.36643/

 

[Fingers]

There are no pouches inside the aluminum cans in prismatic cells.

Wow, I'm sure that I saw a video of them being made; four pouches crammed in to a plastic/alloy case. Ho hum.

they can be used to very quickly build a battery rather than spend hours days and weeks assembling cylindrical cells

Oh, yes, the ones with welded tags, your absolutely right.
I was really thinking of the kind that has the threaded contacts.

They are also less prone to failure than a single "cell" comprised of multiple parallel cylindrical cells.

That surprises me. Why is that?

 

[mrzed001]

I just don't get it........ Maybe you could shed some light?
Why would so many people be fixed on pouches in little blue bricks, instead of cylindrical cells?

Cylindrical cells are wrapped in metal and so to an extent avoid expanding, and I'm guessing easily changed when they go bad.
But when a pouch goes bad in a blue brick you have to A) crack the brick open and see if the expanded pouch has damaged the other pouches, or B) throw the blue brick away.

So what gives? It it just down to purchasing price or have I totally missed something?

That "little blue brick" (called prismatic cell) is 5,3-5,5kg and has almost 1 kWh capacity ?

Inside there is 1 or 2 pouch cell(s).
Yes the box/prismatic shape is not as resilient as the cylindrical shape against the inner pressure.
And that is why you need to use fixture with prismatic cells.

Cylindrical batteries are mostly Li-ion NMC/NCA. And that is a fire and explosion danger by itself.
For LiFePO4 cells the prismatic shape is enough because that will not explode, does not need such a strong case (there are cylindrical LFP batteries too, not much).
And because prismatic uses less space, and this blue cells are used in EVs and Electric buses .

 

[Fingers]

That "little blue brick" (called prismatic cell) is 5,3-5,5kg and has almost 1 kWh capacity

What ah is it?

prismatic shape

Brick shape? And it's blue, why blue? They should have made a nice vermilion or orange

 

[sunshine_eggo]

Wow, I'm sure that I saw a video of them being made; four pouches crammed in to a plastic/alloy case. Ho hum.

Oh, yes, the ones with welded tags, your absolutely right.
I was really thinking of the kind that has the threaded contacts.

That surprises me. Why is that?

There are typically more cylindrical cells in a pack due to the need for larger capacity. If you have 8 cells, you have a given probability of a single cell failing. If you have 84 cells, you have a higher probability of a single cell failing.

What ah is it?

Typical is 280Ah

Brick shape? And it's blue, why blue? They should have made a nice vermilion or orange

Because everybody uses blue shrink wrap. You could certainly do your own color if you like.