# Battery pack height

Does anyone know what height would 21700 be in a double layer staggered pattern? I have a 4cm deep enclosure (+1-2mm with insulation) and I really want to fit them in.

### Face centered “cubic”

Face centered cubic packing is nested to take up less room. Calculating the size takes a little geometry, which follows:

The size is L x W x H where

L = (n +½)D
W = [0.866(p-1)+1] D
H=H

p is the number of rows wide.

i hold 0 liability of such information

2 Likes

Looks correct. This is stuff you learn in materials science when talking about atomic packing factors.

L looks like the horizontal length, while W looks like the vertical “width” here.

I think n here is the number of cells in the horizontal length (so n=3 in the example)
D is the diameter of your cells (so 21mm) and p is given as the number of rows wide.

I’m having a hard time understanding this. English is not my native language, different letters were used referring to certain values when they taught me this. Could you simplify it if possible?

K picture was messed up - here is the proper one

1 Like
1 Like

If you have experience in cad, you could just draw it up for two layers and than measure out the hight.
Optional just draw it up on a paper and measure it.

2 Likes

This is assuming no insulation, but I’m getting similar values.
There’s simply no way you can fit them in if you only have 4cm unless you want to go without insulation.

It’s close enough to work fine just use a rubber gasket or weather stripping of whatever thickness is needed between deck and enclosure to accommodate the difference

7mm/1/4" rubber strips on Amazon works pretty good for getting a little more room.
I superglued mine to affix it then used a silicone(but better)type adhesive to seal from the inside.
Sont forget to account for series connections. You’re probably gonna want to use braid to keep the height down

1 Like