It can also be used for underslung flat packs.
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I’d be interested in a 10s pack, no battery building experience though, have done my research for building my own but never got around to sourcing materials etc
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This just became very intriguing. How much space does it take up in a flat pack configuration? Like how much additional space would I need in terms of thickness, length, and width?
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Here’s an illustration of the spacing. 12 cells in a row (electrical connections not shown in this case), my design on top, optimal packing on the bottom.
Regular welded pack (cells touching each other) optimal total length with 21700 is 21mm*12 = 252mm, width 21mm.
In my design the cell spacing is 22mm, cell diameter + 1mm, so with 21700 → 21mm + 1mm = 22mm. With 18650 it would be 19mm and this goes for the whole honeycomb pattern. Width of the cell is the outmost dimension. The mechanical structure adds 2,55mm to both ends.
EDIT: my design also has the added benefit that the cells can’t mechanical and electrically come into contact with each other, unless the pack mechanically fails.
EDIT2: In the cells length direction it’s about 76mm in total with the mechanical structure.
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@rusins
How big were those NESE modules in the cell’s length direction? I’m just wondering how much space you have in the pelican style case that you used with the NESE-modules?
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Each 1s6p Nese module dimensions are: 140.7 × 80 × 23.5 mm
My box’s INTERNAL dimensions are 235mm x 170mm x 95mm.
My 11+1s 7p battery brick really had to get squeezed in to fit. Shouldn’t be an issue with any 12s4p battery I think, as long as the parallel rows are staggered in a hex-shape.
And what about height?
Internal usable space?
in a brick format a 12S7P (21700 cell) would be this big (mechanical XY-dimensions with the pack marked), height would be 76mm. Could drop one parallel cell to squeeze the Y dimension 22mm down from the 169.1mm to 147.1mm for 12S6P
I was referring to the flat pack, but I guess according to this picture it’d be 0 added height? So, for a flat pack that would be 0 to height, ~1.35 mm per cell width wise, and 6 mm per row length wise, right?
Just trying to figure out the dimensions in order to calculate maximum capacity for existing under slung enclosures.
I guess my next question would be does this work better for the enclosures that are one big compartment, or could you make it work with flexible segmented enclosures?
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Yep, that’ll fit perfectly 
But let’s not jump to that big unless that’s a size you specifically want to test. I’d prefer to start with 12s4p.
Also, have you accounted for Molicel P42A cells being slightly larger than 21mm in width? Like 21.2 - 21.8 on average I think
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I’m not exactly sure are you talking about the dimensions in relation to the picture or in relation to a physical cell, where that 1.35mm came from?
So here’s a 3D-cell. In it’s length direction there will be an extra 3mm at both ends added from the pack structure for a total of 76mm.
Then there is an added 2.55mm added in from the edge of the last cell. In the pictures (below) in the top-down direction there is no extra dimension needed, the cell itself is the outermost piece.
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That much more then the nominal 21mm? Measured couple of my Samsung 50E and they are about 21.2mm max diameter. Can you double check that 21.8mm for the P42As?
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They are spec’d by Molicel to be 21.4mm, but I have measured as much as 21.7mm. If you want a decent press-fit-without-fucking-up-the-heat-shrink tolerance, then I would plan accordingly
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Guess I’ll have to do 22.5mm (+0.5mm) honeycomb grid for them then, but good to know, wouldn’t have thought about that little bit of extra in the diameter.
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Here’s a 12S4P pack for the P42A cells with the outermost dimensions marked. It’s a bit of a special layout, but this is possible to implement with the design.
How many amps were you planning to pull from this pack? Continuous and burst?
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No need to create a square profile, I would have been fine just with this:
When used as a range-extender pack for other boards I would like it to be good for up to 60A burst current, but if I choose to use it as a light-weight pack for my mountainboard, then 90A burst current would be great, and 120A would be ideal! 
Continuous current is usually 30A when I ride full speed.
(Wow, that’s kind of a lot! I didn’t expect to see that, but that’s what my ride logs say. Damn.)
I have tested the pack structure with a 1S4P pack of the 50Es and have done 10 minute 40 Amp discharges on it. Now it was quite warm at the end of the 10 minutes, but considering that the 50Es are rated for 9.8 Amp I’m not that surprised that they had risen like 30-35C in temperature. Takeaway is that most of the heat seemed to be coming from the cells themselves and not from any contact resistance.
Do you mind if I design it in the configuration I showed? Note that the longer pack was already pretty near the dimensions you gave for your case and it didn’t have the slightly larger diameter of the P42A cell taken into account.
No problem
In fact, looks like it’ll then fit the cool battery boxes 3ds make:
Edit: wait, that huge price is without cells. I’m not that rich lol
I’d be interested in a set of pieces for an underslung/flat pack.
Is it possible to do higher voltages - 18s/20s/22s?
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Not necessarily in a single pack, but chain them together, sure. Is your use case in an esk8, or something else?
Is it a rigid underslung/flat pack or a segmented/bendy pack?
Also, how many parallel cells?