Triangular 14s7p cell layout

[titan_rw]

Hello.

I'm looking to build a custom triangular pack for my mountain bike.

I have a 3d printer that I'd be using to print cell holders, and the packs 'skin'. Cells would be spot welded together.

I have the battery bag (the lunacycle one), and I've printed off a test-fit piece to verify that it'll fit.

This is 98 cells, so 14s7p. Planning on using 21700 cells. Not sure on which particular cell at this point. I've done my best to layout the cell groups such as to maximize the number of series connections given the confines of the layout. The points that have minimal series connections (red to purple in the top left corner) will have extra nickel strips, or additionally wire connections soldered to the nickel strips in between cells. I'm anticipating about 50 amps max, and more like 15 amps average.

Here's a blank outline of the cell holder:



This is how I came up with grouping them into 7p sets. Different colors represent cell groups, not polarity.



And this last one adds the series flow. This is just a visualization. All cells in one set would be connected (as much as possible) to all cells in the next set.



Is there a more efficient layout? This was the 3rd iteration I made, and don't think it's too bad given the footprint. If anybody has suggestions on alternate layouts, the first blank file can be scribbled on in paint, showing cell groups.

Thanks.

 

[titan_rw]

Maybe this iteration is a bit better. Red / Blue indicates polarity with black cell dividers to show parallel sets.

Worst case scenario for series connections is 3 cells beside 2 cells. Worst case on the above example was 2 beside 2.

 

[titan_rw]

Due to the overwhelming response on this I decided to redo the layout.

This new one is worst case scenario of 3 besides 3 instead of 3x2. This is how I've actually built the battery. Solid copper wire 'bus bars' (~18 awg equiv) were added to the more limited series connections. So on the worst case series connections of 3 besides 3, I've got 5 nickel strips (8mm x 0.15mm pure nickel). Then 2 or 3 18 awg copper wires soldered to the nickel strips in between cells.



Spent the last month and a half going back and forth with grin over email. Would have been nice to have had a few 5 minute phone calls instead, but it is what it is. If they weren't a decently local Canadian company I would have went somewhere else by now.