Here's the batteries.
I was originally thinking of cutting a slit in the busbar, and then bending it up to make a tab that I could drill a hole in. That does have the possibility of creating a flimsy, bending tab. I also have to be careful of how close I get to the main terminals for the pack. Battery Hookup sends some very nice cables with plugs on them to tie the batteries in series, or to make connections. Of all these plugs, I have 5 that are 90° plugs. Those will come in handy, especially on the two 4S batteries, where space is a little tight. Now I'm thinking of cutting a 1/2" slit on each side of the "arch", then sliding a plate that has a couple holes in it through the slit. Then I can take an identical plate from the top, and "clamp" down onto the arch. With that method, I am cutting parallel to the cell, and not down into it. Less chance of an error causing a big problem. Attached is a rough sketch of my idea.
These plates wont be the primary current path, they'll be like a busbar extension, so that essentially I'll have a 14S4P battery pack. I'll also attach my balance leads to those tie points as well. Each individual battery is already either a 5S2P or a 4S2P respectively.
When ordering batteries, my original plan was to use two completely parallel strings, with two BMS units. After some more reading, I have decided to go with just one BMS, and parallel up the cells. That avoids some nasty problems. After reading this document, I changed my mind.
https://www.orionbms.com/manuals/pdf...el_strings.pdf
i know this will present unique challenges compared to the Leaf packs, but that's OK.