20s9p Tesla battery for my buddy’s ebike 
This will be my largest battery to date (180 cells! 
) as well as my first high voltage battery. Can you believe that everything I have done up to this point has been 12s or less?!
I also thought of a new technique for fishpaper-ing p-groups in a brick battery (though I’m sure others have thought of this before too).
As anyone who has made a brick battery will know, getting all the p-groups to fit together nicely is always a challenge, especially if it’s a stagger stacked layout.
Trying to apply whole sheets of fishpaper to each groups means carefully and frustratingly pressing the paper into each crevice between the cells to make sure it perfectly follows the peaks and valleys in the p-group, otherwise when you go to assemble the pack, your p-groups wont fit together nicely! And then your battery turns out larger than you quoted the customer, it doesn’t fit in their enclosure, they get mad, blah blah blah.
So what I figured out is that using small strips of fishpaper rather than one continuous sheet means you can get groups that fit together perfectly, every time, with minimal effort!
Basically my thinking is that cells in a stagger stacked layout only have two points of contact with their neighboring p-groups, since that’s the nature of stacking circles (or cylinders in this case). So we dont need fish paper covering every square inch of the p-group, just im the two spots where cells contact!
By cutting a bunch of 20mm wide fish paper strips and applying them to the faces of each cell that contacts the neighboring p-group, you get full protection from abrasion while using less fish paper and, most importantly, ensuring that your fish paper is as compact to the surface of your p-groups as possible so all your p-groups fit together perfectly!
