Better to make the p group solid on a pcb backer in that case and allow flex between groups.
1 Like
A lot of things seem like overkill before rigorous testing or outright failures tell us what the limit of underkill is.
âseems good enough to meâ doesnât cut it in my book for things involving lots of angry pixies under your feet.
Agreed wholeheartedly, but that requires all the extra cost of a PCB, etc.
My suggestion was a workaround to an already-built pack with a possible design weakness.
2 Likes
As a quick experiment, I hot glued a strip of ~1mm aluminum to my desk and applied 500g of lateral force to the end, first perfectly flat, and then with a hump.
See for yourself, how much more deflection the hump allows.
1 Like
As a demonstration of your point, thatâs great. But as a test related to cells which are spaced close enough to be almost touching each other, it is irrelevant.
How far apart are you planning to space your cells? Longest pack ever.
I see this more as a âwhy wouldnât you add some slack marginâ than a âwhy would youâ.
1 Like
got a link for those corner cutters?
As a demonstration to my point, I used a piece of material several times thicker than the nickel used in any esk8 battery, and wider than most. This was to exaggerate the effect I was trying to explain. Hyperbole, if you will.
1 Like
https://www.google.com/search?q=corner+chompers
theyâre a crafting tool. called âcorner chompersâ crop-o-dile is a brand some have bought.
2 Likes
That beam conformation exists on both ends of the cells, which are glued together, fiberglass taped and then fishpaper wrapped. The flex between cells in a p group should be undetectable to the human eye and this, inconsequential in its effects.
Obviously if you have 6, 7, 8 cells in a flat lay P group then the flex could increase, but thatâs fixed by changing the layout of the pack
1 Like
Just tiller that shit and when it burns blame the customer 
6 Likes
yes. this is a common port BMS where C- and P- are wired together. common port bms usually has higher charge rating.
3 Likes
14 Likes
Whatâs the nickel count and thickness. 5p p42A should safely put out 150 amps. Thatâs a husky battery
2 Likes
Thickness is 0.2mm, width 10mm. Every series connection is made with at least 5 connections.
This battery will be used with ebike esc which can pull up to 45 amps 
4 Likes
I can totally dig building to a use case scenario, but it does irk me a little to see such little nickel there.
It looks beautifully made tho
2 Likes
There are 4 layers of nickel on some places. Itâs hard to tell from photo. Overkill in any case
3 Likes
Got the nickel! Thank you @ZachTetra ! The battery build continues. I am pretty happy with the progress so far.
Cut the nickel into suitable sizes for the 12S4P.
Corner chompers are definitely useful. 1/4" cut radius.
Welds. My first time spot welding. Malectrics spot welder, and some random old car battery. I had to use quite long pulses to get decent welds, but otherwise it turned out ok I think.
P groups done.
Tied the side-by-side P-groups together and added more insulation.
Ready for soldering.
11 Likes
Holy shit that looks absolutely perfect
5 Likes
Where did you get the fish paper and fiber tape? And whatâs the corner chomper you use?
1 Like