# How to calculate number of nickel strips for 12S5P battery build.

Hey guys,

I decided to take the plunge and buy a Sunko spot welder to start making my own battery packs. I got 60 Samsung 40T 21700 to make a 12S5P pack, in a “stacked” configuration (2 cells on top of 3 in a pyramid).

One thing i’m having trouble with is calculating the number of nickel strips I need to put on each + and -. I have 0.15mm thick x 8 mm wide nickel strip, and all of the videos/websites i can find say each strip is good for about 5A. Now, that is fine for a 20A e bike battery, where you’d only need 4 strips on top of each other to cover the amps, but I have 2 VESC that are about 60A each so i want the battery to be rated for at least 120A (why i got these high amp cells). According to the 5A each number for the strips, i would need to stack 120/5 = 24 strips? How can I reduce the number of strips you need to something manageable?

The layout makes a huge difference, see how this has a connection from a cell to its partner with no extra material and bottle necking? I have a single layer of 10mm * 0.15mm and fold the thing in half with a spacer. The one on the negative side is the parallel connection for both cells as it doesn’t carry much current and the overhang is for balance leads.

thanks for the reply. I’m just not sure how you can get away with only one strip there, where the capacity of each cell is 35A. Wouldn’t you need to go at least 35/5 = 7 strips deep?

I attached an image of how I guess I would do the connections. I’m not sure though, how do you continue building the string after you fold the one group of 5 in half?

One strip is enough as only one cells current goes through each strip

Also on your picture why not connect the last 2 the same as the middle ones?

Also check the latest thread by @b264

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