And here is the battery pack building process.
Unsolder the original wires on the BMS and solder them on opposite side of the board (for proper cable management)
You can see this 80A BMS uses two 10AWG silicone insulated wires on each side
Make sure all the battery cells have the same voltage withing +/-0.01 V. All the batteries in my case were withing +/-0.0005V
Stick the insulation rings on the positive terminals of the cells
Cut the battery holders to have space for the BMS
Here is the CAD model of what had to be built
Wrap the cells ends with masking tape so the cells fit snug into the cells frame
Assemble the cells into the holders
3D printed the BMS support out of ABS plastic
Attached the support to the BMS with double sided adhesive film
Masked the battery cells with masking tape wrapped the battery pack with 2 layers of 2" Kapton tape sticking the tape in between the cell with a plastic squeegee
Spot welded negative battery terminals out of two layers of 0.2mm thick 10mm wide nickel strips (I welded it on low adhesion conductive surface (on aluminum) with high power low timing setting on the welding machine to have good weld between the nickel strips). Bent one strip and the second kept flat. Soldered 12AWG silicone insulation wires to them. Insulated the solder joints with Kapton tape
Welded the first group negative terminal
I laser cut template to place the welding pencils in the correct place during welding
Welded next groups one by one following the rule to weld all series in the group first, them weld parallel
To flatten the nickel strips after cutting them with scissors I used a hard rubber roller on a plywood
Here is how I cut the balancing nickel terminals
Applied some solder on the terminal before welding to the battery
The balancing terminals are located on the left and the right side of the battery pack
Finished the positive battery terminals as the negative (3 silicone insulation wires 12AWG each attached to 2 layers of 0.2mm x 10mm nickel strips each)
And there you have it
Insulated the both sides of the battery back with a couple of layers of Kapton tape
Managed the balancing leads following the BMS wiring diagram
Trimmed the balancing leads
Soldered the balancing leads
Added programming leads, BMS switch leads and BMS temperature sensors leads
Trimmed and soldered the negative battery terminal leads to the BMS leads
Covered the joint with heat shrink tubes
Connected the balancing leads to the BMS and taped down the BMS in place