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Due to issues welding the EMS Sigma 60 directly to the cells(requires too much weld energy, so you can’t do a lot of welds in a short time), nickel strips need to be welded to the cells and the sigma 60busbar.[3]
In MSXIV they found that thinner nickel strips were better – 3 criteria were considered: Power loss and heat dissipated, Manufacturability, Safety
Power loss was marginally higher with the thinnest strips(0.1mm vs 0.15 and 0.20mm) but since a low weld energy was needed to be safer and allow lots of welds to be done, the 0.1mm nickel was chosen
Weld projections(basically hole-like impressions) were added to the nickel strips – helps spot welding to be more effective)
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