The "must-have" tool for building off-grid systems and lithium battery pack assembly. Lithium batteries are easily damaged by excessive heat and cannot be welded with solder irons, the only way to assemble them is via a suitable spot welder. The spot welder we have in the shop is large and not suitable for this kind of work.
The best tool should be able to reliably weld pure 0.3mm thick nickel strips which will allow to build high amperage batteries (like 50A+ continuous output) that are required for modern applications like e-bikes, etc. The only model that is well reviewed, affordable and reliably does 0.3mm nickel is kWeld: https://www.keenlab.de/index.php/product-category/kspot-welder-kit/
Ideally, it would be great if we could get a full kit with supercapacitors, but even the basic one (https://gridrewired.com/en-us/products/kweld-spot-welder-kit) would allow doing the job using lithium battery packs.
US reseller could be found here: https://gridrewired.com/en-us/collections/all , but, I think, it could be found cheaper.