I did intensive testing with other metals. My es thread
I did many battery packs with 0.1 copper. It seems to be the best.
I managed to weld 0.2 copper as well but it damages the fets. I didn’t test 0.15 because it was not in stock.
My tests with aluminium were disappointing. Low flux times have no effect and high times make holes. Besides it is extremely difficult to solder. I’d say impossible without aluflux. Aluminium is very cheap yet I couldn’t find sheets at a reasonable price so I lost interest. Copper is the best.
I shared pics and videos in this very thread and the sphere’s.
Take a look if you have some time.
Be careful with the copper. Proper cooling ,glasses and gloves are a must.
Share with us your experience please.