The all-in-one models with the Lipo pouch battery inside won't have enough power to do much more than .10 mm nickel. In addition, the internal battery will deteriorate because it's cheap and you cannot control the storage voltage, After a month, neither of mine could even do the .10 nickel plated steel provided. Junk.
There are a lot of little circuit board welders that run off a car battery, 3S Lipos, or super caps, I've tried these two model. The purple one blew up. The red will also blow up, but I had found youtube video that showed how to add a capacitor to make it reliable. Can't buy that model any more, but I bought a spare and have done thousands of welds with them, Tradeoff is being limited to .15mm nickel. I can do .20 mm, but at those power levels, it's too easy to blow a hole in the cells if I misplace the probes.
Edit: Per Shonan, I0mm x .15mm nickel should handle occasional current up to 10A series current.
I'm sure there are improved models out there, but I build small packs.
I run it on a 3S 12v5AH Turnigy Lipo. It's 70-140C, which says it can do 350A pulses. Then I needed an RC charger, so I bought the AC-B6. After a welding session, I put the battery down to 40% for storage. The battery seller says it's necessary for safety. It's also for longevity. The battery will swell up in a few months if put away with significant charge. The charger is a balance charger, and I have found it useful to connect to up to six cellgroups on an ebike battery to manually balance them.
So a hundred bucks for the two junk integrated welders. Fifty bucks on the circuit board welders. Could have bought a Maletrics or a Kweld when the Kweld was under $200,. Still needed the battery and charger.
What I've built are a few brick batteries with 18650 and 21700 cells, They go into bags on a rear rack. Then I built some 36V and 48V bottle batteries, inside real water bottles, No longer interested in bricks. I'll buy empty Hailong or Dolphin cases with the cell forms, and stuff cells in them. I feel the nickel plated steel you get with these kits is good enough for a 20-25A battery, and it's easier to weld than nickel.
