The old welder couldn’t stack copper and hand-building was a detour, so he got the Douyin no. 1 seller, the AWithZ U3 Pro (picked up at the Cainiao station, 11000mAh). Unboxing: main unit box, the welding pen looks pretty thick, nickel strip too (check the thickness), the small holes on the cable are for the switch; long-press to power on, the screen shows interval / preheat (milliseconds) and mode auto; the top port is USB output for charging a phone, there is a separate charging port; the M key is the manual weld key (trigger in manual mode). First try in auto mode, set it down and it fired without pressing the switch, ‘gave me a fright, a bit fierce’, went straight through the 0.1 (steel strip), probably the gear wasn’t set right; switched to manual, where it only welds when you press the switch; that last weld was very solid, steel strip 0.05. Gears: 9 coarse gears each with fine steps, 99 gears in all; interval not adjusted. Two light welds of 0.05 copper on a 26650: can’t pull it apart, it already tears, and pulled off it still leaves two welds behind that won’t come off, welded very securely, much better than the old welder, handy and compact and doubles as a power bank; no cells on hand so the test ends there; spending your power-bank money on this is a good deal. 550 comments: the Xiaoqiang capacitor welder stacks 0.15 copper and is more reliable (creator: buy buy buy); why buy another battery welder, still on the detour, capacitor is the way to go (getting ready for a 45A battery next time); don’t mess with NMC, it explodes; for value it’s still Xiaoqiang; AWithZ really is good, well built; microwave-transformer welder was no good so also got an AWithZ 539; going to buy a Glitter 811H; a dual-900W transformer welder is far stronger, battery welders max out at 0.4 and the internal battery fades; with that money buy a Xiaoqiang.