#U3 Pro

I was always too scared to touch spot welding — afraid something would blow up. The day my U3 Pro arrived I practiced on scrap nickel strip all afternoon, and today I did it for real. Six salvaged cells, sorted by internal resistance. Tested it with a flashlight after welding: in 38 minutes it charged my phone full twice. Grinning like I'd found money on the street. My wife says I'm acting like a kid. Yep.

7.4V battery for a small fan, two 18650s in series, but after welding it only reads 3.7V. Did I put the nickel strip in the wrong place? I'll add pics tomorrow, just asking first whether this is a common mistake... feeling a bit down.

3D-printed shell + strong magnets + a 2S battery pack, welded with the U3 Pro. The step-by-step tutorial is in the project, print files included. The happiest moment in any DIY build: the last screw goes in and the thing actually works.

18650 in 3S8P, U3 Pro at gear 55, 0.15 nickel-plated strip. I'd watched a dozen-plus tutorials and still didn't dare start. Once I actually did it, it wasn't that scary, and the welds are stronger than I expected. The moment the light came on at the campsite — totally worth it. Thanks to everyone in the comments who taught me.