LV3
12V portable power station pack, my first build, lit up on the first try
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.
How to build a 12V outdoor-power Li-ion pack from 18650 cellsProjectsLookAgain