Jidian Research Institute builds a battery for his own Lujun Yihao electric impact wrench (case rated 21V 6000mAh). Lay out the cells (10 purple cells, 5 columns × 2 rows); spot-weld them with the AWithZ H2 welder; place the BMS according to the cell polarity; tin the BMS, attach the leads, tin the wire ends; tin the nickel strips on the cells and solder the matching leads to each; add insulation (green tape); measure the BMS output (multimeter −19.86V); tighten the four case screws and it is done, fit it to the wrench. Comments ask what the welder is called, how much it costs, whether it is a Quanyou pin-type; ‘welding is silky smooth, clean welds’.