Crash after crash flying RC has left him a pile of Panasonic 21700s, and he rebuilds these battle-hardened veterans into 6S2P. These power cells discharge at 40A and heat up and catch fire easily if shorted, so before assembly fish paper goes on both ends of each cell; nickel-plated steel strip links them up before welding: add a piece here, join underneath with this one, join again with this one, the current comes up here, goes down, turns the corner, up and down, weld the bottom on (explaining the series-parallel routing). Multimeter shows 3.5V per cell, 6S is × 6, about 22V, fine; then weld the charging balance leads: red to positive, black to each group’s negative; check each port with the meter, the voltages step up in order, so the charger can balance every cell and fill them together; the full 6S2P 8000mAh is done and goes up for a flight. Comments: link for the welder?; discharge rate (10C); what voltage did you weld at; does vertical vs horizontal layout affect current handling; where to buy “lollipop” cells and what brand; make me a 36V; three aircraft gone for good.