Solder fumes are bad for your health, so just build an extractor: strip dad's vacuum cleaner for the big motor; buy an air-conditioner drain hose for two yuan, heat the end evenly with a heat gun and gently slide it over the motor's intake; the newly bought six-yuan Li-ion cell has internal resistance 18, not bad; a burst of gibberish welding, very dashing — AWithZ UF20B plug-in spot welder, the perfect spot weld (screen shows a W318000 reading); finally run a red wire between the cell and the motor, the perfect weld; fire it up and test, looks fine, hold it a bit further away and it can't pull the fumes at all, worse than my little fan. 311 comments: 'for the perfect weld skip straight to 17 seconds if you're in a hurry' (pinned); dad: well thank you very much (he's working late and not home yet); a violent fan pulls fumes so fast (where can you strip a violent fan from); switch lanes (you recommend one and I'll follow); first time seeing a girl into this.