#Content-inspired search

Won't tearing into the board like that get it locked?

An old bank mobile-terminal laptop (card reader, fingerprint) whose battery only showed 4% and would not climb. The creator had turned down re-cell requests before because “brand laptops lock the board when power is cut”, but this battery was already dead, so it was worth a try. Opening the pack: Samsung cells, total voltage looked normal, but per-group readings were 1.790V / 3.395V / 4.11V — left too long, badly unbalanced, scrap. New cells are 2900mAh (original 2600), internal resistance all around 19mΩ; the BMS has current sensing and will limit, so extra capacity would go unused anyway. With the new handheld welder (light) he tried gears 2 through 5 on nickel strip; the whole cell can is negative so no spacer is needed, the positive end gets insulating paper. Along the way: the layout shorts easily, the nickel strip is sharp, and with no jig it is awkward to handle — the three-cell junction was a struggle. Reinstalled, the laptop booted straight up, charge went 6% → 7%, and it did not lock the board after a power-off/on; he cleaned the old glue, checked balance (very consistent), fixed the temperature probe with 704 silicone, and rubber-banded it for a day while the glue cured. Later it showed 0% for an hour (suspected conflict with the BMS); he used the powercfg battery report to read the capacity history. A comment warned that re-celling may still need the battery-management chip (BMS) data reflashed.

Unboxing a ¥100-class mini handheld spot welder: in the box are the welding pen, a charging cable, a sheet of sandpaper and a pack of nickel strip. The body has 11 gears, a manual / auto indicator and a battery indicator; long-press to power on, button to change gear, long-press to switch mode; Type-C charging, arrived fully charged. Tested on an 18650 and a coin cell (which a soldering iron basically can’t solder): gear 8 auto mode, two welds first, then six, pulled and torn and they won’t come off — the strip tears instead; welds on the coin cell are round and solid. Verdict: for the modest volume of home use, worth recommending. In the comments the creator replies the strip thickness it can weld is 0.2; a top comment questions the built-in battery’s lifespan, saying a supercapacitor model would be better.

The creator takes 54 × 5C-discharge 18650 cells (about 16mΩ internal resistance; IR and voltage tested first, any 20mΩ cells swapped out) and loads them into snap-together triple holders for a 3S18P pack, 12.6V full and 36000mAh; fish paper on the positive ends against shorts. Spot-welded with double-layer nickel strip on the high-power AWithZ welder; midway the two pens touched and blew through the strip and one cell, so that cell was pulled and replaced. A 120A balancing BMS goes on, the main + and − are brought out with copper wire wrapped around and flooded with solder from the iron, then wrapped in fish paper and fibre tape. The box gets a bidirectional smart meter (with shunt), a 220V socket, power switch, 90W USB fast-charge module, wireless charging module, a CC/CV buck-boost charging module with 5–30V input (output set to 12.6/12.8V, about 5A, diode in series), a 600W / 1200W-peak pure sine wave inverter, two fans + three 40℃ thermostat switches in parallel (one each on the inverter heatsink, the BMS and the buck-boost module), and finally a carry handle. It can cook rice and run a hot pot, drive power tools, jump-charge an e-bike, and charge straight from any 5–30V charger or solar panel.