Once you’ve mastered hand-building Li-ion packs you’ll never buy a power bank again — all the old power banks at home can be re-celled! Haha

Lefeng heads home for National Day with gear (multimeter, AWithZ U3, cells bought online, iron, nickel strip) and opens a 10,000mAh power bank at home: 3 of the 5 cells are fakes with no voltage — ‘fake Li-ion cells have a long history’; removes them, keeps 2 good cells, adds new ones in parallel; tape for insulation; U3 set to gear 5 (screen shows 3.2) welding 0.15 nickel-plated stacked with 0.1; a nickel-strip short blisters his hand; assembled, charges a phone, shell glued

Opens with a burnt hand by accident; looking at the delivery-order numbers these days, no more grind — home for National Day, with gear: multimeter, AWithZ spot welder, the ‘fake’ cells bought online (a joke), a small soldering iron, solder wire, the bought cells, nickel strip; also found a power bank at home (3.7V 10,000mAh) and opened it — of the five cells, three are different and not connected together, two are connected; turns out those three are fake Li-ion cells, ‘fake Li-ion cells have such a long history’; measured no voltage on the three, removed them with the iron; red +, black −; the good ones and the new cells go in parallel and back in; nickel-strip leftovers, only this tape at home for insulation. At the key moment out comes the AWithZ spot welder, because it’s small and light — bringing the big welder home would be too heavy and a hassle; screen shows gear 3.2, ‘set it to about 5’; 0.15 nickel-plated steel strip is a lot thicker, a layer of 0.1 stacked on top; welded, + and − soldered with the iron; (BGM) hand straight-up burnt with a blister; power bank assembled, charge the phone as a test before fitting the shell; shell glued on. Comments: the pulse is too long, it’s arcing (so that’s it, thanks); get an internal-resistance tester and match cells, it’ll last longer (coming later); a nickel-strip short did it (stay safe); can it still be saved (isn’t that what you’re doing); put those two in as well (they’ve been around too long, no good).

Outcome

Steps5 steps · click a frame to jump

1. 
   1. Home for National Day with gear; open a 10,000mAh power bank

   Burnt hand; no more grind, going home; gear: multimeter, AWithZ spot welder, (fake) cells bought online, small iron, solder wire, cells, nickel strip; found a power bank at home and opened it.

   00:01 – 00:32
2. 
   2. 3 fake cells with no voltage; removed with the iron; good cells in parallel

   3.7V 10,000mAh; three not connected together, two connected; the three turn out to be fake Li-ion cells, a long history; measured no voltage; removed with the iron; red +, black −; three (good + new) in parallel and back in.

   00:37 – 01:13
3. 
   3. Tape for insulation; AWithZ U3 small and light; gear set to 5 (screen shows 3.2)

   Nickel-strip leftovers, only this tape at home for insulation; at the key moment out comes the AWithZ spot welder, small and light, the big one is too heavy; screen shows gear 3.2, about 5 will do.

   01:18 – 01:52
4. 
   4. 0.15 nickel-plated stacked with 0.1 welded; + and − soldered with the iron

   0.15 nickel-plated steel strip is a lot thicker, a layer of 0.1 stacked on top; welded; + and − soldered on with the iron, OK.

   02:05 – 02:42
5. 
   5. Hand blistered; assembled, phone charging test; shell glued

   Hand straight-up burnt with a blister; power bank assembled; charge the phone before fitting the shell; shell glued on, OK.

   03:13 – 03:41

Bill of materials

Creator’s tips

• Open an old power bank and measure each cell first; fake cells with no voltage go straight in the bin 00:52
• A portable welder is the one to bring home; the big one is too heavy 01:29
• Charge a phone to verify before fitting the shell 03:13

Pitfalls

• A nickel-strip short blistered his hand (comment: the pulse is too long, it’s arcing) 00:01
• Fake cells mixed into the power bank 00:37
• No proper insulation material, just ordinary tape 01:18

Li-ion safety

• A nickel-strip short while spot welding will burn and blister you — stay safe 03:13

Quotes