Can't fix it, but I'll build it — POV hand-made pack

Blind Tool Repair ep. 37, ‘batteries — can’t repair them but can build them’: a hot-glue gun that won’t heat is a loose wire; a customer asks original or home-made battery — a 15-cell tool pack built on the spot, 3.95V per cell, ¥130; then a stripped screw, worn carbon brushes, a tripped breaker, 607/608 bearings, ¥40 housing; 320k likes

A customer’s hot-glue gun lights up but won’t heat; open it, a wire has come off, stick it back, nothing wrong. Another wants a battery ‘delivered to Hanlin Huafu’ and asks whether to use an original or have me build one — ‘whichever works’; take 15 cells, open the cover, beautiful; measure a single cell at 395 (3.95V); pack assembled, done, ¥130. Then: a stripped screw inside a drill, apply some tricks (scorching hot; I have a way to fix it, done in the open, no secrets); an angle grinder won’t turn, the carbon brushes are worn, and the breaker tripped again (protecting the motor); another one also brushes and a broken wire, brushes are aftermarket not original; bearings are all gone, housing ¥40, bearings ¥10, swap in 607 and 608 bearings; ¥10 each. 9339 comments: top comment ‘original battery or one I make’ at 240k; ‘original isn’t as good as hand-built’; experienced viewers advise not to stick paper on the cell sides (absorbs water), use PET; someone asks whether the assembled pack can be recharged.

Outcome

Steps6 steps · click a frame to jump

1. 
   1. Hot-glue gun won’t heat: a loose wire

   The light is on for ages but it won’t heat; open it, a wire came off, stick it back, nothing wrong.

   00:01 – 00:20
2. 
   2. ‘Original or shall I build you one’

   Build me a whole battery, deliver to Hanlin Huafu; original or shall I build you one; whichever works; 15 cells.

   00:19 – 00:47
3. 
   3. Build the pack on the spot: open the cover, measure 3.95V, done, ¥130

   Open the cover, beautiful; call the courier; done; measure 395; sorted; 130.

   00:47 – 01:43
4. 
   4. Stripped drill screw: scorching hot, apply the trick, no secrets

   A screw inside is stripped, apply some tricks; scorching hot; most people keep the trick to themselves, I do it in the open; done.

   01:45 – 02:30
5. 
   5. Angle grinder brushes worn, breaker tripped; aftermarket brushes; broken wire

   Brushes worn and the breaker tripped again, it protects the motor; another one also brushes and a broken wire; aftermarket brushes; ten yuan.

   02:31 – 03:15
6. 
   6. Bearings and housing all replaced: housing ¥40, bearings ¥10, 607/608

   Bearings and housing are all gone, in stock; housing 40, bearings 10; grab a 607; the neck bearing is gone too, swap it; grab a 608, also worn out; ten yuan.

   03:17 – 04:42

Bill of materials

Measured on camera

Creator’s tips

• Worn brushes often come with a tripped breaker; it is protecting the motor 02:31
• Comment: don’t stick absorbent paper on the cell sides, use PET or nothing

Pitfalls

• The hot-glue gun not heating was just a loose wire 00:19
• A stripped screw needs a ‘trick’ 01:45

Li-ion safety

• Disassembled parts are scorching hot 02:03

Quotes

Cost & time