This lesson is all detail for beginners — the chapter of the hand-built Li-ion course that keeps you from getting blown up, bro! Old hands, now it’s your turn to roast me

Lefeng’s 20S Jiashikai 32140 (6045) big pack, ‘don’t get blown up’ chapter: mark the series positions after the fish paper; punch the 0.2×50 copper strip, thread the wire, solder, then seal with glue; the 1–20 link order and its flip-side match; P60F at gear 587 (of 999), copper strip under, nickel strip on top; repeated warnings that a wrong link on the other face is a short that blows you up — have respect; continuous welding makes the pen hot, 11 pieces done then off to deliver orders

A detail lesson for beginners. After the fish paper is on, always write the series-group number at each position, so the connection order lines up. Mark and cut the 0.2 copper strip (it’s quite heavy), punch holes in it: when soldering, twist the wire into the hole first, then add just a touch of solder, then seal with a dab of glue. Connection logic: on the first face join 1 to 2, 3 to 4, 5 to 6… up to 10; on the underside the matching positions are 4–5, 5–6, 6–7, 7–8, 8–9, 9–10; group 10 gets a long strip across to the far side; flip over and do 11–20 the same way. Someone said laying that piece on top is dangerous — it isn’t dangerous right now because the underside isn’t connected yet; once the underside is connected, laying it like that will spark. Join it cluster by cluster: finish this side, flip, then join the matching face — never connect the wrong ones, a wrong connection is a short that blows you up, bro. Settings: AWithZ P60F, gear 587, settled after a lot of trial runs; it tests your technique: copper strip underneath, nickel strip stacked on top, then weld; trim the surplus corners. When you flip, the two cells joined underneath on this side must not be joined again on top, or it shorts; group 20 is effectively the main positive; laying four like this is fine, laying six like that shorts; you must have respect for it — getting blown up is truly terrifying, no joke. Partway through, lift the strip now and then to check the welds are solid — the gear has been tuned countless times but still check. Continuous welding makes the pen hot; 4 pieces on that side, 8 on this side, then 3 more — 11 pieces — off to the evening rush to deliver orders, more when there’s time. Comments: is it Jiashikai 32140 (Jiashikai); copper strip 0.2×40? (0.2×50); can the UF20B stack 0.2 copper (no; with a nickel base it can stack 0.1–0.15 copper); building a 6045? (yes); which gear? (P60F has 999 gears, I use around 600); everyone says AWithZ is junk, is it true; when will you upgrade to laser welding.

Outcome

Steps8 steps · click a frame to jump

1. 
   1. Mark the series positions after the fish paper

   Laying it like this will spark (teaser); after the fish paper is on, write the series-group number at each position so the connection order lines up.

   00:01 – 00:14
2. 
   2. Cut and punch the 0.2 copper strip, thread the wire, a touch of solder, seal with glue

   Mark and cut the 0.2 copper strip, it’s quite heavy; punch holes, and when soldering twist the wire into the hole first, then just a touch of solder; then seal with a dab of glue; quirky ideas.

   00:15 – 00:42
3. 
   3. Link order: 1–2 / 3–4… to 10, long strip across, flip for 11–20

   On the first face join 1 to 2, 3 to 4, 5 to 6; underneath the matches are 4–5, 5–6… 9–10; group 10 gets a long strip across to the far side; flip and do 11, 12… the same way.

   00:42 – 01:54
4. 
   4. Why laying the piece isn’t dangerous yet — underside not linked; do this face first

   Someone said laying that piece on top is dangerous; not dangerous now because the underside isn’t linked; once it is, laying it there sparks; main idea: link 1–2… 20 on this face first, then the unlinked ones on the next face; ready to weld.

   01:59 – 02:40
5. 
   5. P60F at gear 587; copper strip under, nickel strip on top

   Settings: AWithZ P60F at gear 587, settled after a lot of trial runs; it tests your technique; copper strip underneath, nickel strip stacked on top, start welding; trim the surplus corners.

   02:44 – 03:12
6. 
   6. Flip-side links: never get the matching face wrong; the two joined underneath must not be joined again on top

   Join cluster by cluster, finish this side, flip and join the matching face; a wrong link is a short that blows you up, bro; after flipping, look closely — the two cells joined underneath on this side must not be joined on top, or it shorts; group 20 is effectively the main positive.

   04:04 – 05:02
7. 
   7. Placement demo: fine here, sparks there; four is OK, six shorts; have respect

   Positions don’t change after the flip; laying it like this sparks — scary — because the two underneath are already joined; laying it like this is fine; four like this, add more and six shorts; you must have respect, getting blown up is truly terrifying; weld top and bottom faces.

   05:04 – 06:11
8. 
   8. Check the welds partway; hot pen; 11 pieces then off to deliver

   See what’s different about this cluster; lift now and then while welding to check the welds are solid — even with the gear tuned, check partway; continuous welding makes the pen very hot; 4 + 8 (3) pieces, 11 in total; evening rush deliveries, more when there’s time.

   06:12 – 07:14

Bill of materials

Creator’s tips

• After the fish paper, mark the series positions to avoid wrong links 00:01
• Punch the copper strip, thread the wire, then a touch of solder and seal with glue — saves solder and holds well 00:15
• Finish one whole face before flipping; when you flip, note the two cells already joined underneath and never join the same two on top 04:04
• For stacked welds, copper strip underneath and nickel strip on top 02:57
• Even with the gear tuned, lift and check the welds partway 06:26
• Continuous spot welding makes the pen hot — work in batches 06:41

Pitfalls

• On a 20S big pack a wrongly placed strip = instant short that blows you up (demonstrated repeatedly) 05:04
• Continuous welding makes the pen hot; only 11 pieces per session 06:41
• Comment: the UF20B can’t stack 0.2 copper

Li-ion safety

• Before welding a high-series pack, be clear on what is already connected; confirm a nickel / copper strip won’t bridge anything before laying it down, or it shorts, sparks and blows up; have respect for it 02:11

Quotes

Cost & time