Beginner’s money-saving guide to hand-building lithium packs

Shougong Wang’s money-saving guide for beginners: of the three-piece kit only the welder is a must, skip the internal-resistance meter and load tester for now — buy cells straight from official brand channels like EVE and there is basically no need to test them; buy the most expensive welder your budget allows and go for a big brand (this is his third); recommends the U3 Pro’s semi-auto weld button (position first, then press, so beginners don’t weld crooked and ruin a cell) and its repeat-pulse mode (up to 3 welds on the same spot, for copper); nameplate 4.2V / 11000mAh, pure nickel 0.2, nickel-plated steel / iron 0.35, copper 0.1; consumables are glass-fiber tape / heat-shrink film / fish paper; everything on a cell except the positive is negative, fish paper on the positive is a must

Sharing money-saving experience from hand-building lithium packs so beginners spend as little as possible. The three-piece kit: the welder is essential, the internal-resistance meter is optional, the load tester is optional — a beginner only needs a welder, skip the other two for now; early on, only build small packs and order straight from the cell brand’s official channels (EVE official site / Tmall / Alibaba; the page shows 18650 3.6V 3200mAh / 2850mAh etc.), which basically needs no testing — with a welder you can build right away; think about instruments later when going to big capacity. Key point — which welder suits a beginner: buy the most expensive one you can accept within your budget, and go for a big brand as far as possible; this is the third welder I’ve bought (AWithZ); one feature is very beginner-friendly: the pen sits on the cell for ages and nothing happens, because the manual weld button hasn’t been pressed — press it and it welds instantly, the semi-auto mode; beginners often mis-place the spot or set the nickel tab crooked, and if the pen welds the moment it touches, the cell is ruined, so a semi-auto button is best to have; there is also a repeat-pulse mode that welds the same spot repeatedly, suited to copper sheet that needs more power — hold the pen steady and it fires up to 3 welds in quick succession. Mine is the AWithZ U3 Pro: pure nickel 0.2mm MAX, and it also does steel and copper sheet (copper 0.1 MAX; nickel-plated / steel / iron 0.35 MAX); nameplate U3 battery spot welder, 4.2V MAX, Type-C 5V/2.1A, USB 5V/2.4A, 11000mAh 40.7Wh, Juequi Technology; plenty for a beginner. Consumables: glass-fiber tape, heat-shrink film, fish paper. A special note on cells: this is the positive, this side is negative — many people don’t know the whole can is negative; open one up and everything except the positive is negative, so positive insulation is critical, always use positive fish paper. Non-essential accessories aren’t covered; get the three-piece kit straight and you save a lot. Comments: asking for the EVE official link (search results are all ads) (2); lend me the welder for two spots nearby; can UV glue join them; what battery for a 24-set net-hauling boat; a mis-weld ruins the cell? can’t you pull it off and re-weld?

Outcome

Steps6 steps · click a frame to jump

1. 
   1. Three-piece kit: only the welder is a must; official-channel cells need no testing

   The welder is essential, the internal-resistance meter and load tester are optional, skip them for now; early on, order small-pack cells straight from the brand’s official channels (EVE site / Tmall / Alibaba) and there is basically no need to test; with a welder you can build; buy instruments when going to big capacity.

   00:01 – 00:37
2. 
   2. Choosing a welder: the priciest within budget, big brand; this is the third

   Which welder suits a beginner: the most expensive one you can accept within your budget, big brand as far as possible; this is the third welder I’ve bought (AWithZ).

   00:37 – 00:51
3. 
   3. Semi-auto weld button: position first, then press, so beginners don’t weld crooked and ruin a cell

   The pen sits there for ages and nothing happens because the manual weld button wasn’t pressed; press it and it welds instantly — semi-auto mode; beginners mis-place the spot or set the tab crooked, and if it welds on contact the cell is ruined, so a semi-auto button is best.

   00:51 – 01:18
4. 
   4. Repeat-pulse mode: up to 3 welds on the same spot, for copper; U3 Pro capability label

   Repeat-pulse mode welds the same spot repeatedly, suited to copper sheet that needs more power — hold the pen steady and it fires up to 3 welds in a row; the U3 Pro does pure nickel 0.2 MAX and also steel and copper sheet (copper 0.1 MAX).

   01:19 – 01:38
5. 
   5. Nameplate: U3 4.2V, Type-C 5V/2.1A, USB 5V/2.4A, 11000mAh; three consumables

   Nameplate U3 battery spot welder, 4.2V MAX, Type-C 5V/2.1A, USB 5V/2.4A, 11000mAh 40.7Wh, Juequi Technology; plenty for a beginner; consumables are glass-fiber tape, heat-shrink film, fish paper.

   01:38 – 01:51
6. 
   6. Everything on a cell except the positive is negative — fish paper on the positive is a must; wrap-up

   This is the positive, that side is negative; many people don’t know the whole can is negative; open one and everything except the positive is negative, so positive insulation is critical — always use positive fish paper; non-essential accessories not covered; get the three-piece kit straight and you save a lot.

   01:44 – 02:17

Bill of materials

Creator’s tips

• Beginners buy only a welder; cells from the brand’s official channel can skip internal-resistance / load testing 00:15
• Buy the priciest welder within budget, from a big brand 00:43
• Semi-auto button: position first, then press, so a crooked placement isn’t welded and ruined 00:57
• Repeat-pulse mode for copper and other materials that need more power 01:11
• The whole cell can is negative; fish paper on the positive is a must 01:51

Pitfalls

• In fully automatic mode a beginner’s crooked placement welds on contact and the cell is scrap 01:11
• Comment: searching for the EVE official site mostly turns up ad sites

Li-ion safety

• Insulation between the positive and the can (negative) is critical 01:51

Quotes