You can build a lithium pack at home

6 × 18650 in 3S2P for a 12V pack: waterproof box + holder + 12V BMS + DC charge/discharge port, acrylic sheet for insulation, spot-welded with an AWithZ; tested on a car-projector-headlight flashlight and a DIY drill press, charger LED goes green → red

Ajie shows how to build an 18650 12V pack at home. Parts: a waterproof box, 6 × 18650, a cell holder, a 12V Li-ion BMS, wired 3S2P. During assembly the cells are spot-welded with an AWithZ welder (watermark on screen); when fitting the BMS there must be insulation underneath — a thin acrylic sheet, first held with fiber tape; the BMS wiring diagram is shown on screen (12V Li-ion BMS REV2.0, charge/discharge, for motors / drills, no shorting, 12.6V). Finished: the waterproof box gets a frosted surface and a DC charge/discharge port. Discharge test: first a flashlight built from a car projector headlight, high and low beam both fine; then powering a DIY drill press he built earlier to drill a small board; charging test, LED goes green → red as normal. Comments: internal resistance, where to buy the welder, why a BMS, how big a BMS for 3S10P; the top comment asks whether to start a car with 3S 12.6 or 4S 16.8.

Outcome

Steps7 steps · click a frame to jump

1. 
   1. Parts list: waterproof box, 6 × 18650, holder, 12V BMS

   Build a 12V pack from 18650s; waterproof box, 6 × 18650, cell holder, 12V Li-ion BMS; configuration 3S2P.

   00:00 – 00:26
2. 
   2. Spot-welded assembly (AWithZ)

   Assembly begins; on screen the nickel strip is spot-welded with an AWithZ welder (sped up, no narration).

   00:26 – 00:44
3. 
   3. Insulation under the BMS: acrylic sheet + fiber tape; wiring diagram

   When fitting the BMS there must be insulation underneath — a thin acrylic sheet, first held with fiber tape; BMS wiring diagram: 12V Li-ion BMS REV2.0, charge/discharge, for motors / drills, no shorting, 12.6V; 2P3S.

   00:44 – 01:11
4. 
   4. Finished: frosted waterproof box + DC charge/discharge port

   All done; the top of the waterproof box is frosted and a DC charge/discharge port is added.

   01:21 – 01:35
5. 
   5. Discharge test 1: car-projector-headlight flashlight

   A flashlight built from a car projector headlight; switch on, high and low beam both fine.

   01:36 – 01:55
6. 
   6. Discharge test 2: DIY drill press through a board

   The DIY drill press built earlier, powered from this pack, drills a small wooden board.

   02:00 – 02:22
7. 
   7. Charging test: LED green → red

   Test the charging — the LED goes from green to red, charging normally; if you like it, DIY one at home.

   02:31 – 02:43

Bill of materials

Creator’s tips

• There must be insulation under the BMS (thin acrylic sheet) 00:44
• Add a DC port to the waterproof box — one port for charge and discharge 01:21
• Follow the BMS wiring diagram on screen (2P3S) 00:54

Pitfalls

• Comment: couldn’t follow the BMS wiring, the video goes through it too fast

Li-ion safety

• The BMS is marked “no shorting” 01:08

Quotes