Fitting a BMS — 4S in the next video

Jidian Yanjiusuo (Electromechanical Lab) shows how to fit a 3S / 4S BMS (this episode 3S, 12V): first spot-weld a bit of nickel on each cell’s + and − with the handheld H2 so they tin easily; on the 3S board B+ goes to pack positive, B2 to the first cell at 4.2V, B1 to the second at 8.4V, B− to pack negative; solder the 4 wires to the board first, then to the cells in order; the multimeter shows the BMS already has output, the 12V pack is done; 4S next episode

Today: how to fit 3S and 4S BMS boards; spot-weld the cells first, again with the AWithZ H2 handheld spot welder; here both positive and negative get a bit of nickel strip welded on so they tin easily. A 3S BMS is used (12V-DGL-BHB V1.0) with B+, B−, B1, B2: B+ goes to the pack positive; B2 to the first cell, 4.2V; B1 to the second cell, 8.4V; B− to the pack negative, that’s it; solder the 4 wires on first; once the board looks like this, the board’s soldering is done; tin the cells; with the tinning done, line it up and solder the four wires in the order just given, soldered; check the BMS with a multimeter and it already has output (about 11.6V), a 12V pack is made. 31 comments: shares (3); does this board charge and discharge through the same port (1); can it work as a motorcycle jump starter; with your tool I could make anything; I have 6 cells in total.

Outcome

Steps6 steps · click a frame to jump

1. 
   1. Intro: fitting 3S / 4S BMS boards; spot weld first with the handheld H2

   Today, how to fit 3S and 4S BMS boards; spot-weld the cells first; still using the AWithZ H2 handheld spot welder.

   00:00 – 00:12
2. 
   2. Weld a bit of nickel on each cell’s + and − so it tins easily

   Spot-weld a short piece of nickel strip onto both the positive and negative so they tin easily.

   00:12 – 00:38
3. 
   3. 3S BMS: B+ to pack positive; B2 first cell 4.2V; B1 second cell 8.4V; B− pack negative

   The 3S board has B+, B−, B1, B2; B+ goes to the pack positive; B2 to the first cell, 4.2V; B1 to the second cell, 8.4V; B− to the pack negative.

   00:38 – 01:02
4. 
   4. Solder the 4 wires to the board first; tin the cells

   Solder the 4 wires on first; once soldered, the board is done; tin the cells.

   01:02 – 01:19
5. 
   5. Line it up and solder the 4 wires to the cells in order

   With the tinning done, line it up and solder the four wires in the order just given; that’s the soldering done.

   01:19 – 01:32
6. 
   6. Check the BMS output on a multimeter, 12V pack done

   Measure the BMS with a multimeter and see it already has output; a 12V pack is made.

   01:32 – 01:41

Bill of materials

Measured on camera

Creator’s tips

• Spot-weld a short piece of nickel on the cell terminal first, then tin it — avoids putting the iron straight on the cell 00:25
• 3S board wiring rule: B+ pack positive, B2 first cell 4.2V, B1 second cell 8.4V, B− pack negative; solder the 4 wires to the board first, then to the cells 00:46
• When wired, confirm output with a multimeter 01:32

Pitfalls

• A comment asks whether the board is common-port — not answered

Li-ion safety

• The B1 / B2 sense wires must not be swapped 00:46

Quotes