Building a battery pack for an electric impact wrench
Creator’s own settings as stated in the video (timestamps link to the moment). Not official values — test on scrap first.
Bill of materials
Welder, accessories, consumables and parts used in this build; quantities and specs are editable Download BOMDescription
A battery pack for a Lujun Yihao electric impact wrench (case rated 21V 6000mAh): lay out 10 purple cells, spot-weld on an AWithZ H2, place the BMS by cell polarity, tin and wire it, tin the nickel strips and solder the matching leads, insulate, measure 19.86V at the BMS output, four screws to close the case
Jidian Research Institute builds a battery for his own Lujun Yihao electric impact wrench (case rated 21V 6000mAh). Lay out the cells (10 purple cells, 5 columns × 2 rows); spot-weld them with the AWithZ H2 welder; place the BMS according to the cell polarity; tin the BMS, attach the leads, tin the wire ends; tin the nickel strips on the cells and solder the matching leads to each; add insulation (green tape); measure the BMS output (multimeter −19.86V); tighten the four case screws and it is done, fit it to the wrench. Comments ask what the welder is called, how much it costs, whether it is a Quanyou pin-type; ‘welding is silky smooth, clean welds’.
Outcome
| Goal | Build a battery pack for an electric impact wrench |
| Build | 10 cells 5S2P + BMS + Lujun Yihao case |
| Result | 19.86V output, case closed · verified on camera: 93–107s multimeter 19.86V, case closed and fitted to the tool |
Steps5 steps · click a frame to jump
1. Lay out the cells (case rated 21V 6000mAh)Building a battery for the Lujun Yihao impact wrench; lay out the cells (purple cells, 5 × 2).
00:00 – 00:17
2. Spot-weld on the AWithZ H2Spot-weld the cells with the AWithZ H2 welder, nickel strip on both faces.
00:17 – 00:42
3. Place the BMS by cell polarityLook at the cell polarity to position the BMS.
00:42 – 00:57
4. Tin the BMS and attach leads; tin the nickel strips and solder leadsTin the BMS, attach the leads, tin the wire ends; tin the nickel strips on the cells and solder the matching leads to each.
00:57 – 01:20
5. Insulate; measure 19.86V output; four screws to close the caseAdd insulation (green tape); measure the BMS output at 19.86V; tighten the four case screws and it is done.
01:20 – 01:47
Bill of materials
| Purple-wrapped cells ×10 | 5S2P |
| Lujun Yihao battery case ×1 | Rated 21V 6000mAh · Case |
| AWithZ H2 ×1 | Spot welding |
| BMS ×1 | 5S · Protection |
| Soldering iron / solder | Wiring |
| Multimeter ×1 | Measure the output |
Measured on camera
| BMS output voltage | 19.86 V 01:40 |
Creator’s tips
- Position the BMS by the cell polarity; tin the nickel strips before soldering the leads 00:42
- Measure the BMS output before closing the case 01:33
