4S2P 21700 Battery Kit - Copper Busbars, Tray & Optional Cells

4S2P 21700 Battery Kit

Build a 4-series, 2-parallel 21700 lithium-ion pack using a purpose-matched tray and precision battery-building materials. Choose the kit only or add one of the listed cell models. A cell-inclusive selection contains 8 cells total.

Choose Your Configuration

• Kit only - no cells: battery-building hardware without cells.
• Cell option: adds 8 cells of the selected model and links those cells directly to Shopify inventory.
• 0.2mm copper + 12 AWG: lighter build option.
• 0.3mm copper + 10 AWG: heavier-conductor option for builders prioritizing lower conductor resistance.

Kit Contents

• Custom lightweight 4S2P tray for 8 21700 cells
• Precision-cut copper busbar set for the selected build option
• Stainless-steel welding circles for copper-to-cell sandwich welding
• Matched power leads for the selected cable option
• Selected cells only when a cell-inclusive option is chosen

This is an unassembled DIY battery-building kit, not a finished battery pack. Spot welding, insulation, BMS/protection selection, balance wiring, pack validation, and final enclosure are the builder's responsibility.

Important Electrical Guidance

Pack capability depends on the selected cells, weld quality, current sharing, conductor geometry, BMS limits, fusing, cooling, and the completed pack design. Manufacturer data-sheet maximum ratings are limits, not automatic recommendations for continuous pack operation. Design with appropriate current and thermal headroom.

Safety Warning

Use only new, matched cells in a properly engineered pack. Insulate all conductive layers, protect against shorts and abrasion, use correctly rated BMS and fusing, verify polarity before welding, and monitor cell voltage and temperature during assembly and testing. Lithium-ion cells can vent, ignite, or cause serious injury if shorted, crushed, punctured, overheated, overcharged, over-discharged, or assembled incorrectly. Intended for experienced battery builders.