DIY Battery Spot Welding Pen | Copper Core 3mm Threaded Tip

DIY Battery Spot Welding Pen with 3mm Copper Core

Take your battery pack builds and DIY electronics projects to the next level with this handheld battery spot welding pen. Engineered for makers, hobbyists, and electronics enthusiasts, this spot welding accessory features a genuine red copper (not brass) core for superior conductivity and minimal heat buildup — even under high current loads. With a threaded tip for secure needle fixing and hydraulically tightened joints throughout, this pen is built to deliver consistent, reliable welds every time.

Made in Mainland China.

Key Features

• Pure Red Copper Construction: Conductivity is 3–5× higher than brass, resulting in far less heat generation during high-current welding passes.
• Threaded Tip Fixing: The spot welding needle is securely locked in place via a threaded tightening mechanism — no slippage mid-weld.
• Hydraulically Tightened Joints: All connections are hydraulically compressed for maximum contact surface area, ensuring safe and stable current flow.
• Compatible with 100mm Welding Needles: Use a standard 100mm refill, or cut it into two sections for flexible tip length options.
• Large Cable Compatibility: Copper tube inner diameter of 8mm accepts cables up to 4 AWG (~7.5mm) — suitable for high-amperage spot welding machines.
• Handheld & Ergonomic: Comfortable grip designed for precise, controlled spot welding on battery strips, nickel strips, and more.

Specifications

• Core Diameter: Approx. 2.3–2.4mm (manually processed; ~8mm length tolerance)
• Copper Tube Inner Diameter: 8mm
• Maximum Cable Gauge: 4 AWG (~7.5mm)
• Welding Needle Length: Compatible with 100mm needles (can be cut into 2 sections)
• Material: Red Copper (high-conductivity)
• High-Concern Chemicals: None
• Package Includes: 1× Spot Welding Pen Set

Installation Tips

When connecting a 4 AWG (~7.5mm) cable, smooth out the wire strands first, then slowly twist them and feed into the copper tube (leave 10–15mm of exposed wire for best contact). It is strongly recommended to use hydraulic pliers to tighten the cable connection — hydraulic compression far outperforms screw-type fixing when dealing with high currents and ensures a full, firm contact between cable and pen body.

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For general electrical safety guidelines when working with high-current tools and equipment, refer to OSHA's Electrical Safety Resources.

Important Notes

• Due to manual processing, please allow a measurement tolerance of 1–3mm.
• Product color may vary slightly from images due to monitor display differences.

Frequently Asked Questions

Q: What type of welding needle is compatible with this DIY spot welding pen?

A: This spot welding pen is compatible with standard 100mm welding needles. You can use a full 100mm needle or cut it into two sections for versatility. The needle core diameter is approximately 2.3–2.4mm with a manually processed tolerance of about 8mm in length.

Q: Why is red copper used instead of brass for the spot welding pen core?

A: Red copper offers 3–5× greater electrical conductivity compared to brass. This means significantly less resistance and heat generation when high current passes through the pen, resulting in cleaner welds and a longer-lasting tool — especially important during intensive battery pack assembly sessions.

Q: What is the maximum cable size I can connect to this spot welding pen?

A: The copper tube has an inner diameter of 8mm and can accept cables up to 4 AWG (approximately 7.5mm in diameter). For best results when inserting a 7.5mm cable, smooth out and twist the strands before feeding them into the copper tube, leaving 10–15mm of wire exposed inside.

Q: Do I need special tools to install the cable into the spot welding pen?

A: Yes — it is strongly recommended to use hydraulic pliers to tighten the cable connection. Hydraulic tightening creates a full-contact, secure joint that screw-type fixing cannot match, especially when large currents are involved. This ensures welding safety and optimal performance.