1. Introduction
The Kerpu Mini Spot Welder is a portable, energy-storage spot welding machine designed for DIY enthusiasts and professionals. It features adjustable power settings and is suitable for welding various battery types and thin metal sheets. This manual provides essential information for safe and effective operation.
2. Safety Information
Please read all safety warnings and instructions carefully before using the device to prevent electric shock, fire, or serious injury.
- Always wear appropriate personal protective equipment, including safety glasses, during operation.
- Ensure the work area is well-ventilated and free from flammable materials.
- Do not operate the spot welder in wet conditions or expose it to rain.
- Keep the device out of reach of children.
- Avoid touching the welding pens or welded materials immediately after welding, as they may be hot.
- The device has built-in over-charge, over-discharge, and over-temperature protection. If overheating occurs, the unique overheating protection device will automatically cut off power.
- Do not attempt to disassemble or modify the device. Refer all servicing to qualified personnel.
3. Package Contents
Verify that all items are present in the package:
- 1 x Kerpu Mini Spot Welder (Model DSH)
- 1 x User Manual
- 1 x 1M Type-C USB Cable
- 1 x Metal File
- 2 x 40CM Spot Welding Pens (integrated with cables)
- 1 x 2M Nickel Sheet

Image: Contents of the Kerpu Mini Spot Welder package, including the main unit, welding pens, charging cable, nickel sheet, and file.

Image: A visual representation of the items included in the package, such as the spot welder, user manual, USB-C cable, metal file, nickel sheet, and welding pens.
4. Product Overview
Familiarize yourself with the components and controls of your Kerpu Mini Spot Welder.

Image: Detailed view of the spot welder showing the spot welding pen interfaces, gear indicator lights (red), power indicator lights (blue), power gear key, on/off key to switch modes, automatic/manual mode indicator light (yellow), manual spot welding key, and Type-C charging port.
- Spot Welding Pen Interface: Connect the welding pens here.
- Gear Indicator Lights (Red): Indicate the current output power gear (1-11 gears).
- Power Indicator Lights (Blue): Show the remaining battery charge (75-100%, 50-75%, 25-50%, 10-25%, <5%).
- Power Gear Key: Press to adjust the welding gear.
- On/Off Key / Mode Switch: Press to switch between automatic and manual modes. Press and hold to turn the device on/off.
- Automatic/Manual Mode Indicator Light (Yellow): Indicates the selected welding mode (right for manual, left for automatic).
- Manual Spot Welding Key: Used to trigger welding in manual mode.
- Type-C Charging Port: For charging the device.
5. Setup
- Charge the Device: Before first use, fully charge the spot welder using the provided Type-C USB cable and a 5V/2A power adapter (not included). It takes approximately 2.5 hours for a full charge. It is recommended to keep the power above 50% during spot welding for optimal performance.

Image: The Kerpu Mini Spot Welder connected to a wall adapter via its Type-C port for charging, illustrating its 5000mAh capacity.
- Connect Welding Pens: Insert the gold-plated connectors of the welding pens into the corresponding interfaces on the top of the spot welder. Ensure a secure connection.
Video: Demonstrates how to connect the welding pens to the Kerpu Mini Spot Welder and prepare for operation.
- Prepare Materials: Ensure the nickel sheet and battery surfaces are clean and flat. Use the provided metal file to lightly abrade the contact points if necessary to ensure good conductivity.
6. Operation
6.1 Power On/Off and Mode Selection
- Power On: Press and hold the On/Off key until the indicator lights illuminate.
- Select Mode: Briefly press the On/Off key to toggle between Automatic Mode (yellow light on left) and Manual Mode (yellow light on right).
Video: Illustrates the power on/off function and how to switch between automatic and manual welding modes on the device.
- Adjust Gear (Output Power): Press the Power Gear key to cycle through the 11 available gears. Higher gears provide more welding power. Start with a lower gear and increase as needed for your material thickness.

Image: Diagram showing the 11 adjustable gears for output power, with corresponding red indicator lights. It also notes the ability to spot weld up to 0.2mm/0.007 inches in nickel-plated sheet.
- Power Off: Press and hold the On/Off key until the indicator lights turn off.
6.2 Welding Procedure
The spot welder is suitable for 18650 and other cylindrical lithium batteries, nickel metal hydride batteries, and cadmium nickel batteries. It can also weld iron, steel, and stainless steel sheets with a thickness less than 0.2 mm (0.007 inch) to other iron, steel, or stainless steel materials.
- Position Materials: Place the nickel strip firmly against the battery terminal or metal sheet where you intend to weld.
- Position Welding Pens: Hold one welding pen firmly on the nickel strip, then bring the second welding pen to the desired spot on the nickel strip, ensuring both tips are in contact with the strip and the underlying material. Apply firm but not excessive pressure.
Video: Demonstrates the effect of spot welding on materials, showing the process of applying the welding pens to create a weld.
- Initiate Weld:
- Automatic Mode: The device will automatically detect contact and initiate a weld after a short delay (0.5 seconds trigger time interval).
- Manual Mode: Press the Manual Spot Welding Key to initiate the weld.
- Inspect Weld: After each weld, visually inspect the joint. A good weld should be strong and secure. If the weld is weak, adjust the gear setting or ensure better contact.
Video: Shows the spot welding process on 0.15mm and 0.2mm thick materials, demonstrating the effectiveness of the welder.
7. Maintenance
- Cleaning: Regularly clean the tips of the welding pens with the provided metal file to remove any residue and ensure optimal conductivity.
- Storage: Store the spot welder in a cool, dry place away from direct sunlight and moisture.
- Battery Care: For long-term storage, ensure the battery is charged to approximately 50-75% to prolong its lifespan.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Weak welds / No weld | Low power setting; Dirty welding tips; Insufficient pressure; Material too thick. | Increase gear setting; Clean welding tips with file; Apply more firm pressure; Ensure material thickness is within specifications (max 0.2mm). |
| Device not turning on | Battery is depleted. | Charge the device fully. |
| Overheating | Continuous use without cooling; High ambient temperature. | Allow the device to cool down. The device has automatic overheating protection. |
9. Specifications
| Brand | Kerpu |
| Model Number | DSH |
| Battery Capacity | 5000mAh (Lithium Polymer) |
| Charging Input | 5V/2A (Type-C) |
| Adjustable Gears | 11 Gears |
| Welding Pen Length | 40cm / 16 inches |
| Max. Welding Thickness | 0.2mm / 0.007 inches (nickel-plated sheet) |
| Weight | 0.5 Kilograms / 1.1 pounds |
| Material | ABS |
10. Warranty and Support
Kerpu is committed to providing high-quality products and excellent customer service. If you encounter any issues or have questions regarding your spot welder, please do not hesitate to contact our expert after-sales team.
- Technical Support: Lifetime technical support is available.
- Availability: Our team is available 24 hours a day, 7 days a week.
- Contact: For assistance, please refer to the contact information provided in your product packaging or on the official Kerpu website. We are dedicated to ensuring a pleasant shopping experience and will assist with replacements or refunds as needed.

Image: Illustration of Kerpu's customer support, highlighting lifetime technical support, 24/7 availability, and regular customer care.


