Battery powered MIG welder

Portable Trail Welder (Karnage-Style)

Trail welders are notoriously difficult to source in Europe. This project allows you to build a high-performance, battery-powered welder comparable to the US-made Karnage system. Powered by two 12V/22Ah batteries, it supports both Flux-Core and MIG (with shielding gas) welding.

The design features a "cold tip" (the wire is not live until the trigger is pulled) and full polarity control (DCEN or DCEP).

Key Features

• Dual Mode: Supports Flux-Core (gasless) and MIG (gas-shielded via air quick-connect).

• Flexible Power: Internal batteries or external power via Anderson 120 connector.

• Smart Charging: Integrated cigarette lighter socket for charging or 12V output.

• Safety First: Uses heavy-duty TE EV200 contactors to handle high-current switching safely.

Technical Specifications

• Polarity: Configurable DCEN (Direct Current Electrode Negative) or DCEP.

• Switching: ON-OFF-ON double pole switch for system isolation and mode selection.

• Wire Feed: PWM-controlled motor for precise wire speed adjustment.

⚠ Safety & Disclaimer

High Current Hazard: This project involves high-amperage lead-acid batteries capable of delivering over 300A. Short circuits can lead to explosions, fire, or severe injury.

• Build this ONLY if you have experience with high-current DC electronics.

• Always use appropriate PPE (Welding helmet, gloves, apron).

• Never leave the unit unattended while charging or in use.

• Ensure all high-current connections are torqued correctly and insulated.

Bill of Materials (BOM)

• Hard case internal :430x350x190mm  temu

• Generic MIG wire feeder e.g. aliexpress

• Generic MIG torch e.g. aliexpress

• 2x 12V 500A relais TE EV200 aliexperss

• 12v NC relay e.g. aliexpress

• Shielding gas adapter part 1  aliexpress

• Shielding gas adapter part 2 aliexpress 

• Welding wire spool aliexpress

• Anderson 175 plug aliexpress 

• ON-OFF-ON  double pole switch 16/20A aliexpress

• Dinse plugs and sockets aliexpress 

• Wire speed controller PWM aliexpress 

• 12V cigarettes lighter socket aliexpress

• Battery meter aliexpress

• 16mm^2 welding cable, internal wiring and ground cable

• Tinned Copper Lugs Ring Crimp Terminals several sizes

• 2.5mm^2 wire 

• 0.75mm^2 wire

• Ring Crimp Terminals

• M3 Button head wide head screws or normal head with washer

• M3 heatset inserts long

• 1m M6 threaded rod

• M6 Nuts

• M6 button head screws

• 2x 12V/22ah batteries (Maximum Discharge Current above 300A for 5sec), e.g.  Kung Long 12V 22Ah WP22-12NE

• Automotive fuses 5A/10A

Construction Tips

1. Wiring: Use the 16mm² cable for all paths carrying welding current. Use 2.5mm² for the wire feeder motor and 0.75mm² for signal logic.

2. Heatset Inserts: Ensure you use the "Long" M3 inserts for maximum grip in the printed chassis.

3. Frame: use peaces of M6 threaded rod to connect and adjust to fit the case.