Should the battery cable be disconnected when welding a car?

[SerenityLynn]

When welding a car, the battery cable should be disconnected. Here is more relevant information: 1. Hazards: During the welding process, incidents such as battery explosion, wire burnout, and circuit board damage can occur. These are real risks primarily because high currents flow through electrical equipment. A welding machine can operate with currents as high as hundreds of amperes, with no-load voltages reaching up to 70V and working voltages up to 30V. The 12V circuits in a car cannot withstand such high voltages, especially given the extremely high currents involved—short-circuit currents can exceed 100A. Therefore, improper handling during welding can easily lead to the burning out of related electrical equipment. 2. Method for welding without disconnecting power: Place a ground wire near the welding area. This ensures that current only passes through the localized welding area and not through other parts of the car body.

[RoseLee]

Disconnecting the battery when welding is absolutely a good habit. With years of car repair experience, I've seen too many accidents—electrical sparks from welding can flow back into the car's circuits, potentially causing a short circuit. At best, it blows a fuse; at worst, it damages the Electronic Control Unit (ECU), which is expensive. Especially with modern cars having numerous electronic components, a short circuit can cause serious issues. Safety first—disconnecting is actually simple: park and turn off the engine, first disconnect the negative terminal, then wrap it with insulating tape. Don’t forget to reconnect and test the system after welding. This not only prevents accidents but also extends the lifespan of the car's electronic systems. Don’t be lazy—make this precaution a habit.

[LukasLee]

Hey DIYers, always disconnect the battery when welding on your car! Last time I was helping a friend weld his frame, he forgot this step, and sparks flew to the battery, nearly causing a fire. The process is super simple: turn off the engine, wait a few minutes, then use a wrench to loosen the negative terminal, disconnect it, and wrap it up. This prevents electrical interference with the welder, avoids short circuits, and stops the ECU from throwing errors. I also recommend checking the frame's grounding to ensure stable and efficient welding. The whole job is safe and quick—don't let a small oversight turn into a big problem. Just add it to your checklist from today onward.

[DiNaomi]

I learned my lesson from welding cars: that year I forgot to disconnect the battery, and the backflow current during welding fried the ECU, costing over a thousand to fix. A hard lesson indeed—welding high voltage can flow back into the battery system through the ground wire, causing short circuits or damaging sensitive components. Always disconnect and isolate the circuit; just remove the negative terminal 10 seconds before starting. This not only protects the car but also ensures more stable welding, avoiding sparks that could harm your vision. Remember this—double-check before every weld to save money and hassle.

[Axel]

Disconnecting the battery during welding is a necessary precaution. I've researched the reasons: welding current flowing back into the electrical system can cause voltage fluctuations, damaging electronic control modules or triggering false trouble codes. Removing the negative terminal isolates the power source and reduces short-circuit risks. Operationally, disconnect immediately after turning off the engine and ensure the welder has independent grounding. This also prevents interference with radios or other electronic devices. This small step ensures safer operation, and I recommend combining it with regular maintenance to check for wiring harness aging and prevent potential hazards.