Ever wanted to build custom battery packs for electric bikes, solar power banks, or RC projects but found commercial spot welders too expensive? I've got the perfect solution! In this Instructable, I'll show you how to build a powerful yet affordable battery spot welder from scratch. This isn't just another simple project—it's a professional-grade tool that uses the classic NE555 timer and parallel MOSFETs to deliver precise, controlled welding pulses.