- Apr 7, 2021
With the hundreds of YouTube videos about making a spot welder from old microwave transformers I made one. Months ago I had already cut the secondary off the microwave transformer and threaded one turn of welding cable in its place. And there it sat for months. Last Sunday I wanted to spot weld some 18650’s. Behold, the “Frankenstein 530”. Here are the specs: With 120vac on the primary I get 1.7 vac on the secondary so a step down ratio of 70.59. When I spot weld I only measured the current on the primary which peaks at 7.5 amps. So from the law of conservation of energy, I must be spot welding with 529.4 amps. But then, I never studied law.