Wednesday, June 1, 2011


Pulse 1 on this welder is to burn away oil and dirt and pulse two makes the actual weld. I have many guys telling me that they set pulse one much higher to get two welds in one. Unfortunately, that's not how it works. Pulse one will join the two metals lowering the resistance and the energy of pulse two will take the shortest path to the other electrode doing basically nothing. In other words, If a 3ms pulse is enough to adhere the metals being welded and you set pulse one to 3ms and pulse two to 12ms then you will get one weak weld formed by the 3ms pulse and not the 12ms pulse.

To make decent welds with a dual pulse welder you should turn pulse one off and find a voltage and pulse 2 setting that gives you  good solid welds. Leave the welder on the determined  voltage and set both pulse potentiometers to 0, adjust pulse one to a low setting and make a weld. Keep on adjusting pulse one higher until the metals starts to adhere, decrease pulse one potentiometer about 3%. Set pulse two to the determined setting above and you should get really good welds.

The size of your electrodes and cable to your electrodes makes a big difference. A 4 feet long #0 welding cable will give you twice the current than a 4 Feet #8 welding cable. Do not make your cables shorter than 4 feet though.


  1. Hello all,

    Today, I was performing some welds with the welder I've built making use of Fritz's plans. These were performed with opposing electrodes, and a dual pulse of 3ms/35 ms at 13.9 volts delivered into a doubled band of 0.012 inch/0.31 mm tin-plated steel. Beautiful performance. This work was a for a cookie cutter-type stencil, and suggests many other ways of working with this welder. The applications to which I'm able to apply spot welds is limited only by the different probe types I'm able to make. I'll post a few of these over the summer months.

    David Floren

  2. Hmmm, I've got some AWG4 probe cables trimmed to 39 inches (1 metre). Conductor O.D. is 0.254 inches. This is not the recommended 48 inch minimum; are these going to be usable?

  3. That should be fine Ogi with #4 cable. Don't go shorter than 4 Feet when using #0 cable.

  4. Hi Fritz,

    Thanks for the very clear description of how to adjust the welder for best performance.


  5. Hi Fritz,

    Pretty amazing bit of kit you've put together - very well done!!!

    I'm very interested in building this project but I'm curious about the comment "do not make your cables shorter than 4 feet though".

    Can you explain why not? I've seen commercial cell welders with ~12 inch cables...


  6. Batt-man, it is just when you use #0 welding cable. The thicker the cable the lower the resistance. It is just a precaution to keep some resistance in the circuit and protect your welder from an over current. Thinner wire have a higher resistance and can be shorter. Roughly, 4 feet #0 welding cable will have a resistance of 0.001 Ohm + your welders internal resistance +-0.0005. 0.001 + 0.0005 = 0.0015. I = V/R...20V/0.0015 = 13333 Amps

  7. Here is a great image detailing conductive paths relative to weld electrode position:


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