13 October 2020

Dark Welder 2: My battery tab spot welder!After the failure of my $16 battery tab spot welder, I saw Kevin Dark’s DIY version.

But it wasn’t exactly what I needed, so I decided to build a modified version.

The Modified Dark Welder, or Dark Welder 2.0, has a foot switch that triggers a precise welding current pulse that is always the same length of time – no matter how long you hold down the button.

And in my new version, the button is now a foot pedal to keep your hands free.

The best part is: IT WORKS!

Off we go:

Stuff mentioned in the video:

Also, don’t miss his nifty 18650-powered DIY electric skateboards!


Click to view larger version:

Dark Welder 2 SchematicParts List (some affiliate links):

That’s all, folks!

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Dark Welder 2: My DIY battery tab spot welder
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4 thoughts on “Dark Welder 2: My DIY battery tab spot welder

  • 5 December 2020 at 23:23

    Hi Scottie.
    Although your design for the spot welder is a slight improvement on Kevins,it falls short in as much as you have not addressed that over time the contacts will get pitted and weld themselves together.the addition of a capacitor and a resistor across the contactor terminals will do much to aliviate the arcing much the same as a condenser was used in a car distributor to help protect the points back in the day.
    also it would be very easy to add a visible or audible device to indicate the fact the contacts were welded
    Hope thats given you something to think about.
    Have a nice day.

  • 31 December 2020 at 06:33


    Thank you to share the modification for the Kevin’s spot welder.
    Is it mandatory to have a 4700uF 63v? I have one on 25v is it enough?
    Thank you in advance for your answer.
    Happy new year.


    • 31 December 2020 at 11:46

      That should be just fine. I just went a bit nuts with the 63V rating – I like to over-design things!

      • 31 December 2020 at 12:56

        Thank you very much for your answer.
        Best regards.



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