There is a new software version 3.3.3 available.


  • fixes the slow progress bar drawing problem on “Auto Pulse” mode that sometimes occured.

It is available on my Github: Arduino Spot Welder V3.3.3 Software

What it does

When you use the Spot Welder in Auto Pulse mode you can set the delay time in the menu of the welder. For example if you set it to 1.5 seconds you can touch the nickel strip with both welding tips and after 1.5 seconds the pulse will be activated.

During this 1.5 seconds the welder will display a progress bar on the screen that acts kind of like a count down until the weld happens. But sometimes this progress bar took way longer than the set 1.5 seconds to finish. This problem seems to be caused by the latest SSD1306 display library.

With the code improvement in V3.3.3 the delay will always be exactley the delay time that was set.

19 thoughts on “New Software Version 3.3.3 available

  1. bob mutch says:

    Just a couple of questions about your spot welder. 1. With the malectric welder the adjustment for different welds is in time (ms). I’m just wondering if there will be a difference in the weld energy used in each weld when your battery is fully charged and when the battery is close to the LVC? or will the setting of 50ms delivery the same energy from the first weld when the battery is fully charged to the last weld when the battery is as discharged as the system allows?

    2. When you change from an approved LiPo battery to an approved SLA battery will the same 50ms deliver the same energy to each weld with the two different batteries?

    • Marc Schoenfleisch says:

      1. If your battery is empty the weld energy will be a bit less with the same pulse time setting compared to a fully charged battery. But with a car battery you can do a few thousdand welds before its empty. I recommend to charge it after every battery build, because thats best for the battery lifetime. And then you only use it in the top 70 – 100 % state of charge and never have to worry about changing the pulse time setting.

      2. When changing the battery you need to adjust the pulse time setting for the new battery. The welder only controlls the time. The Amps depend on the battery used.

      • bob mutch says:

        >>> And then you only use it in the top 70 – 100 % state of charge and never have to worry about changing the pulse time setting.

        Ok so between 60% and 100% SOC on an approved battery there is no noticeable different in weld energy?

      • Frank says:

        My unit is at least 2 yrs old and 99.9% certain I have never upgraded the software, will this latest 3.3.3 version work on older units???

        Also, I recently converted an old auto jump pack to house my welder. The weld leads are original (same length as new) but the attachment points that run from the unit to the battery are longer, is that a problem in any way???

        Thank You!

        • Marc Schoenfleisch says:

          The V3.3.3 software is compatible to all V3 welders.
          You can see what version you have on the backside of the pcb.
          Or when you turn on the wleder it should show you the Version on the Splash Screen.
          If you got an older V2 version, the new software is not compatble.

          The cables from the battery to the welder should not be to long. I would say up to 20cm should be no problem.
          Very long cables could cause bad welding performance or even soltage spikes that could damage the welder.

          • Marc Schoenfleisch says:

            The 20cm is meant for the connection between the welder and the negative battery pole.
            The welding cables are longer (50cm), that is correct.

  2. Rasko says:

    is the 0.5s maximum welding time in software hardware based or just arbitrary selected time? I am thinking about more “garage” use of the spot welding machine for general sheet and stainless sheet use with bigger puck electrode sizes, and I am not sure if this device would be good for this use. On the other hand I like the possibility to set low times for the odd battery or other job. In other words, one size fits all would be preferable to multiple devices.


    • Marc Schoenfleisch says:

      On very long pulse times the mosfets and especiallythe mosftes legs will become to hot and eventually melt.
      I dont think the welder is suitable for the application you have in mind.

  3. Alexander Bittner says:

    I wanted to use a 1.3″ display instead of the little 0.96″.
    But now i see that the 1.3″ has the SH1106 controller instead of SSD1306.
    But the adafruit SSD1306-Driver does not support the SH1106.
    But the U8g2 does support both.
    The problem is, that the whole software of this welder is written for adafruit.
    Is it possible to rewrite the software for U8g2, so we all could use some displays?

  4. Nguyên says:

    I am having a small problem that the + 5V power supply will work normally and the + 12V power supply will warn the battery is low.

    • Marc Schoenfleisch says:

      Whats the voltage it reads when the low battery warning screen appears ?
      You can adjust the low battery warning voltage in the menu. Maybe it is set to high.

  5. Bob Kimsey says:

    Hi, I just wanted to let you know that there are 2 typos in the new version 3.3.3. They are in the comments at the very top at line 11 and don’t affect the program. (You need to have the Ardafruit_GFX library and the Ardafruit_SSD1306 library ), you have added an extra “r” in the name, should be Adafruit GFX and Adafruit SSD1306. I only point this out because you have done an amazing job with this project. I just started looking at it because I an building a spot welder for myself. I was planing to build the control circuitry with hardware, like one shots, monostable multivibrators, and other logic chips, I have tons or that stuff and I hate programing. When I found your build, It look so refined and polished, I built the front end to see how it worked, it’s pretty nice. So I had to tell you of the typos, If you have heard this a thousand times I’m sorry. On a different note, can you answer a question for me. Why did you put the FET driver on the control board and run 8 wires, rather then putting the driver with the FETs on the same board and running 1 control wire to the driver? Thank You for all your hard work, Bob

    • Marc Schoenfleisch says:

      Thanks for pointing ot the typo. I will correct it in the next software release.
      The mosfet driver is on the control board because there was simply no good position for it on the mosfet board.
      In the current V3.3 of the welder the 8 pin header would theoretically not be neccessary. Because all 8 pins are connected together on the mosfet board side.
      It would be enough to have a single pin connection from the controll board to the mosfet board.
      I chose to keep it like this, because this way all V3 version of the control board are compatible with all V3 versions of the mosfet board.
      So there is no possibility for the user to damage the welder for example by using an older control board with a latest version mosfet board.

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