There is a new software version 3.3.4 available.


  • fix weld counter, it can cow count up to 65535
  • add over volatge warning when input voltage is 14.5 V or higher

It is available on my Github: Arduino Spot Welder V3.3.4 Software

Update Procedure

To upload the software to the Arduino Nano you can use the Software Installation Tutorial for V3.3.2. Its exactley the same procedure for this new V3.3.4

When you update from an older V3 sofware you need to perform a full reset of the welder through the system menu after the update. Otherwise the welder will not work properly.

The improved Weld Counter

In earlier versions the weld counter could “only” count up to 10.000 welds and did then automatically reset to zero. Now it can count up to 65535 before it will automatically reset.

The High Voltage Warning

The welder can handle input voltages up to 14V for safe operation. People sometimes forgot about this and managed to blow up their welders. Because of this a high voltage warnig has been implemented. It will be triggered if the input voltage is above 14.5V .

19 thoughts on “New Software Version 3.3.4 available

  1. BMSir says:

    Hello. 9mOhm resistor, to count amp. Its wire from battery to board + wire from board to welder tips, for both and + resistance aluminum ( all FETs open?). Thanks.
    And if somebody make its by self, founded 1 bug. I’m usuning 4.04 voltage divide, and off sets low, then 0. Its store like 65500 value, and show wrong data. ( I add extra -10 to voltage reading place).

    • Marc Schoenfleisch says:

      The 9 mOhm resistance is meaured from the end of the positive welding cable, through the negative welding cable, through the welder with fets open.
      But the amp rading it shows in the measurement screen is not super accurate since the resistance can change quite a bit depending how good contact the welding tips have to the nickel strip and how far apart they are placed.
      That can end up in the amp reading being about +- 100A off.

  2. steve hole says:

    hi, i am having major issues since last update. i have followed instructions to the letter.
    installed new software. but i keep getting messages saying voltage at 0.1v and then next it will read high voltage at 16.8v. even though i have done a reset and a battery recalibration. what do you suggest to fix this?


    • steve hole says:

      i have just re downloaded 3.3.3 and tried that and im getting the exact same issue? was fine untill i tried updating it. any ideas of the cause?


      • steve hole says:

        another update. i have set all the Adafruit SSD1306 V1.2.9 back to this version, along with the Adafruit GFX V1.5.3. just incase the newer versions where having issues, but made no difference. it apears the issue is with the battery calibration data. its not storing it correctly. i set it at 10v when it was reading 10v from my psu, and it would read 9v, so i upped the psu voltage to 14v and calibrated it to 14v and when restarting it it comes up with 4.1v.
        i cant use this anymore

  3. Roy Ireland says:

    I downloaded the zip file V3.3.4 but the file still needs a password to open it. I need to open the file to access the upgrade, so please let me have the information.

    I have just completed the assembly of the kit you sent me, and it was pretty straight-forward. The only suggestion I have, is that the housing for the boards should have had a place to zip tie the foot peddle switch onto. The cable is relatively long and heavy just to dangle on the two thin wires that go to the circuit board (in my opinion).

    On another matter, since my first writing to you, I have been receiving strange emails from other sources that look like phishing links. I have deleted them all and blocked that sender; however, it is troubling.

  4. BMSir says:

    pData.batteryOffset += (int16_t)measuredVoltage – (int16_t)batteryVoltage;
    if batt vottage > meansured .
    offset <0, and safe to eeprom 65555 or something like this.
    batteryVoltage = (uint8_t)( analogRead( PIN_BATT_V ) * 5.0 * 4.03 * 10.0 /
    1023.0 + pData.batteryOffset );
    will test it if decrease * 4.03 (voltage divider)

  5. Marko says:

    Thank you for the update, Marc!
    FYI, updated Adafruit libraries (SSD1306 2.3.0 and GFX 1.9.0) seem to work perfectly.

      • Zoran says:

        I delete it every time. Whichever version that uplaud behaves the same. does not reset the welding counter and the screen is rotated 180 degrees.I also have a problem with setting the time in ms.

  6. Zoran Trumbetaš says:

    I delete it every time. Whichever version that uplaud behaves the same. does not reset the welding counter and the screen is rotated 180 degrees.I also have a problem with setting the time in ms.

  7. Zoran Trumbetaš says:

    “You need to do a full reset in the sytem menu” .It should be done with an arduino program or something else.

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