Spot Welder Software Update 3.2.1

The Version 3.2.1 Update introduces a weld pulse measurement feature.

This feature allows the Spot Welder to measure the voltage drop across the two welding cables and the Spot Welder itself. From that value it then calculates the Amps. If you are connecting the Spot Welder directly too the car battery and dont use the fuse on the positive welding cable side, the measured voltage will be exactley your car batteries voltage during the pulse.

How to activate this feature:

Please note this feature only works with V3.2 or later Spot Welders.

First you need to update the Arduino Nano on your Spot Welder with the new V3.2.1 Software. The Software can be found on my Github.    How to do a Software update can be found here

You need to follow almost all the steps in the software update tutorial for V3. Instead of V3 use the V3.2.1 Software. Just the Bootloader on the Arduino Nano does not need to be updated because it already has the Optiboot Bootloader on it if you purchased a V3.2 Kit.

Make sure you set the processor in the Arduino IDE to “ATmega328P OptiBoot” instead of “ATmega328P” . (See Step 1 and Step 4 of the “Updating the Arduino Nano Bootloader” Chapter in the Software Update tutorial) Steps 2 and 3 are not relevant for updating existing V3.2 Spot Welders.

Then it is pretty simple to use. The measurement will be displayed if you hold down the foot switch for more than 2 seconds after a pulse or if you leave the welding tips on the nickel strip for more than 2 seconds after a pulse. Too leave the measurement screen simply push the rotary encoder button.

Details and Tips

The Amp calculation works with a fixed system resistance value of 9mOhm because it is not possible for the Spot Welder to measure the resistance. This means that the Amp calculation will only be accurate if you are using the original welding cables and place the tips on the nickel strip about 1 cm apart.

If you put the welding tips very far apart, the real system resistance will be way higher than 9mOhm and the Spot Welder will calculate to high Amps.

Also make sure when using the Fuse that you connect the 12V power cable that goes to the Spot Welder to the welding cable side of the fuse. Connecting it to the other side or even directly to the car battery will change the voltage drop the Spot Welder measures and therefore create wrong Amp calculation results.

 

Hacking V3.1 or older Spot Welders to make the pulse measurement work

The pulse measurement only works on V3.2 or newer welders. There was a little change in the V3.2 pcb layout that connects the input voltage from the 12V input pad directly to the voltage measurement circuit on the pcb. In V3.1 or older the voltage was taken from behind the schottky diode. This voltage does not drop during the weld pulse because the shottky diode prevents this.

To enable the pulse measurement you need to do a little modificaton to the pcb.

First cut the pcb trace marked in red on the picture.

Next take a piece of thin wire and connect the 12V input pad to the left pad of R12.

 

23 thoughts on “Spot Welder Software Update 3.2.1”

  1. Hello Marc, last month i received my spotwelder kit and its working perfectly, now my question is can i symply upload the new sketch and then its finished or do i need to follow the complete procedure described as in the software update tutorial

    1. Hi,
      Yes you need to follow almost all the steps in the software update tutorial.
      Just the Bootloader on the Arduino Nano does not need to be updated because it already has the Optiboot Bootloader on it if you purchased a V3.2 Kit.

      Make sure you set the processor in the Arduino IDE to “ATmega328P OptiBoot” instead of “ATmega328P” . (See Step 1 and Step 4 of the “Updating the Arduino Nano Bootloader” Chapter in the Software Update tutorial)
      Steps 2 and 3 are not relevant for updating existing V3.2 Spot Welders.

  2. Marc, I bought a new Arduino Nano board. Is it possible to programm this new board with the version 3.2.1 software and simply replace it with the arduino nano on the spot welder.
    In this case i have the latest version and the version just before i can take.

  3. I really sorry but i just can’t seam to follow this direction you have posted, I have had no problems with any of your old software but this one with the the bootloader and trying to configure the SSD1306 is just impossible and the Optiboot does not show up in the Arduino Processor: “ATmega328P Optiboot”, I have loaded 1.6.12 and tried to find this with no luck

    1. If you cant get the Optiboot Bootloader working you can also use the “standard” Arduino Nano Bootloader. (Choose “ATmega328P” as the processor) Only difference is that the automatic reboot from the system menu will not work.

      1. I will need to do some reading on the programing and editing of the library files and will give this another try. My programing is not great at all but I will learn it one way or the other.

      2. I got the V3.0 working on its software.
        I also have the Optiboot working
        But now I keep getting this fault when trying to load the new software V3,2,1: Arduino: 1.6.12 (Windows 7), Board: “Arduino Nano, ATmega328P OptiBoot”
        C:\Users\VE3VXY3\AppData\Local\Temp\arduino_modified_sketch_777549\Arduino_Spot_Welder_V3.2.1.ino:111:20: fatal error: printf.h: No such file or directory
        #include “printf.h”

        ^
        compilation terminated.
        exit status 1
        Error compiling for board Arduino Nano.

        This report would have more information with
        “Show verbose output during compilation”
        option enabled in File -> Preferences.

        1. There is no difference in uploading the Software V3.1 or V3.2 or V3.2.1 . Did you follow the update tutorial ? https://malectrics.eu/2017/12/13/arduino-spot-welder-software-update-tutorial/
          Are you getting the same error on all 3 versions or just on the latest 3.2.1 ?
          If you unzip the downloaded software from Github there should be a printf.h file in the folder.
          Also you could try the latest Arduino IDE. Maybe there is a problem in your version.
          I am currently using Version 1.8.5

          1. I switched to 1.8.5 and everything worked great, I now have the 3.2.1 preloaded and the other 3.1 and 3.2 work great

  4. hello Marc,
    i just updated my arduino with the new software 3.2.1 and it is working fine.
    What i am wondering is that on my system the measuredVoltage/ Amps are about 12,3 V 1440 Amps. (and calculated that 12,3/9mOhm gives 1366 amps – so is my battery to strong??)
    I am using 2 parallel 12V 12AH batteries and a pulse of 5 ms.
    i already welded a block of Cells 7×7 for a 24v Volt system and am happy so far with it:-)))
    Thanks of all the work you have done great job!!!!

    1. Hi Franz,
      I looked up your order and i think you are using a V3.1 Spot Welder, right ? The pulse measurement only works on V3.2 or newer Welders. I added a mini tutorial to this blog post how to modify older welders to enable the feature.

  5. Hi MArc,
    I have done the modification and now it shows depending on the number of parallel 12V batteries – each one has 12AH – from 3,2 up to 4.5 Volts and according to this the estimated AMPS.
    Great work, thanks for all!

    1. If you put everything you need to the shopping cart it will automatically calculate the shipping cost and total.

  6. Hi Marc,
    I own your newest version 3.2.1
    It works great , but have you ever been thinking of making a pen electrode holder for just one hand?
    Perhaps you like the thought

    Best regards
    Richard

  7. Hello Marc
    I own the version 3.2.1 and my pulse voltage is only 4.6 v and current is 526amps
    Is this normal that the voltage is so low, i am on 12 ms pulse time
    Ihave a sls lipo 3s 5100 mah 140c capable.
    Thanks marc
    Richard

    1. Hey Richard,
      This looks pretty normal. 140C at 5000mAh (5Ah) would be 700A maximum current.
      So the 526A is ok. The voltage of the Lipo/car battery has to drop so far because of current = voltage / resistance
      Also please note that the current measurement of the Spot Welder is not super accurate. Real current can be about +-50A different.

      1. Ah yes 0,009ohm or so
        Do you think the pulse current could be more with a better battery.
        This is the best i have, i have test all my batteries.
        800 amps or so is my goal.

        Richard.

  8. Hy Marc
    I have your version3.2.1 and my pulse voltage only has 4.6 v and 526 amps with an sls lipo 3s 5100 mah 140 c capable,
    Is the voltage drop normal ?
    Thanks marc
    Richard

  9. Thanks marc
    Ah yes you said its about 9 ohm or sou
    Is it possible to reach more amps than the 526 ones.
    I have no stronger battery.
    Richard.

  10. Hello Marc
    Do you think there is a battery strong enough for 800 amps or so
    Or is this too much for the batteries negative pole

    1. Why would you want that much current ?
      If you put two 4000mAh 3s 130C packs in parallel you could get close to the 800A.
      But that is then pretty close to killing the spot welder. I only tested it with a 800CCA car battery maximum.

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