DIY Arduino Battery Spot Welder Prebuilt Kit V3


VAT exempted according to UStG §19
Delivery Time: available for immediate delivery

Additional costs (e.g. for customs or taxes) may occur when shipping to non-EU countries.

Expected to be back in stock arround October 18, 2017

Please note that the prebuilt kits are currently out of stock. If you order now it is estimated to ship on October 18, 2017.

Available on backorder

SKU: sw-pbkit-v3 Category:


What you get:

  • basically you get what you see on the product pictures
  • A prebuilt kit of the spot welder V3 with all the electronics already soldered to the pcbs.
  • 4 M3 screws with nuts to screw the two pcbs together sturdy if you like. (They also stay together without the screws installed)
  • The Arduino is programmed with the latest version of the spot welder software.
  • All kits are assembled and tested at our shop in germany

Please read the Quick Start Guide before using the Spot Welder !

You can add OPTIONAL:

  • Welding Cables: 2 about 50cm long, high flexible 16mm² welding wires with solid copper welding tips and crimped cable shoes.
  • Foot Switch: to activate the welding pulse manually if you dont want to use the AutoPulse feature.

What you need to finish it:

  • a footswitch with cables (optional)
  • 12V car battery with battery terminals to supply the welding current and power the Spot Welder

There is some easy soldering required to finsih this product (solder one wire to the 12V input pad on the arduino pcb). All pcb files, part list, Arduino code… can be found at my Github page. More detailed information can also be found at the instructables and in the video.

Update 09.2017

Improvements in the V3:

  • Mosfet PCB now with 2oz copper layer and wider traces which connect the high current carrying mosfet legs to the u-shaped aluminum part
  • “AutoPulse” feature, which automatically activates a pulse after a defined delay time when both welding tips touch the nickel strip (thanks to Petr Zverina for the idea)
  • 7 segment display replaced by OLED display
  • potentiometer replaced by rotary encoder
  • Menu system to easy adjust the low battery alarm, AutoPulse delay and short pulse time
  • powered directly by car battery, no more need for extra power supply
  • TVS diode integrated on the mosfet pcb, no external diodes necessary
  • upgraded Mosfets to IRFB7430 (they can handle up to 1000A welding current with no problem)
  • Standby feature: after 5 minutes of inactivity the Spot Welder will go to standby and the foot switch and AutoPulse will be deactivated while in standby.
  • u-shaped aluminum parts is now riveted to the pcb

What is it?

An Arduino Nano based Spot Welder for battery welding

This Spot Welder can be used to weld 18650 batteries. It  uses a 12V car battery as welding current supply. Typically one 40Ah 440A battery delivers enough current to get good welds with 0.15mm nickel strips and even 0.25mm nickel strips. For thicker nickel strips maybe you will need bigger battery or two in paralell.

The Welder generates a double pulse, where the first one is 12% of the time of the second one by default. Pulse time of the main pulse is adjustable by the rotary encoder and displayed on the screen in mS so you can exactly adjust the time. Its adjustable from 1 … 999 mS.


The new menu and OLED display features:

The main screen shows the Pulse Time (adjustable by turning the rotary encoder), the battery voltage, the total welds done and if the AutoPulse feature is activated.

You can enter the menu by “clicking” / “pushing on” the rotary encoder.

  • Auto Pulse: Here you can turn the AutoPulse on or off and set the delay time. The “AutoPulse” feature automatically activates a pulse after a 2 second delay (default) when both welding tips touch the nickel strip. If it is activated you can not use the foot switch to activate a pulse. The main screen will show “AUTO” in the right bottom corner if it is activated and “MANU” if it is deactivated.
  • Btry Alarm: you can set the voltage at which the battery alarm should be triggered (default 11V). If the alarm gets triggered the spot welder will stop working and show a low battery warning until a voltage higher than the set battery alarm is reached. (typically after recharging your battery)
  • Shrt Pulse: you can set the duration of the short pulse in %  (1 …100) . For example if it is set to 10% and the main pulse is set to 20ms the sort pulse will be 2ms. The short pulse will always be at least 1ms no matter what % value is set. So if the  main pulse is 5ms and short pulse is set to 10% it will still be 1ms and not 0.5ms.



Video on how to use it:

(Assembly starts at 0:48)

Additional information

Weight 120 g
Dimensions 75 x 51 x 40 mm


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