Arduino Spot Welder FAQ

Recommended is at least a 12V 400A (CCA) car battery. The 600A (CCA) car battery size turned out to be the optimal power to weld all kinds of nickel strip. I do not recommend to use a so called “deep cycle” battery. They look like a car battery but these are not made to deliver very high currents for a short time. They are meant to deliver little current like 20A to 50A for some hours. They are maybe capable of delivering the high welding current, but could be damaged after some welds.

The Spot Welder works with 3s Lipos only. 4s or more cell lipos have a to high voltage for the welder. It does need 400A current at least to do good welds. The maximum current should not exceed 800A. You can calculate the maximum current your Lipo can deliver by muliplying the C rate with the capacity. For example: 5Ah (5000mAh) x 130C = 650A (650000mA) maximum theoretical current.

The following Lipos have been tested and approved to work good with the spot welder:

Turnigy Nano-Tech 5000mAh 3s 65-130C or

SLS Quantum 5000mAh 3S1P 11,1V 65C/130C

You should use 0.1mm to 0.25mm nickel strips. Typically 0.15mm nickel strip is good for all standard applications.

0.3mm nickel strip is possible if the pulse time is increased to about 50ms (this time was set with a 440 A or CCA car battery). Also try to use slotted nickel strips if you want to use 0.3mm ones because the slotted ones give you better welding spots with less current or shorter pulse time.

The PulseTime highly depends on how strong your welding battery (car battery or lipo) is and what welding cables you use. Here are some PulseTimes as a basic orientation used with a 400CCA 12V car battery and the welding cable set from the shop.

  • 0.15mm nickel strip: 20ms
  • 0.2mm nickel strip: 26ms
  • 0.25mm nickel strip: 35ms

You can use any switch that is NO (normally open). The foot switch does not carry any current, so even very tiny switches will work. (Example foot switch) . Do not wrap the foot switch wire arround a welding cable and try to make a hand switch. This can damage the Spot Welder because of inductive voltage.

Make the cables as short as possible. I recommend 10mm² (7awg) or 16mm2 (5awg) 0.5m for each cable. If you make the cables longer the welding pulse will become weaker unless you use thicker cable. Also it is more likely that you damage the Spot Welder with very long cables because of the high inductive voltage that is generated in longer cables.

The V3 does not need a seperate power supply for welding times below 50ms. It can be directly connected to the car batteries or Lipos positive pole. For the older V2 a 12V 2A or 1A power supply works good. Alternatively a 3s Lipo / Liion battery also works perfectly.

Yes in the new V3 you can directly power it from the car battery or Lipo for welding times below 50ms. For V2 or older in the standard configuration you need a seperate power supply or battery.

But if you add a 470µF 25V capacitor between the Arduinos Vin and GND you can power the V2 and older Arduino Board from the car battery. More infos on the Mod

No, you need a car battery or Lipo. A pc power supply can not give you enough Amps to weld. You need at least 400A. Typicall power supplys can deliver maximum 50A. Also power supplys usually dont like to be shorted, which is what the welder does.

A customer used a capacitor bank and made a pretty detailed article on it.
His construction may be a bit overkill, but this article gives a good overview how it can be done.

Yes, some jump starters may work with the spot welder. I made a blog post about this topic. Please read it to find out what jump starters you can use.

When you connect the Arduino Nano to your computer with an USB cable it should automatically install the drivers for the Arduino Nano.

If it does not, you need to install the driver for the USB chip manually. CH340 Windows DriverCH340 Mac DriverCH340 Linux Driver