What you get:
- A prebuilt kit of the spot welder V4 with all the electronics already soldered to the pcbs.
- 2 M3x20 screws with nylon nuts to screw the two pcbs together sturdy if you like. (They also stay together without the screws installed)
- 8 M3x8 screws with M3 nuts to mount the aluminum parts
- about 30cm thin wire to connect 12V to the Spot welder PCB
- 2 pin connector with 25cm cable to connect a foot switch
- 2 M6x10 screws with nuts to mount the welding cable or XT90 adapter
- The Arduino Nano is programmed with the latest version of the spot welder software.
- All kits are assembled and tested at our shop in germany
- you need to order accessories like welding cables, battery terminals etc. extra
Please read the Quick Start Guide before using the Spot Welder !
Minimum Setup to start welding:
- Prebuilt Kit
- Welding Cables: 2 about 50cm long, high flexible 10mm² welding wires with solid copper welding tips and crimped cable shoes.
- Car Battery (recommended 12V 400…600 CCA)
- Battery Terminals
Additional parts that can be added:Ba
- Foot Switch: to activate the welding pulse manually if you dont want to use the AutoPulse feature.
- ANL 300A Fuse: to protect the Spot Welder in case of a failure
- Case Kit
- Battery Extension Cable if a car battery is used to power the welder
- XT90 adapter: if a Lipo battery is used to power the Spot Welder
The new V4 of the prebuilt kit can be finished without soldering required. In case you want to do modifications/improvements to the Spot Welder you can find all pcb files, part list, Arduino code… at my Github page. More detailed information will be avaulable in a video soon.
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. You can use about 400 – 600 A (CCA) size batteries. For best results a 60Ah 600A (CCA) battery is recommended. It 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 (max. 800 CCA)
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 … 100 ms by default. (adjustable up to 500ms in the system menu)
The menu and OLED display features:
In the menu and system menu you can change all imortant settings. See the Quick Start Guide for detailed information.
Improvements in Spot Welder V4:
- buzzer to make audible alarms
- teperature sensor for overheating protection
- additional 470µF capacitor – weld times 100-150 ms possible without reboot problem
- SMD mosfet driver – no more contact problems because directly soldered to the pcb
- SMD mosfets – better contact, therefore less heat generation
- new alu parts – both parts the same and simpler shape – easier to make for DIY people
- stronger mosfet board protection diodes – physically bigger and better heat dissipation
Improvements in V3.3.4 Software:
- weld counter can cow count up to 65535
- add over volatge warning when input voltage is 14.5 V or higher
Improvements in V3.3.2 Software:
- Weld time can be set down to 1ms (before minimum was 3ms)
- Short Pulse (preheat pulse) percentage can be adjusted down to 0% (0% turns the short pulse off)
- on weld times below 3ms the short pulse (preheat pulse) will be automatically disabled
- battery voltage only updates about every 15 seconds now
- low battery message can be canceled by clicking the rotary encoder
Improvements in V3.3 Mosfet Board:
- Much wider traces on the bottom of the pcb for the high current connection to the u-shaped aluminum part
- Mosfet gate resistors directly on the mosfet board, very close to the mosfet gate pins
- All 8 Pins of the female 8 pin header that connects the Arduino and mosfet board are now connected to each other, which eliminates contact problems.
Improvements in the V3.3:
- Arduino software update that improves the AutoPulse feature with a progress bar
Improvements in the V3.2.3:
- Arduino software update, so the weld counter automatically is reset to zero when reaching 9999 welds. This was necessary due to display problems when displaying 10.000 welds.
Improvements in the V3.2.2:
- Arduino software update that removed software reset function. This makes it possible to use the standard Arduino Nano bootloader instead of the optiboot bootloader which makes it much easier for the user to do software updates in the future.
Improvements in the V3.2.1:
- Arduino software update that enables the measurement of pulse voltage and pulse current
Improvements in the V3.2:
- the Arduino Board was updated so it does now come with a terminal block installed to the 12V and GND input pads. This way the prebuilt kits can be finished without soldering.
- the voltage measurement now connects directly to the 12V input pad instead of behind the schottky diode. This guarantuees a more precise voltage measurement.
- the 8 small SMAJ13A-13-F TVS diodes have been removed from the mosfet board. There is now one of these diodes on the Arduino board that protects all mosfet gates at once.
Improvements in the V3.1:
- 4 SMD TVS diodes in parallell on the Mosfet PCB
- with the 4 diodes installed it is possible to use car batteries up to 800CCA
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
Customer Batteries built with the “DIY Arduino Battery Spot Welder”
Videos about the Welder:
English: Click to open Youtube Video (Outside In Un-Boxing & Review & Tutorial & Test) Spanish: Click to open Youtube Video (TeknoTronik)
Luigi (verified owner) –
I bought the welder (one month ago) and am very satisfied.
it is very well assembled except the display that looks a little unstable if it is touched. It’s not a problem because I put it all in a plastic box that holds the welder.
I do not use a car battery but a 300A jump starter (suaoki) that is small and light and everything works smoothly.
Marc Schoenfleisch –
Thank you for the positive feedback. The display problem has been fixed. All prebuilt kits from now on come with the display mounted on 12mm standoffs to the pcb.
Carlo.c (verified owner) –
Hi today i got my kit fast delivery i tested nicely and thats very good i am satisfied.
Bradley Tompkins (verified owner) –
Delivery was fast to the USA, about a week. The welder works wonderfully and its performance has gone beyond my expectations. Thank you for producing such an affordable kit that works so well.
Damien Milk (verified owner) –
My welder arrived in remote West Australia yesterday, and after a small amount of assembly, it was up and running. Straight away it was producing first class welds, solid and reliable. Its easy to use, professionally crafted and more than affordable.
Florian Münter (verified owner) –
I bought the spotwelder a while ago and it works really really good. I spotweldet a battery for my electric mountainbard with 3 layers of nickel stacked on top of each other with no problems. The kit came pre-assembled and the instructions were very clear. Very good product!!
Frank Ortisi –
I just bought this thing about 2-3 wks ago, assembly into the cases were a breeze, very well made kit!
I purchased a used battery locally for just $30 then went on to build my first two battery packs, VERY pleased with the operation and quality of this tab welder! TY!
Joshua R (verified owner) –
I purchased one of the v3.2 kits and it is one of the best items I have owned. I tried other avenues, home built options, the Sunkko setup, etc…. but none compare to the quality and ability of this welder. I am using a 3S Lipo pack rated for 5000mah and 60C with no problem. I have welded up to .25mm nickel plated steel strips easily and it keeps going. If you are looking to get into spot welding, save your time and money and go with this one. Some of the welding boxes seen on Amazon, Alibaba, etc…are okay, but are twice the cost and a fraction of the quality.
The version 3.2.1 looks even better and I am tempted to get a new setup and use my existing as a back-up – it is that good. Make sure you have sufficient battery C or CCA rating, that would be the only issue I have had and it was easily corrected.
Great product, hands down
Amazing product package. Easy to assemble. Weld quality is better than what I received from a Chinese spot welding machine. auto weld is a great option, makes it easy to use. I’m amazed by the amount of careful details and work that has gone into this creation!
Awesome kit 🙂 To save money, bought just the tips, PCBs and welding leads. Parts locally had cost me only 25eu(had to substitute mosfets with cheaper ones, but the same specs). 50euros for 4Ah 75C LiPo, custom case and now I have perfectly good spot welder for cheap . Total cost – less than a 100eu. Tried spotwelding to 1mm stainless sheets and it just did it flawlessly! 🙂 Just leads get very how after 10 or so 1mm welds.
Jason Moore (verified owner) –
Delivered quick to the UK, Easy to put together, far better than those junk Chinese units on Amazon and Ebay. Mine is connected to a 200-500A Car jump starter power bank …..works a treat.
Jan (verified owner) –
I bought this small welder and it is working great. It seams it will weld also thicker strips used in aku for hand tools.
Thank you for great job.
Hugh (verified owner) –
A very nicely built spot welder that works well and is easy to use. Running mine from a LiIon car jump pack with EC5 connectors and it works very well. Much better than the cheap Chinese auto-weld PCBs that you can get.