An Arduino Nano based Spot Welder for battery welding

This Spot Welder can be used to weld 18650 batteries. It needs a 7-12V power source (12V recommended) and uses a 12V car battery as welding current supply. Typically one 45Ah battery delivers enough current to get good welds with 0.15mm 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 1/8 of the time of the second one. Pulse time of second pulse is adjustable by the potentiometer and displayed on the screen in mS so you can exactly adjust the time. Its adjustable from 1 ... 20 mS.

Watch the Video to get detailed instructions on how to build it.


Project Files:


Due to many requests for the PCBs

If you guys want to buy a set of pcbs to build your own spot welder please take a look in the comments below this instructable. Some people who ordered boards at PCB manufactures are willing to sell some of them. I don't have any more pcbs left for sale.

Step 1: Making the PCB

You can find the Eagle files for the PCBs on my Github.

Easyest way is to order the boards at an PCB manufacturer. For example at pcbway.com .There you get 10 boards for about 20 €. The necessary gerber files for ordering at pcbway.com can be found in my Github.

You can support me by registering through this link http://www.pcbway.com/setinvite.aspx?inviteid=128...

This way you get a 5$ coupon for your order and i get some credits at the shop which i can use for upcoming projects.

But if you like diy you can also build it on a prototype pcb board with hand wiring. This is how i did the first prototype of the spot welder. In the pictures you see a manufactured board looks much cleaner.

<p>Jeg har noen kort, sender i Norge kr. 100.- for kort display og frakt :-)</p>
<p>do you have one for sale?</p>
ill take it if still for sale
<p>Hi,</p><p>Would you have one or two spare PCBs that would would be willing to sell ?</p><p>Cheers,</p><p>Akira (from Paris)</p>
<p>Akira,</p><p>I have a couple extra boards.</p>
<p>Great project and design.</p><p>If anyone in the UK needs a PCB's I have 8 pairs available, it's a green FirstPCB board and needs scoring/cutting into the two boards. Price is beer + P&amp;P.</p><p>Just drop me a PM is anyone is interested.</p>
Wattshere.<br><br>2 pairs to Danmark?
<p>I think the postage is a bit expensive to Denmark, &pound;8.</p>
Hello. It is OK. Can you send me an email at olesjwv@gmail.com Thanks Ole .
It's ok with me ... What is the total price of the 2 pairs and the postage?
Ok, here is the problem. I have finished the spot welder but it was in a mode of continuous passthrough of the mosfets. I have took out all the mosfets and soldered the new ones but it was still doing the same fault. At last I have considered that maybe the drivers were faulty. Here is the input signal:<br><br>http://hizliresim.com/qE8rlQ<br><br>Only one of the drivers working properly and giving the right output:<br><br>http://hizliresim.com/Mkgry2<br><br>Two of them were giving no output and one of them were in continuous mode:<br><br>http://hizliresim.com/QQY9lG
<p>How many amps would you need if you were to use a wall power supply for the arduino board? Is 1.5a ok? Thanks in advance.</p>
<p>Why is there only one <a href="https://www.reichelt.de/Buchsenleisten/BL-1X20G8-2-54/3/index.html?ACTION=3&LA=20&GROUP=C142&GROUPID=7435&ARTICLE=51827&START=0&SORT=artnr&OFFSET=16" rel="nofollow">BL 1X20G8 2,54</a> in the reichelt shopping list when more are clearly visible in the video? I ordered the reichelt list and am now left without the right number of socket strips :(</p>
<p>The Arduino typically comes with pins and sockets. So you only need one 8 Pin header and socket and 2x 2 pins and sockets for the ground connection (JP1 and JP2) of the two pcbs. </p>
<p>Hi, </p><p>Really need your help to get this things working. There are so many confising things on the instructions. I have rebuilt it twice and still not working. Free flow of current is going trough no matter what I do.</p><p>Few things to note about misleading pictures and video:</p><p>1. The first picture, plus in the video the MOSFETs have 2 of their legs cut off. That is the gate too. For noobs like me, I just followed what I saw and cut those legs, even thought it made no sense at the time. Only to realize at the end that they were only cut because they were reused from another project and had the gate cut before. However it was completely omitted from he video, when and how he did connect the gate to the board.</p><p>2. The JP points. Again missing in any of the videos or pictures. Do I need to connect those (I am guessing, for common ground of the signal).</p><p>3. The 6 pin on top of the Arduino, it is part of the parts list and also I see everyone has it soldered in, but it seems quite useless for this device.</p><p>Anyway all that aside. I am really going nuts here. I don't know what is wrong. The control board seems to work fine, led, timers, etc all doing what they are supposed to.</p><p>The bottom plate is giving constant pass trough of current. I have reorder new board from PCB ways. Used a new set of MOSFETs, but still the same problem.</p><p>Is this thing supposed to be open in the off state? That is if the controller is not connected is it supposed to pass through the current to the probes?</p><p>Any ideas what I should look at? </p><p>I will add pictures if needed.</p><p>Thank you.</p><p>Alex</p><p>PS: I have a few sets of board pairs (8 paris). I am happy to distribute them here in EU. Contact me for details. </p>
<p>Hi @pompecukor, I have the same problem, the bottom plate is giving constant pass through of current. How did you correct this problem?</p>
<p>Just to let everyone know, I am out of pcbs</p>
<p>Hi, do you have one pair still? how much will you ask for sending it to Portugal?</p><p>Thanks</p>
<p>Yes it is still available, I have 6 pairs left. I will send you message with my email. I just posted a set to France, so I know the price of shipping, to anywhere in the EU is about 5 euros (with tracking and priority). Plus you buy me two bottles of beer and a set or two is yours. :) Deal?</p>
<p>Thank you for pointing out the problems. I updated step 3 of the instruction so hopefully its more clear now.</p><p>Ps: the Arduinos i ordered came with the 6 Pin header pre installed. I was just to lazy to unsolder them.</p>
<p>Hi, i made same mistakes :</p><p>- You have to solder the 4 JP points, after that your welder should work</p><p>No matter if the mosfets middle leg is cut or not, because the contact is made on the aluminum bar (look at the schema, in red)</p>
<p>Hi Whitehawk. Yes, I am happy to report that it is working now. It was the JP connects.</p><p>I would call it out mistake, but rather the video guide was misleading. It gave the impression that it was complete. Also there is not a sigle picture from that angle. Moreover in the video, at the end where is turns it all around: a) the focus is off most of the time, b) he is turning too fast, so more parts are blurred. </p><p>But I guess it is still a help and free moreover. So I am not complaining, just putting this out there. Would have saved me from buying an extra complete set unnecessarily if the instructions were clear. Also would have save me spending twice the amount if the guy in the video, explained that his mosfet legs were only cut due to it being a reuse for the original project and that &quot;The Mosfet gate legs HAVE TO STAY INTACT&quot; (don't cut them to look like the ones in the video). I followed exactly what I saw and that was my demise.</p>
<p>It should work with the mosfet legs cut ! :)</p>
<p>No is will not. I don't mean the middle leg. I mean the left one. That is the gate, it is needed. Only the middle can be cut. But if you look at his picture, you will see that 2 legs are cut. That is just because he reused it from another project.</p><p>The gate is the logic leg, it cannot work without it.</p>
<p>Oh ooook ! ^^ A lot of people here post photos where we can see only the middle leg is cut, I have read all the posts before buying components :)</p>
Can we use 12v 60a switching power supply instead of car battery?
Hello. I have used IRF1405 and I am about to finish the project. I want to use this welder with 3s lipo. What should be the maximum capacity of the lipo?
<p>You mean powering the welder with lipo's? The hobby cells can deliver a fair few amps, but isn't creating a dead short across a lipo a bad idea? Even if it's just done momentarily it may cause problems after a few welds. </p><p>I think a modest sized lead acid battery is better suited as they're designed to deliver lots of amps and start engines, it's better than damaging your lipos or creating an unwanted indoor fireworks display :)</p>
3s 3000mah 30c lipo can deliver 90A
awesome design , I have extra pcb boards made at pcbway latest version printed 3weeks ago , if anyone in the USA interested pm me and I can ship it to you, thank you.
<p>Would you be willing to ship a set to Canada?</p>
<p>hello, I have printed 6 pcb black color. I can send from Spain, 5 e + shipping. carlosgl86@hotmail.com contact me</p><p>diy diy</p>
<p>I need to order more mosfet as blew them and need to change.</p><p>Can I use this one? IRF1324</p><p>Thank you.</p>
<p>For us in North America i've started a list for Mouser but not 100% sure if i have the right parts. Below is what i have so far, also posted this on Endless-sphere hopefully we could possibly update the docs with a mouser shopping cart!</p><p>The links are what i've found on mouser... some i couldn't find a compatible part. Let me know what you think/see</p><p>Mosfet IRF1405 55V 169A IRF 1405 1.15 &euro; 9.20 &euro; <a href="http://www.mouser.com/ProductDetail/Infineon/IRF1405PBF/?qs=%2fha2pyFaduj7MXkE9%2f%2fgmDrs1nVe70vn6O%252b8qYoYC30RfgXKwb4V2FORCVRRaZaJ" rel="nofollow">Infineon / IR IRF1405PBF</a><br>Mosfet Driver MCP14E10-E/P MCP 14E10-E/P 1.70 &euro; 6.80 &euro; <a href="http://www.mouser.com/ProductDetail/Microchip/MCP14E10-E-P/?qs=%2fha2pyFaduiK%252bzV9xLHb5QdgBW%252bT%2f00l4%2fdh1wPtiKwfWRHWKNowJfSmZGFgUXhdODiseL0%252bIng%3d" rel="nofollow">Microchip Technology MCP14E10-E/P</a><br>Poti 6mm Linear 50K RK09K113-LIN50K 0.99 &euro; <br>7 Segment Display SC 56-11 RT 0.84 &euro; <a href="http://www.mouser.com/ProductDetail/Kingbright/SC56-21EWA/?qs=%2fha2pyFaduhC59Humhok116%252bpSOSbqYIXY75OExBNV91Nwcz5gCSYRSMjIJIcSFW" rel="nofollow">Kingbright SC56-21EWA</a><br>1x20pol female header BL 1X20G8 2,54 0.26 &euro; <a href="http://www.mouser.com/ProductDetail/Harwin/M20-7822046/?qs=%2fha2pyFaduh2v%252b0OBRjFzNOTWjD968Z59MrSIrYVuqw1g1JJqdVIdQ%3d%3d" rel="nofollow">Harwin M20-7822046</a><br>1x36pol male header SL 1X36G 2,54 0.17 &euro; <a href="http://www.mouser.com/ProductDetail/3M/929647-01-36-I/?qs=%2fha2pyFadug97%2fLAehBJvdrxTX4rOj1oZvCXvtwyTnK7QE1mt%2fNI7EJ2FWUfO8N4vm15dwVI3Bwe6ekr6pZg0vHA0ml8iiWj" rel="nofollow">3M Electronic Solutions Division 929647-01-36-I</a><br>PCB connector set 2pin PS 25/2G WS 0.29 &euro; <br>IC socket 8 pole GS 8 0.03 &euro; 0.12 &euro; <br>diode 1N5817 1N 5817 0.06 &euro; <a href="http://www.mouser.com/ProductDetail/ON-Semiconductor/1N5817RLG/?qs=%2fha2pyFaduiZaMrYrLxOTDwO4DMVFpvYFH8lJ1Sr3fPPix8gkqDGnw%3d%3d" rel="nofollow">863-1N5817RLG</a><br>elektrolytic capacitor 1 &micro;F RAD 1/63 0.04 &euro; <a href="http://www.mouser.com/ProductDetail/Cornell-Dubilier/SK010M063ST/?qs=%2fha2pyFadug4JIzDYXzcpqw60vo7Y9rO2CmQGGHRArGUPcAN3W463A%3d%3d" rel="nofollow">598-SK010M063ST</a><br>ceramic capacitor 100pF KERKO 100P 0.06 &euro; <br>Resistor 221 Ohm METALL 221 0.08 &euro; 0.16 &euro; <a href="http://www.mouser.com/ProductDetail/Yageo/MFR-25FBF52-221R/?qs=%2fha2pyFadui%252bnL3Q99GBfguh2CWHI%2fx2rn3%252byZU7M86ExXJaXLeptmtFvQHzmhSR" rel="nofollow">603-MFR-25FBF52-221R</a><br>Resistor 100K-Ohm METALL 100K 0.08 &euro; <a href="http://www.mouser.com/ProductDetail/TE-Connectivity/LR1F100K/?qs=%2fha2pyFadugZbks9V501ar%252bo%2fCfpl0bKxhdvsti4BD5YAdT%2fHh%252bHbA%3d%3d" rel="nofollow">279-LR1F100K</a><br>LED 5mm green LED 5MM GN 0.06 &euro; <a href="http://www.mouser.com/ProductDetail/Lumex/SSL-LX5093GD-TR/?qs=%2fha2pyFadui7ivFq1vSLB70eX4IfdKX3RMDoz%2fMLTtn8ei294yXM6A%3d%3d" rel="nofollow">696-SSL-LX5093GDTR</a></p><div></div>
<p>I've posted my Mouser project and other parts from eBay here: https://endless-sphere.com/forums/viewtopic.php?f=31&amp;t=80315&amp;p=1215403#p1215403</p>
<p>Hello, very nice and interesting project, I'm interested in welding <br>stainless steel sheets with thickness of 0.3 - 0.5 mm, believe it would <br>be possible, and if so, what changes should be made?<br>Thank you.</p>
<p>I think it should work well as stainless steel is not very conductive.</p>
<p>For anyone needing the template for the aluminium, here it is. I scanned it so not the best quality, sorry.</p>
<p>Hi All, </p><p>Has anyone still have PCBs to sell? to France. I can pay via Paypal.</p><p>Thanks ;-)</p>
<p>Just to let everyone know, I am out of pcbs</p>
<p>i want to change the schematic to suit my needs, can i edit the gerber files or do i need earlier files from the process?</p>
<p>Hello to all, I made it! It works great, I use a old car battery 45 Ah.</p><p>- arduino nano I use http://www.aliexpress.com/item/1PCS-Nano-3-0-controller-compatible-with-nano-CH340-USB-driver-NO-CABLE-NANO-V3-0/2035011839.html?spm=2114.13010608.0.72.FtHzxY</p><p>- foot pedal switch http://www.aliexpress.com/item/Promotion-SPDT-Nonslip-Metal-Momentary-Electric-Power-Foot-Pedal-Switch/32428553147.html?spm=2114.13010608.0.80.FtHzxY</p><p>Thanks KaeptnBalu! </p>
<p>hi. can i ask for the list of all components needed. thanks! very much appreciated</p>
<p>Hi, a question<br>but the mosfet legs are welded all 3?<br>or only the two most external?<br>thank you</p>
<p>No matter, you can do like you want</p>
<p>Hi,</p><p>I have a few packs of the following:</p><p>- PCB: PCB printed by PCBWay, latest design (13Jun2016), single piece to be cut.</p><p>- Foot switch: Foot switch from kEK, 10 x 6 x 3.5 cm </p><p>- Arduino: Arduino Nano v3 (ATMEGA328P-AU, CH340) in antistatic bag.</p><p>13 EUR + shipping from .HU</p><p>Drop me a message if you are interested.</p><p>R, Janos</p>
<p>Hello. The thickest copper wire for welding tips I have found in local shops is 6mm sqare. Does it do the job?</p>
<p>I have printed 8 pair of PCBs in EU, shipping plus few buck and you can have a pair :)</p>
<p>Hi, I was wondering if you can feed with from home 220v transformer.<br>For example transformer of a microwave oven.<br>thank you</p>
<p>Nope, that's AC&mdash;this is only for DC. For a MOT you can control the primary. Refer to http://www.avdweb.nl/tech-tips/spot-welder.html and http://www.avdweb.nl/arduino/hardware-interfacing/spot-welder-controller.html</p>

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