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.


Two boards in the United State, Virginia, $10 includeds shipping and tracking. PM if interested. You will need to cut them yourself.
<p>I would be interested in an arduino battery spot welder board if you would have one left. Thank you for your time. And how would you get paid.</p><p>W. Encil Scott</p>
<p>9 PCB's available in France (Paris) ;-)</p>
<p>Hi <a href="http://www.instructables.com/member/ripleyxlr8" rel="nofollow">ripleyxlr8</a>,</p><p>Do you still have available PCBs? </p><p>I would be interested in one set. Can you PM me or send me more info.</p><p>Thx,</p><p>IK&lt;</p>
<p>That is what I was looking for... Very well done. Can you use main charger for it of just a car battery?</p><p>Ripleyxlr8: </p><p>I would be interested in two sets - Ireland. send me some info on freederix [at] gmail [dot] com thank you</p>
<p>Hi,</p><p>Still have 3 packs - PCB+Arduino+Footswitch - available. </p><p>R, Janos</p>
<p>I am interested how much do you want for them?</p><p>-Cardinal</p>
Hi, <br><br>How much for the pack?<br><br>-Sondre
<p>R.Janos,</p><p>can you tell me the price off one package incl. mailing cost to Holland?</p><p>Janvt</p>
<p>I have 5 spare sets of boards for sale in Australia, I accidentally ordered two different colour boards (red control board and green mosfet board) colour does not affect functionality! Please let me know if interested.</p><p>More details about build to come later. Thanks</p>
<p>I am interested how much with shipping to USA zip 45430</p>
Hey buddy any boards left I'm in melb west side if that helps?
Hey mate do you have any left?
<p>Nice build, but do the electrons move faster through the red board? Did you have to change the code to compensate? The electrons are already upside down so may fall out of the PCB.</p>
Close, but to be honest it has nothing to do with the electrons, it is all temperature related, the green keeps the mosfets a lot cooler, I was worried that they might get a bit hot on a red board.
<p>Ahh, that makes perfect sense, the red one would also be so much easier to solder. I just feel bit stupid now :-)</p>
<blockquote>You said:</blockquote><blockquote>&quot;In the new Version you have to connect JP1 on the Arduino Board with JP1<br> on the Mosfet Board and JP2 on the Arduino Board with JP2 on the Mosfet<br> Board.&quot;</blockquote><blockquote>I found JP1 and JP2 on the Mosfet Board, but I can't see them written on the Arduino Board. Please post a photo of the 2 locations... A photo would show how to connect them also, so please help me.</blockquote>
<p>I've bridge them in hope that this is what you meant, but the problem remains. I made a video with the bridge, and the problem. Please tell me your ideas...</p><p><iframe allowfullscreen="" frameborder="0" height="281" src="//www.youtube.com/embed/Ls8kJCh61W4" width="500"></iframe></p><p>Thank you for your time.</p>
I Made it. And making enclosure. I am using chip soldering gun enclosure. You can looking pictures.
Great job mate.
Thank you.
<p>Does anyone know if a rewrapped 4awg microwave transformer will work? I would like to be able to mount this into a soldering gun and have the power source come from the wall if possible.</p>
<p>Could I use copper alloy welding tips for the probes or is pure copper required?</p><p>Thanks</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, 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>Could anyone please tell me if the connections for the JP points are included in the github parts list and if not what is required?</p><p>Many Thanks</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>
<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,</p><p>i need PCB or 2 (Germany)......</p><p>Thank you</p><p>Michael</p>
<p>I can send you. I have 20 piecess</p>
<p>Hello <a href="http://www.instructables.com/member/barancanaydin" style="">barancanaydin</a>,</p><p>Do you still have any of the Battery Spot Welder PBS's available? I live in Belfast Northern Ireland and would obviously cover costs and postaged if you have any. Many thanks for you time.</p><p>I can be contacted via crusher70@gmail.com or via PM.</p><p>Crusher</p>
<p>Merhaba!! Elinizde var mı hala PCB?</p>
Evet var
<p>Hi All - I can solder (poorly) but am very limited in electrical knowledge but desperate not to buy an unreliable chinese spot welder...</p><p>I am gathering parts at the moment but have a question about wiring b4 they arrive.</p><p>I can see a red and black cable coming from the pcb in one of the completed images above. Is this power to the PCB? Do those cables go back to positive and negative of the 12v lead acid battery? I can't find any image anywhere showing where they connect.</p><p>Thank you</p>
<p>T&uuml;rkiye'den almak isteyen arkadaşlar i&ccedil;in link aşağıdadır.</p><p>For those who want to get from Turkey. Link can you look bellow</p><p><a href="https://www.sahibinden.com/ilan/ikinci-el-ve-sifir-alisveris-teknik-elektronik-devre-montaj-battery-spot-welder-pil-punto-devresi-348501227/detay/" rel="nofollow">https://www.sahibinden.com/ilan/ikinci-el-ve-sifir...</a></p>
<p>Anyone got a board Europe ?I need one</p>
<p>Hi , i would like 2 pcb for Greece, is there anything please</p>
<p>Still have the following kit in EU (can also ship to RU or USA):</p><p>- PCB</p><p>- Arduino</p><p>- Foot switch</p><p>Drop me a message is you are interested!</p><p>Regards, Janos</p>
<p>How many will be costs in RU PCB?</p>
<p>Has anybody in EU finished product for sale?</p>
<p>I finished my spot welder today. Uses copper bus bars and avalanche protection mod. Lots more info in my build log which starts on page three of this thread: https://endless-sphere.com/forums/viewtopic.php?f=31&amp;t=80315&amp;p=1215403#p1215403</p>
<p>I cannot thread opened, can you tell me which nummer TVS dioda ?, thanks.</p>
I saw diode series with(?) between plus and min accu, what dioda is that ?

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