Update 12.2016

Due to many requests for the PCBs

I do currently have some PCB Sets and prebuilt kits in stock. Take a look here:


You can also take a look in the comments below this instructable. Some people who ordered boards at PCB manufactures are willing to sell some of them.

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 take a look in the comments below this instructable. Some people who ordered boards at PCB manufactures are willing to sell some of them.

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.

(Update 12.2016)

The trace that connects the two boards in the combinde gerber is only a ground connection not needed for the spot welder to work. It is only there to make clear to the pcb manufacturer that this is meant as one board and they dont need to make v-cuts or something else. With this modification it should be possible to order at pcbway without problems.

<p>KaeptnBalu, there have been several threads elsewhere (endless-sphere) about it being a good idea to add a TVS diode and a Schottky, to help dissipate avalance current. Have you reviewed this and think it's a good idea or necessary for your design? Also the suggestion of adding ~82 Ohm resistors between the FET drivers and the FET gates. Thanks for your work on this!!</p>
<p>Do you have a link to the thread with the information so i can take a look ?</p><p>I have done several hundres welds with the spot welder and there was no problem so far. Therefore i did not think about adding more parts to it.</p>
<p>This is best explanation, but doesn't include the reference to the FET gate resistors from the drivers for stability reasons.</p><p><a href="https://endless-sphere.com/forums/viewtopic.php?f=14&t=81400&start=550#p1218325" rel="nofollow">https://endless-sphere.com/forums/viewtopic.php?f=...</a></p>
<p>This is a noob question so please forgive me if it is a no brainer :-). I am currently building the spot welder....I had a qeustion about the power. I see on the schematics and the PCB board that there is a spot to put a 12V input and GRD, but I have seen pictures of others builds where while running the spot welder the power and GRD are not hooked up? Does the spot welder run off of the 12v automotive battery? Is the power input only if it is not hooked up to the automotive battery?</p>
<p>Thanks a lot to <a href="/member/KaeptnBalu" rel="nofollow">KaeptnBalu</a> for the instructable.</p><p>I finally managed to assemble my spot welder. I kept wire length very short (less than 30cm total, so 60cm of total wire for positive and negative wires).</p><p>However I used a pair of 14AWG wires for each side to keep the thing light and flexible.</p><p>My spot welder never really worked. If I use a weak battery as input, it works as expected. However if I use an automotive battery as input, each time I make a weld the MOSFETs die (at least a pair). They die in the way that they short (Drain, Source and Gate are all shorted) and this causes some very big sparks at my tips when it happens.</p><p>If I replace the defective pair, it works again as the first time.</p><p>I thought it must be an inductance problem so I installed protection diodes as mentioned below, and I don't see any voltage spikes anymore (25V max and -10V min).</p><p>So I really don't understand why the MOSFETs still short. Any idea?</p><p>Thanks again!</p>
<p>Did you check the mosfet drivers ? If always a pair of mosfets blows up, maybe it is a bad driver because there are 2 mosfets conencted to each driver.</p>
<p>I've got some extra boards - PM if anyone needs them.</p>
<p>Anyone with a new PCB that can send to Portugal?</p><p>Please PM me.</p><p>Thank you</p>
<p>Anyone created a 3d printed case for this yet? If so, would you mind sharing the STL files for it?</p>
<p>I have plans to create one but I do not have a completed project to collect measurements. I am waiting on serveral components to begin the build. Feel free to share case ideas or inside measurements.</p>
<p>Dear KaeptnBalu,</p><p>You explained that the second pulse time is adjustable by the potentiometer between 1 and 20 ms and will be displayed on the screen.</p><p>How is it possible to read a value between 10 and 20 ms from a display which only can show one digit. (0....9)</p><p>Regards,</p><p>J.A. Seegers.</p>
<p>Hi Seegers, </p><p>The display changes between the two digits about every second if you are higher than 9 ms. For example if you adjust it to 14ms it shows 1 , 4, 1, 4, 1, 4, 1, 4 ....</p>
<p>Dear KaeptnBalu,</p><p>I still have an other question,</p><p>Can I connect the 12V PCB powersupply on the same battery as I use for the weld current or should it be better to use a separate power supply?</p><p>Regards,</p><p>J.A. Seegers.</p>
<p>Better use a seperate power supply. 1A 12V should be enough. Or use a 2-3s Lipo battery.</p>
OK, very clever! Thanks.
<p>Cutted Boards available in France, 5&euro; + shipping :)</p>
I want one set please. Please send amount required to ship to Canada.<br>postal code is L1B1J6.<br>regards Dennis
<p>11&euro; for worldwide shipping with tracking</p>
boards arrived safely a couple days ago..... thank you sir.
&euro;11 is OK. I'll need your PayPal user name or you can pm me and I'll send immediately. For some reason the reply link failed to connect us. Thank you for putting me on your list of buyers.<br>Dennis
<p>Up, 7 cutted boards still available, 5&euro;/unit + 6&euro; worldwide shipping with tracking </p>
<p>I would like a set. I am in the US. Postal code: 84664. Let me know how much for shipping. </p><p>Thanks!</p><p>Jason</p>
<p>11&euro; for worldwide shipping with tracking</p>
<p>Have you considered making a parts bag to sell with the pcb?</p>
<p>Arranging and packing all the parts is allmost the same amount of work as soldering them to the pcb. So i decided to make some prebuild kits instead of part sets.</p>
<p>Quick question, the IRF1404 is cheaper and has a lower resistance. What would be the drawback of using the IRF1404 instead of the IRF1405? Thanks.</p>
<p>The IRF1404 also works. I used the IRF1405 because it is rated a little bit higher Amps but costs the same as the 1404 here in Germany.</p>
<p>I have one board left for the US folks. </p><p><a href="https://store.quietstove.com/pcb-boards.html" rel="nofollow">https://store.quietstove.com/pcb-boards.html</a></p><p>$6.00 plus ship.</p>
<p>please people buy from kaeptnbalu store </p><p>not from monk3e </p><p>respect the job of kaeptnbalu </p>
i didnt realise he was still selling the complete units. i dont want to step on anyones toes. i deleted the post. you can calm down now
<p>Hey guys, I do currently have some PCB Sets an 3 prebuilt kits in stock. Take a look here:</p><p><strong><strong><a href="https://www.tindie.com/stores/KaeptnBalu/" rel="nofollow">https://www.tindie.com/stores/KaeptnBalu/</a></strong></strong></p>
i didnt realise this was the case. i was told you were no longer making the built units. i apologise. i will remove my comments. great work man. i dont want to upset anyone
<p>I have some white uncut PCBs to sell. I am based in France.</p><p>Price is 5&euro; for one PCB plus shipping.</p><p>Please contact me via message.</p>
<p>hi there, how much will it cost to send to UK? thanks</p>
<p>Hi, I can send to you one cutted board, 10&euro; with tracking from france</p><p>Send PM if interested, Regards</p>
<p>5 PCB left.</p><p>Shipping is usually around 5&euro; for European countries (e.g. if you want two PCB, it will cost you about 15&euro; total).</p>
<p>Spare Boards in the U.S. if anyone is intersted. PM for more Info</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 would be interested in a finished product if you can build.</p>
<p>I seem to be having a problem with email notifications going to my junk box.</p><p>I have 3 sets of PCB left and most parts to make one. I am happy to sell the 2 sets of PCB without parts but the third will be sold with parts. 1 set is $10 AUD posted to anywhere in Australia or $12 AUD worldwide.</p><p>Parts were ordered from reichelt and include the following. $65 AUD for this set including boards, it's cheaper than what I paid, cheaper then jaycar and better quality than Aliexpress.</p><p>Thanks</p><p>Parts Include</p><p>Mosfet IRF1405 55V 169AMosfet Driver MCP14E10-E/PPoti 6mm Linear 50K7 Segment Display1x20pol female header1x36pol male headerPCB connector set 2pinIC socket 8 polediode 1N5817elektrolytic capacitor 1 &micro;Fceramic capacitor 100pFResistor 221 OhmResistor 100K-OhmLED 5mm green</p>
<p>Happy to supply parts for less due to I only need 1 welder. Make it $55 AUD including parts posted above, boards and postage (within Australia)!</p>
Hello, any boards left for sale in Australia?
<p>Yes, please see other reply if you are still interested.</p>
<p>I'm in Australia and interested, any left?</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>

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