I have the same $16 battery tab spot welder. It also died. I have been using a large car battery and starter solenoid with a switch to spot weld. I wanted to have more control than the switch and like the idea of using the method you demonstrated with the capacitor. I tried to find a module that I could use to control the pulse to the solenoid with no success. I then went back to the $16 battery tab spot welder after I learned of the design flaw. I added the missing capacitor and managed to remove all the mosfets with a regular soldering iron and some patience. Only one was bad. Then I got an idea. Instead of replacing all the mosfets I installed only one good one and left all the other pads empty. I connected the output of the $16 battery tab spot welder to the solenoid and added a 12v light as in indicator. You will need to set the welder to manual and add a foot pedal or switch otherwise it will continue to trigger the solenoid constantly. Now I have a way to trigger the solenoid using the $16 battery tab spot welder and can control the pulse with some precision. So basically instead of throwing away that cheap $16 battery tab spot welder you can combine it with a car battery and solenoid and have pretty amazing machine.
The idea with the mosfets is to control the pulse up to 25ms width. You can never get a solenoid to switch on/off that quickly. Also solenoids contacts can weld themselves and thus cause a fire. These ideas with solenoids are not good. Design around mosfets for precise control and safety.
@@rajatsewal9203 Yes, its true the starter solenoid can weld it self together. It happened to me recently after I finished 4 ebike batteries (70-90 cells each) and switched to a large truck battety. I got through the last battery pack by triggering the solenoid a couple of times after a few welds. It feels like the solenoid is wearing out and I should probably replace it every so often. I have had more trouble with mosfets failing closed especially with the thick nickel strips I use for building high power ebike batteties.
@@saifcathum3423 If you can limit the current to around 30A then the solenoid will last MUCH longer. One way to do so is place an inductor in series. Be careful, the inductor can/will create some back emf and generate some sharp voltages too.
Looking at building my own pack to replace lead acid in a golf cart soon, and this solves one of my biggest issues. Thanks for posting results, schematics, and math behind this!
This is the miniature version of the "trick" that off-road/overland folks use for emergency welds. 2 x 12 volt batteries, a supply of welding wire, jumper cables and something to protect your eyes. "Trail Weld Kits" I had fun learning this at an Expo, something that brought me back to HighSchool shop class.
On a trail a friend of mine had a motor mount fail, the motor dropped hit a rock and put a hole in his oil filter. We were able to use tow straps to put the motor back in place and then we used your trick to weld the oil filter so it no longer leaked. Good times!
I built almost the same thing for my supercapacitor bank charged to only 6VDC. I have a Li-Ion pack attached with a 12VDC linear regulator to charge the capacitor with enough power to activate a large current relay (instead of the solenoid you are using) and after playing with the capacitor sizes, I ended up with a value way smaller. My circuit board has a small header to hold the capacitor so I could change the value based on the thickness of the nickel sheets I am welding. I placed my two welding probes through a wooden handle with the two tips bend so they are almost touching and I installed a pushbutton switch into the end of the wooden handle so I can activate the weld with my thumb.
I am buying one of the cheap spot-welders (the $16 one you reviewed before) just to use the timer control board to control the timing of the relay. This will be much more accurate than the timing of the capacitor.
You're brilliant Scottie. My sister finally understands why her Bluetooth watch was so bad to wear. Thank you so much for everything you share. Hi Cleatus! (This spelling means 'Illustrious', I hope I have it right.)
Blue tooth ear pods are super dangerous...They only use bluetooth to connect and then switch to regular wifi to send the HDR sound. I know the linux standard for this switching from bluetooth to wifi is called "fluoride" ....isnt that special.
Another GREAT IDEA! Thanks! Scottie, I'm surprised I don't see a 3D printer in your shop? As you know, I'm new and just subscribed and started watching. Point is, with your great ideas you could build up a nice housing for your widgets... That's what I like to do, myself. Everyone has their own ideas... Keep up the good work and continue sharing like you do!
I used a Microcontroller and LCD Screen to actuate the Solenoid with a foot switch. I can now control exactly how long the Solenoid stays 'ON' with 'UP' and 'Down' push buttons.
I made this from the same plans but reworking it using the jumbo pouch cells from battery hookup and I 3d printed a probe holder as well as i designed a holder mount for a drok timer relay. It's been apart for months now but worked great with loose wires and a 600cca lead battery
Bare in mind that a reverse diode across the relay coil will also cause the relay to stay engaged longer, another trick is a 1 or 5watt zener diode around 50 volts, or use a neon that will shunt at ~80volts. That way the relay will turn off quicker and less chance of the contacts in the relay welding on. Also if you got a really large CCA battery using longer wire leads would reduce the peak current, if it's to high use a longer wire to introduce a little more resistance.
Hi, great videos. I'm going to use a Dark Welder but with your mods. I have a recovered cap but it's a 5600 uF 63V, will this be close enough? I assume it will be a slightly longer discharge. I also had the cheap spot welder, blew up on first use. I removed the blown mosfet, installed the capacitor mod and it worked. But it was just rubbish, no power, hence the need to build a better one.
Great video. Actually years ago I used a similar idea using a car headlamp , switch a capacitor with diode . worked ok, Now have a portable which has till now worked good, but when it's internal battery goes it becomes a throw out or a mod job as cannot find spares and trying to ask sellers, well, you get nowhere.
I got a spotwelder like the red one , from bang good, it exploded, and caught fire for a second, and didn't even make a weld!! I built one with a solenoid, and a SSR, with a timer circuit, it works well, but is cumbersome, a bit awkward, I wanted something smaller, I'm just going to modify my original design, to make it smaller and easier to use! But I'm here looking for ideas!!
SCOTTIE, is there ANY way to reduce amps cheaply & effectively? I thought of 1 or more old-school automotive headlight bulbs inline - seems for sure it would blow them out but I can logically decide why. (Won't a circuit with a bulb only pull as much amps thru as required by bulb?) I built a kvdrk setup, trying to use my lawn mower batt, but its 375 cca, blowing out my welds. Much thanks for the updated design & great explanation! And really great tip on blunt electrodes!
The trouble is that the amount of current for the weld is so large that limiting would be kinda difficult. If you used a light bulb, the welding electrodes would just complete the circuit on the metal surface of the battery (or whatever) but the small current through the bulb wouldn't actually weld anything. You can connect a 12V automotive light bulb across the car battery, and it won't explode since the bulb limits the current. Now, if you had a 12V 1000W+ lightbulb, that would do the trick! That would be one CRAZY bulb, tho.
great video, thank you. one question though. wouldn't it be better to connect your old welder to this battery/relay/switch -combo, just to have the option to adjust the timing? if my welder burns up (same as your old one), i think to mod it this way.
I tried a 120v welder, with a SSR , and timer, it didn't work! Maybe using a solenoid on the lvdc side, maybe, but the relay can only react so fast, mine the timer can pulse faster than the solenoid, and welds best if the solenoid barely fires, with 12v. Most welders are about 24-36v. It may just burn everything! Even with the faster pulse
Very cool. Have you thought about doing the same design with a DC SSR? I am wondering about longevity of the solenoid contacts. I have the cheapo spot welder and it seems to be working so far. I think there may have been design changes over a couple years. Hope mine lasts. If not, I will build a Dark Welder 2, but might take it into the microcontroller SSR world for a Dark Welder 3.0.... :)
I was thinking of just using an adjustable 555 timer set-up for the switching of an old Ford starter solenoid. You know... less math. Unless there is something I'm missing here, and it wouldn't work.?.?
I have one suggestion, instead of buying copper nails why not take a couple of inches of 14 gauge nomex strip the wire and you have copper terminals? I am glad I came across this. I am getting ready to rebuild some nicad battery packs and it was highly recommended for safety that lipo batteries be tab welded instead of soldered.
Awesome video... Is there a name for that alloy you are referring to that does not fuse with the nickel strip (so that I don't have to file the electrode pen tips off like you similarly mentioned) ?
It seems it's nothing terribly fancy... There are these, for example: amzn.to/3wDnC0P They're a standard alloy that's apparently 99.1% copper and 0.9% Chromium. Well, it's not 100% clear... It could be a different type of Class 2 copper alloy, like Chromium Zirconium Copper (they add a bit of zirconium which helps prevent the tips from sticking during welding). Just note that if you use anything other than pure copper, the conductivity of the tips goes down, so that will also change the weld you end up with. You might need more current, or a longer weld time, etc.
@@ScottiesTech Wow awesome man, thanks a lot.. So I guess it's a bit of a tradeoff then huh? Like you sacrifice a bit of conductivity for a little less sticking by going with the .9% zirconium? You don't need to respond, this was great info and maybe down the road I can try those out. Thanks again, definitely subscribed to your channel, you have really really helpful videos.
Just wondering why your timer circuit couldn't be used to fire 8 mosfet board that that was properly heat sinked. An if so what changes would be needed.
“It’s not electronically controlled”. Actually, as soon as you added a capacitor, it is electronic. General usage of the word electronic today implies computerized, but by strict definition you created RC and RLC switched circuits which are both electronic. Great job explaining the design and function. You might have mentioned that using a different battery or solenoid would affect the size of the capacitor needed to get a good weld. Thanks for sharing your experience.
So I just built this spot welder. I have a 12v 20ah battery. My capacitors are the 4700uF but 50V I bought the Starter solenoid from the link and the schottkey Diode. I had a lighted push button and I used solid 8Guage copper grounding wire soldered to the end of 6 awg wire. I used a 25 watt 150 ohm resistor versus a 2 watt. I am excited and was doing some test welds with bad 18650 cells. I am pleased but every now and again I get a more powerful weld that Burns through the nickel .15 bus bar. I am not sure why sometimes it is different. Any ideas on how to make it more stable every time. I tried to very quickly press the foot switch but sometimes it is way more powerful. any help would be greatly appreciated.
It's probably the larger battery. Most likely, the 20Ah battery (vs my 10Ah) has a higher CCA rating. That means the larger battery will dump more current into the weld in a given time period. So, you might try a smaller cap instead (like 2200uF) and see if the shorter welding time is enough to limit the current. This is exactly the problem Kevin Dark had with his setup when he switched to a beefier battery: he had to tap the momentary switch in his setup more quickly to get proper welds and avoid burning thru the nickel strips. Hope that helps!
@@ScottiesTech Yeah I was worried about the bigger battery. I will try to get my hands on a smaller cap. I have a much smaller 100uF but I don't think these can be daisy chained like a resistor can. I may try to scrounge up a smaller battery. I am very excited. I also may try to make my welding rods smaller. I also may use 10 awg wire instead of 6 to attach them. I think I just deliver too much current. Normally i have the opposite trouble.
@@SolarBuck Capacitors add when connected in parallel (the opposite of resistors). So, you can also grab multiple caps of smaller values and connect them all up to test and find what total value gives you the best weld. Lemme know what you discover!
Thinking of different nickel strip thickness, would having 3 or so different capacitors on a selector switch help tune the spot welder. Ps I’m going to build one as the keep it simple approach always delivers reliability.
How do you increase the weld time for a slightly thicker nickel strip? I want to use the old strips from Ni-cad batteries. They are just a tiny bit thicker and will not attach with this type of welder.
Hi still got bit of Kevin's welder Found it wasn't very good though it needed a timer looking at yours you have rethought it and sounds ok have you fully tested it ? see you didn't do a distruction test by pulling apart the nickel off the battery is there any adjustments for thicker nickel tabs good video pitty about that pipe work behind you really bad 😀👍
For thicker metal tabs, you'd probably want either a larger battery (more current) or a larger capacitor (longer weld time). The welds I've done with 0.15 nickel strips have been pretty strong. The nickel tears before the welded spots break. The pipes are antiques. Minimum 50 years old, probably more like 70 years old. They still work tho (for heating), so I won't complain.
thanks for your comment ! when you say cost !! priced battery and solinoid was about £50 plus the other bits all about £90 plus to build this [ thinking!] is it cheaper buying a shop bought spot welder ?? love making your own things but you have to stop and think costs some time dont you think cheers
@@robertsingleton2364 Yeah, I went easy (Amazon) but I oould have nabbed all the parts needed from eBay or AliExpress and then waited... Also, a local farm supply store has DIY batteries (not sealed) that are about 2.5X cheaper than sealed ones... and they last just as long. So, I reckong you COULD do it cheaper. Actually, now that I think about it, I already had a spare small battery! D'OH!
No, since it would have to carry a LOT of current and therefore be hugemongous. But what you CAN do is choose a different battery with higher/lower CCA rating and adjust the capactor value for shorter/longer pulses.
How would you use it this circuit with a lawn tractor starter solenoid? It trigers the relay but not long enough to let current pass through the circuit.
@@countryside8122 It depends on how much current the solenoid needs to fully close - just briefly. What I did is hook up my solenoid to 12V, then monitored the current on my oscilloscope. That let me see the peak current needed to activate the solenoid. Then I used the capacitor calculator (see description) to get a rough estimate of the capacitance needed. And then I tested it, and POOF! Worked like a charm. If you don't have a scope, you could just use a multimeter to measure the current going thru the closed solenoid when you apply 12V, and then increase maybe 30% to get a rough estimate for the cap calculator.
Great Video Scottie. Loved it. I have 3 questions. (1) If i replaced the copper nails with plain Iron nails, what would be the result ? (2) Copper has a better conductivity than Nickel strips, why is tinned copper strips not used (to rule out the possibility of oxidation), (3) Using an Arduino and generating a pulse to control the Solenoid could offer flexibility in timing. Keep posting and keep developing.
You can probably use iron nails, but they'd be less conductive than copper ones and I'm not sure what kind of weld you'd get in the end. As for the strips, I'm not sure... I read a whole lot, and I learned very quickly that spot welding is complicated. So, I just used what most people said was best for spot welding 18650 cells. The metal alloy of the batteries matters, the metal alloy of the strips matters, the nails/welding probes matter (including their pointiness or lack thereof), the amount of pressure you put on the strips matters during a weld, and the current pulse matters (incl. duration and even the shape of the pulse). Mostly I was just looking for something quick and dirty and above all, simple!
@@chrisfojtik7391 if you use a 1meg resistor the current is in the micro amps so not really, you can use a 1k resistor and it will discharge the cap much faster and you probably want to go with a 1/4 watt resistor, but even a 1/8 watt would probably do since the wattage is going to be about 156 miliwatts for about 4.7 seconds. Higher resistor values = slower discharge and less current. it really depends on how fast you want to discharge it, too fast and you are affecting the on time for the pulse on time. But I dont think anything between 10k and 1 meg will alter the performance.
I tried building the original Dark Welder and it didn't work for me. It burned holes through the bus strips and didn't weld the strips to the batteries. I ended up soldering them on instead.
What ever happened to the good old fashioned clicker switch that disengaged just after you touched the switch You pushed down. It clicked and disengaged after the click. You could still be pushing the switch and it would still disengage the power.
Thanks for ur video I always wonder why in all relay circuit there always those diode tie across the coils , and is there a way to very the capacitance to change the pulse time for different nickel thickness
Well... I was thinking about that, and my idea was pretty crude, but: I would wire up several capacitors of different values, and then use a switch to select which cap should be connected to the circuit. Using the discharge calculator linked in the description, you could get a rough idea of weld time. If 4700uF is 5ms as measured, then 2200uF would be roughly 2.5ms, 9600uF would be about 10ms, 18000uF would be 20ms, etc.
What, no affiliate link for the relay/solenoid? I was really hoping to be super duper lazy and click through and buy everything at once. I've been putting off buying/building a spot welder and half the time when I start filling my cart the links are always old or like in this case Kevin's links are all UK and old, so I never quite get everything and then it just kind of annoys me and I chase the next shiny ball passing by. Your links are actually good, I add things to the cart on Amazon and go back and right back where I should be and not teleported to some Tonga ad loop where I have to force close to get to the previous item. This is so close but I don't want to watch more videos and sift through more links. I know you don't want to do a shameless cash grab but you have given Kevin all the kudos required. Just because Kevin isn't keeping up with his links and providing some good old US links for those of not in the friggin UK it doesn't mean you have to continue the tradition. He's leaving money on the table by not keeping up with them. You improved his design of the spot welder right? Well do the same with the parts list. You have given him plenty of props. Give us a complete list, ideally with everything from Amazon. Make a wish list and share it if you don't want that affiliate money. It's 3am and I'm shopping, I don't want to navigate some craziness, I would love it if you could facilitate a one stop shopping experience with US links all from one cohesive cart. It doesn't have to be Amazon. There are tons of affiliate programs to join. Don't feel bad about making money from this. Sometimes you work your ass off and get next to nothing so it's ok to grab some low hanging fruit.
You really need a slow blow fuse in case the solenoid seizes, then the battery would stay delivering current and you could be trouble ...melt down situation.
You can get them on AliExpress, but I just ordered some from Amazon (which also came from China in the end). There are all different sizes, or rolls: amzn.to/2J1YygO
Can't figure out this guy's accent. Good pronunciation, especially the ending 'L' as in 'weld'. North American locution. I'm thinking Canadian but 'o' in his 'constance' suggests mid-western states.
Probably a teeny-tiny amount, but nothing like an actual arc welder. Arc welders dump tons of current through the metal via an electric arc that glows VERY brightly and emits tons of UV - hence the need for eye protection (against the brightness + UV) and face/hand protection (against molten bits of metal/sparks). If an arc welder is a brontosaurus, this little spot welder is more like an ant!
@@ScottiesTech Well im really glad i found this video bc i was considering picking up welding as a hobby but its a very pricey hobby, especially for the job i needed it lol. Also I read somewhere that arc welders give off infrared as well as UV? Makes me wonder how a tig welder (the one i wanted to get) differs from the other 2 as far as frequencies and intensity is concerned. Tiny welder seems a lot more safer because it's not as intense I guess. I wish there was a cheap way to test what they give off, would a simple emf or rf meter (dont know the difference lol) do the job? Again thanks for all your informative videos 🤗 I really do enjoy them
@@Magiaimelissa Well, arc and tig welding are a WHOLE different animal. My little spot welder is only really good for thin layers of metal, and even then it's nowhere near as good as a customizable pro spot welder. There are also big spot welders that are extremely powerful for welding big pieces of metal. High power welding is fairly safe if you use good protective gear: mask (preferably with auto-dimming visor to protect your eyes), good welding gloves, a heavy apron (leather or similar), and above all good ventilation and/or a respirator to avoid breathing in all the fumes generated. It's a dirty job, but lots of fun!
@@Magiaimelissa You do understand everything in the universe gives off infrared radiation... anything that is above absolute zero in temperature anyway. Infrared is light and part of the electromagnetic spectrum just like the light you can see, and no more harmful than Sunlight. To learn how to weld I would start off with a used Mig welder which can be had for around £20-50, then move on to Tig which is much harder to master, but a new tig inverter welder can be had for as low as £40+ on places like eBay now, or find an old Ark welder but don't try and weld anything thin. :) Anyway good luck!
I have the same $16 battery tab spot welder. It also died. I have been using a large car battery and starter solenoid with a switch to spot weld. I wanted to have more control than the switch and like the idea of using the method you demonstrated with the capacitor. I tried to find a module that I could use to control the pulse to the solenoid with no success. I then went back to the $16 battery tab spot welder after I learned of the design flaw. I added the missing capacitor and managed to remove all the mosfets with a regular soldering iron and some patience. Only one was bad. Then I got an idea. Instead of replacing all the mosfets I installed only one good one and left all the other pads empty. I connected the output of the $16 battery tab spot welder to the solenoid and added a 12v light as in indicator. You will need to set the welder to manual and add a foot pedal or switch otherwise it will continue to trigger the solenoid constantly. Now I have a way to trigger the solenoid using the $16 battery tab spot welder and can control the pulse with some precision.
So basically instead of throwing away that cheap $16 battery tab spot welder you can combine it with a car battery and solenoid and have pretty amazing machine.
:O That's a GREAT idea! Why didn't I think of that?! Well done!
The idea with the mosfets is to control the pulse up to 25ms width. You can never get a solenoid to switch on/off that quickly. Also solenoids contacts can weld themselves and thus cause a fire. These ideas with solenoids are not good. Design around mosfets for precise control and safety.
@@rajatsewal9203 Yes, its true the starter solenoid can weld it self together. It happened to me recently after I finished 4 ebike batteries (70-90 cells each) and switched to a large truck battety. I got through the last battery pack by triggering the solenoid a couple of times after a few welds. It feels like the solenoid is wearing out and I should probably replace it every so often. I have had more trouble with mosfets failing closed especially with the thick nickel strips I use for building high power ebike batteties.
@@saifcathum3423 If you can limit the current to around 30A then the solenoid will last MUCH longer. One way to do so is place an inductor in series. Be careful, the inductor can/will create some back emf and generate some sharp voltages too.
EXCELLENT presentation w explanation, good detail, good video, GOOD audio & great humor!
Don’t ever stop what you are doing scotty. You are a great man 🙏🏻🌹🇬🇧
Excellent presentation. A mix of "organic engineering" with just enough electrical engineering to bring it together. Thanks for posting.
Looking at building my own pack to replace lead acid in a golf cart soon, and this solves one of my biggest issues. Thanks for posting results, schematics, and math behind this!
Perfect video, excellent theoretical foundation and clever elaboration, the best I have seen so far of many, class!
Even a novice like me was able to understand what you were saying. Thanks for a great intuitive video.
This is the miniature version of the "trick" that off-road/overland folks use for emergency welds. 2 x 12 volt batteries, a supply of welding wire, jumper cables and something to protect your eyes. "Trail Weld Kits" I had fun learning this at an Expo, something that brought me back to HighSchool shop class.
On a trail a friend of mine had a motor mount fail, the motor dropped hit a rock and put a hole in his oil filter. We were able to use tow straps to put the motor back in place and then we used your trick to weld the oil filter so it no longer leaked. Good times!
I built almost the same thing for my supercapacitor bank charged to only 6VDC. I have a Li-Ion pack attached with a 12VDC linear regulator to charge the capacitor with enough power to activate a large current relay (instead of the solenoid you are using) and after playing with the capacitor sizes, I ended up with a value way smaller. My circuit board has a small header to hold the capacitor so I could change the value based on the thickness of the nickel sheets I am welding. I placed my two welding probes through a wooden handle with the two tips bend so they are almost touching and I installed a pushbutton switch into the end of the wooden handle so I can activate the weld with my thumb.
I am buying one of the cheap spot-welders (the $16 one you reviewed before) just to use the timer control board to control the timing of the relay. This will be much more accurate than the timing of the capacitor.
You're brilliant Scottie. My sister finally understands why her Bluetooth watch was so bad to wear. Thank you so much for everything you share. Hi Cleatus! (This spelling means 'Illustrious', I hope I have it right.)
Blue tooth ear pods are super dangerous...They only use bluetooth to connect and then switch to regular wifi to send the HDR sound. I know the linux standard for this switching from bluetooth to wifi is called "fluoride" ....isnt that special.
@@melgibson6331 Thank you for that info, I didn't know they switched over. It does make perfect sense though. Isn't that special indeed!
Another GREAT IDEA! Thanks! Scottie, I'm surprised I don't see a 3D printer in your shop? As you know, I'm new and just subscribed and started watching. Point is, with your great ideas you could build up a nice housing for your widgets... That's what I like to do, myself. Everyone has their own ideas... Keep up the good work and continue sharing like you do!
thank you Scottie, I am in the need for one... I will making this in the next weeks
Good morning Cletus and Scottie 🖖🏻. Getting coffee and trying to stay awake for the new video.
I used a Microcontroller and LCD Screen to actuate the Solenoid with a foot switch. I can now control exactly how long the Solenoid stays 'ON' with 'UP' and 'Down' push buttons.
Since we're welding 18650's couldn't you build a battery pack with 18650's? I have them, what I don't have is a motorcycle battery.
I made this from the same plans but reworking it using the jumbo pouch cells from battery hookup and I 3d printed a probe holder as well as i designed a holder mount for a drok timer relay. It's been apart for months now but worked great with loose wires and a 600cca lead battery
Bare in mind that a reverse diode across the relay coil will also cause the relay to stay engaged longer, another trick is a 1 or 5watt zener diode around 50 volts, or use a neon that will shunt at ~80volts. That way the relay will turn off quicker and less chance of the contacts in the relay welding on. Also if you got a really large CCA battery using longer wire leads would reduce the peak current, if it's to high use a longer wire to introduce a little more resistance.
It is better to use a small inductor (just coil the wire 5-10 turns) so that the peak current is limited.
Excellent video loved the explanations and detail. Thanks for posting.
Hi, great videos. I'm going to use a Dark Welder but with your mods. I have a recovered cap but it's a 5600 uF 63V, will this be close enough? I assume it will be a slightly longer discharge.
I also had the cheap spot welder, blew up on first use. I removed the blown mosfet, installed the capacitor mod and it worked. But it was just rubbish, no power, hence the need to build a better one.
Yeah, 5600 is close enough. You'll get a slightly longer pulse, but not by much.
Great video. Actually years ago I used a similar idea using a car headlamp , switch a capacitor with diode . worked ok, Now have a portable which has till now worked good, but when it's internal battery goes it becomes a throw out or a mod job as cannot find spares and trying to ask sellers, well, you get nowhere.
I got a spotwelder like the red one , from bang good, it exploded, and caught fire for a second, and didn't even make a weld!! I built one with a solenoid, and a SSR, with a timer circuit, it works well, but is cumbersome, a bit awkward, I wanted something smaller, I'm just going to modify my original design, to make it smaller and easier to use! But I'm here looking for ideas!!
SCOTTIE, is there ANY way to reduce amps cheaply & effectively? I thought of 1 or more old-school automotive headlight bulbs inline - seems for sure it would blow them out but I can logically decide why. (Won't a circuit with a bulb only pull as much amps thru as required by bulb?)
I built a kvdrk setup, trying to use my lawn mower batt, but its 375 cca, blowing out my welds.
Much thanks for the updated design & great explanation! And really great tip on blunt electrodes!
The trouble is that the amount of current for the weld is so large that limiting would be kinda difficult. If you used a light bulb, the welding electrodes would just complete the circuit on the metal surface of the battery (or whatever) but the small current through the bulb wouldn't actually weld anything. You can connect a 12V automotive light bulb across the car battery, and it won't explode since the bulb limits the current. Now, if you had a 12V 1000W+ lightbulb, that would do the trick! That would be one CRAZY bulb, tho.
great video, thank you. one question though. wouldn't it be better to connect your old welder to this battery/relay/switch -combo, just to have the option to adjust the timing?
if my welder burns up (same as your old one), i think to mod it this way.
I tried a 120v welder, with a SSR , and timer, it didn't work! Maybe using a solenoid on the lvdc side, maybe, but the relay can only react so fast, mine the timer can pulse faster than the solenoid, and welds best if the solenoid barely fires, with 12v. Most welders are about 24-36v. It may just burn everything! Even with the faster pulse
Very cool. Have you thought about doing the same design with a DC SSR? I am wondering about longevity of the solenoid contacts. I have the cheapo spot welder and it seems to be working so far. I think there may have been design changes over a couple years. Hope mine lasts. If not, I will build a Dark Welder 2, but might take it into the microcontroller SSR world for a Dark Welder 3.0.... :)
I was thinking of just using an adjustable 555 timer set-up for the switching of an old Ford starter solenoid. You know... less math.
Unless there is something I'm missing here, and it wouldn't work.?.?
This does the job. Can be adjusted from 1ms up to 99 ms.
@@Graeme758 : Did you mean to post a link in your response? If so, it didn't show up...
I have one suggestion, instead of buying copper nails why not take a couple of inches of 14 gauge nomex strip the wire and you have copper terminals? I am glad I came across this. I am getting ready to rebuild some nicad battery packs and it was highly recommended for safety that lipo batteries be tab welded instead of soldered.
Can you use a 12v 30amp horn relay instead of the starter relay? Thank you for the very descriptive information on how it work with the schematic s
I don't think so since the starter relay can handle more current than the horn relay.
Awesome video... Is there a name for that alloy you are referring to that does not fuse with the nickel strip (so that I don't have to file the electrode pen tips off like you similarly mentioned) ?
It seems it's nothing terribly fancy... There are these, for example: amzn.to/3wDnC0P
They're a standard alloy that's apparently 99.1% copper and 0.9% Chromium. Well, it's not 100% clear... It could be a different type of Class 2 copper alloy, like Chromium Zirconium Copper (they add a bit of zirconium which helps prevent the tips from sticking during welding). Just note that if you use anything other than pure copper, the conductivity of the tips goes down, so that will also change the weld you end up with. You might need more current, or a longer weld time, etc.
@@ScottiesTech Wow awesome man, thanks a lot.. So I guess it's a bit of a tradeoff then huh? Like you sacrifice a bit of conductivity for a little less sticking by going with the .9% zirconium? You don't need to respond, this was great info and maybe down the road I can try those out. Thanks again, definitely subscribed to your channel, you have really really helpful videos.
Just wondering why your timer circuit couldn't be used to fire 8 mosfet board that that was properly heat sinked. An if so what changes would be needed.
Scottie, great video, very helpful.
“It’s not electronically controlled”.
Actually, as soon as you added a capacitor, it is electronic. General usage of the word electronic today implies computerized, but by strict definition you created RC and RLC switched circuits which are both electronic.
Great job explaining the design and function. You might have mentioned that using a different battery or solenoid would affect the size of the capacitor needed to get a good weld.
Thanks for sharing your experience.
So I just built this spot welder. I have a 12v 20ah battery. My capacitors are the 4700uF but 50V I bought the Starter solenoid from the link and the schottkey Diode. I had a lighted push button and I used solid 8Guage copper grounding wire soldered to the end of 6 awg wire. I used a 25 watt 150 ohm resistor versus a 2 watt. I am excited and was doing some test welds with bad 18650 cells. I am pleased but every now and again I get a more powerful weld that Burns through the nickel .15 bus bar. I am not sure why sometimes it is different. Any ideas on how to make it more stable every time. I tried to very quickly press the foot switch but sometimes it is way more powerful. any help would be greatly appreciated.
It's probably the larger battery. Most likely, the 20Ah battery (vs my 10Ah) has a higher CCA rating. That means the larger battery will dump more current into the weld in a given time period. So, you might try a smaller cap instead (like 2200uF) and see if the shorter welding time is enough to limit the current. This is exactly the problem Kevin Dark had with his setup when he switched to a beefier battery: he had to tap the momentary switch in his setup more quickly to get proper welds and avoid burning thru the nickel strips. Hope that helps!
@@ScottiesTech Yeah I was worried about the bigger battery. I will try to get my hands on a smaller cap. I have a much smaller 100uF but I don't think these can be daisy chained like a resistor can. I may try to scrounge up a smaller battery. I am very excited. I also may try to make my welding rods smaller. I also may use 10 awg wire instead of 6 to attach them. I think I just deliver too much current. Normally i have the opposite trouble.
@@SolarBuck Capacitors add when connected in parallel (the opposite of resistors). So, you can also grab multiple caps of smaller values and connect them all up to test and find what total value gives you the best weld. Lemme know what you discover!
Solenoid close time varying? sticky contacts?
Brilliant, thank you for sharing!
Thinking of different nickel strip thickness, would having 3 or so different capacitors on a selector switch help tune the spot welder. Ps I’m going to build one as the keep it simple approach always delivers reliability.
Thanks for posting the facts!
How do you increase the weld time for a slightly thicker nickel strip? I want to use the old strips from Ni-cad batteries. They are just a tiny bit thicker and will not attach with this type of welder.
Using a larger capacitor should do the trick. See the Capacitor Discharge calculator in the video description.
Back EMF But a good circuit very simple as my Dad used to say KISS it works
Hi still got bit of Kevin's welder
Found it wasn't very good though it needed a timer looking at yours you have rethought it and sounds ok have you fully tested it ? see you didn't do a distruction test by pulling apart the nickel off the battery is there any adjustments for thicker nickel tabs good video pitty about that pipe work behind you really bad 😀👍
For thicker metal tabs, you'd probably want either a larger battery (more current) or a larger capacitor (longer weld time). The welds I've done with 0.15 nickel strips have been pretty strong. The nickel tears before the welded spots break. The pipes are antiques. Minimum 50 years old, probably more like 70 years old. They still work tho (for heating), so I won't complain.
thanks for your comment ! when you say cost !! priced battery and solinoid was about
£50 plus the other bits all about £90 plus to build this [ thinking!] is it cheaper buying a
shop bought spot welder ?? love making your own things but you have to stop and think costs some time dont you think cheers
@@robertsingleton2364 Yeah, I went easy (Amazon) but I oould have nabbed all the parts needed from eBay or AliExpress and then waited... Also, a local farm supply store has DIY batteries (not sealed) that are about 2.5X cheaper than sealed ones... and they last just as long. So, I reckong you COULD do it cheaper. Actually, now that I think about it, I already had a spare small battery! D'OH!
Good stuff Scottie, would it be possible to put a potentiometer into the circuit to be able to adjust the weld amperage?
No, since it would have to carry a LOT of current and therefore be hugemongous. But what you CAN do is choose a different battery with higher/lower CCA rating and adjust the capactor value for shorter/longer pulses.
@@ScottiesTech Yes of course, thanks Scottie, great work you do, we really appreciate it.
Can I use that spot welding for jewelry soldering of silver jewelry
How would you use it this circuit with a lawn tractor starter solenoid? It trigers the relay but not long enough to let current pass through the circuit.
You might have to change the capacitor to a larger value to trigger the beefier solenoid.
@@ScottiesTech well the question would be how much larger? and would I still need the resistor?
@@countryside8122 It depends on how much current the solenoid needs to fully close - just briefly. What I did is hook up my solenoid to 12V, then monitored the current on my oscilloscope. That let me see the peak current needed to activate the solenoid. Then I used the capacitor calculator (see description) to get a rough estimate of the capacitance needed. And then I tested it, and POOF! Worked like a charm. If you don't have a scope, you could just use a multimeter to measure the current going thru the closed solenoid when you apply 12V, and then increase maybe 30% to get a rough estimate for the cap calculator.
Great Video Scottie. Loved it. I have 3 questions. (1) If i replaced the copper nails with plain Iron nails, what would be the result ? (2) Copper has a better conductivity than Nickel strips, why is tinned copper strips not used (to rule out the possibility of oxidation), (3) Using an Arduino and generating a pulse to control the Solenoid could offer flexibility in timing. Keep posting and keep developing.
You can probably use iron nails, but they'd be less conductive than copper ones and I'm not sure what kind of weld you'd get in the end. As for the strips, I'm not sure... I read a whole lot, and I learned very quickly that spot welding is complicated. So, I just used what most people said was best for spot welding 18650 cells. The metal alloy of the batteries matters, the metal alloy of the strips matters, the nails/welding probes matter (including their pointiness or lack thereof), the amount of pressure you put on the strips matters during a weld, and the current pulse matters (incl. duration and even the shape of the pulse). Mostly I was just looking for something quick and dirty and above all, simple!
@@ScottiesTech Thanks Scottie. I will attempt to do just that and will keep you posted.
Thanks again for your time.
@@madhavdivya Any Updates?
Might be a good idea to wear safety glasses just in case there was a spark tag put material up into the air.
Elegant solution
put like a 1meg resister across the capacitor, it will drain it down nicely once you turn off the power to it.
D'OH! Good idea.
Does it matter what watts?
@@chrisfojtik7391 if you use a 1meg resistor the current is in the micro amps so not really, you can use a 1k resistor and it will discharge the cap much faster and you probably want to go with a 1/4 watt resistor, but even a 1/8 watt would probably do since the wattage is going to be about 156 miliwatts for about 4.7 seconds. Higher resistor values = slower discharge and less current. it really depends on how fast you want to discharge it, too fast and you are affecting the on time for the pulse on time. But I dont think anything between 10k and 1 meg will alter the performance.
What about the clicker petal switches they used to have.
Are 3g phones still viable? I understand that carriers are not going to support them any longer.
Depends on where you live. 3G will be around for awhile yet in many places.
I tried building the original Dark Welder and it didn't work for me. It burned holes through the bus strips and didn't weld the strips to the batteries. I ended up soldering them on instead.
Nice!
Yay, no mosfets! My only concern is if the solenoid decided to weld itself together
It hasn't so far, and it's for a starter motor - so you'd think that'd be sturdy enough to withstand the pulse.
A better solution would be a cheap fix for the original red spot welder, I am sure many will have the same problem of burnt mosfets ?
What ever happened to the good old fashioned clicker switch that disengaged just after you touched the switch You pushed down. It clicked and disengaged after the click. You could still be pushing the switch and it would still disengage the power.
SPMC - single pole momentary contact.
www.gardnerbender.com/en/p/GSW-22/SPST-Momentary-Contact-Push-Button#
Thanks for ur video I always wonder why in all relay circuit there always those diode tie across the coils , and is there a way to very the capacitance to change the pulse time for different nickel thickness
Well... I was thinking about that, and my idea was pretty crude, but: I would wire up several capacitors of different values, and then use a switch to select which cap should be connected to the circuit. Using the discharge calculator linked in the description, you could get a rough idea of weld time. If 4700uF is 5ms as measured, then 2200uF would be roughly 2.5ms, 9600uF would be about 10ms, 18000uF would be 20ms, etc.
interesting , seems like easy when someone will show how :)
What, no affiliate link for the relay/solenoid? I was really hoping to be super duper lazy and click through and buy everything at once. I've been putting off buying/building a spot welder and half the time when I start filling my cart the links are always old or like in this case Kevin's links are all UK and old, so I never quite get everything and then it just kind of annoys me and I chase the next shiny ball passing by. Your links are actually good, I add things to the cart on Amazon and go back and right back where I should be and not teleported to some Tonga ad loop where I have to force close to get to the previous item. This is so close but I don't want to watch more videos and sift through more links. I know you don't want to do a shameless cash grab but you have given Kevin all the kudos required. Just because Kevin isn't keeping up with his links and providing some good old US links for those of not in the friggin UK it doesn't mean you have to continue the tradition. He's leaving money on the table by not keeping up with them. You improved his design of the spot welder right? Well do the same with the parts list. You have given him plenty of props. Give us a complete list, ideally with everything from Amazon. Make a wish list and share it if you don't want that affiliate money. It's 3am and I'm shopping, I don't want to navigate some craziness, I would love it if you could facilitate a one stop shopping experience with US links all from one cohesive cart. It doesn't have to be Amazon. There are tons of affiliate programs to join. Don't feel bad about making money from this. Sometimes you work your ass off and get next to nothing so it's ok to grab some low hanging fruit.
Oops! Here ya go: amzn.to/2Igv1jB
nice listening to you, but I believe You should do better simplifying that overcomplicated explanation in the future. I know, it is not easy :)
Thanks for the note on the electrodes. A very fine tip does not work.
I think the best way to control time of each pulse
Is by using 35238mp relay board cost only 2$
You really need a slow blow fuse in case the solenoid seizes, then the battery would stay delivering current and you could be trouble ...melt down situation.
Can you talk more about this? How would it work in this design?
Where do you get the nickle strips?
You can get them on AliExpress, but I just ordered some from Amazon (which also came from China in the end). There are all different sizes, or rolls: amzn.to/2J1YygO
Thank You . . .
you can simply do it mecanically using a limit switch
👍
Interesting, this is the first video i see that says 150CCA is good enough, usually i am told that at minimum its 250.
What if I use a 500F capacitor?
You mean like a Maxwell Durablue 16V 500F supercap? That would probably work quite well in place of the battery.
Just check it's internal impedance. If it's below 20 milliohms it should be ok. 500 farads.. must be huge! Probably needs to be 16V or above rated
Can't figure out this guy's accent. Good pronunciation, especially the ending 'L' as in 'weld'. North American locution. I'm thinking Canadian but 'o' in his 'constance' suggests mid-western states.
Midwest!
I prefer electronic switch...
I know why the MOSFETs died.
@ 0:42
That would be me. 😆😄🖒
Comment from 2 months ago on this video: ruclips.net/video/RYU_shrscoo/видео.html
Tag you're it
Does this little welder not give off radiation like the usual ones that you have to wear gloves and masks for?
Probably a teeny-tiny amount, but nothing like an actual arc welder. Arc welders dump tons of current through the metal via an electric arc that glows VERY brightly and emits tons of UV - hence the need for eye protection (against the brightness + UV) and face/hand protection (against molten bits of metal/sparks). If an arc welder is a brontosaurus, this little spot welder is more like an ant!
@@ScottiesTech Well im really glad i found this video bc i was considering picking up welding as a hobby but its a very pricey hobby, especially for the job i needed it lol. Also I read somewhere that arc welders give off infrared as well as UV? Makes me wonder how a tig welder (the one i wanted to get) differs from the other 2 as far as frequencies and intensity is concerned. Tiny welder seems a lot more safer because it's not as intense I guess. I wish there was a cheap way to test what they give off, would a simple emf or rf meter (dont know the difference lol) do the job? Again thanks for all your informative videos 🤗 I really do enjoy them
@@Magiaimelissa Well, arc and tig welding are a WHOLE different animal. My little spot welder is only really good for thin layers of metal, and even then it's nowhere near as good as a customizable pro spot welder. There are also big spot welders that are extremely powerful for welding big pieces of metal. High power welding is fairly safe if you use good protective gear: mask (preferably with auto-dimming visor to protect your eyes), good welding gloves, a heavy apron (leather or similar), and above all good ventilation and/or a respirator to avoid breathing in all the fumes generated. It's a dirty job, but lots of fun!
@@Magiaimelissa You do understand everything in the universe gives off infrared radiation... anything that is above absolute zero in temperature anyway. Infrared is light and part of the electromagnetic spectrum just like the light you can see, and no more harmful than Sunlight.
To learn how to weld I would start off with a used Mig welder which can be had for around £20-50, then move on to Tig which is much harder to master, but a new tig inverter welder can be had for as low as £40+ on places like eBay now, or find an old Ark welder but don't try and weld anything thin. :) Anyway good luck!
Too much talking 😳
That is not the right way to make a spot welder.
An electronic timer gets rid of the diode and the capacitor , by timing the solenoid in millisecond increments.