wow this was a great video. I came away with a genuine understanding. I actually watched your repair video first and didn't quite get it. Now I feel confident in not only carrying out the modification but my overall understanding of all the requirements of the device for success.
@@Luca_Techy Thanks! Will do. My plan is to do your mod and then power the purple board with a 16V 83F supercap bank. If I understand it right, having that much current capacity will allow me to keep my pulse time super low. (And allow me to weld nickle plated copper at 0.15mm or .2mm sandwich)
This is probably the best tutorial on spot welds I have come across TH-cam. Very well explained with crystal clear concepts on this subject. Thanks a lot for posting this .
Hi and thanks - if you would like to see a more complete video you should check out my latest FAQ one where I go a bit more in depth on the subject (it should be linked at the end of this one or just check my Spot Welder playlist).
Hi, when resistance welding the pressure at the weld site is important, too much pressure reduces the resistance and therefore the heat attained. It is a delicate dance to keep the pressure adequate to produce the heat without sparking which is the material being expelled.
An observation from using the “purple” 99G & the very similar green pcb, (8 gear, only one chip, FMD mcu clone) both with the de-coupled gate-drive cap mod, is if I use a low ESR cap the welds are visually hotter & hold better on the strip-removal test. I purchased an oscilloscope which will arrive soon, & I will capture the gate waveforms to observe if there is indeed any difference in the rise-time or fall-time. (I don’t think the fall-time will be affected as that’s from pull-down resistor value, to my understanding) But, just in practice, the fets seem audibly “snap” on and off better with the low ESR cap. There are other factors that could be at play that I haven’t tested yet though such as the measurement and quality of the original caps I used for the mods. I’ll learn more from further testing. Also I can confirm that the mod you show on the purple pcb also works on the very similar green one that differs only slightly, having fewer logic components and a single digit display with “8 gears”. It simply has larger time-increments between each weld-level setting, with eight steps. (gears) Edit: I’m also using longer, larger gage leads & running a beefy TVS diode across the output. I haven’t noticed any negative effects, or had any mosfets blow this far using beefier leads. (input and output) Edit: After further testing the low esr cap theory, I’m not convinced that it’s valid. It appears that any decent cap is capable of charging the gates in a similar timeframe, with largest factor being to use high enough capacitance value cap that voltage sag doesn’t occurs on the decoupled gates. The 470uf cap does seem sufficient to accomplish this as there isn’t much v drop on the gates. (25v rated or better) I likely jumped the gun a bit on my assumptions with the low-esr caps & the increase in weld performance that I perceived, with other factors probably being the cause for any perceived differences. but, we live and learn!
57:53 would it be problematic to connect both red wires on the input side istead of on the output side? just for convenience giving more room to maneuver
Nothing beats the chinese Mini Spotwelder generation1 with two 4s 3000Mah LIPOs in parellel. That is just how it is... we are about to start implementing the Mini Spotwelder gen1 in our assemply floor at the Sachsenurt Skoda car assembly production line for bodywork parts. We use E42 on the mini's display for the thinner bodyparts and E73 for the thicker areas.
That is possible but *beware* (disclaimer below!) the internal battery is a ONE CELL battery. Typical battery packs are 2 or 3 or more cells in series - you would have to have a single LiPo cell battery (the circuit is designed for one 4.2V LiPo cell only o no series, even if very large in capacity - 2 identical cells maybe be put in parallel though). Also, if you really want to remove and disconnect the internal cell, be VERY careful when you attempt to remove it as if you even just slight short the 2 terminals that will fuse the contact point and the battery will catch fire burning everything in proximity. Always cut one terminal first while keeping the other well isolated, isolate the cut terminal with good tape then cut the other. DISCLAIMER *I highly advise against this procedure if you don't have experience and take no responsibility for any fire or injury that may be caused by this*.
Hi, you really need a battery for this to work properly (a PSU that powerful would cost you a fortune), a 3S LiPo 50C 5000mAh or a 12V AGM 45Ah (or slightly larger) car battery are suggested. Check out my FAQs video in the playlist for more info.
what resistance must be between contacts of mosfets when on board (purple)? mine stopped working because I used fresh 110ah car battery and used thicker wires so I assume mosfets went bad. I do not see any visual markings that something burned, and LCD is still working.
I'm not sure what you mean: if you don't get welds/triggers and you don't hear any beep confirming the trigger then something definitely has broken. If you hear the trigger but don't get a weld then your FETs are not getting a gate pulse. Assuming they are all ok and not all blown open (rare) your optocoupler might have failed. You need though a scope to check if the opto output junction is working.
Thanks for the new video! It's good info for the DIY/low-budget builders like me:-]. My old maple mini is still getting the job done. But it's good to see more/new stuff. Watching your video makes me wonder....if you were to design your own ideal battery welder circuit, what would it look like? I have a little experience with PCB layout but lack circuit design skills. Might be fun to work together and do some sort of open-source/low budget welder build. It's hard to find time for stuff like that, but if your ever interested let me know!
Yes I've thought of designing an open source spot welder and even started it some time ago but to make something at a decent level of quality the cost would be rather high (over 75 USD or so) and to make something less by cutting corners gives you what is already on the market. Yes maybe making something along the middle could also be viable but it would still cost more than what is available even if "improved". Anyhow I will think about it time permitting, you never know and thanks for the availability!
Great video Luca - do you know if this can be used with a car jump starter pack if so what would the max amps be as I see some jump starter packs go up to 2000/2500 peak Amps. Is this too much or would actually be better than the 1000 peak rating variants? Also is there a max 12v car battery this can be used with would a 70Ah 640CCA be ok?
Yes you could though you really have to be careful as if the peak currents are realistic it can be destructive for the FETs so use at your peril - but luckily usually it's all most marketing hype and the realistic values are well under 500 peak Amps which are more than enough to start any car. A 70Ah will also do if in working order just always start with the lowest setting like 2ms and go upwards.
Hi, very interesting!! However I think the problem with these small welders is that most of them work with only ONE pulse (with regulation of amps and milliseconds in the same pulse) and it's very difficult to find the precise regulation for a good welding without burn or hole in the strips with different thickness. It's the same issue with a modified micro-wave transformer and a simple control board for amps and welding time. With 2 or 3 very quick pulses the strip does not burn , we don't need so much amps for a good welding, and I think it's also better for the battery and the mosfets. A good spotwelder allows to control the amps, the milliseconds, the number of pulses and the delay between each pulse to get the best result. I have a big one like this , ...and also a new little MinderRC DH30max : I can modify the amps but not the milliseconds (I think it's 20ms), and i choose between 3 positions for welding, but i have no scope to control if it's simply a variation of the milliseconds or a possible pulse choice . I must say it works very well for occasional use (always in position 2 or 3 and less amps), but I don't trust it for its lifetime, in particular its (10.000mAh but in fact 8000) battery. It's really for very occasional little work but it does not burn the thin strips with good welding. And I must survey the auto-discharge when not used.
Hi Michel, yes a multi pulse solution would be better (like the Malectrics has) of course as it primes the surface before the proper weld but these are cheap devices with a very small MCU that allows a limited amount of code. As I showed with the first red mini spot welder I was able to replace the standard MCU with an Arduino and get it working so that would give you any variation on the pulse you want to program. All portable spot welders only use time as pulse power as it is impossible to limit the current with just a battery and no calibrated shunt for current detection - the cost is very high and only applies to larger professional devices.
@@Luca_Techy OK Luca , I think we judge welding tools "with the same glasses" . I just add after some trys that my little DH30 allows 1 , 2, or 3 pulses with variable delay , a good technical solution for 40€ and to build simply some little packs (for screwdrivers and else...) . I just soldered 2 wires on the + and - of the battery with a female jack , to choose and control the charge (storage charge for example) and also the voltage level by use with an Imax B6 with better precision, compared to the little included card. I have the best welding if I only gently press the electrodes , simply to get a good "quiet" contact between the strip and the cell and not more , so I get maximal heat with limited intensity , and I clean the electrodes , light but very often with fine sandpaper, to maintain the best result . Your explained precautions are very useful if we decide to open these little welders , lot of thanks!
You need an extreme amount of peak current, over 150 Amps at least to spot weld. A normal PSU won't deliver that current. As previously explained (check my FAQs video) ordinary PSUs are not designed for such peak currents and will 'trip' their short circuit protection if you try. You would need at least 2-3kW rated PSU to even attempt to spot weld. This is also why people modify MOTs for this purpose, but it can trip your household current protection breaker.
You’re doing Gods work my friend. Really making it easy for us self taught electronics hobbyists to understand these spot welder PCB boards. I’m curious though what is the difference between input current and weld current? Just a random guess but since weld current usually has to be above 800A is weld current the input current multiplied by the number of fets?
The current that travels along a series circuit is the same in all places along that circuit (I = V/R) so the input current *is* the weld current, whether you measure it on the battery leads or just before the weld point. What changes is the measured Voltage based on where you measure it: it's a series circuit adding the resistance of the weld "Spot" + the leads' resistances + the FETs' internal resistances + the battery internal resistance. This is why in these mini spot welders you need a certain amount of "slack" resistance with the cable length and type and rated battery pack to avoid destroying the FETs. You need a certain resistance in the spot weld area also so that you can convert that current into heat and weld (hence why you shouldn't press the electrodes too hard). If you had a perfect conduction between the 2 surfaces there literally would be no weld. The issue is to keep the peak current below a critical value (
@@Luca_Techy That actuallly helped me understand a few things I was having trouble with. I had wondered why the Kweld manual had a formula for the leads and suggested not going too short or too long. So is it possible that using too large of cable (say 2AWG) would actually be a bad thing? Is 6AWG big enough for a short pulse of 1500A? I see some welders now come with what they claim is 25mm2 cable but I do wonder if its actually copper. Probably CCA...25mm2 is 4AWG. I think the Kweld uses 6AWG silicone or EDPM but either way its pure copper. And is matching fets about resistance? just got an RC3563. \ Couple more questions. I see my spot welder has "copper aluminum electrode tips" and thought this was an interesting choice of metals....is it a good choice? I'm thinking of taking the 10Ah battery from my old welder (not much use) and adding it to my new welder in parallel. If I just make sure to never set the power too high (say never over 50%) I should be fine, right? Then slowly I can try it a little higher.
48:14 Wow, that's amazing and quite well might be a solution to my problem. Now: 1) Where can you get matched FETs? I suppose Aliexpress will be full of fakes. 2) If I get not-matched FETs and "blow" one? Will it still work with 9 FETs? Wouldn't a really dirty solution be to just buy a bunch of FETs and keep blowing them one by one, until a stable setup is found? Yeah, dirty and labor intensive, but would it be a solution? 3) The bars are just some brass rods? Would a piece of thick copper wire work for the backside?
Properly matched FETs are sold in bundle by official distributors such as Digikey, Mouser, RS etc. When you parallel FETs and one "blows", you can still use the welder as long as the faulty/shorted FET is removed. The bars are just brass rods yes (doubtful it's copper) and they are there to help the conductivity and reduce resistance. You can also bolt the Positive red terminals together on one hole to bypass the positive bus entirely as the switch (FETs) is on the negative side (N-MOS FETs).
Very professional Video, I have a same black box model as yours, I used cell phone fast charger, it doesn't work now. I replaced charge chip, charging is ok, but the light is always on, I checked the FET works well, I measured the voltage on the optocoupler, pin #1, 3.023V, #2, 3.967V, #3, 13.326V, #4, 0V, #2 is through a resistor to MCU pin #5, I suspect the MCU damaged but not very sure. it is much appreciated that you can spare some time give me a guidance for further check. I read some forum it is consist of a NPN and PNP to drive the MOS, but my PCB shows both are NPN, its silk print is J1, and is there any method to reset the MCU? I took it out and just connect the VCC and ground, pin #9 and pin #10 to the PCB, but #10 output low voltage to let the light always on.
Hi, I suggest scoping the opto input pin to see if it's getting any pulse (probably not but check). If there is no pulse it's probably the mcu (does it behave normally like pulse settings change apart from no pulse?)
Hi i use same purple solder with lipo 3S 5200Mah 80C and on gear 11 welding perfect 0.1 nickel strip ,but sometimes casualy i got a lot of sparks. What cause this sparks casualy?some high resistance? maybe not pushing corectly the pins?or pins not cleaned?
Hi, the sparks can be cause by dirty contacts betwee the strip and battery terminal which causes "sputtering" which is material being blown out by overheating from the contact spot. It also happens if for ex. you have some solder on the nickel strip or battery: this will be ejected violently when you spot weld due to high temperature so be careful - always wear protective glasses. Also if you do not press down enough this also can cause sputtering which is not good either. You need to find a good pressure zone, not too much but not too little to get a well bonded weld. Some sputtering is ok, but not too much and not too little. I am preparing a video also on this argument so stay tuned if you're interested!
@@Luca_Techy Thanks for your response. I would like to tell you that I found a possible defect on the copper tips of the probes that i weld with, they were not crimped propery, they had a bit of play, so I used a bit of tin to weld them so that they stay fixed so as not to create false resistance and now it seems to me that the machine welds very well even without sparks, but as you said, only if the two surfaces are perfectly clean. Sorry for my english and thank again
There was a video of someone who has a review where he had tested 5 welders. He said one of them was spot ine out of the box and did not need any mods. I cannot find the video to see which one he showed.
It's one LiPo cell so it's 3.6V (4.2V charged, 3.3V discharged). Judging by it's volume and the contact width I'd guess it's about a 5000mAh 50C minimum.
If you're referring to the all-in-one black box mini spot welder there is no specific mention; judging by the size of the cell it's certainly at least a 40C (or more) and the cell capacity is around 4000-5000mAh but to be certain one would have to test it with a full charge/discharge cycle.
Hi, I got the purple one and saw that you connected it to limited current power supply. Can I use it like that to weld included nickel 0.15mm? If yes, what current settings did you use? Thanks for the video, helped a lot
@@samuellos it's fine as long as you leave the original cables shipped with the welder and start from 5ms working your way upwards little at a time. You should get decent welds with .12-.15mm at settings around 15-20ms. If you need to exceed 30ms your battery is not performing well or it's not hooked up tightly to the terminals.
@@Luca_Techy Hi, so I connected it to the battery, tested welding on lowest setting, it was weak but working but after couple welds it looks like the battery died, I saw display slowly turning off. So I charged the battery over night and now its makeing holes when welding on lowest setting and big sparks on that spot, with no beep sound. What could bé the problém please? I hope im not bothering
@@EDIPSOSTT that deoends: apparently yours is not triggering, if it beeps but doesn't weld the FETs aren't getting driven (no gate pulse) - you need a scope to investigate. You can try my lamp test (check out the video about it).
@@EDIPSOSTT It's not triggering the FETs: do you hear the weld beep when you try to weld? If so the FETs' are not getting any trigger - did it ever work or was it like this when you received it?
Im very interested in this purple one. Im going to ise a motorcycle battery as power source. In your opinion Loca with your mods would you recommend me this one?
The purple one is ok with the gate drive mod. As usual don't overdrive it, these welders can't handle very high currents for prolonged weld periods meaning that you shouldn't weld over .15mm or you risk destroying the FETs. Always start testing from 5ms or less. This goes for all these mini spot welders. Be sure you have a good battery and don't shorten the cables to start with (they limit the peak current). This welder needs a cover to protect it so get the version with plexiglass or 3D print a cover. The Wise Maple version is also not bad "out of the box" if you add an "anti spark" XT-60 plug for LiPos or do the inrush current limit mod as shown in my videos (check the playlist it's all explained there).
@@simplyfocus9937 0.2mm is too much for these welders, it welds up to .15mm if you have a good battery else you risk destroying the FETs if you overdrive it.
@@Luca_Techy You are right. How did you do with the maletric spot welder. I did more than 10000 spot weld without any problem. Too bad it is broken due to user errors.
Thanks for this video. I have on of the units with self contained battery with a different design. Its pretty good but after 10 welds, as you said you need to wait 5 mins for the battery to recharge. It makes welding slow. I was interested in purchasing a more expensive unit that would last longer and be more servicable for up to $200. I was curious what you think of supercap based designs and if you had any recommendations. Or are battery based designs able to get better welds at my max budget of $200. Thanks!
With that budget you can certainly go for a more high end type such as the Malectrics DIY Arduino based for under 170USD. There is little assembly in the complete ready made DIY kit and it is certainly a more complete and proper design (there is a model for 12V AGM battery or LiPo pack) with power calibration - check it out on their site. They also sell components for a complete DIY build if you have the skills which means you can also always repair it yourself later if something breaks. Supercaps are a good add on but if you have a decent car battery and proper AWG cables you can do without - it all depends on the amount you weld and the thickness of the strips you want to weld. For basic hobby or personal use it may be an overkill - but if you're looking for a more resilient and capable product it certainly seems to be (though I have neither tested nor analyzed it hands on, I merely have seen the specs and characteristics and some of it's design from the site).
@@Luca_Techy Thanks so much Luca for getting back to me. I took a look at Malectrics DIY Arduino unit and it looks pretty good. Do you have any thoughts on the kweld units from keenlab? They also seem to have a kweld-ultracapacitor-module you can attach. I'm if you have heard anything regarding there units. It looks like it might be a little over my budget though and I don't know if that extra money would actually translate into a better product or if it's best to just go with a car battery and one of these other units :) Thanks again for your advice.
@@petersvideofile Yes I'm aware of Kweld - certainly a comparable professional product with similar characteristicts probably even more potential as it has a supercap kit option - they're both good from what I can see (again, never had any hands on experience with them). The only major difference is that the "MCU" on the Kweld is custom placed on their pcb (I don't know what it is) and requires a seperate level converter and adapter to reflash/update whereas the Arduino Welder uses a standard Nano module which you can easily replace if needed. Again I always think about the repair possibilities as these devices are all prone to fail sooner or later based on the use - but that's just me. Maybe the Kweld is even designed better, I can't really say as for that I'd need to see schematics & layout.
@@Luca_Techy Thanks so much, also very good point about repairability of the Malectrics unit. I hadn't thought of that, I think I will probably buy one when the time comes :)
@@ericklein5097 Thanks so much for this super informative comment :) I'm going to follow up on this some time. I still didn't buy another spot welder yet so your input is very valuable to me!
I’m shocked at how flaky the entire batter spot welder industry is. The kweld kit seems to be the most reliable but it’s not accessible to everyone. Even the infamous Sunkka line doesn’t have a perfect record - or perhaps I’m seeing lots of fakes.
This black box welder is very poor. If the battery shorts out you will not just maybe damage your equipment but maybe burn your whole house down! The power is very very weak, why don't you just say it is crap.....
Well I wouldn't say it's rubbish: it works "out of the box" and even if it has limited power you don't have to open or modify anything (considering the others this is already a plus!). The fire hazard is comparable to any other with attached an external LiPo pack if you think about it - worse if it's without a protective case...
@@Luca_Techy I said it's weak and it is very weak. There are far superior welders for way less money that will easily weld 0.20mm strips. The battery has NO protection and is not detachable like other devices which have XT60 easy disconnection. Your not impartial in your analysis.
@@lancelink88 I'm sure there are better versions, and I concur that the battery is not detachable (I do underlime this, it is all self contained) and also point out the reduced life of the whole device, I merely state that whether you are using a detachable LiPo pack (which mind you is preferrable for obvious versatility) or using this or other self contained models the risks are the same (if you use a detachable LiPo battery pack and the welder FETs short and terminals fuse, the risk of fire is there likewise). The internal single LiPo cell doesn't just short out by itself unless punctured or overloaded just as any other LiPo. Don't get me wrong, the welder is a cheap device and I state this but saying that it has no protection implies that one would have to open it to expose the terminals something which you're not supposed to do and I advise not to unless you know what you are doing. In other words all these mini spot welder are a fire hazard especially when used with LiPos something which I have always warned about (in fact I suggest 12V AGM batteries which are safer and don't explode nevertheless one always deals with large currents). I hope this cleared my point regarding the concept of protection (which no LiPo pack or cell for this purpose has respect to LiIon packs whcih are required by commercial law to have based on their application) and fire hazard in regards to LiPo cells.
bro you have case in box when you been speaking about to its danger... literally a transparent box you have on the table and you speak about how it will be good to make one heh :) check first what you have before speaking about it without researching.
I really don't understand your point - the clear acrylic container option for the purple welder offers some protection against accidental shorts instead of having just the pcb lying around with no isolation at all.
@@Luca_Techy there is acrylic isolation on top and back from sides in that brown plastics its just wrap . its up to you how to protect it you right . all good :)
So i have had a bit of a night mare. I wanted to add mosfets so i followed someones link and bought the wrong fets (IRLS3034-7P) They look good quality and would work because i have 10 but hardly worth doing. I made a second order for the correct fet off another seller (IRL40SC228)but they look very suspect. terrible quality so i don't think i should put them on. My spot welding board currently has no fets installed.
Well TBH if you think the 3034-7P are original then you could just as well mount them - don't think that there will be any major observable difference if they are a batch of properly matched FETs (consider that the only major difference is that the 3034 has an RDS-ON of about 1 milliohm and the SC228 has .5 milliohm, but the prior can withstand nearly 100A more peak current) - I would be more skeptical of the capability of the board driver to drive ALL the 10 Gates as the combined capacitance is pretty large. I don't know what board you have but if it has a basic optocoupler used as driver like the purple one then I would only mount 5 and go with that (and be sure that there are no mods to be done to keep the Gate driver output decoupled) unless you add your own driver like an MCP1406/7.
@@Luca_Techy Thanks man. I've tested the moody looking fets and am getting the same value as the one I took off. Am just going to try them and see what happens. Thanks again..
@@nickdarling5557 That's what I was explaining in my series, these designs are not really meant for sucb a number of FETs as the driver and ancillary circuits aren't engineered to handle them. 4-5 FETs are more than enough to spot weld .15mm or at max .20 if you have well matched FETs and a good battery. Exceed this and you risk smoking everything.
@@Luca_Techy yer the fets are suspect for sure. Need gear 70 to get a good weld on 0.2 that's worse than 5 original fets. My battery is a car battery but its not in the best of health and won't be helping. Thanks man. Can you recommend another? I want to weld 0.2 - 0.3 I use to use a car battery snd a selanoid but the selanoid burns out to quick. Good welds though..
wow this was a great video. I came away with a genuine understanding. I actually watched your repair video first and didn't quite get it. Now I feel confident in not only carrying out the modification but my overall understanding of all the requirements of the device for success.
Glad to hear, I suggest you watch if you haven't already the FAQ video which has other information regarding the spot weld process.
@@Luca_Techy Thanks! Will do. My plan is to do your mod and then power the purple board with a 16V 83F supercap bank. If I understand it right, having that much current capacity will allow me to keep my pulse time super low. (And allow me to weld nickle plated copper at 0.15mm or .2mm sandwich)
@@CriticoolHit yes as long as you don't overdrive the FETs (with a 3S 5000mAh and original power leads you're ok).
This is probably the best tutorial on spot welds I have come across TH-cam. Very well explained with crystal clear concepts on this subject. Thanks a lot for posting this .
Hi and thanks - if you would like to see a more complete video you should check out my latest FAQ one where I go a bit more in depth on the subject (it should be linked at the end of this one or just check my Spot Welder playlist).
Yes Sure , why not . let me look at them too . @@Luca_Techy
Wonderful work here, Luca. Can't thank you enough for providing this analysis.
Hi, when resistance welding the pressure at the weld site is important, too much pressure reduces the resistance and therefore the heat attained. It is a delicate dance to keep the pressure adequate to produce the heat without sparking which is the material being expelled.
Hi, yes this is all explained in my latest FAQ video, feel free to check it out.
I love this series! Thank you Luca!
An observation from using the “purple” 99G & the very similar green pcb, (8 gear, only one chip, FMD mcu clone) both with the de-coupled gate-drive cap mod, is if I use a low ESR cap the welds are visually hotter & hold better on the strip-removal test.
I purchased an oscilloscope which will arrive soon, & I will capture the gate waveforms to observe if there is indeed any difference in the rise-time or fall-time. (I don’t think the fall-time will be affected as that’s from pull-down resistor value, to my understanding)
But, just in practice, the fets seem audibly “snap” on and off better with the low ESR cap. There are other factors that could be at play that I haven’t tested yet though such as the measurement and quality of the original caps I used for the mods. I’ll learn more from further testing.
Also I can confirm that the mod you show on the purple pcb also works on the very similar green one that differs only slightly, having fewer logic components and a single digit display with “8 gears”. It simply has larger time-increments between each weld-level setting, with eight steps. (gears)
Edit: I’m also using longer, larger gage leads & running a beefy TVS diode across the output. I haven’t noticed any negative effects, or had any mosfets blow this far using beefier leads. (input and output)
Edit: After further testing the low esr cap theory, I’m not convinced that it’s valid. It appears that any decent cap is capable of charging the gates in a similar timeframe, with largest factor being to use high enough capacitance value cap that voltage sag doesn’t occurs on the decoupled gates.
The 470uf cap does seem sufficient to accomplish this as there isn’t much v drop on the gates. (25v rated or better) I likely jumped the gun a bit on my assumptions with the low-esr caps & the increase in weld performance that I perceived, with other factors probably being the cause for any perceived differences. but, we live and learn!
57:53 would it be problematic to connect both red wires on the input side istead of on the output side? just for convenience giving more room to maneuver
It makes no difference, you can screw them together on the positive side you prefer.
Nothing beats the chinese Mini Spotwelder generation1 with two 4s 3000Mah LIPOs in parellel.
That is just how it is... we are about to start implementing the Mini Spotwelder gen1 in our assemply floor at the Sachsenurt Skoda car assembly production line for bodywork parts.
We use E42 on the mini's display for the thinner bodyparts and E73 for the thicker areas.
Could I remove the internal battery and install a wired TX60 connector to use an better external battery
That is possible but *beware* (disclaimer below!) the internal battery is a ONE CELL battery. Typical battery packs are 2 or 3 or more cells in series - you would have to have a single LiPo cell battery (the circuit is designed for one 4.2V LiPo cell only o no series, even if very large in capacity - 2 identical cells maybe be put in parallel though). Also, if you really want to remove and disconnect the internal cell, be VERY careful when you attempt to remove it as if you even just slight short the 2 terminals that will fuse the contact point and the battery will catch fire burning everything in proximity. Always cut one terminal first while keeping the other well isolated, isolate the cut terminal with good tape then cut the other. DISCLAIMER *I highly advise against this procedure if you don't have experience and take no responsibility for any fire or injury that may be caused by this*.
Very nice explanation Luca. bought one DIY spot welder but I don't know what type of power supply to use to get good work. Can you help?
Hi, you really need a battery for this to work properly (a PSU that powerful would cost you a fortune), a 3S LiPo 50C 5000mAh or a 12V AGM 45Ah (or slightly larger) car battery are suggested. Check out my FAQs video in the playlist for more info.
what resistance must be between contacts of mosfets when on board (purple)? mine stopped working because I used fresh 110ah car battery and used thicker wires so I assume mosfets went bad. I do not see any visual markings that something burned, and LCD is still working.
I'm not sure what you mean: if you don't get welds/triggers and you don't hear any beep confirming the trigger then something definitely has broken. If you hear the trigger but don't get a weld then your FETs are not getting a gate pulse. Assuming they are all ok and not all blown open (rare) your optocoupler might have failed. You need though a scope to check if the opto output junction is working.
Thanks for the new video! It's good info for the DIY/low-budget builders like me:-]. My old maple mini is still getting the job done. But it's good to see more/new stuff. Watching your video makes me wonder....if you were to design your own ideal battery welder circuit, what would it look like? I have a little experience with PCB layout but lack circuit design skills. Might be fun to work together and do some sort of open-source/low budget welder build. It's hard to find time for stuff like that, but if your ever interested let me know!
Yes I've thought of designing an open source spot welder and even started it some time ago but to make something at a decent level of quality the cost would be rather high (over 75 USD or so) and to make something less by cutting corners gives you what is already on the market. Yes maybe making something along the middle could also be viable but it would still cost more than what is available even if "improved". Anyhow I will think about it time permitting, you never know and thanks for the availability!
Hi Lucas, happy new year to you too. Great video
Great video Luca - do you know if this can be used with a car jump starter pack if so what would the max amps be as I see some jump starter packs go up to 2000/2500 peak Amps. Is this too much or would actually be better than the 1000 peak rating variants? Also is there a max 12v car battery this can be used with would a 70Ah 640CCA be ok?
Yes you could though you really have to be careful as if the peak currents are realistic it can be destructive for the FETs so use at your peril - but luckily usually it's all most marketing hype and the realistic values are well under 500 peak Amps which are more than enough to start any car. A 70Ah will also do if in working order just always start with the lowest setting like 2ms and go upwards.
Hi, very interesting!! However I think the problem with these small welders is that most of them work with only ONE pulse (with regulation of amps and milliseconds in the same pulse) and it's very difficult to find the precise regulation for a good welding without burn or hole in the strips with different thickness. It's the same issue with a modified micro-wave transformer and a simple control board for amps and welding time. With 2 or 3 very quick pulses the strip does not burn , we don't need so much amps for a good welding, and I think it's also better for the battery and the mosfets. A good spotwelder allows to control the amps, the milliseconds, the number of pulses and the delay between each pulse to get the best result.
I have a big one like this , ...and also a new little MinderRC DH30max : I can modify the amps but not the milliseconds (I think it's 20ms), and i choose between 3 positions for welding, but i have no scope to control if it's simply a variation of the milliseconds or a possible pulse choice . I must say it works very well for occasional use (always in position 2 or 3 and less amps), but I don't trust it for its lifetime, in particular its (10.000mAh but in fact 8000) battery. It's really for very occasional little work but it does not burn the thin strips with good welding. And I must survey the auto-discharge when not used.
Hi Michel, yes a multi pulse solution would be better (like the Malectrics has) of course as it primes the surface before the proper weld but these are cheap devices with a very small MCU that allows a limited amount of code. As I showed with the first red mini spot welder I was able to replace the standard MCU with an Arduino and get it working so that would give you any variation on the pulse you want to program. All portable spot welders only use time as pulse power as it is impossible to limit the current with just a battery and no calibrated shunt for current detection - the cost is very high and only applies to larger professional devices.
@@Luca_Techy OK Luca , I think we judge welding tools "with the same glasses" . I just add after some trys that my little DH30 allows 1 , 2, or 3 pulses with variable delay , a good technical solution for 40€ and to build simply some little packs (for screwdrivers and else...) . I just soldered 2 wires on the + and - of the battery with a female jack , to choose and control the charge (storage charge for example) and also the voltage level by use with an Imax B6 with better precision, compared to the little included card.
I have the best welding if I only gently press the electrodes , simply to get a good "quiet" contact between the strip and the cell and not more , so I get maximal heat with limited intensity , and I clean the electrodes , light but very often with fine sandpaper, to maintain the best result .
Your explained precautions are very useful if we decide to open these little welders , lot of thanks!
May i ask some question?pls, I make this module,use 500watt transfomar 12v o/p. But not work.why?
You need an extreme amount of peak current, over 150 Amps at least to spot weld. A normal PSU won't deliver that current. As previously explained (check my FAQs video) ordinary PSUs are not designed for such peak currents and will 'trip' their short circuit protection if you try. You would need at least 2-3kW rated PSU to even attempt to spot weld. This is also why people modify MOTs for this purpose, but it can trip your household current protection breaker.
You’re doing Gods work my friend. Really making it easy for us self taught electronics hobbyists to understand these spot welder PCB boards.
I’m curious though what is the difference between input current and weld current? Just a random guess but since weld current usually has to be above 800A is weld current the input current multiplied by the number of fets?
The current that travels along a series circuit is the same in all places along that circuit (I = V/R) so the input current *is* the weld current, whether you measure it on the battery leads or just before the weld point. What changes is the measured Voltage based on where you measure it: it's a series circuit adding the resistance of the weld "Spot" + the leads' resistances + the FETs' internal resistances + the battery internal resistance. This is why in these mini spot welders you need a certain amount of "slack" resistance with the cable length and type and rated battery pack to avoid destroying the FETs. You need a certain resistance in the spot weld area also so that you can convert that current into heat and weld (hence why you shouldn't press the electrodes too hard). If you had a perfect conduction between the 2 surfaces there literally would be no weld. The issue is to keep the peak current below a critical value (
@@Luca_Techy That actuallly helped me understand a few things I was having trouble with. I had wondered why the Kweld manual had a formula for the leads and suggested not going too short or too long.
So is it possible that using too large of cable (say 2AWG) would actually be a bad thing? Is 6AWG big enough for a short pulse of 1500A? I see some welders now come with what they claim is 25mm2 cable but I do wonder if its actually copper. Probably CCA...25mm2 is 4AWG. I think the Kweld uses 6AWG silicone or EDPM but either way its pure copper.
And is matching fets about resistance? just got an RC3563.
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Couple more questions. I see my spot welder has "copper aluminum electrode tips" and thought this was an interesting choice of metals....is it a good choice?
I'm thinking of taking the 10Ah battery from my old welder (not much use) and adding it to my new welder in parallel. If I just make sure to never set the power too high (say never over 50%) I should be fine, right? Then slowly I can try it a little higher.
48:14 Wow, that's amazing and quite well might be a solution to my problem. Now:
1) Where can you get matched FETs? I suppose Aliexpress will be full of fakes.
2) If I get not-matched FETs and "blow" one? Will it still work with 9 FETs? Wouldn't a really dirty solution be to just buy a bunch of FETs and keep blowing them one by one, until a stable setup is found? Yeah, dirty and labor intensive, but would it be a solution?
3) The bars are just some brass rods? Would a piece of thick copper wire work for the backside?
Properly matched FETs are sold in bundle by official distributors such as Digikey, Mouser, RS etc. When you parallel FETs and one "blows", you can still use the welder as long as the faulty/shorted FET is removed. The bars are just brass rods yes (doubtful it's copper) and they are there to help the conductivity and reduce resistance. You can also bolt the Positive red terminals together on one hole to bypass the positive bus entirely as the switch (FETs) is on the negative side (N-MOS FETs).
Very professional Video, I have a same black box model as yours, I used cell phone fast charger, it doesn't work now. I replaced charge chip, charging is ok, but the light is always on, I checked the FET works well, I measured the voltage on the optocoupler, pin #1, 3.023V, #2, 3.967V, #3, 13.326V, #4, 0V, #2 is through a resistor to MCU pin #5, I suspect the MCU damaged but not very sure. it is much appreciated that you can spare some time give me a guidance for further check. I read some forum it is consist of a NPN and PNP to drive the MOS, but my PCB shows both are NPN, its silk print is J1, and is there any method to reset the MCU? I took it out and just connect the VCC and ground, pin #9 and pin #10 to the PCB, but #10 output low voltage to let the light always on.
Hi, I suggest scoping the opto input pin to see if it's getting any pulse (probably not but check). If there is no pulse it's probably the mcu (does it behave normally like pulse settings change apart from no pulse?)
P.S. no there is no way to reset the MCU it either works or it's toast that's why I asked if the settings were working.
Thank you, I guess MCU' problem, I give up continuing repair it, no purple output from MCU, and the setting doesn't work. @@Luca_Techy
Thank you for helping me understand why my spot welder is not working.
Hi i use same purple solder with lipo 3S 5200Mah 80C and on gear 11 welding perfect 0.1 nickel strip ,but sometimes casualy i got a lot of sparks.
What cause this sparks casualy?some high resistance? maybe not pushing corectly the pins?or pins not cleaned?
Hi, the sparks can be cause by dirty contacts betwee the strip and battery terminal which causes "sputtering" which is material being blown out by overheating from the contact spot. It also happens if for ex. you have some solder on the nickel strip or battery: this will be ejected violently when you spot weld due to high temperature so be careful - always wear protective glasses. Also if you do not press down enough this also can cause sputtering which is not good either. You need to find a good pressure zone, not too much but not too little to get a well bonded weld. Some sputtering is ok, but not too much and not too little. I am preparing a video also on this argument so stay tuned if you're interested!
@@Luca_Techy Thanks for your response.
I would like to tell you that I found a possible defect on the copper tips of the probes that i weld with, they were not crimped propery, they had a bit of play, so I used a bit of tin to weld them so that they stay fixed so as not to create false resistance and now it seems to me that the machine welds very well even without sparks, but as you said, only if the two surfaces are perfectly clean.
Sorry for my english and thank again
There was a video of someone who has a review where he had tested 5 welders. He said one of them was spot ine out of the box and did not need any mods. I cannot find the video to see which one he showed.
Maybe you are referring to my All Mini spot welders videos where I test all the models (there are 2)? Check in the playlist.
Hello, nice review. Could i use something like a 12-16volt/5 - 8amp DC power supply? Regards
No that won't cut it, you absolutely need a power source capable of delivering 150-250Ah peak - check out my FAQ video for more info!
Very interesting , what voltage and amp is the cell in that spot welder
It's one LiPo cell so it's 3.6V (4.2V charged, 3.3V discharged). Judging by it's volume and the contact width I'd guess it's about a 5000mAh 50C minimum.
Just a question , What was the rating of the battery in the spot welder ?
If you're referring to the all-in-one black box mini spot welder there is no specific mention; judging by the size of the cell it's certainly at least a 40C (or more) and the cell capacity is around 4000-5000mAh but to be certain one would have to test it with a full charge/discharge cycle.
Hi, I got the purple one and saw that you connected it to limited current power supply. Can I use it like that to weld included nickel 0.15mm? If yes, what current settings did you use? Thanks for the video, helped a lot
I connected it to a PSU for testing and diagnostic purposes not for real welding. To.weld you *need* a LiPo or AGM battery as stated.
@@Luca_Techy thought so, I was just curious. Thanks for the fast reply!
@@Luca_Techy One more question, I have 12V 75Ah lead battery, is that too much?
@@samuellos it's fine as long as you leave the original cables shipped with the welder and start from 5ms working your way upwards little at a time. You should get decent welds with .12-.15mm at settings around 15-20ms. If you need to exceed 30ms your battery is not performing well or it's not hooked up tightly to the terminals.
@@Luca_Techy Hi, so I connected it to the battery, tested welding on lowest setting, it was weak but working but after couple welds it looks like the battery died, I saw display slowly turning off. So I charged the battery over night and now its makeing holes when welding on lowest setting and big sparks on that spot, with no beep sound. What could bé the problém please? I hope im not bothering
I got the purple spot welder no matter what battery i connect there is no spark no welding it only beeps. I am waiting to see you try it or modifying
Stay tuned!
@@Luca_Techy You believe there is a solution to this issue?
@@EDIPSOSTT that deoends: apparently yours is not triggering, if it beeps but doesn't weld the FETs aren't getting driven (no gate pulse) - you need a scope to investigate. You can try my lamp test (check out the video about it).
@@Luca_Techy i tried the lamp test. no light
@@EDIPSOSTT It's not triggering the FETs: do you hear the weld beep when you try to weld? If so the FETs' are not getting any trigger - did it ever work or was it like this when you received it?
Im very interested in this purple one. Im going to ise a motorcycle battery as power source. In your opinion Loca with your mods would you recommend me this one?
The purple one is ok with the gate drive mod. As usual don't overdrive it, these welders can't handle very high currents for prolonged weld periods meaning that you shouldn't weld over .15mm or you risk destroying the FETs. Always start testing from 5ms or less. This goes for all these mini spot welders. Be sure you have a good battery and don't shorten the cables to start with (they limit the peak current). This welder needs a cover to protect it so get the version with plexiglass or 3D print a cover. The Wise Maple version is also not bad "out of the box" if you add an "anti spark" XT-60 plug for LiPos or do the inrush current limit mod as shown in my videos (check the playlist it's all explained there).
I have this device, it works with 0.1mm. I posted the video 3 days. It cannot do 0.2mm at any level
@@simplyfocus9937 i have bought the purple one. I got it 3 days ago. Will maken the Luca mod on it befor using it
@@simplyfocus9937 0.2mm is too much for these welders, it welds up to .15mm if you have a good battery else you risk destroying the FETs if you overdrive it.
@@Luca_Techy You are right. How did you do with the maletric spot welder. I did more than 10000 spot weld without any problem. Too bad it is broken due to user errors.
Thanks for this video. I have on of the units with self contained battery with a different design. Its pretty good but after 10 welds, as you said you need to wait 5 mins for the battery to recharge. It makes welding slow. I was interested in purchasing a more expensive unit that would last longer and be more servicable for up to $200. I was curious what you think of supercap based designs and if you had any recommendations. Or are battery based designs able to get better welds at my max budget of $200. Thanks!
With that budget you can certainly go for a more high end type such as the Malectrics DIY Arduino based for under 170USD. There is little assembly in the complete ready made DIY kit and it is certainly a more complete and proper design (there is a model for 12V AGM battery or LiPo pack) with power calibration - check it out on their site. They also sell components for a complete DIY build if you have the skills which means you can also always repair it yourself later if something breaks. Supercaps are a good add on but if you have a decent car battery and proper AWG cables you can do without - it all depends on the amount you weld and the thickness of the strips you want to weld. For basic hobby or personal use it may be an overkill - but if you're looking for a more resilient and capable product it certainly seems to be (though I have neither tested nor analyzed it hands on, I merely have seen the specs and characteristics and some of it's design from the site).
@@Luca_Techy Thanks so much Luca for getting back to me. I took a look at Malectrics DIY Arduino unit and it looks pretty good. Do you have any thoughts on the kweld units from keenlab? They also seem to have a kweld-ultracapacitor-module you can attach. I'm if you have heard anything regarding there units. It looks like it might be a little over my budget though and I don't know if that extra money would actually translate into a better product or if it's best to just go with a car battery and one of these other units :) Thanks again for your advice.
@@petersvideofile Yes I'm aware of Kweld - certainly a comparable professional product with similar characteristicts probably even more potential as it has a supercap kit option - they're both good from what I can see (again, never had any hands on experience with them). The only major difference is that the "MCU" on the Kweld is custom placed on their pcb (I don't know what it is) and requires a seperate level converter and adapter to reflash/update whereas the Arduino Welder uses a standard Nano module which you can easily replace if needed. Again I always think about the repair possibilities as these devices are all prone to fail sooner or later based on the use - but that's just me. Maybe the Kweld is even designed better, I can't really say as for that I'd need to see schematics & layout.
@@Luca_Techy Thanks so much, also very good point about repairability of the Malectrics unit. I hadn't thought of that, I think I will probably buy one when the time comes :)
@@ericklein5097 Thanks so much for this super informative comment :) I'm going to follow up on this some time. I still didn't buy another spot welder yet so your input is very valuable to me!
Thank you)
Correct polarity is so overrated on these LIPO spotwelders 18:54
Thanks fo this vidoe , felice anno nuovo
Grazie, altrettanto!
"Do not replace or extend the cable without authorization." Sounds like something that would be said by someone living under the rule of the CCP.
I just receiver this one. And ik going to do your mods. Also solder the mosfets better on the board
Let me us if Lucas mods works
I bought the purple one
What do you use power source for that?
@@shobxo have never used it.
I’m shocked at how flaky the entire batter spot welder industry is. The kweld kit seems to be the most reliable but it’s not accessible to everyone. Even the infamous Sunkka line doesn’t have a perfect record - or perhaps I’m seeing lots of fakes.
This black box welder is very poor. If the battery shorts out you will not just maybe damage your equipment but maybe burn your whole house down! The power is very very weak, why don't you just say it is crap.....
Well I wouldn't say it's rubbish: it works "out of the box" and even if it has limited power you don't have to open or modify anything (considering the others this is already a plus!). The fire hazard is comparable to any other with attached an external LiPo pack if you think about it - worse if it's without a protective case...
@@Luca_Techy I said it's weak and it is very weak. There are far superior welders for way less money that will easily weld 0.20mm strips. The battery has NO protection and is not detachable like other devices which have XT60 easy disconnection. Your not impartial in your analysis.
@@lancelink88 I'm sure there are better versions, and I concur that the battery is not detachable (I do underlime this, it is all self contained) and also point out the reduced life of the whole device, I merely state that whether you are using a detachable LiPo pack (which mind you is preferrable for obvious versatility) or using this or other self contained models the risks are the same (if you use a detachable LiPo battery pack and the welder FETs short and terminals fuse, the risk of fire is there likewise). The internal single LiPo cell doesn't just short out by itself unless punctured or overloaded just as any other LiPo. Don't get me wrong, the welder is a cheap device and I state this but saying that it has no protection implies that one would have to open it to expose the terminals something which you're not supposed to do and I advise not to unless you know what you are doing. In other words all these mini spot welder are a fire hazard especially when used with LiPos something which I have always warned about (in fact I suggest 12V AGM batteries which are safer and don't explode nevertheless one always deals with large currents). I hope this cleared my point regarding the concept of protection (which no LiPo pack or cell for this purpose has respect to LiIon packs whcih are required by commercial law to have based on their application) and fire hazard in regards to LiPo cells.
@@lancelink88 if ther are cheaper and better alternatives out ther, can you help us/me to point them out. URL link pleas.
bro you have case in box when you been speaking about to its danger... literally a transparent box you have on the table and you speak about how it will be good to make one heh :) check first what you have before speaking about it without researching.
I really don't understand your point - the clear acrylic container option for the purple welder offers some protection against accidental shorts instead of having just the pcb lying around with no isolation at all.
@@Luca_Techy there is acrylic isolation on top and back from sides in that brown plastics its just wrap . its up to you how to protect it you right . all good :)
So i have had a bit of a night mare. I wanted to add mosfets so i followed someones link and bought the wrong fets (IRLS3034-7P) They look good quality and would work because i have 10 but hardly worth doing. I made a second order for the correct fet off another seller (IRL40SC228)but they look very suspect. terrible quality so i don't think i should put them on. My spot welding board currently has no fets installed.
Well TBH if you think the 3034-7P are original then you could just as well mount them - don't think that there will be any major observable difference if they are a batch of properly matched FETs (consider that the only major difference is that the 3034 has an RDS-ON of about 1 milliohm and the SC228 has .5 milliohm, but the prior can withstand nearly 100A more peak current) - I would be more skeptical of the capability of the board driver to drive ALL the 10 Gates as the combined capacitance is pretty large. I don't know what board you have but if it has a basic optocoupler used as driver like the purple one then I would only mount 5 and go with that (and be sure that there are no mods to be done to keep the Gate driver output decoupled) unless you add your own driver like an MCP1406/7.
@@Luca_Techy Thanks man. I've tested the moody looking fets and am getting the same value as the one I took off. Am just going to try them and see what happens. Thanks again..
10x moody mosfets installed and it's the same or less powerful than before.
@@nickdarling5557 That's what I was explaining in my series, these designs are not really meant for sucb a number of FETs as the driver and ancillary circuits aren't engineered to handle them. 4-5 FETs are more than enough to spot weld .15mm or at max .20 if you have well matched FETs and a good battery. Exceed this and you risk smoking everything.
@@Luca_Techy yer the fets are suspect for sure. Need gear 70 to get a good weld on 0.2 that's worse than 5 original fets. My battery is a car battery but its not in the best of health and won't be helping. Thanks man. Can you recommend another? I want to weld 0.2 - 0.3 I use to use a car battery snd a selanoid but the selanoid burns out to quick. Good welds though..