Super Cheap Spot Welder

[@thehobe2111]

You had the same problem I had on my first attempt. The 12V input source dropped and did not provide enough gate voltage for the switching FETS. The FETS did not get to or remain at their low resistance state and dissipated a huge amount of power, overheating them. The FET internal silicon melts internally and shorts out. I solved this by using a separate 12V supply to power the board and connected the positive welding probe to it's own high current 8-12V separate source. The negative welding probe is fine connected to the normal board connection. Connect the high current negative source to the normal board connection as well. I am using 3 3000F supercapacitors in series (8V) for the welding power source. The board works fine for me with only three of the original power FETS.

[@hawkeye292002]

Bought one a week ago. Sparked one time and it was done. Keep watching the tracking , took 10 days to get it. Couldn’t wait. One spark done.

[@SAHILKHAN-lu8oq]

Absolutely no. Those welders are awesome. The main fault is of the operator. Because if you use a week battery, the voltage drops while the welding pulse initiated, which doesn't supply enough voltage for the N channels, they become high resistance, then overheat and fail. If you use strong enough battery, these won't happen. You are supposed to use minimum 60C 5Ah battery - which means minimum 300A capable battery. The one used in the video definitely can't do so. Another modification can be done - search Maker Fabio's videos. He explained this and suggested a modification.

[@GregOnSummit]

Yep, that's what I've seen too. Weak battery and you get smoke. Instructions say you need a battery with at least 50ah, I think, so a car battery with ~363 CCA (50 x 7.25). CCA / 7.25 will give you a close estimate of the AH of a car battery.

[@lvstreeter]

I was curious about all those cheap welders I've been seeing on the internet lately and now I know not to mess with them 🤣👍

[@SAHILKHAN-lu8oq]

Absolutely no. Those welders are awesome. The main fault is of the operator. Because if you use a weak battery, the voltage drops while the welding pulse initiated, which doesn't supply enough voltage for the N channels, they become high resistance, then overheat and fail. If you use strong enough battery, these won't happen. You are supposed to use minimum 60C 5Ah battery - which means minimum 300A capable battery. The one used in the video definitely can't do so.

[@JulianIlett]

Does 'manual' mean 'for as long as the footswitch is held down'? Maybe auto uses the timing function.

[@f091537]

It probably means that you have to manually press the switch. Auto would initiate the weld when it detects low resistance between the probes. At least that's how it works on the much less dodgy kWeld.

[@AdamWelchUK]

A good question but I’m fairly sure I had the foot switch engaged for longer than the current was flowing (although I’m fairly sure that it was flowing longer than my suggested 10ms). I’m interested in looking a little further at this unit and that’s something worth checking out. Cheers Julian.

[@AdamWelchUK]

We’ve both had our mosfet mishaps this week eh?

[@sargetester99]

@@AdamWelchUK touch the probes to a 12 volt light bulb for your first press of the switch. This will tell you alot.

[@electrojessy4270]

I used the auto function and it give up after 1 weld its a piece of landfill now

[@airwavested]

Thank you Adam. $20 well spent! It's worth at least twice that in entertainment value! Mine you the video title is a little misleading. It should read "Super Cheap Smoke Machine... single use only"

[@AdamWelchUK]

I’ll update that now. :-)

[@martdaymo]

Adam that spot welder isn't, dead just rip out the burnt MOSFET and use a more powerful slightly higher voltage battery.

[@micver1091]

Its more like somthing went wrong my spotwelder from just 7 euro from Alie express is Just a super welder and really works verry good i must say my buids is a lifepo 4 56 ah 13.33 volt 800 watt accu by the way

[@martdaymo]

The right battery selection is critical, If he use a stronger battery the spot welder will still work even after the smoke.

[@GoatZilla]

Your battery probably sagged under load. It's a known issue with these devices; should add a cap to the control power supply if I recall.

[@sarkybugger5009]

Before: Ooh, I've wanted one of these doodads for ages... After: I think I'll hold off for a while longer.

[@Flav_M]

Diddos...and I even went through a dual makita battery rebuilt(with solder ::smh::). Still holding albeit a bit fat around the waist (bulge from solder lol)

[@haydenc2742]

@@Flav_M Or it might be a good idea to hack it as soon as you get it and fix the solder on the mosfet run so it doesn't smoke...and try to start small rather than hit it so hard it burns a hole in your desk (good to know it has the oomph to actually spot weld alot...because boy howdy did it ever!)

[@Flav_M]

@@haydenc2742 We really ought to shift this way of approach. We know if we bark loud enough we can get a decent product. If I have to set up the solder station I might as well detach them all and replace with proper ones. I just did this to the switches of my EXACTLY 1yr(you guessed it, 1yr warranty, and we f'n accept this as normal) old Logitech G502 mouse. Glad I looked into it... well known issue, across multiple brands, something I have adequate skills for. So I did them both(obviously) which resulted in a working part going in the bin. This is probably why there's plastic in our food. Oh I went off the rails there. My bad, have a good day ✌:).

[@astrolite3192]

It's missing protection diodes to handle the avalanche current causing the mosfets to fail.

[@largepimping]

The chances of this working reliably are about the same as Leicester winning the league... again. Thanks for taking the hit for our amusement!

[@AdamWelchUK]

Matching the mosfets is key I think - and perhaps it needed a few more in parallel. Or better build quality!

[@ahaveland]

@@AdamWelchUK You could remake it using an arduino with your skills very easily. More mosfets would help, maybe add an extra layer, as would bulking the main tracks with lots of copper "rebar" to carry and distribute the current more evenly and effectively. Thanks for taking one for the team!

[@fredstarkey3425]

@@AdamWelchUK you don't have to "match" mosfets.

[@MistaTerps]

You didn’t watch the video about modding it with a 16v 680uf cap then? Loads of people are saying it works great. The problem is the controller chip switching off because of voltage drop & leaving the mosfets to stick open & fry. You can also reinforce those traces either side of the mosfets with copper wire. You really need to use a 100ah battery minimum & ideally lithium.

[@jeromyweise8831]

Yes this! It works great when you follow some simple instructions. Ignorant folks keep blowing them up using those weak ass SLA batteries.

[@ATW643]

Adam Welch , your sacrifice is much appreciated.

[@martdaymo]

I had the same problem with the first two that I tried. They failed after the first three weld. I received the third one and decided to used some lithium ion battery 4-in series (yuasa LEv 46) but they were halfway charge so the voltage was around 14v. The third spot welder works perfectly, After I decided to try the ones that blow up with this new battery and they work fine, even the first one that caught fire. I could be wrong but the problem seems to be voltage drop once the dead short happens for the weld.

[@nickldominator]

Adam, I think you killed the welder as a result of your old battery. These welders require a strong, fully charged battery capable of delivering the current & keeping voltage high enough. This blown FET issue is very common with these, and some people have discovered a fix by adding a cap AFTER the diode that powers the FETs. The cap keeps around enough energy to keep the FETs fully turned on, and not in the resistive state where they burn a lot of energy. Adding this cap and/or using a nice and beefy high C-rate LiPo would've likely let the welder work a treat. and not kill itself.

[@AdamWelchUK]

Cheers. A few people have mentioned this and I’m going to try and see if I can make a follow up video and make a proper weld!

[@newburypi]

Thanks for sharing. I was both sceptical and hopeful as you began. I saw looking for a welder, for use on 18650s, and I guess I will continue that search.

[@SAHILKHAN-lu8oq]

Those welders are awesome. The main fault is of the operator. Because if you use a week battery, the voltage drops while the welding pulse initiated, which doesn't supply enough voltage for the N channels, they become high resistance, then overheat and fail. If you use strong enough battery, these won't happen. You are supposed to use minimum 60C 5Ah Lipo battery - which means minimum 300A capable battery. The one used in the video definitely can't do so. Another modification can be done - search Maker Fabio's videos. He explained this and suggested a modification.

[@pitikaron]

I have this but working pretty well performing 0.3mm no issue ever since.

[@Flav_M]

You might as well go to your local scrap yard(unless you have one at the ready) and pick up a starter relay, since you have the pedal, battery and decent cables. Also been eyeing these for a while, thanks for saving me a few bucks.

[@SAHILKHAN-lu8oq]

Absolutely no. Those welders are awesome. The main fault is of the operator. Because if you use a weak battery, the voltage drops while the welding pulse initiated, which doesn't supply enough voltage for the N channels, they become high resistance, then overheat and fail. If you use strong enough battery, these won't happen. You are supposed to use minimum 60C 5Ah battery - which means minimum 300A capable battery. The one used in the video definitely can't do so.

[@BlockdAccount]

Best review I've seen on this welder. Great work and thank you.

[@jeromyweise8831]

Seriously..

[@fredflintstone1]

I saw the burnt holes in the worktop but did it weld the nickel together :-)

[@AdamWelchUK]

It was a really poor connection that failed very quickly. The wood may have sucked all the heat away from the junction?

[@paul.alarner6410]

this happened to mine on the first weld,i replaced the fets (all were sc),added a cap+ diode on the microcontroller supply,been fine since (about3years ago+ lots of welds),i use a 30ah car battery but always charge it before using it on the welder,it also works for blowing away dendrites on nicad cells too!.

[@benediktschluter7313]

Is it made by Charmhigh?

[@bernardsmith152]

Yep , mine blew up as well - only it let a lot more smoke out . To be fair the suppliers have sent me more mos fets , but it looks a bit fiddly to solder them in. I am now constructing a welder using a 200amp auto relay , I might see if I can use the timer function from this device to control it.

[@WaschyNumber1]

Have I missed the point wher the foot switch get attached to the welder? I'm looking specifically for a video how to attach the foot switch to the welder. 🤔

[@AdamWelchUK]

The welder has a barrel jack connector which is the external manual trigger. You could attach a foot switch or any other type of momentary switch to this connector.

[@AdityaMehendale]

Looking at 11:32 - what is the current-limiter? The R_ds_on of five FETs in parallel? They prolly don't expect you to put a beefy 12V car-battery as the source...

[@murman229]

Mine let the magic smoke out on setting 40 and using a 4s lifepo4. Stick to 3s lipo. Also connect the two red leads to the same screw terminal to avoid dragging all of the current across the entire length of pcb tracks.

[@AdamWelchUK]

Connecting the probe and battery +ve to the same terminal is a good idea - shame it’s unlikely I’ll be using it again!

[@murman229]

@@AdamWelchUK I took a grinder to the first mosfet that blew. Ground through the shorted semiconductor layer. The device came back to life... sort of. The rest died the same way... genuine replacement Fets are $5 each so the ones on these boards are likely rejects or clones.

[@countryside8122]

Did the battery have enough amperage to use for the welder?

[@kishoresoni7917]

Can it be connected with smps DC power supply instead of battery.

[@wolverinex4243]

Can you weld stainless steel wires together?

[@Gowieee]

They are good but you must modify them (some of them anyway) before use. Adding a 16v 1000uf capacitor helps with voltage drop to the drain which causes the mofsets to fail. Beefing up the solder traces with copper wire also helps. To use these stock you must use a 100ah or above battery.

[@AdamWelchUK]

Thanks. I’ll see what I can do to bring this back to life :-)

[@patrickmclaughlin6013]

you can probably triple your view count by putting the word SMOKE in the title

[@AdamWelchUK]

Do you think? I always find that the title that gives away the punch line is always a bit disappointing. I should use more click bait running up to Christmas ;-)

[@patrickmclaughlin6013]

@@AdamWelchUK one I know fans of electronic themed videos is the magic smoke and Thanks for posting so many good videos

[@michaelzweers1807]

cnx-software wrote an article about this unit linking to an other yt video. There is a warning that the controller needs a cap to work properly. (tldr don't burn your IRL40SC228CT because of voltage drop )

[@windshield11]

So that does happen, huh?

[@johncoops6897]

It doesn't need a capacitor if your power supply can supply a literally infinite amount of energy without voltage drop. These poxy old Lead Acid batteries had zero hope of providing enough current

[@windshield11]

@@johncoops6897 Indeed. If you're looking for infinite battery power used EV modules are what you need. Ridiculous amounts of power.

[@ScrewBot]

Can i use a 12v 60amp SMPS. As the retailer suggested that i can use this spot weldet with 12v 40 amp SMPS. Should i use an smps?

[@cr25094]

Hi Could I use a 18v Makita battery to power it??

[@yoni-tongueguru8399]

i got the same welder 2 weld one mosfet blew up removed it and it did 50 more welds then another mosfet blew it now has only 3 of them in and is working great so far with 300 welds under it belt :-) those mosfets are 400amp ones so even with three a small lawnmower battery with max of 325 cca works great on it. I did order new mosfets from china and waiting for them to get here, They are real cheap :-) its two mosfets in each package hence the 6 leads on each one

[@Eratas1]

I have 16$ version without screen. Works fine so far. Welds 0.15 mm pure nickel easily.

[@untungsuharto7991]

yes, I use this spot welder, cheap but Excellent

[@slybunda]

im wondering if the foot pedal was on for too long. the auto function should shoot the current for half a second max usually even shorter time. should have first used it as it came from the box in auto mode.

[@SAHILKHAN-lu8oq]

Absolutely no. Those welders are awesome. The main fault is of the operator. Because if you use a weak battery, the voltage drops while the welding pulse initiated, which doesn't supply enough voltage for the N channels, they become high resistance, then overheat and fail. If you use strong enough battery, these won't happen. You are supposed to use minimum 60C 5Ah Lipo battery - which means minimum 300A capable battery. The one used in the video definitely can't do so. Another modification can be done - search Maker Fabio's videos. He explained this and suggested a modification.

[@دائرةالحق]

I want to ask about this machine. I bought it from the market and started to weld it, but it does not weld well. I used a 12 volt 7 amp dry battery. What is the reason? I hope you will give me an answer to that. Thank you.

[@eddiekytia]

Hey buddy! Hoping you can help me with a clamp meter. I dont know much but truly looking to learn! I want to purchase a clamp meter under 200 for AC AND DC current I'm looking for something SAFE/WELL PROTECTED and capable of reading AC AND DC current from .5 amps to 60 amps as accurately as possible through the clamp. Do you have 1,2 or 3 suggestions. I was looking at the Klein cl800 but someone told me it will not read AC AND DC current through the clamp down to half amp accurately..... THANKS FOR ANY HELP YOU CAN PROVIDE ME

[@AdamWelchUK]

I own this one and it’s been great... kzbin.info/www/bejne/a6rOl4Krq52dkJI

[@G36934]

great video! thanks for showing us the insides and the blown fet.

[@bren106]

Just what I (didn't) need to watch with an Aliexpress order somewhere along the delivery process to me, but not a spot welder. I've been ordering like crazy off them and Banggood as the end of the year and import duty approach and this is the final bag of goodies still on the way.

[@AdamWelchUK]

I’ll be rite. I’ve had very good experience with Ali - I think this is probably my first bust. Fingers crossed for you anyway.

[@ekner]

I have a feeling you could pop off the damaged mosfet, widen out the solder blob, and carry on using it like that, just staying away from the higher power settings. That fet in particular might have been weaker than the rest, or like you said carried most of the current thanks to the incomplete solder job on that trace. Either way it's basically a free repair, so it's worth taking a shot.

[@AdamWelchUK]

I agree. I think there’s a good chance we will see this again :-)

[@pcmalek5]

hi adam big fan i have a question about your epever dashboard , i am setting up my own for my epever UPower inverter charger . i am using ubuntu, python, influxdb, grafana and everything work fine except for the 32 bits register conversion, for example PVwatt is split in two 16 bit data high and low . i noticed that you did a bit of program to solve this issue , i hope you can share your solution . thank you adam

[@paul.alarner6410]

the voltage on the mosfet driver sags and lets the fets go into the linear reigon and kills them instantly!.

[@mitsos_306]

Nice video! Regarding the failure there is mod you can do to maybe prevent this. You connect a capacitor on the control circuit to be sure that MOSFETs are full saturated even if battery voltage is a bit low.

[@pfeerick]

Single Use Chinese Smoke Generator... some assembly required. They really can't get some battery / high power stuff right for cheap... Have a KSGER lithium soldering iron and the balancer board trashed one of the cells, currently testing if the replacement board is any better.

[@Trixor83]

Hi Adam. Check this out - It might be a low batt voltage issue. kzbin.info/www/bejne/nJXRgGOQYtiWoKM

[@johncook5872]

Shouldn't you place one probe on the bottom plate and the other on the top plate so the current passes through both parts and form a resistance weld?

[@electronic7979]

Nice product

[@blg53]

So Adam, what is your assessment of the value to price ratio of this wonder device now?....

[@NYYMANIAC23]

I have an ATX computer PSU that I modified to have a 12v output. Will that work with this welder? Since the ATX PSU is running off of wall power, would I have the same issue with the voltage drop?

[@uawsux]

I bought a few of them at $16 shipped from eBay they're $25 now and you still have to make the repairs

[@TheLightningStalker]

At first I thought this was a kWeld clone but it lacks all of the things the kWeld has that prevent it from destroying itself.

[@jamest.5001]

I Bought one like that, it didnt make a single weld, it blew up, and caught fire for a few seconds, it's the second one that did that! I don't see them working long, if they do work!

[@SAHILKHAN-lu8oq]

Absolutely no. Those welders are awesome. The main fault is of the operator. Because if you use a week battery, the voltage drops while the welding pulse initiated, which doesn't supply enough voltage for the N channels, they become high resistance, then overheat and fail. If you use strong enough battery, these won't happen. You are supposed to use minimum 60C 5Ah Lipo battery - which means minimum 300A capable battery. The one used in the video definitely can't do so. Another modification can be done - search Maker Fabio's videos. He explained this and suggested a modification

[@hansdegroot652]

Hi Adam. How to say this polite. It is good to see I am not the only one that blows stuff up on first try. It also happens to the best 😁. Of course bad luck the thing started smoking. I would have done exacly the same. Asumjng the device would protect it self from buring out.

[@electrojessy4270]

I had the same spotwelder it broke the first time i use it lol Maby my automatic function is broken now i will try a foot switch and see id it still works

[@mrphil2233]

whats the max input voltage?i want to run off lifepo4

[@malicarr1]

Loads of info & mods for this kit going back several months on KZbin

[@chrislincoln489]

Ever Video I watch this same thing happens. Some suggest a mod to make it work better. Wonder why the maker of these don't make the mods before saleing them. I bough one last week and it burnt out on the second weld.

[@itsfpv2561]

which vendor on AliExpress did you buy it from?

[@tomk2165]

If the small battery cannot maintain voltage under load, the microcontroller may reset in mid-pulse, extending the pulse until the FET enters thermal runaway.

[@MrDexi87]

4S lipo 25c 2500mah as power supply ?

[@riz94107]

I bought one of these but haven't tried it yet. Guess I'll check those solder joints before I do...

[@rickloudermilk6351]

I did too. Checking mine also.

[@alfalf2417]

Thanks. Now I know what I'm in for, when using one of these.

[@MARK.NAN69]

Hai tuan, Boleh saya menggunakan Bateri 12v 5.0ah

[@lowtech81]

The issue is that the controll circuit is useing the same power as is used to weld. Add a cap or power supply to the controll and it will work.

[@jeremylister89]

Common wisdom is that the problem is Because the supply for the control electronics dip suddenly when the weld is done. The amount of dip depends on the battery characteristics/health/rating. If the control electronics supply dips this can adversely affect the mosfet gate drive voltage or worse confuse the control logic and drive them permanently on = bang! Others have noted there is a diode from battery positive to the control circuit, but no decoupling/hold up capacitor, a remarkable omission! Adding a large cap on the diode cathode to battery negative has been successful to one determined user. Value,? Not sure but large enough to prevent more than 0.5V dip for the maximum pulse width. I've one of these but, not used or delved into it yet.

[@offgridwanabe]

works just like the one I bought total trash

[@AdamWelchUK]

Sorry to hear that.

[@martdaymo]

Your spot welder isn't dead just use a more stronger battery and it will start working correctly, you need a healthy car battery.

[@offgridwanabe]

@@martdaymo I had a lithium battery on it way more powerful than lead acid.

[@lezbriddon]

build a new output pcb with decent fets in to220.... 75nf75 or 4110's , my go to fets

[@spikeydapikey1483]

Awwwww man! I was really hoping this would be a nice bit of kit, as I've nearly brought one a few times... Kinda glad I haven't now!! Still want one tho...

[@TecSanento]

Get a kweld kit, they are worth it

[@AdamWelchUK]

I could have been unlucky - I guess we’ll never know?

[@micver1091]

€ 7,74 8%OFF | Diy Draagbare 12V Batterij Vlekken Lasser Pen Model Pcb Printplaat Controle Lasmachine 18650 Energie Opslag Spot Soldeer a.aliexpress.com/_BT4I1L this one works y have one and IT works like crazy y used a 54 amp lead accid battery .to power the PCB

[@errolfoster1101]

I have one and it is working fine for me

[@adrianleitch6996]

@@AdamWelchUK I read a number of these units have been dying in user reviews when I looked, same thing FETs detonate. The units with the in-built lithium batteries seem to fare better, possibly due to the low voltage (1S, 3.7V) used. I imagine the output loop on these is nice & inductive and that ~500A @ 12V pulse would likely cause an inductive spike that exceeds the VDS breakdown voltage of the MOSFETs and short the FET permanently. Probably needs MOSFETs with higher VDS voltage.

[@errolfoster1101]

I've have one of these exact units and it's very good I'm very happy with it the only issue is the size of the end of the tip it's a bit big but no problem just filed it down

[@BlackOpsJuJu]

my blew up first weld also have to have a high amp output battery like a 11.1v rc battery works great standard car battery burns the fets every time

[@NigelGastall]

Hi Adam, good review. I followed your links on this and the update video but they don't go to a specific item on Ali express and the search terms don't bring a result either.

[@gavincurtis]

You have a programmable micro with color LCD for $20.

[@kuhrd]

These all have a fatal design flaw where if the input voltage drops too low during the weld the MOSFETs clamp and never receive enough signal to open and they burn up. Usually one or 2 take the brunt of it and if you replace them you are back in business after adding a decent-sized capacitor to the mainboard to allow the circuity enough voltage to break the circuit even if the battery voltage drops too low. I have been through enough of a few of the different models of these and with lipo batteries, or super caps they seem to work ok at the start while the voltage remains high but as the battery goes low they reach a point where they then clamp, burn up and fail.

[@Trailtraveller]

Please repair it for further testing.

[@codiecarroll735]

There’s a fella on Project Evolution that does some DIY mosfet spot welders that perform pretty dam well, maybe there’s some info on his channel you could see to beef this spot welder up.

[@emaglott]

oh dear. you did get your one weld though. did it say anywhere that it was a "reusable" welder? what did you expect?

[@PriorUniform721]

Oh man. I bought one of these a few weeks ago but haven't had a chance to try it yet. The reviews and videos are mixed. Sometimes they work sometimes not. The trouble is these designs get ripped off all the time in China so there could be one manufacturer that is actually making a good product but there may be a dozen mediocre or downright horrible clones. For us hobbyists who buy from eBay, Banggood, Aliexpress or others there's no way to guarantee the providence of a product. Even multiple purchases from the same seller on eBay/Banggood/Aliexpress could have mixed results. The sellers may A) not care B) not know which of their suppliers are legit. Anyway I have one and I'll give it a try. If it goes poof on the first weld I'll thrown in the towel and get a kWeld. (Which is probably what I should have done all along.) Thanks for the video.

[@siov4279]

Just was watching another vid on this same item. MAKE SURE THE AMPS ARE ENOUGH FOR THE MOSFETS TO DISCHARGE!

[@lucasg1988]

i have 90A AGM 900A starting current, first test and device is in short circuit probably transistor KO

[@MaxintRD]

Nice video. Thank you! I would try to repair it and for good measure add plenty of solder on all those mosfets. Perhaps you can even add a second layer of mosfets to split the power that goes through them...

[@SAHILKHAN-lu8oq]

Those welders are awesome. The main fault is of the operator. Because if you use a week battery, the voltage drops while the welding pulse initiated, which doesn't supply enough voltage for the N channels, they become high resistance, then overheat and fail. If you use strong enough battery, these won't happen. You are supposed to use minimum 60C 5Ah Lipo battery - which means minimum 300A capable battery. The one used in the video definitely can't do so. Another modification can be done - search Maker Fabio's videos. He explained this and suggested a modification

[@Graeme758]

At about 6:36 it was clear that the mosfets weren't going to last the length of the video. Battery way too low current. So many of these tests very unfair to these cheap spot welders. Instructions, bad translations, are quite clear about the power supply. Too low, don't saturate the mosfets so they don't trip.

[@thisphone5371]

An easy mod makes these work. Check out Maker Fabio channel. He adds a small capacitor to combat low voltage drops which causes them to explode. Type "maker fabio spot" it comes up.

[@astrolite3192]

Actually, it's missing protection diodes to handle the avalanche current. The mosfets will eventually short.

[@thisphone5371]

@@astrolite3192 Actually watch the video. He has a commercial oscilloscope and tests without the add on capacitor... huge voltage drop. Test with added capacitor... No voltage drops more than 1 volt.

[@astrolite3192]

@@thisphone5371 Actually find the post somewhere on the net explaining avalanche current, probe inductance, flyback / schotty diodes, oscilloscope levels of flyback current with no diodes, with diodes & the datasheet explaining that the avalanche current levels it ships with ultimately cooks the mosfets. I'm busy...

[@thisphone5371]

@@astrolite3192 Wasn't personal. If you want a cheap battery welder, dont give up b4 you try this one. This thing is plagued but delivers results even with an incapable battery. Low voltage safety is just a plus. Mine works fine with no issues after modding b4 first use. Worth a try when using the upgrade.

[@astrolite3192]

@@thisphone5371 Sorry, don't misunderstand, I have this welder and am currently running it fully stock. I just mean the people that developed the kweld &/or the other one went over it all on a fourum somewhere with a full explanation (with oscilloscope readings) showing the avalanche current exceeding the rating in the mosfets datasheet. I just don't have time to find it for about a month.

[@akeem11h]

I may have missed it but at these prices these devices have current limits, maybe you should have took some precautions first. I would love to see this device work for us cheapskates. Nice video.

[@johnmfjw]

According to Maker Fabio you need to add a capacitor in the circuit.

[@thisphone5371]

Been trying to tell them about Fabio. Works.

[@DaveGagliardi]

Great video Adam, and when I say it was disappointing, I mean the failure of the device. Would love to see a follow up video with a repair of that mosfet and a reflow of the solder to see if that unit is worth the time of buying and just reflowing as you pointed out. Cheers.

[@SAHILKHAN-lu8oq]

Those welders are awesome. The main fault is of the operator. Because if you use a week battery, the voltage drops while the welding pulse initiated, which doesn't supply enough voltage for the N channels, they become high resistance, then overheat and fail. If you use strong enough battery, these won't happen. You are supposed to use minimum 60C 5Ah Lipo battery - which means minimum 300A capable battery. The one used in the video definitely can't do so. Another modification can be done - search Maker Fabio's videos. He explained this and suggested a modification.

[@lancelink88]

Unfortunately, this is a well documented issue. You did not have a strong (or well charged) enough battery, and the voltage drop resulted in the mofsets not being saturated and it collapsed. I expected this to happen when you showed 12.6 volts, which is quite a bit below full charge. There is an excellent KZbin video which shows an easy modification by the addition of a capacitor to protect against this blow-out situation arising. It is a great little welder but you need a fully charged and sufficiently strong battery with plenty of amps and voltage.

[@AdamWelchUK]

Cheers. I’ll see if I can resurrect it and if I do, I’ll try another power source.

[@tedvicarri6153]

Oh...I must get one of those....damn...should’ve waited until the end of the video😂

[@mr.makeit4037]

Your very entertaining, Adam. Great video. I rather look for really good 18650 holders for my powerwall project instead of welding.

[@tetradgroup]

Wrong power source, voltage dropped and smoked the mosfet. Need to use the correct battery next time and it makes wonderful welds.

[@ejonesss]

lead acid batteries will lose charge over time that's why if you dont plan on driving your car for a while you need to have someone drive it for a few minutes to recharge the battery. lithium batteries do not self discharge as much unless the bms is faulty or of older design that does not go into sleep mode to save power. anything above 50 and you will destroy the unit especially if you dont make the modification of a capacitor between a diode and ground on the fets.* they recommend use below 30 . the problem with damage caused by going above 50 is that when the battery drops in voltage the fets are no longer saturated and overhead and blow.* *= according to another youtube videos.

[@bartklump]

The issue with these modules is that as soon as you weld, the input voltage goes down, thus the gate voltage goes down, thus the on resistance goes up, meaning the fets will get toasty :P If you mod it that the board itself uses a different 12volt power supply, and just cut off the battery voltage to the control module, the module will keep operating as normal

[@astrolite3192]

...and no circuitry to handle avalanche current.

[@sortofsmarter]

As Dave Jones famously said " I hope it doesn't work, so you can figure it out"..lol I wasn't interested in that one but as strange as it sounds I want one now...

[@ArthursHD]

Thanks! kWeld it is then :) Choose a proper MOSFET :) I looked at them & saw that I won't be able to tell how much power I put in a weld. And knew that the only way they can make it so cheap is to use solder as a conductor so I would need to solder some offcuts of a solid copper cable. Now I see it is even worse - a Chinese MOSFET released the magic smoke.

[@ElTelBaby]

That was SAD 2 C it go up in smoke on the very 1st Spot Weld Sure hope U can fix it;... explain any mods U make in a follow up Video

[@arkatub]

I also got this and they supplied spare mosfets with it, it did 3 more welds then yours before it died, seller refunded immediately, I didn't bother to repair it.

[@stevetobias4890]

Should have started much lower instead of the preset 10. I would have started at about 4 or 5. Also auto might detect the current passing through the MOSFET's and shut off the current at a set point. Edit** I would contact the seller with a link to your video to show that it blew a MOSFET after the first use.

[@jameslund221]

Why, why, did this happen?

[@revivedash2679]

I too have recently bought one of those spot welders and the exact same thing happened to me. I can say that it is a good gadget with slight modification and I have enjoyed it for about a week now. According to another video I have seen (kzbin.info/www/bejne/nJXRgGOQYtiWoKM) The issue lies with the drop of the battery voltage during a weld resulting in the control circuit not putting the mosfets into saturation. The solution to which was to put a bypass capacitor onto the rails of the control board. After doing this (and charging the battery) the spot welder seems to work pretty well and makes strong welds (while only running on 4 fets but I have of course ordered some replacements).

[@AdamWelchUK]

Great news. I’ll take a look and see what I can do. Thanks.

[@evanas142]

Thats what I done when I bought a new and I am using about 2 years on 4s battery 70c and is awesome spot velder,works briliant :)

[@patrickburton6130]

Curious if you can claim a refund.

[@CNCNerd]

Add a cap on the gate driver !!! Without the cap the gate voltage Drops below the threshold

[@pulesjet]

LOL I had two other versions do the smoke test. Don't feel bad.

[@ANDYMCNET]

Uncle Bumble. 👍