@@ScottiesTech I try to avoid buying anything from China so this was an exception. It was ordered on Oct 17, 2020 and I will reverse engineer it and try to upgrade it when it arrives. Another UA-camr, zec23dark did a video where he removed the blown FET and replaced it with good results. ua-cam.com/video/TC30oNb_VP0/v-deo.html If the upgrades work and are easy and cheap, I'll let you know.
I saw the reply from BeiLLiac4 after posting my comments. This is an edit. His solution is elegant, beautiful, and inexpensive. I plan to go a little farther, but his solution may be sufficient for most users. Scottie, I received a different flavor of spot welder from a U.S. seller while waiting for one like yours to arrive from China. These are actually very simple devices that suffer from multiple unwise design compromises. First they use a microcontroller that is extreme overkill, even though they are very cheap. The microcontroller and associated electronics operate from the 12 volt supply common with the welding power source. That is a very big mistake. The one I have here uses a 78L05 regulator, but if the 12V power sags under extreme load, the CPU will not make you happy. This is why a weak main 12 volt supply will cause failure. Cheap small gauge wires feeding the unit will cause a voltage sag under load and also contributes to failure. The voltage sag under load causes insufficient drive to turn the mosfets fully on. A mosfet is likely to fail when it is operating between fully on and fully off where massive power is dissipated in the channel. The first mosfet to fail will short and likely save the others from destruction. The welder controls the negative leg of the power and the positive need not even connect to the board except to power it and possibly detect when pins touch the nickle. I am going to hook up a separate small 12 volt regulated supply to the board and let the main positive wire bypass the board completely. Later a capacitor or other circuit might be added to allow detection of when pins touch the nickle. Please let me know if you want updates on this as more is learned. I believe a few simple inexpensive changes will make a big difference in reliability and performance.
This might be a good time for an update on my approach to battery spot welding.
The main theme could be called "overkill".
The first part is the main power source, super capacitors.
A computer server power supply that can produce 62 amps at 12 volts will charge a bank of five 2600 farad 2.5 volt super capacitors through five 1 ohm 100 watt aluminum clad power resistors on a large aluminum heat sink.
The 12 volts will be switched with a large N channel MOSFET. This has already been prototyped and tested.
I am building the wood mounts for the super capacitors now.
Would it be a good idea to make a video of this ?
I have never done a UA-cam video. This would be a first and very basic effort.
Keep in mind that as far as the bad welds go, you have to press the probes firmly on the tabs and and they have to be on the meat of the cell to get a good weld. Where the tab blew there was an air gap underneath it because you had one of the probes by the edge of the positive terminal of the battery cell. The second time, you welded the tab with nothing underneath it so it would obviously blow. Also, if the spark was too high on your first three welds (not shown) it’s possible that the welding probes needed some polishing/refinement due to an uneven surface or slight charring at the point(s) of contact. There seemed to be other issues with the with the unit, like not beeping prior to the auto-weld, so the unit had its own issues. I thought I’d mention this for anyone watching this video and reading comments. I have extensive experience using high dollar spot welders. Tabs will frequently blow without proper contact between the probes, tab and metal surface.
What you are saying is true, although too much pressure is also bad. However in this case the unit did not beep after about two seconds of contact, just immediately sparked. I would have hoped it would fail open and safe, instead of closed and scarey! You can see this in other videos of it working.
you should change the broken mosfet, put a capacitor after the diode for the control board, the 5v rail. then use a battery like your other spot welder. this battery went down below 5v when you welded and it couldn't close the gates or manipulate the mosfets correctly and you destroyed it. i welded 100 welds with a 150A battery without issues. this welder is actually nice if you mod it with the cap (1000uf 16v).
Even though the experiment failed, the video served its' purpose and warned many people about the frailties of that mini spot welder. So instead of many of us wasting $ 16 we can add another $ 16 or $20 and get a better made welder. Thanks for showing us.
my did the same thing at the beginning then i open it add more solder from terminal to terminal change the positive probe and put it with other positive probe and works great .
Hi, I found the control circuit of this board has an error, i fixed it and changed MOS with stronger ones. Now it is working very well. See my mini spot welder watch before you use.
@@MakerFabio I watched it. Well done!! I couldn't be bothered to try to figure it out myself, but your fix does indeed work. I linked to your video somewhere here in the comments.
There appear to be several modes of failure. When connected to 12V source my welder will drain the capacitor as soon as power switch is turned on. It actually, slowly, brings the voltage of incoming terminals down to ~1.6V even if the 12V battery is connected. You can increase that voltage and get couple welds if you have variable voltage PSU, but DO NOT go over 24V, because it is a 25V capacitor in there and it WILL fail at 30V (ask me how i know...). The capacitor itself appears to have high internal resistance, with welder off, the capacitor takes several minutes to charge up to 12V and the amount of current it draws does not ever register on my PSU.
My unit did the same thing. It will even spark with the unit turn off. So, I disassembly the unit and found that the Mosfet was shorted. So I will cut the foil to isolate the Mosfet one by one to find out which one is shorted. If only one or two , I might be able to use it. If more than that, I need to remove them and replace with new ones. One set of 5 Mosfet in Aliexpress is sbout $5-6
I could have done exactly the same video ! I bought this device from BG, connected it on a 12v car battery, set it in auto with a 10E energy. I couldn't made any weld, from the early beginning the MOSFET was always opened and the only thing i got are splendid electric arcs !
I bought one of these and have so far done over 200 welds with it, with no problems. I was bold and used 0.15mm nickel strip too, so had to ramp it up to level 80 to get a good weld. Sorry about your bad experience, but you seem to have just got a duff one, you should try and get banggood to send a replacement....
His is this correct 120amp minimum? I bought mine off ebay it says in the add ok to use a lipo battery I use a new fully charger 3s 220mah lipo battery showing 12.42v when i tested a weld 2 of the mosfet banged and blew the fronts off them i think the 2200mah 3s battery only give me 2.2amp of power do you think it is because of the lipo battery then would this not happen if i used a car battery? Or anything with a minimum of 120amp Thanks
You need at least 180 Ampere (has nothing to do with Ah). You can calculate it by taking the Ah and multiply it with C ratings of your battery. So you need at least e. G. a 3S 3Ah lipo with a rating of at least 60C. That would give 180A. The battery in this video looks way too weak. There is a mod to prevent blowing up the mosfets with a capacitor.
EPILOGUE: Well, I tried several more welds. The auto mode doesn't work, and neither does manual. In fact, even the when the device is OFF, current still flows through the welding leads... So I basically just have 2 leads connected directly to the battery. Given also that my first 3 welds were successful (if a bit weak), it's definitely dead. :(
I just had exactly the same mode of failure on my spot welder. I was using the auto jump starter for power source. Tried it first on 20% setting, but the weld was too weak. Increased the setting gradually to 60%, but it was still weak. At 80% setting it suddenly provided power, almost melted the strip and the cell. Now it is shorted from input to output, most likely one of the MOSFETs is shorted. For information - my battery was fully charged before I started the testing, I measured 12.7 V. Yesterday I asked Banggood to replace the unit under warranty (I bought it for $16.99 on August 21 and it was shipped 3 days later). Somehow Banggood was not surprised and offered me a full refund. Most likely they knowingly bought a batch of defective welders and sold it to unsuspected public. Now they sell the same welder for $24.99 - maybe they are not defective this time...
you have a blown mosfet or more, check with multimeter - tese spot welder die very fast if you power it with under sized and under rated battery, bro - seriously !!! PB 7Ah battery ? - check my channel video - i use the same spot welder, pcb traces strengthened with copper and solder, and i powered it with 3S80p Lithium ion battery, which can easily output 200-300A pulse current. i welded at 30-40E , but later i tried 80AH car starter battery and it welded at 10E , so conclusion is the bigger and high current the battery is, lower will be the welding time settings and when lower is the time setting the spot welder will less likely to get hot or die. ua-cam.com/video/XjvIRuSl_eo/v-deo.html
i bought a few spot welders, and this was one of the ones i tried, it sucked. i agree with everything your saying, and mine smelled burnt upon arrival. terrible
that little battery is nowhere near enough discharge current to handle the welding. notice they said on the back 3s 5000mah 40-70C rated? that type of battery can provide 200-350 amps!!! the little battery you used can MAYBE deliver 10 amps! that's also why they said to use a car starting battery, the high current. what likely happened to yours, is the battery TANKED in voltage, the controller browned out and shorted on your tab. the design relies on pulses of high current which your tiny battery cannot handle.
Yup, the drop in voltage shorts out the FETs. As this dude explained in this video with oscilloscope and everything. ua-cam.com/video/fdnO0Z-scjA/v-deo.html
I have this welder version BL 01 2k and have done all modifications and I haven't had any problems/issues at all. Used it a lot ans it really works good. This is just user faults when you missed the nickel strip and you really don't need to set the energy so high with good weld.
Needs a capacitor on the control board. The MOSFETs open but the controller doesn't have enough power without the capacitor to close the MOSFETs after they open.
Yes, it work well, I just tested it using 12v 7AH battery for source power.... parallel with battery charger setting of energy on 50 good welding and no modification on it
It's called resistance spot welding. In particular this device is a "single pulse DC spot welder". There may be multiple DC pulses, usually first for cleaning the oxidation layer, and than welding, quench / temper, etc. Also, there is AC resistance spot welding.
Also just want to add in on your note of multiple pulses one being cleaning, well it's amazing these can get such a clean little weld considering no argon or shielding gass is being used.
Mine after 2 weld's. Fake mosfet's. To replace them with real ones. Get these IPLU300N04S4R8XTMA1 from digikey.com $28 bucks + Shipping and a really good soldering iron 60Watt+ or rework station.
You have to replace the mosfet because they are short check with multimeter. Current short pass this way. I burned mine and replaced the mosfet its working fine.
That little battery is the reason it died. I had the exact same thing happen. The mini spot welder needs a hefty battery!! I don't know why the manufacturer would say 5 amps and up. It needs a lipo of 50c or more. I have 3 of those mini spot welders and they work great as long as i use the right battery.
There are a range of these welders, all have various faults from factory. I've bought one, done the recommended mods for my particular model and it seems to work fine. I've welded in such quick succession that the probes get hot to hold so with the right mods its OK.
@@ScottiesTech yeah it's really random. I've just stuck it onto a 40ah car battery with good results. 40ah is the biggest battery they recommend however I dont see why it would be bad if it were bigger, as ah is a rating of capacity, not amps. The instructions I got with it also said not to exceed 50E of power, no idea why.
@@spinnanz Exactly. 5Ah can be 100A for a very short time... Of course, it depends on the design of the battery since lead acids are not all created equal. And with lipos sometimes I've had 'super-huge' ones fizzle out on me, and small ones supply current like crazy.
I think mosfet ratings usually are with a heatsink, which that does not have. Without a heatsink those mosfets will only safely switch a much lower voltage.
Good info and telling it like it is... Thanks for not editing around the issues... For that, I'm joining your group. I'm Currently gonna try out the Super Cap, 3D print a housing, etc... I just received the capacitor... Hope it works for me... Thanks again!
Actually, you can just buy a 500F (maybe less) super farad capacitor and use E=0.5*C*V^2 to charge the capacitor up to a specific voltage given your intended energy. The circuit board in fact did that implicitly. Shorting the capacitor will do the point welding! Another thing is that you need to make sure the circuit board is fully cooled down before the next weld. At $16, I'm pretty sure there is no temperature sensor to throttle the circuit operation, so consecutive welding will surely overheat and damage the MOSFET.
@@XuancongWang there isnt. ever. there is lots of scientific literature on the subject. this is how all the commercial thin guage welders in the world work. there is a reason years of development went in to this process. not sure why you think you are better than hundreds of hours of research by hundreds of engineers and a technology that has been refined over time.
True ,soldering 18650 batteries is dangerous if done improperly. But not impossible as if you get in and out soldering It is no more damaging than spot tab welding. If not at least a tad familiar with soldering don’t as you may hurt yourself or damage your batteries. My opinion only the cat above is very correct.👍👍 and the spot welder in question should be thrown directly in trash.
the same thing happen to me i open it i put more solder by the terminal and the line that go to the other terminal also i change the positive prob cable position and put it with the other positive lid and now works great also before it did not make the beep before it weld now it does thank u for the video
Isn't one of the primary reasons for welding vs. soldering that in high current battery packs can generate enough heat at the terminal that it can melt the solder? I learned that the hard way with helping my grandfather with a resistive foam cutting rig, my joints melted almost immediately.
i have been through the learning process with pulsed welding of battery packs. the best and most cost effcient welder timers are arduinos with foot pedals and custom hand pieces running off high C rated lipo packs.
I guess with so much current flying about it's really important for the mosfet gate and drain connections and low voltage control to have voltage protection devices fitted. Transient voltages will be high with several hundred amps being switched. Might buy one, check the design and fit extra protection if needed.
You used the wrong type of battery, you have to use a high discharge battery. Flooded lead acid batteries like car batteries work as well as high C drone batteries.
Personally, the failure of this device came as no surprise to me. We purchased a $16 Pacemaker for grandma, and experienced exactly the same results. Had grandma survived, we thought we might bump the purchase budget up to $22 ... but, its no longer urgent.
Found this video to get the right settings for the one I bought a while back. First test weld on a dead AA was pretty good. Second weld attempt was extremely weak. Third and fourth were sparks and smoke from the mosfets. What a piece of junk. Shame as the controller seems to want to keep welding. I wonder if I could just replace the mosfets.
your issue is you need to have the electrodoes pushed down hard against the strip otherwise you get the arc that will blow holes. this is spot welding 101. super simple stuff. also its a dual pulse so you have to hold it down until the second pulse is finished. if you use different thickness and types of materials you need to turn it down or up depending or you will blow holes. the mosfets are cheap. just replace them
A 7 Ah UPS lead battery is NOT adequate and nowhere near the current delivering capabilities of a 40-70C 5Ah Lipo battery. Thats why they say car battery and that is also why your welds were weak.
the battery amp hours are no way near enough. i use 2 12v 15ah in parallel and mine works perfect. i also did the capacitor mod and beefed up the tracks with fresh solder.
There are a number of design flaws with this unit and several revisions available for purchase. My particular unit had an issue with the gate drive circuitry, because they chose to use undersized gate drive resistors. The gate drive is a simple totem-pole arrangement of BJT's that drive each MOSFET through a 30 ohm 0603 resistor below that massive capacitor. The problem is that those tiny resistors can't handle the impulse energy for the gate drive (they dissipate peak power of 12^2/30 = 4.8W for a microsecond or so.) So they end up blowing open. with a high impedance gate drive, the gate is not driven hard and can cause the MOSFETs to dissipate thousands of watts and blow instantly, usually short-circuit causing the failure you observed. Mine failed a bit more spectacularly with bang and MOSFET exploding. Also that 10AWG wire is just not thick enough for this application. large diameter wires are quite expensive, might need to find some welding cable since those should handle the current. Another alternative is to power this unit with more voltage and just deal with the voltage drop across the 10AWG wires. If you do a lot of welds on a big bank, the electrodes quickly get too hot to hold in your hand. I found after about 10 welds I had to let the unit cool down. The wires seem to heat up the most.
Also that UPS battery isn't optimal, it will not last long in this application. I'm using one of those lithium ion booster packs to jump start a car, they can deliver in excess of 1000A into a short circuit. Using a lawn mower battery or a car battery would be better. Such cells are designed for high pulse currents, they differ in that they use a lead sponge material with a lot of surface area, as opposed to a deep cycle battery which uses solid lead and has space near the bottom for lead to flake off and build up allowing greater longevity when deep discharged.
What pp have told me about this welder is don’t use a battery above 12v so if youre battery is 12,4 use a load to get it too 12v. I walkt in the cheap trap too i don’t have the welder its in transport and i recomend too start whit e10 not 40 and wal youre way up
I guess you should get two, if you buy one at all, so you will have a backup! I just built one, using a starter solenoid, and a spotwelder timer, it works great, with a 4s lithium battery, it needs to be 12v or higher, to do nice welds, so maybe even a 5s, I use lipo cells capable of 400+ amps, and use 4gauge welder cable, but it has to be set at the fastest pulse, or it will fry everything, I'd like to use a bank of MOSFETs, but I'd use double what these things are using, my rig will probably weld 1/8" steel plate together! Ha-ha....
10:20 you did miss the metal surface on the battery and I think there is some confusion about amp hours and amps? maybe your battery wasn't able to actually deliver a 7.5 amp pulse? but it is an ultra cheap spot welder so ymmv
Actually I have this cheap spot welder and it work firmly without any issue moreover this cheap spot welder can welder from 0.1mm untill 0.3mm nickel strip and I produce and review also.
The electronics are probably fine - they're trying to switch mosfets that failed in the closed position. You could probably get the electronics to switch another circuit, one with better protection for the MOSFET's, or switch something like a solenoid. You'd have to design it so that any residual energy from the coil is dumped back into the battery's negative rather than into the control circuit, but you can do that with simple diodes if you select them carefully. Whether or not a solenoid can switch fast enough is another thing, but it's probably worth a little time experimenting!
The mosfets are fine...it's your technique. You burned through the nickel strip because you positioned the probes off of the battery terminal underneath the nickel strip. If you reposition the probes on the nickel strip with the battery terminal directly underneath the strip it will weld fine as the battery terminal actually absorbs much of the energy from the pulse which is what effects the actual weld. I have one of these welders and have done dozens of batteries but it does take a little practice in the beginning. Also increment the weld power gradually ...no more then 10 units at time until you get a good weld. Each power supple battery is different as is the thickness of the nickle strip...the .15mm strip takes more power than the .10mm. Try it again...I think it's ok.
Just had the same problem with mine.... (I got it for 25USD!!!) if only I had seen your video earlier! I tried with 3S lipo and with pb 12V7.2Ah. It seems that there is no count down time, and no matter what adjustment I do, it gives full powen! I will contact Banggood for a replacement... If anyone has a work around please let us know...
@@robmc3338 that's what I did and beefed up the bad solder alongside the mosfets and bought a 5000 mah 11.1 Lipo battery before I tryed it cuz thay are junk without doing it
You obviously misunderstood the label printed in the back of the welder. Your 7ah, 12v acid lead battery is NOT adequate for this welder. It will cause damage to the mosfets. You need an adequate car battery that supports hundreds of amps of current or a 5ah lithium (actually lipo) battery that allows 40-70C discharge rate. Even a good li-ion battery pack ( e.g. for bikes) less than 25 ah is not adequate for this welder. When a capacitor is added to deal with this, one still needs an adequate battery and let the welder to cool down after 40 welds. It will last if used properly.
@ 07:01 A car battery would be a far better choice as you need at least 300 A to spot weld I think. 🤔 The other option is using like 6 2.7 V Maxwell supercapacitors of at least 200 F capacitance connected in series. 🙄
I saw other successful vids with this welder, so I ordered one. Just tested it out fully charged 3s 8ah. Started on one, hardly anything, worked my way up to 15 and it popped. Never got even close to a weld. Have you tried to repair yours?
Fully charged automotive battery is at 12.7-12.8 V. The Infineon datasheet for this 4N04R7 MOSFET shows drain to source voltage as 40 V. How can 12.8 V cause the damage, if 12 V is fine?
@@mikhailshneyder9131 well then I guess I'm wrong. I thought car batteries were closer to 14 volts. But if the fets can handle 40 then I don't know what is causing them to sort.
Unless, of course, its a Kit Kat Bar. Imagine the disappointment of friends and family (not to mention millions of viewers of television ads) if when they sang: "Break me off a piece of that Kit Kat Bar!" You were unable to break it. 🤔
My welder is shorted input to output after about 10 welds at low power. I took it apart for diagnostics, but cannot see any visual damage. The control board still works like it should, the problem is on the bigger main board. I believe the 5 MOSFETs are used to switch the -12V from a battery ON and OFF. +12V goes straight from input to output. Anybody knows how to check the MOSFET without its removal? How do you remove one if you have to? I've got the datasheet for 4N04R7 MOSFET and it shows a big soldering pad at the bottom. It may be very difficult to remove if solder got there. On the opposite side of the same board right under the MOSTETs there are 5 little devices marked BG. Not sure what they are, but they only have 2 contacts. Four of them measure about 65 ohm accross, but the last one (closer to the power switch) is only 1 ohm. It may be shorted. Anybody knows what that is?
Well, one problem is that the MOSFETs may be labeled, but there's a lot of knock-off stuff floating around - especially in unusually cheap gizmos shipped direct from China. So who knows if those FETs really are what they say they are.
@@ScottiesTech I was thinking "knock offs" too...but then the thought that the chineese are smart enough to avoid their own cheating....and a factory that can design and manufacture sophisticated electronics has smart people ! I would agree that if the product was sold by showing huge mosfets "under the hood" but none off us would have known how they achieved the end result...i.e. it just works...like others....I can't wait for your followup video....Great education for us all....
Just finished watching your diy smartphone faraday box from 2 years ago.. would you still use aluminum foil or copper? Would you do it any differently if you were to build a new box?
I bought this last week I connected it to a new fully charged 11.1v 3s lipo showing 12.42v it did not weld the nickel strip together only burn Mark's I then turned the unit up to full power after 3 attempts it blew the front off 2 of the mosfet? It does state in the add lipo is ok to use I have now had a full refund do you think it is because of the lipo power? Would it be better using a car battery I'm not sure why it blew the mosfet up it made a loud bang I would think the 3s lipo would be enough power?
The battery matters, but even if you use one according to the included specs, it will still fail due to a design flaw. This guy fixed it: ua-cam.com/video/fdnO0Z-scjA/v-deo.html
Scotty, the buzz about an EMP requires a run-down on what an EMP is and how to protect against it -- lots of sellers selling EMP protection products but how can the average joker know if they would work?
Should have used a heavier battery. you need a quick switch on those Mossies, small 12v 9Ah batteries take to long to activate the mossies and cook em. use a smallish car battery next time.
It's funny that after so many of these have failed that the price of these has jumped up to about $40. I did find one for about $24 and I will do the upgrade before I use it.
Maybe buy a couple of capacitors and manually dump the current on the spots. I remember seeing a video last year. There is a math to it (to keep it within safe limits). It should be worth a try.
You need to retry! But first, change that small 7.2Ah battery with at least 30Ah or greater. Small battery capacity pose 2 risks: bad weld result, damaged mosfet switch. But then..., does your welding kit still working?
I just happened to notice this video that says that a low voltage condition can undersaturate the MOSFETs and cause them to blow. He also has a simple mod for that. Re-move the space after the dot to get the link: 'Cheap 18650 Spot Welder Reliability Mods and Test' youtu. be/u5khY6d3qds?t=170
DO NOT attempt to use this unit before modifying it! This unit has a design flaw, which is explained and fixed here: ua-cam.com/video/fdnO0Z-scjA/v-deo.html Sellers may claim that your battery is inadequate as gate voltage does sag, but in reality this is an obvious design oversight that could be easily fixed with a hardware revision. Gate voltage must be kept high by local capacitance on the control board or Source-to-Drain resistance will rise rapidly and blow one or more MOSFETs. If they fail closed (shorted), which is most common, then you will have a permanent, and dangerous, dead short between the electrodes, as seems to be the case for Scottie. As of 2020-12-24, the Banggood price has doubled in just a few months due to high demand. Though still a reasonable value when compared with higher-quality competitors, I would not pay more than US$25 for this kit, even if they eventually fix the gate voltage problem.
Yeah, a too-small battery shouldn't make a difference. It should just not weld quite as well due to a lack of current. Technically, I followed their directions in terms of sizing the battery. Maker Fabio (the link you posted) is dead on the money, IMO. He has more patience than me, that's for sure! I preferred to make my own instead of spending the time to fix somebody else's design.
You broke it by using the incorrect supply battery. Using that small battery caused the supply voltage drop low enough to cause a fault with the controller chip. Use a car battery or a 5000mah lipo. A 7ah AGM battery can't supply enough current
Regardless of setting, using a car battery, it sent the tiniest zap with no evidence of welds. am i doing something wrong? attempting .15mm nickel strips
The fets have no protection from the inductive voltage that builds up in the leads and when the mosfets switch off and as it has no where to go the mosfets go into avalanche and allow the voltage through. This eventually destroys the mosfets and they go short circuit. One of your fets is likely short circuit so there is no switch on and off which is why it melted your nickel. A tvs diode and a flyback diode fixes the issue. No idea why the circuit designers did not add these as it’s freely available online in both maletronics and kweld circuit diagrams. Cutting costs I guess.
@@iRoNiiC_H3R0 According to ua-cam.com/video/XjvIRuSl_eo/v-deo.html these boards already have five SMAJ13A TVS diodes (13V) but may be used for the mosfet's gate trigger circuit
you ignored the instruction. It says the battery should be capable of 40-50C at 5Ah. Somewhere around 200A - 250A instantaneous current. That is possible with high quality 3S Lipo but not with a backup UPS battery. A car battery that has a CCA of 400 and up is good.
When the Chinese government locked down the country in February - March I saw the SUNKKO brands being advertised / sold for $50.00 on EBAY and thought it was very cheap. Now I realise that it was a steal at that price. Not sure if they were secondhand or new?
UPDATE: Heck with this thing! I built my own, and it works great: ua-cam.com/video/pyQ-gbYM8Og/v-deo.html
@@mikehodgetts4864 It's got pretty much NUTHIN... Not a very well-designed unit.
@@ScottiesTech I try to avoid buying anything from China so this was an exception.
It was ordered on Oct 17, 2020 and I will reverse engineer it and try to upgrade it when it arrives.
Another UA-camr, zec23dark did a video where he removed the blown FET and replaced it with good results.
ua-cam.com/video/TC30oNb_VP0/v-deo.html
If the upgrades work and are easy and cheap, I'll let you know.
I saw the reply from BeiLLiac4
after posting my comments. This is an edit.
His solution is elegant, beautiful, and inexpensive. I plan to go a little farther, but his solution may be sufficient for most users.
Scottie, I received a different flavor of spot welder from a U.S. seller while waiting for one like yours to arrive from China.
These are actually very simple devices that suffer from multiple unwise design compromises.
First they use a microcontroller that is extreme overkill, even though they are very cheap.
The microcontroller and associated electronics operate from the 12 volt supply common with the welding power source.
That is a very big mistake. The one I have here uses a 78L05 regulator, but if the 12V power sags under extreme load, the CPU will not make you happy.
This is why a weak main 12 volt supply will cause failure.
Cheap small gauge wires feeding the unit will cause a voltage sag under load and also contributes to failure.
The voltage sag under load causes insufficient drive to turn the mosfets fully on.
A mosfet is likely to fail when it is operating between fully on and fully off where massive power is dissipated in the channel.
The first mosfet to fail will short and likely save the others from destruction.
The welder controls the negative leg of the power and the positive need not even connect to the board except to power it and possibly detect when pins touch the nickle.
I am going to hook up a separate small 12 volt regulated supply to the board and let the main positive wire bypass the board completely.
Later a capacitor or other circuit might be added to allow detection of when pins touch the nickle.
Please let me know if you want updates on this as more is learned.
I believe a few simple inexpensive changes will make a big difference in reliability and performance.
They need a cap on the board it drop voltage at mosfet and resistance gets to high that's how I fixed mine
Scottie,
This might be a good time for an update on my approach to battery spot welding.
The main theme could be called "overkill".
The first part is the main power source, super capacitors.
A computer server power supply that can produce 62 amps at 12 volts will charge a bank of five 2600 farad 2.5 volt super capacitors through five 1 ohm 100 watt aluminum clad power resistors on a large aluminum heat sink.
The 12 volts will be switched with a large N channel MOSFET. This has already been prototyped and tested.
I am building the wood mounts for the super capacitors now.
Would it be a good idea to make a video of this ?
I have never done a UA-cam video. This would be a first and very basic effort.
Keep in mind that as far as the bad welds go, you have to press the probes firmly on the tabs and and they have to be on the meat of the cell to get a good weld. Where the tab blew there was an air gap underneath it because you had one of the probes by the edge of the positive terminal of the battery cell. The second time, you welded the tab with nothing underneath it so it would obviously blow.
Also, if the spark was too high on your first three welds (not shown) it’s possible that the welding probes needed some polishing/refinement due to an uneven surface or slight charring at the point(s) of contact.
There seemed to be other issues with the with the unit, like not beeping prior to the auto-weld, so the unit had its own issues.
I thought I’d mention this for anyone watching this video and reading comments. I have extensive experience using high dollar spot welders. Tabs will frequently blow without proper contact between the probes, tab and metal surface.
What you are saying is true, although too much pressure is also bad. However in this case the unit did not beep after about two seconds of contact, just immediately sparked. I would have hoped it would fail open and safe, instead of closed and scarey! You can see this in other videos of it working.
That battery in nowhere close to handling the current required. This is nothing more than user error.
I agree, the manual says about 40 ah
The information I have seen regarding this spot welder reads 25 to 40 amp-hour 12 volt battery.
you should change the broken mosfet, put a capacitor after the diode for the control board, the 5v rail. then use a battery like your other spot welder. this battery went down below 5v when you welded and it couldn't close the gates or manipulate the mosfets correctly and you destroyed it. i welded 100 welds with a 150A battery without issues. this welder is actually nice if you mod it with the cap (1000uf 16v).
Tell me more. I actually need to mod this. I wondered before I do it Ill find some info from internet who already had this issue
Even though the experiment failed, the video served its' purpose and warned many people about the frailties of that mini spot welder. So instead of many of us wasting $ 16 we can add another $ 16 or $20 and get a better made welder. Thanks for showing us.
Nope,
He doesn’t know how it works
ua-cam.com/video/cBrLQ75ffY4/v-deo.html
my mini spot welder is perfectly functinning and still four whole years
my did the same thing at the beginning then i open it add more solder from terminal to terminal change the positive probe and put it with other positive probe and works great .
Hi, I found the control circuit of this board has an error, i fixed it and changed MOS with stronger ones. Now it is working very well. See my mini spot welder watch before you use.
I mean: i made a fix video on youtube
@@MakerFabio I watched it. Well done!! I couldn't be bothered to try to figure it out myself, but your fix does indeed work. I linked to your video somewhere here in the comments.
There appear to be several modes of failure. When connected to 12V source my welder will drain the capacitor as soon as power switch is turned on. It actually, slowly, brings the voltage of incoming terminals down to ~1.6V even if the 12V battery is connected. You can increase that voltage and get couple welds if you have variable voltage PSU, but DO NOT go over 24V, because it is a 25V capacitor in there and it WILL fail at 30V (ask me how i know...). The capacitor itself appears to have high internal resistance, with welder off, the capacitor takes several minutes to charge up to 12V and the amount of current it draws does not ever register on my PSU.
My unit did the same thing. It will even spark with the unit turn off. So, I disassembly the unit and found that the Mosfet was shorted. So I will cut the foil to isolate the Mosfet one by one to find out which one is shorted. If only one or two , I might be able to use it. If more than that, I need to remove them and replace with new ones. One set of 5 Mosfet in Aliexpress is sbout $5-6
This unit also benefits from an extra capacitor on the control board.
I could have done exactly the same video ! I bought this device from BG, connected it on a 12v car battery, set it in auto with a 10E energy. I couldn't made any weld, from the early beginning the MOSFET was always opened and the only thing i got are splendid electric arcs !
I bought one of these and have so far done over 200 welds with it, with no problems. I was bold and used 0.15mm nickel strip too, so had to ramp it up to level 80 to get a good weld. Sorry about your bad experience, but you seem to have just got a duff one, you should try and get banggood to send a replacement....
Read the insTructions .120amp minimum
His is this correct 120amp minimum? I bought mine off ebay it says in the add ok to use a lipo battery I use a new fully charger 3s 220mah lipo battery showing 12.42v when i tested a weld 2 of the mosfet banged and blew the fronts off them i think the 2200mah 3s battery only give me 2.2amp of power do you think it is because of the lipo battery then would this not happen if i used a car battery? Or anything with a minimum of 120amp Thanks
You need at least 180 Ampere (has nothing to do with Ah). You can calculate it by taking the Ah and multiply it with C ratings of your battery. So you need at least e. G. a 3S 3Ah lipo with a rating of at least 60C. That would give 180A. The battery in this video looks way too weak. There is a mod to prevent blowing up the mosfets with a capacitor.
TY you saved me anxiously waiting for the traditional Banggood 6 - 8 week delivery (slow boat from China)
EPILOGUE: Well, I tried several more welds. The auto mode doesn't work, and neither does manual. In fact, even the when the device is OFF, current still flows through the welding leads... So I basically just have 2 leads connected directly to the battery. Given also that my first 3 welds were successful (if a bit weak), it's definitely dead. :(
I just had exactly the same mode of failure on my spot welder. I was using the auto jump starter for power source. Tried it first on 20% setting, but the weld was too weak. Increased the setting gradually to 60%, but it was still weak. At 80% setting it suddenly provided power, almost melted the strip and the cell. Now it is shorted from input to output, most likely one of the MOSFETs is shorted. For information - my battery was fully charged before I started the testing, I measured 12.7 V. Yesterday I asked Banggood to replace the unit under warranty (I bought it for $16.99 on August 21 and it was shipped 3 days later). Somehow Banggood was not surprised and offered me a full refund. Most likely they knowingly bought a batch of defective welders and sold it to unsuspected public. Now they sell the same welder for $24.99 - maybe they are not defective this time...
@@mikhailshneyder9131 I received mine 4 days ago and ditto. Banggood gave me refund though.
you have a blown mosfet or more, check with multimeter - tese spot welder die very fast if you power it with under sized and under rated battery, bro - seriously !!! PB 7Ah battery ? - check my channel video - i use the same spot welder, pcb traces strengthened with copper and solder, and i powered it with 3S80p Lithium ion battery, which can easily output 200-300A pulse current. i welded at 30-40E , but later i tried 80AH car starter battery and it welded at 10E , so conclusion is the bigger and high current the battery is, lower will be the welding time settings and when lower is the time setting the spot welder will less likely to get hot or die.
ua-cam.com/video/XjvIRuSl_eo/v-deo.html
i bought a few spot welders, and this was one of the ones i tried, it sucked. i agree with everything your saying, and mine smelled burnt upon arrival. terrible
Exactly the same here.. from AliExpress
that little battery is nowhere near enough discharge current to handle the welding. notice they said on the back 3s 5000mah 40-70C rated? that type of battery can provide 200-350 amps!!! the little battery you used can MAYBE deliver 10 amps! that's also why they said to use a car starting battery, the high current. what likely happened to yours, is the battery TANKED in voltage, the controller browned out and shorted on your tab. the design relies on pulses of high current which your tiny battery cannot handle.
Yup, the drop in voltage shorts out the FETs. As this dude explained in this video with oscilloscope and everything. ua-cam.com/video/fdnO0Z-scjA/v-deo.html
I have this welder version BL 01 2k and have done all modifications and I haven't had any problems/issues at all. Used it a lot ans it really works good. This is just user faults when you missed the nickel strip and you really don't need to set the energy so high with good weld.
Needs a capacitor on the control board. The MOSFETs open but the controller doesn't have enough power without the capacitor to close the MOSFETs after they open.
Yes, it work well, I just tested it using 12v 7AH battery for source power.... parallel with battery charger setting of energy on 50 good welding and no modification on it
It's called resistance spot welding. In particular this device is a "single pulse DC spot welder". There may be multiple DC pulses, usually first for cleaning the oxidation layer, and than welding, quench /
temper, etc. Also, there is AC resistance spot welding.
Also just want to add in on your note of multiple pulses one being cleaning, well it's amazing these can get such a clean little weld considering no argon or shielding gass is being used.
Nice video. You did a great job of extending a 90 second presentation into almost 18 minutes. I book-marked your video as a sleep aid.
I'm always happy to be of service to others.
I also had the same device and the mosfets blew up on the third weld.
Mine after 2 weld's. Fake mosfet's. To replace them with real ones. Get these IPLU300N04S4R8XTMA1 from digikey.com $28 bucks + Shipping and a really good soldering iron 60Watt+ or rework station.
Its due the board needing an extra capacitor.
Thanks for saving me $16.99! Saw it on eBay and though it might be good for a laugh.
You have to replace the mosfet because they are short check with multimeter. Current short pass this way. I burned mine and replaced the mosfet its working fine.
That little battery is the reason it died. I had the exact same thing happen. The mini spot welder needs a hefty battery!! I don't know why the manufacturer would say 5 amps and up. It needs a lipo of 50c or more. I have 3 of those mini spot welders and they work great as long as i use the right battery.
There are a range of these welders, all have various faults from factory.
I've bought one, done the recommended mods for my particular model and it seems to work fine. I've welded in such quick succession that the probes get hot to hold so with the right mods its OK.
Yeah. And unfortunately, it even seems that different models come with different instructions as to what battery to use. SIGH...
@@ScottiesTech yeah it's really random. I've just stuck it onto a 40ah car battery with good results. 40ah is the biggest battery they recommend however I dont see why it would be bad if it were bigger, as ah is a rating of capacity, not amps. The instructions I got with it also said not to exceed 50E of power, no idea why.
@@spinnanz Exactly. 5Ah can be 100A for a very short time... Of course, it depends on the design of the battery since lead acids are not all created equal. And with lipos sometimes I've had 'super-huge' ones fizzle out on me, and small ones supply current like crazy.
It is a great little wield with the correct battery
All you need is a 470-1000uF 16V(or higher) capacitor
Putting it where?
@@Quentyn73 it on UA-cam to show you how
@@BillyBob-fd5ht you mean this: ua-cam.com/video/fdnO0Z-scjA/v-deo.html
@@Quentyn73 Yes that the site, Look at this spot welder ua-cam.com/video/TI_ZV-5WHi4/v-deo.html
Wow! Glad to know that I am not the only one where these thinkgs don't always work as advertised. Thanks so much for showing us what really happens.
Hes using it wrong 😑
I think mosfet ratings usually are with a heatsink, which that does not have. Without a heatsink those mosfets will only safely switch a much lower voltage.
Good info and telling it like it is... Thanks for not editing around the issues... For that, I'm joining your group. I'm Currently gonna try out the Super Cap, 3D print a housing, etc... I just received the capacitor... Hope it works for me... Thanks again!
I made a video on this welder using a 3s 8ah pack and it is my best welder under my K-Weld.
You have an old version with the capacitor on the wrong side of the diode. You can fix yours by replacing the FETs and adding a cap
Actually, you can just buy a 500F (maybe less) super farad capacitor and use E=0.5*C*V^2 to charge the capacitor up to a specific voltage given your intended energy. The circuit board in fact did that implicitly. Shorting the capacitor will do the point welding! Another thing is that you need to make sure the circuit board is fully cooled down before the next weld. At $16, I'm pretty sure there is no temperature sensor to throttle the circuit operation, so consecutive welding will surely overheat and damage the MOSFET.
no. it wont work. you will blow holes. it requires a timer circuit becasuse it needs to be two pulses timed perfecly one after the other.
@@freelectron2029 why 2 pulses?
@@XuancongWang first one pre heats the metals and squashes them down flat with each other so there is no gap and chance for arcing, second one welds.
@@freelectron2029 I see. What if there is only one pulse, assuming the contact is good and there is no gap for arching?
@@XuancongWang there isnt. ever. there is lots of scientific literature on the subject. this is how all the commercial thin guage welders in the world work. there is a reason years of development went in to this process. not sure why you think you are better than hundreds of hours of research by hundreds of engineers and a technology that has been refined over time.
True ,soldering 18650 batteries is dangerous if done improperly. But not impossible as if you get in and out soldering
It is no more damaging than spot tab welding. If not at least a tad familiar with soldering don’t as you may hurt yourself or damage your batteries.
My opinion only the cat above is very correct.👍👍 and the spot welder in question should be thrown directly in trash.
Did you try turning the power down to like maybe 20e or even 10e . There is no problem with your battery.
My experience is that fets without snubbers go " boom" almost all the time. i have to admit that was a hilarious video though..
the same thing happen to me i open it i put more solder by the terminal and the line that go to the other terminal also i change the positive prob cable position and put it with the other positive lid and now works great also before it did not make the beep before it weld now it does thank u for the video
Isn't one of the primary reasons for welding vs. soldering that in high current battery packs can generate enough heat at the terminal that it can melt the solder? I learned that the hard way with helping my grandfather with a resistive foam cutting rig, my joints melted almost immediately.
i have been through the learning process with pulsed welding of battery packs. the best and most cost effcient welder timers are arduinos with foot pedals and custom hand pieces running off high C rated lipo packs.
your power supply battery does not have the correct amperage, as per the instructions...Great Vid!
I guess with so much current flying about it's really important for the mosfet gate and drain connections and low voltage control to have voltage protection devices fitted. Transient voltages will be high with several hundred amps being switched. Might buy one, check the design and fit extra protection if needed.
I still enjoyed the video Scottie thanks for the experiment!
Too funny... well, they did say 'small amount of batteries'. I'm looking for one now, thanks for sharing, love your videos.
Yeah, and apparently "small amount of batteries" is exactly equal to 1.5 cells. :(
You used the wrong type of battery, you have to use a high discharge battery. Flooded lead acid batteries like car batteries work as well as high C drone batteries.
Personally, the failure of this device came as no surprise to me.
We purchased a $16 Pacemaker for grandma, and experienced exactly the same results.
Had grandma survived, we thought we might bump the purchase budget up to $22 ... but, its no longer urgent.
😂
Found this video to get the right settings for the one I bought a while back. First test weld on a dead AA was pretty good. Second weld attempt was extremely weak. Third and fourth were sparks and smoke from the mosfets. What a piece of junk. Shame as the controller seems to want to keep welding. I wonder if I could just replace the mosfets.
your issue is you need to have the electrodoes pushed down hard against the strip otherwise you get the arc that will blow holes. this is spot welding 101. super simple stuff. also its a dual pulse so you have to hold it down until the second pulse is finished. if you use different thickness and types of materials you need to turn it down or up depending or you will blow holes. the mosfets are cheap. just replace them
this guy sells good hand pieces and batterys for power supply.
A 7 Ah UPS lead battery is NOT adequate and nowhere near the current delivering capabilities of a 40-70C 5Ah Lipo battery. Thats why they say car battery and that is also why your welds were weak.
the battery amp hours are no way near enough. i use 2 12v 15ah in parallel and mine works perfect. i also did the capacitor mod and beefed up the tracks with fresh solder.
There are a number of design flaws with this unit and several revisions available for purchase. My particular unit had an issue with the gate drive circuitry, because they chose to use undersized gate drive resistors. The gate drive is a simple totem-pole arrangement of BJT's that drive each MOSFET through a 30 ohm 0603 resistor below that massive capacitor. The problem is that those tiny resistors can't handle the impulse energy for the gate drive (they dissipate peak power of 12^2/30 = 4.8W for a microsecond or so.) So they end up blowing open. with a high impedance gate drive, the gate is not driven hard and can cause the MOSFETs to dissipate thousands of watts and blow instantly, usually short-circuit causing the failure you observed. Mine failed a bit more spectacularly with bang and MOSFET exploding.
Also that 10AWG wire is just not thick enough for this application. large diameter wires are quite expensive, might need to find some welding cable since those should handle the current. Another alternative is to power this unit with more voltage and just deal with the voltage drop across the 10AWG wires. If you do a lot of welds on a big bank, the electrodes quickly get too hot to hold in your hand. I found after about 10 welds I had to let the unit cool down. The wires seem to heat up the most.
Also that UPS battery isn't optimal, it will not last long in this application. I'm using one of those lithium ion booster packs to jump start a car, they can deliver in excess of 1000A into a short circuit. Using a lawn mower battery or a car battery would be better. Such cells are designed for high pulse currents, they differ in that they use a lead sponge material with a lot of surface area, as opposed to a deep cycle battery which uses solid lead and has space near the bottom for lead to flake off and build up allowing greater longevity when deep discharged.
You use improper technique here. You must press and hold the probes until it pulses. Lifting on and off like you did will cause an arc.
Yeah wish I had see this before I ordered 😱 what do you use for your projects and tried and tested 👍
What pp have told me about this welder is don’t use a battery above 12v so if youre battery is 12,4 use a load to get it too 12v. I walkt in the cheap trap too i don’t have the welder its in transport and i recomend too start whit e10 not 40 and wal youre way up
Ha ha couldn’t stop laughing (w/you, not @you). Better you than me! Thanks for the informative demo!
I guess you should get two, if you buy one at all, so you will have a backup!
I just built one, using a starter solenoid, and a spotwelder timer, it works great, with a 4s lithium battery, it needs to be 12v or higher, to do nice welds, so maybe even a 5s, I use lipo cells capable of 400+ amps, and use 4gauge welder cable, but it has to be set at the fastest pulse, or it will fry everything, I'd like to use a bank of MOSFETs, but I'd use double what these things are using, my rig will probably weld 1/8" steel plate together! Ha-ha....
You need 5Ah 3S 50C baterry. So batery must be possible to put more than 150A. This small gell bateries are not able tu give more than 50A.
10:20 you did miss the metal surface on the battery
and I think there is some confusion about amp hours and amps?
maybe your battery wasn't able to actually deliver a 7.5 amp pulse?
but it is an ultra cheap spot welder so ymmv
Thanks Scottie. I was just looking to make some Li-On packs.
Actually I have this cheap spot welder and it work firmly without any issue moreover this cheap spot welder can welder from 0.1mm untill 0.3mm nickel strip and I produce and review also.
mine did the auto funktion work on, but the weld was to weak can pull it right of the battey again
The electronics are probably fine - they're trying to switch mosfets that failed in the closed position. You could probably get the electronics to switch another circuit, one with better protection for the MOSFET's, or switch something like a solenoid. You'd have to design it so that any residual energy from the coil is dumped back into the battery's negative rather than into the control circuit, but you can do that with simple diodes if you select them carefully.
Whether or not a solenoid can switch fast enough is another thing, but it's probably worth a little time experimenting!
Hold that thought! I made my own welder and will post a vid about it soon.
@@ScottiesTech 👌👍
Hi Scottie,
Can you use Milwaukee M12 6Ah battery as a source of power?
That's probably too small.
The mosfets are fine...it's your technique. You burned through the nickel strip because you positioned the probes off of the battery terminal underneath the nickel strip. If you reposition the probes on the nickel strip with the battery terminal directly underneath the strip it will weld fine as the battery terminal actually absorbs much of the energy from the pulse which is what effects the actual weld. I have one of these welders and have done dozens of batteries but it does take a little practice in the beginning. Also increment the weld power gradually ...no more then 10 units at time until you get a good weld. Each power supple battery is different as is the thickness of the nickle strip...the .15mm strip takes more power than the .10mm. Try it again...I think it's ok.
How do you set the welder into Auto and Manuel Mode? Or i guess you could say how do you switch from one to the other.
Just had the same problem with mine.... (I got it for 25USD!!!) if only I had seen your video earlier!
I tried with 3S lipo and with pb 12V7.2Ah. It seems that there is no count down time, and no matter what adjustment I do, it gives full powen! I will contact Banggood for a replacement...
If anyone has a work around please let us know...
Will this device last long? Amazon reviews, it breaks after initial use.
It is garbage.
Two things, you need a good battery. And you need to put a extra capacitor on the control board. There are videos on this mod
@@robmc3338 that's what I did and beefed up the bad solder alongside the mosfets and bought a 5000 mah 11.1 Lipo battery before I tryed it cuz thay are junk without doing it
You obviously misunderstood the label printed in the back of the welder. Your 7ah, 12v acid lead battery is NOT adequate for this welder. It will cause damage to the mosfets. You need an adequate car battery that supports hundreds of amps of current or a 5ah lithium (actually lipo) battery that allows 40-70C discharge rate. Even a good li-ion battery pack ( e.g. for bikes) less than 25 ah is not adequate for this welder. When a capacitor is added to deal with this, one still needs an adequate battery and let the welder to cool down after 40 welds. It will last if used properly.
Waiting for a follow up !
Would this spotwelding be ok for high A aplications? Is there a max on these welds? 150A-200A
The instruction say that you need a car battery and use a working current between 120 to 180 amps, lower power source will blow your MOSFET.
@ 07:01
A car battery would be a far better choice as you need at least 300 A to spot weld I think. 🤔
The other option is using like 6 2.7 V Maxwell supercapacitors of at least 200 F capacitance connected in series. 🙄
I saw other successful vids with this welder, so I ordered one. Just tested it out fully charged 3s 8ah. Started on one, hardly anything, worked my way up to 15 and it popped. Never got even close to a weld. Have you tried to repair yours?
D'OH! No, I didn't try to repair mine. I built my own: ua-cam.com/video/pyQ-gbYM8Og/v-deo.html
you killed it because that 7A battery is WAY to weak for the job! You really need a big car battery or a high C rating 3S lipo!
So this battery 18650 is not anymore usable?
I think that using more than 12 volts is what causes the problem. maybe the fets cant switch at the higher voltage.
Fully charged automotive battery is at 12.7-12.8 V. The Infineon datasheet for this 4N04R7 MOSFET shows drain to source voltage as 40 V. How can 12.8 V cause the damage, if 12 V is fine?
@@mikhailshneyder9131 well then I guess I'm wrong. I thought car batteries were closer to 14 volts. But if the fets can handle 40 then I don't know what is causing them to sort.
Great video, your first welds at 9:16 were funny! Keep up the great work.
This seems to be a ripoff without screen working. Mine has working screen and adjustable joules. Welds well without any problems
I hate that when you buy something and it breaks right off
Unless, of course, its a Kit Kat Bar.
Imagine the disappointment of friends and family (not to mention millions of viewers of television ads) if when they sang:
"Break me off a piece of that Kit Kat Bar!"
You were unable to break it.
🤔
The welder works great.
1.You didnt use high enough amperage battery.
2. See 1
My welder is shorted input to output after about 10 welds at low power. I took it apart for diagnostics, but cannot see any visual damage. The control board still works like it should, the problem is on the bigger main board. I believe the 5 MOSFETs are used to switch the -12V from a battery ON and OFF. +12V goes straight from input to output. Anybody knows how to check the MOSFET without its removal? How do you remove one if you have to? I've got the datasheet for 4N04R7 MOSFET and it shows a big soldering pad at the bottom. It may be very difficult to remove if solder got there. On the opposite side of the same board right under the MOSTETs there are 5 little devices marked BG. Not sure what they are, but they only have 2 contacts. Four of them measure about 65 ohm accross, but the last one (closer to the power switch) is only 1 ohm. It may be shorted. Anybody knows what that is?
I would like to think Bodragon is right....how could that tiny battery stress 1500 amp rated Mosfets.....???
Well, one problem is that the MOSFETs may be labeled, but there's a lot of knock-off stuff floating around - especially in unusually cheap gizmos shipped direct from China. So who knows if those FETs really are what they say they are.
@@ScottiesTech I was thinking "knock offs" too...but then the thought that the chineese are smart enough to avoid their own cheating....and a factory that can design and manufacture sophisticated electronics has smart people ! I would agree that if the product was sold by showing huge mosfets "under the hood" but none off us would have known how they achieved the end result...i.e. it just works...like others....I can't wait for your followup video....Great education for us all....
What happened is the strip was not flat making it arc on the inside. When I apply the probes push on them to flatten out strip
Just finished watching your diy smartphone faraday box from 2 years ago.. would you still use aluminum foil or copper? Would you do it any differently if you were to build a new box?
The copper tape was easier to work with, and it's a better conductor. Definitely copper!
@@ScottiesTech Thank you!
I bought this last week I connected it to a new fully charged 11.1v 3s lipo showing 12.42v it did not weld the nickel strip together only burn Mark's I then turned the unit up to full power after 3 attempts it blew the front off 2 of the mosfet? It does state in the add lipo is ok to use I have now had a full refund do you think it is because of the lipo power? Would it be better using a car battery I'm not sure why it blew the mosfet up it made a loud bang I would think the 3s lipo would be enough power?
The battery matters, but even if you use one according to the included specs, it will still fail due to a design flaw. This guy fixed it: ua-cam.com/video/fdnO0Z-scjA/v-deo.html
@@ScottiesTech nice one thanks it seems a nice little unit I will mod mine cheers for that mate
Scotty, the buzz about an EMP requires a run-down on what an EMP is and how to protect against it -- lots of sellers selling EMP protection products but how can the average joker know if they would work?
Should have used a heavier battery. you need a quick switch on those Mossies, small 12v 9Ah batteries take to long to activate the mossies and cook em. use a smallish car battery next time.
It's funny that after so many of these have failed that the price of these has jumped up to about $40.
I did find one for about $24 and I will do the upgrade before I use it.
Maybe buy a couple of capacitors and manually dump the current on the spots. I remember seeing a video last year. There is a math to it (to keep it within safe limits). It should be worth a try.
the problem was your battery. Well it's not your fault, since the circuit has a bad design, but if you use a better battery it doesn't die as quickly.
You need to retry! But first, change that small 7.2Ah battery with at least 30Ah or greater. Small battery capacity pose 2 risks: bad weld result, damaged mosfet switch. But then..., does your welding kit still working?
I just happened to notice this video that says that a low voltage condition can undersaturate the MOSFETs and cause them to blow. He also has a simple mod for that. Re-move the space after the dot to get the link: 'Cheap 18650 Spot Welder Reliability Mods and Test' youtu. be/u5khY6d3qds?t=170
DO NOT attempt to use this unit before modifying it! This unit has a design flaw, which is explained and fixed here:
ua-cam.com/video/fdnO0Z-scjA/v-deo.html
Sellers may claim that your battery is inadequate as gate voltage does sag, but in reality this is an obvious design oversight that could be easily fixed with a hardware revision. Gate voltage must be kept high by local capacitance on the control board or Source-to-Drain resistance will rise rapidly and blow one or more MOSFETs. If they fail closed (shorted), which is most common, then you will have a permanent, and dangerous, dead short between the electrodes, as seems to be the case for Scottie.
As of 2020-12-24, the Banggood price has doubled in just a few months due to high demand. Though still a reasonable value when compared with higher-quality competitors, I would not pay more than US$25 for this kit, even if they eventually fix the gate voltage problem.
Yeah, a too-small battery shouldn't make a difference. It should just not weld quite as well due to a lack of current. Technically, I followed their directions in terms of sizing the battery. Maker Fabio (the link you posted) is dead on the money, IMO. He has more patience than me, that's for sure! I preferred to make my own instead of spending the time to fix somebody else's design.
Thanks! Learned a new phrase today: “and Bob’s your uncle.” (“There you have it!”)
You look like a cross between Seth Rogan and Luke Perry 😀
You broke it by using the incorrect supply battery. Using that small battery caused the supply voltage drop low enough to cause a fault with the controller chip. Use a car battery or a 5000mah lipo. A 7ah AGM battery can't supply enough current
Regardless of setting, using a car battery, it sent the tiniest zap with no evidence of welds. am i doing something wrong?
attempting .15mm nickel strips
yes, you're using .15mm nickel strips when it says .12mm is max
@@SorenX2008 other people get far more power than i need with the same welder
The fets have no protection from the inductive voltage that builds up in the leads and when the mosfets switch off and as it has no where to go the mosfets go into avalanche and allow the voltage through. This eventually destroys the mosfets and they go short circuit. One of your fets is likely short circuit so there is no switch on and off which is why it melted your nickel. A tvs diode and a flyback diode fixes the issue. No idea why the circuit designers did not add these as it’s freely available online in both maletronics and kweld circuit diagrams. Cutting costs I guess.
Where would you solder the diode. Would this be on the positive and negative rails after the MOSFETs?
@@iRoNiiC_H3R0 google 'endless sphere tvs schottky' JP Spot Welder forum thread page 23 has the info
@@iRoNiiC_H3R0 According to ua-cam.com/video/XjvIRuSl_eo/v-deo.html these boards already have five SMAJ13A TVS diodes (13V) but may be used for the mosfet's gate trigger circuit
you ignored the instruction. It says the battery should be capable of 40-50C at 5Ah. Somewhere around 200A - 250A instantaneous current. That is possible with high quality 3S Lipo but not with a backup UPS battery. A car battery that has a CCA of 400 and up is good.
Mine didn't come with any mention of 40-50C... Just "minimum 5Ah at 12V". Oops.
When the Chinese government locked down the country in February - March I saw the SUNKKO brands being advertised / sold for $50.00 on EBAY and thought it was very cheap. Now I realise that it was a steal at that price. Not sure if they were secondhand or new?
*_STEAL_*
>