Cheap Battery Spot Welder 18650, Yes its awesome!

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Testing and explaining the cheap mini battery spot welder. If used incorrectly it will cause damage.
This welder can be found in these links below.
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www.amazon.com/dp/B08M5GMC33/...
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[@oldmanonamotorbikeinbucks7604]

At last, someone who reads the notes and watches the Vids, so many reviewers using the wrong batteries, not just back up batteries, thanks for an objective review...

[@cerij4242]

This tutorial is dare I say it, spot on.

[@novasilas9306]

you probably dont give a damn but does anyone know of a way to log back into an instagram account..? I somehow lost my login password. I would love any help you can offer me!

[@manueljustice1278]

@Nova Silas Instablaster :)

[@novasilas9306]

@Manuel Justice I really appreciate your reply. I found the site thru google and Im trying it out now. Takes quite some time so I will reply here later with my results.

[@novasilas9306]

@Manuel Justice it worked and I now got access to my account again. Im so happy:D Thanks so much you saved my ass!

[@manueljustice1278]

@Nova Silas You are welcome :)

[@mygamertag2010X]

Awesome video. I'm using a 45Ah AGM deep cycle battery and setting 30E, using .15T nickel strip, on 18650 cells. Works great. And this is coming from someone who uses a $10k dual-pulse battery spot welder professionally. I absolutely recommend this little thing to DIYers and enthusiasts.

[@sporadic29414]

You'll be fine going over mah. What matters is the discharge rate (50c on the lipo / CCA on the car battery). If the battery can't discharge quick enough, the voltage will sag and the mosfets won't fully turn on (saturate) which can cause them to heat up and let the magic smoke out. Mosfets have a spec called RDSon which is a curve of resistance as it relates to gate voltage. When the battery can't discharge quick enough, voltage drops so the mosfet gate voltage drops, and resistance through the mosfet goes up. Resistance = heat = smoke. Good video by the way and good explanation for people aren't familiar with electronics

[@tetradgroup]

Thank you for comment and the clarification. I keep several tubes of magic smoke on the shelf, it's just a pain to get back in the component sometimes 😁

[@alklapaxida850]

as a engineer of 30 years DUDE you nailed it ! most fools should watch and learn from you

[@davemonger3190]

I spent a couple of days researching this little piece of kit before I buy one. This is by far the best and most informative review I've found. You confirmed my own thoughts and I'm now happy to buy one of these. Well done and thank you - keep up the good work.

[@tetradgroup]

Thank you, you will enjoy this little spot welder 👍

[@xibidit]

there are several versions, depending on what version you got, there are different issues needing care and mods.

[@cannab-al9582]

Same here. Ordered it halfway through the vid after my thoughts were reaffirmed. Its the truth for most stuff you buy. Use it right and it works. Try to cut corners or use it improperly and itll be crap. Same issue people have woth fluxcore migs. It wont work if you dont use it right lol.

[@stevetobias4890]

I have a cheap unit similar, my first few welds (tab to tab) were useless but like you showed us, I was holding vertically and pressing hard. Getting much better welds now, thank you.

[@kaylor87]

OMG, you're my friggin hero! So, I bought these little battery powered spot welders off Amazon, and was super excited to test them out. They have decent reviews, so I was expecting them to work. They're similar to what you've got there, but different in the fact that they have their own internal battery/power supply. I have tested them over and over, medium strength, max strength, thinner nickel, still I couldn't get a proper weld to save my life. Even when the strip stuck, I could easily peel them off, no good at all. I was getting pretty sad, about to just give up and send them back to Amazon, but I decided to do some more research first... In watching your video, you just hit the nail right on the head for me! I was pushing really hard, and even harder when it wasn't working. I was trying my best to get the probes straight up and down as well, thinking that a nice firm, solid contact would be best... Jesus, was I wrong!! I decided to try your advice, pushing less hard, using the corners of the probes, just being gentle with it... For the first test, I also turned the power down to a medium range. Holy sh*t, what do you know, after trying and failing dozens of times, I just got an AMAZING weld for the first time!!!! I can't yank this strip off at all, it's on there gooood!!! 😊😊 I am so happy man, thank you so much for the informative video!!

[@Edwardjonez]

your post put a smile on my face thank you very much sir😁

[@diggleboy]

100% correct of the operation and requirements for the mini battery spot welder. Excellent explanation!

[@greebo7857]

I just now got my little welder in the mail. You have just saved me from blowing it up. Thank you.

[@richardosborne8581]

Thank you for your great instruction. After watching you video at least three times, I just finished using the spot welder to assemble 15 Sub-C batteries to rebuild a Dewalt 18-volt battery pack. Everything worked just as you described.

[@rc6392]

Based on your review I ordered one. Experimented with various AH batteries and found the higher the AH the lower the weld # required. Stared with a 18AH AGM motorcycle battery, good welds at a setting of 60 I settled with an 80AH deep cycle battery. Perfect welds at a setting of 10. Great little unit, especially considering the price. Thank you for your efforts.

[@shermkeys]

Sir you have gave me the best advice ever thank you so much I was pushing down way to hard on my maletronics(best spot welder ever imo)probes, welds looked crappy and burnt looking and I had to dial that sucker to 60ms to get the welds to stick which I now no was ridiculously to high.But since I have been applying less pressure man what a difference my welds look clean and almost machine like now and I'm only using 15ms of power now and have to use pliers to get that sucker off now.I'm glad I stumbled upon your video because god knows how long I would have been welding the wrong way,so thanks again for this amazing and in depth video.

[@aromaticpillow]

Same here! This is a very common mistake for people.

[@blg53]

A good easy to understand review, well done. What I gleaned from other videos about this welder was that being made in China, it does depend on luck a little bit in terms of quality. The mods other videos talk about are to address that uncertainty in quality. The typical problems are too thin and uneven PCB traces making the MOSFETS not truly parallel, but putting an unfair proportion of the current through one or two of them. Also lack of voltage maintaining capacitor over the control circuit is a serious design oversight. It is that absence of the capacitor that requires powerful batteries to operate this welder reliably. A smaller battery drops its voltage during the welding pulse. That results in the drop of voltage on the gates of the MOSFETS bringing them out of saturation regime into linear one and blowing them as a result, as no MOSFET can survive the currents involved when in the linear regime. By inserting the capacitor (Fabio's fix) the voltage on the control circuit and correspondingly on gates of the MOSFETS is maintaned high during the welding pulse, so you can safely use a smaller battery. Aslo reinforcing and evening out the PCB traces improves reliability and hopefully reducing the heating up this video poster reported.

[@michaelcoceski5442]

Thank you bro. Well explained. I have purchased a simpler version than what you used but have not yet used it . You have potentially saved me a headache of blowing mine upon first use. Thank you - a great video.

[@SuperWhizy]

Outstanding illustration of inducing resistance (localized hot spot) by not jabbing the probes into the nickel strip and battery! Thanks for the video.

[@aswingsharif6729]

I watch this video twice. Once before buying the welder and now after I bought it, just need some practical info on how to use it properly.Thanks for sharing !

[@jamesdean9944]

Much appreciate the clear product overview along with the very informative best-use insights.

[@clifffiftytwo]

Your advice worked on my welder which I just received (Feb 2022). I tried it with a 30A radio power supply (didn’t work) before buying a 200 CCA riding mower battery which works fine. Still, I had to re-learn what you said about not pushing too hard on the leads. Every instinct is to crush them down and that just doesn’t work. Just short of firm gives a bit of spark and a useful weld. Fortunately the circuit is robust enough to support a learning curve. Very helpful video!

[@marierosellev]

Thank you. The best informational video on this spot welder so far! I'm excited for mine to get delivered.

[@johnrhodes3350]

Thanks for the electrode 'pressure' tips, and all the other explanation. Really useful.

[@rolandgeter534]

Thank you Sir... Excellent, down to the barest of bare explanation of what's needed to make this product work like it was designed to do

[@davidstringfellow229]

Wow, what a great video. And reading the manual...I love it!

[@damichl9684]

best video on KZbin with this welder THANK YOU! :D

[@tetradgroup]

Thanks for the comment 👍

[@torbjornsandberg9263]

Spot on, yes you are correct. The battery voltage drop causes the mosfets to blow up. I have seen modifications that would help but the key as pointed out is a battery that can delivers enough amps to do the weld with minimal voltage drop.

[@johnswoodgadgets9819]

a BHVR might help (Big Hairy Voltage Regulator)

[@uploadJ]

@@johnswoodgadgets9819 Really, a half Farad capacitor as mentioned by one commenter is all that's needed.

[@JD_Manufacturing]

Thankyou much. I was going to spend close to 200. On what I thought I needed in a battery spot welder. Going to save big.

[@TxRiverElf]

You are an awesome instructor!! Thank you! This is the most informative and practical video on these little spot welders, so far. I was backing off from giving it a go.. until I saw your common sense observations. Thanks again!!

[@themaldivian4115]

3 mins into the video. And now I'm a subscriber.

[@johnwhite6005]

This by far is the best video I have seen explaining on how to use this device. Thanks and God Bless you.

[@alexdefelice2448]

Thanks for this very informative intro to spot welding. Freakin' sweet little gadget too.

[@HobokenHam]

One of the best videos on a tech issue I have seen. Thanks!

[@tetradgroup]

Thanks for the comment!

[@fccmbc87]

you are perfectly correct regarding the battery usage on this mini spot welder on other youtubers. who are using small batteries .

[@MrJockito]

I bought a brand new lawnmower battery 250 CCA and it's not working at all..

[@MakerFabio]

Thanks, now i see why i randomly having bad welding, i was focus more on tip distance , but pressing too much.

[@DaviddoesStuff]

Thanks for the video! It’s truly amazing the amount of current a LiPo can put out. If you were planning a busy day you could run a small balance charger i the LiPo. Have a great day and be safe out there!

[@guyonhayklan9457]

Sir. You clearly understand this very well, I keep trying to explain to people about C rating or just the amount of amps a battery can safely dump... many are not really clear about that.

[@Sugarkryptonite]

Thanks for this vid dispelling all those myths about this unit. Very helpful.

[@abbii1661]

appreciate your explanation. best video on battery tab spot welding.

[@richardwasserman]

Thanks. I'm going to upgrade to welding my zinc strips. no more soldering.

[@russellferguson1491]

Best how to use it video that I have found so far. Thanks for the great work.

[@aaronbinder6903]

What a great video man!! I thought i knew what i was talking about spot welding but now i realize i really didn't understand everything. Thanks so much for the information and for the heads up about that sweet little spot welder!! I'm ordering that bad boy next payday. Great vid !! Aaron

[@EG-vy2lm]

Appreciate you taking time to make this video, all of my questions we're answered in this video. Gave you a thumb up and subscribed to the channel. Keep doing what you do best and enjoy the day.

[@dannylu6230]

Thank you for explaining everything so well, now I'm going to try one of these welder!!

[@keeponroading]

Lots of practices even as a hobby mig welder for few years but hard to weld until I heard that "just barely touching it to keep that strip". Many thanks mate.

[@fgaryam]

The difference between this and a mig or tig welder is that the operator can select the current for mig and tig; but these cheapos rely upon the "touch" because all you can change is the time the current flows. That's the setting everyone is talking about adjusting. >>>NO real Current control at all

[@robertotrinanes1744]

Thanks for clarifying issue about that stay safe.

[@digdouglasdig]

Thank you, saved me. I really appreciate your effort to help me!

[@melquesedekcastro7480]

Brother you're great. Simple and efficient info in how to get the right results. Thank you.

[@EmmeryCheung]

Awesome tips. I definitely would've just pushed too hard and not got a good weld. I've definitely seen videos of people doing similar things on youtube. Some reviews even say they burned a hole without getting a good weld and this explains it perfectly.

[@stvdmc2011]

great video and info....so many people fried this thing by using moped battery than they complain cheap thing didn't work.

[@tetradgroup]

Thank you. Not only that everyone thinks you have to do the low voltage capacitor mod, which is cool but I don't think it's needed if you have the right battery and keep it charged. Im sure I've done over 1000 spot welds with not a single issue.

[@davidthurman3963]

yea nailed it. there is a vid on adding a capacitor to protect the mosfet from low voltage and that is a good thing to do. i use a 2200 80c lipo.

[@Animatronicbear]

Is it possible to provide a link to the above referenced video?

@@Animatronicbear kzbin.info/www/bejne/bJuQd5aIgbalj9Usi=I19h5f866orUa6oh (Diy Mini Spot welder capacitor mode)

[@cmalc8]

Great tip on not pressing too hard ! ( Too much pressure = too low resistance = no heat = no weld)

[@ek8710]

That's incredible, there's so many amps you see the wires repel each other as the current flows.

[@demolitionwilliams7419]

Thank you! You saved me so much money and trouble

[@daveqlockard]

Thank you brother! I have a different unit, and was frustrated that my new scooter battery didn't seem to have the umph. Your breakdown was very useful to help me understand. While it's enough to crank a scooter, the 6ah isn't enough potential for the welder to do its job. Unfortunately, my directions were 100% Chinese, but you came to the rescue!

[@stevecahill9106]

Love the fact the welder will auto weld, no trigger needed. I DiY mosfet welder last year with car battery. Works great, but I use foot switch. Had this been available would of bought this. Would like to compare with one I built.

[@dcsmith5839]

Thank-you for postng.I've been leery of these welders because of the high failure rates in the reviews. I'm like you,only interested at the hobby,tinker level,not building a solar power system.Guess I'll pull the trigger.Thanks again.

[@kariminou1]

Great video I was putting too much pressure with the leads on the strip and did not get a good weld. Thanks

[@sweegyboii7095]

2:54 this explanation is very clear, it helped alot. Thanks!

[@justintothetruth]

Wow man! Great video! You obviously just started your channel not to long ago ( I’m guessing). Great audio, great voice, great at explaining shit. I’d recommend you crank out as many videos ASAP. I could see people really liking you. Much appreciated and once again, 👏. Looking forward to seeing your channel take off.

[@leinadalan]

Like the analogy!!! Makes perfect sense!

[@roberthill4239]

I have always found that if I want and need something to work I can find a way to make it work. But for 25 bucks if I had to blow one up to get past tge learning curve id say it would be worth it. I spent 250 on my welder and its bad ass but I'm also going to pick up tge cheapo for the money thanks to your video it will be nice to have a spare laying around

[@johnheath1668]

good explanation on how to get the welder working thank you .

[@wallyky]

A well-reasoned and practical review. Subbed.

[@tetradgroup]

Thank you 👍

[@curiosity2314]

I agree with your theories here. Never had a use for this unit but what you have shown looks to be correct.

[@thehobe2111]

I am an Electrical Engineer and had problems initially because the seller sent me the unit with NO instructions. Your explanation is very good, especially the recommendation of using a slightly lower pressure on the probes when welding. Before going to the internet (UTUBE), I blew up and removed two of the FETS that were shorted out. I solved my problem with using two separate power supplies, one for the weld (8V) and another for the control circuit (12-14V). Other solutions on the internet are good as well. Adding the 1000uF capacitor to the control circuit AFTER the onboard diode is another good solution. I am using 3 series 3000uF supercapacitors as the welding supply (8V) using the positive probe straight from the "welding" supercapacitor supply. The 8V supply was not sufficient when powering both the control circuit and the welding circuit. The FETS need at least 7V at their gates in order to provide their low resistance for proper welding. I do not have to worry about any voltage drops through the PC board. The negative onboard probe connection works fine and my board has only 3 FETS still switching after removing the two shorted devices. The lighter pressure you suggest allows a better heat buildup under the probes just as you described with your analogy of the mechanical switching/arcing points under light pressure. The bad FETS on a damaged board can be identified by measuring the resistance from each of the gate input (pin 1 on the FET source side) to the source (or drain) and identifying the ones with lower than 10 Ohms resistance. Remove the bad ones with a lot of solder and replace if desired but the board will still work fine with 3 FETS if you are careful with the "welding" supply. I have ordered some FETS from AliExpress and will be offering them on Ebay shortly for those interested in replacing some or all of them. Very good explanation on your video!

[@tetradgroup]

Thank you so much for the reply. Do you have a video explaining your mods by chance? I would definitely order some fets just to have on stand by.

[@thehobe2111]

@@tetradgroup I don't do videos but tried to make it clear that the board design could have been improved significantly by just add the capacitor that other videos have described. I did not investigate the board to find out that they had already used a diode to isolate or protect the circuit; if I had, I would have also just added the capacitor. I did not desire to use a large and heavy battery since I already have the supercapacitors to supply the welding current. I have also ordered a stack of 6 500F (2.7V x 6=16.2V max) capacitors to see if this would be a lightweight solution to the heavy battery problem. I would also add the capacitor with these smaller supercapacitors. The probes being delivered with these units also seem to vary from video to video. My probes have an offset machined smaller diameter tip; some use what appears to be a crimped copper pipe with a small tip.

[@Conservator.]

@@tetradgroup Here’s a video of the mod: kzbin.info/www/bejne/nJXRgGOQYtiWoKM

[@bbesser1138]

stunning video tutorial !!! Thank you so much for the video !!!

[@peterxyz3541]

This is perfect for a few dozen battery. Thanks

[@OverlandSubaru]

excellent explanation, I was skeptical based on the reviews, but your video definitely sold me.

[@GregOnSummit]

Excellent video. True DIYer and great explanation.

[@ronniepaulinc]

purchased one because of this video and followed all your specs and blew on first use!

[@housinit]

Not enough juice in a voltage source causes the MOSFETs to blow, they won't switch fast enough and they overheat. There is a fix for it by adding a capacitor to the board......but too late for that now. I'm sure you've seen all the videos on it by now. For a couple bucks you can replace the fet(s), thats what I'd do just cuz I hate adding more shit to the landfill. Bummer it blew on you first time around.

[@AbelMata-ng4bl]

I love your video and your plain simple explanation. It really works, thank you.

[@danrussell3439]

Thanks for sharing your knowledge. Excellent video.

[@justabouteverythingelse9826]

Great video, thanks for making it!

[@hal109]

Nice job explaining everything! I still put the mods into my version 1 red welder. Maybe not needed in my case, but sure works well,

[@lorenzocividino4719]

Nice explanation. Really appreciate the demo on contact pressure. I understand now why the other video I watched had the unit fail. As mentioned by others, the battery voltage drops if not enough capacity or wiring resistance not low enough. The FET's will not have enough voltage to keep them on hard. That could be solved with a separate source for the FET control but understand for the price, using a good source works. Not sure if anyone noticed but if you watch the wires going to the battery, especially on the higher power setting, they move slightly during the pulse. There is high current and resultant magnetic field moving those wires just in case there are doubters about the current capacity needed. The small LiIon battery worked because it has much lower internal impedance and higher current capacity as you stated. With a lead acid battery, it needs to be much larger to provide that high current. Thanks for the video!

[@aromaticpillow]

That's a known issue with many of these and there is a modification that can be done to prevent it. It involves adding a capacitor to the board to prevent the voltage to the driver from dipping too low. I did the mod to mine with great success. There are videos about it on KZbin.

[@guiterman6263]

Thanks dude good job im going to buy one of them welders now .

[@QsTechService1]

Looks like you got the second version of it what the problem is is the controller chip dying keeping the feds open circuit well dying by adding a capacitor and circuit with the controller chip make sure it doesn't die well the spot weld is in progress protecting the feds Awesome explaining the batteries Thanks for sharing

[@HGSuper]

Thanks for the explanation. Clear as a bell.

[@mikey4406]

Very good video. Your explanation is very clear. Thank you.

[@usnchief1339]

Resistance is the culprit. Thanks for the upload.

[@tomaszbuchtyar4288]

I rarely comment on videos, however this one is worthy of a big thank you for an effective explanation, demonstration and review

[@tetradgroup]

Glad it was helpful!

[@EnddyFishing]

nice discussion and very clear how to use it in a proper way..

[@SuperiorSumitomo]

Thanks for such a good explaination video for this subject ❤

[@markpinther9296]

Nice job on this video. Read the instructions. Good reminder. Well done sir!

[@Masterokt]

Excelent Video, i never spot weld before and was thinking exactly as you mention, push hard y strait

[@mr.berlingo8211]

Thanks, that's a really useful video, I just ordered one of these then hour on loads of the doomster videos! I have about eighty stainless steel iButton canisters to weld solder tabs to, as I am rebuilding some temperate data loggers to have replaceable batteries.

[@w5cdt]

45 degree angle for electrodes is best as you mention. Cold cranking amps implies the battery's internal impedance and does not directly relate to battery capacity in Ah. You are correct that the reason the MOSFETS blow is because the supply voltage sags and there is insufficient MOSFET gate drive to keep the MOSFETS fully "on". When that happens they dissipate a ton of power, get super hot, and blow. So you are right...using a wimpy battery with too high of an internal impedance will cause the supply voltage to sag and thus kaboom. My solution: 12V 7Ah battery in parallel with 0.5 farads of capacitance. Works fine! Most people don't have a 0.5 farad capacitor laying around unless you have one of those kick butt stereos in your car. Nice video!

[@bachmagiao]

Thank you, now I know exactly to weld properly

[@geebonzo]

I bought one of these in September. Blew it up, I guess. What you are saying about low voltage makes sense. I ran across the capacitor repair video first, and then this vid, but I think you are saying the same thing. One problem I had was I thought I had a 35 aH battery. It was a bit old and it tested as 10 AH. I got a second welder. I don't understand having a battery that is too big. The current should be a function of the circuit, but maybe this circuit is messed up. Seems like they are close and would have a decent welder with a bit more work. Nice to see people working together for DIY. Big thumbs up!! You have some beautiful weld and I appreciate the tips on how to make contact. Little things like that could make people give up.

[@billspradlin9619]

George, he's talking about current not voltage, in regards to needing high/more current.

[@eideticgoone7035]

A weld is almost like a direct short. The only things that limit the current passing through the weld is the internal battery resistance, and the resistance in the metal of the weld. But the MOSFETs have a maximum current rating. If too much current is pulled through them during a weld, they will burn up. A big battery that can deliver too much current is bad. If the battery is too small, then the large current draw will cause the battery voltage to drop. If the voltage on the mosfet's gate is below its saturation voltage, the mosfet goes into a region where it has more internal resistance to current flow. This is called the linear region where current is proportional to gate voltage. If too much current passes from drain to source, the internal resistance will heat up the mosfet and cause it to fail. Thus the battery should not be too small or too large. The li-ion batteries with the high current rating will have very little voltage sag and will not cause the problem of too little gate voltage. However choosing a battery of any chemistry that can supply too much current can blow up the mosfets. This is because the circuit does not limit the current. There are videos that describe adding a capacitor to supply voltage so the gate voltage doesn't fall below the saturation threshold. That seems like a good idea. Here is a video that explains the linear and saturation modes of mosfets: kzbin.info/www/bejne/a5aqZ3asmKp7gJo.

[@a.lexiconn9387]

@@eideticgoone7035 -- if the MOSFETs were passing their max, you would be right, current would be limited by batt int. resistance and weld; but they aren't. Here, MOSFET current is determined by the adjustable gate voltage NOT how much current the input can deliver. So battery being 'too big' cannot ever be a problem with this device until you had the power level set to maximum by which time you'd have welds burning and lots of other problems.

[@eideticgoone7035]

@@a.lexiconn9387 I'm currious how you know that the MOSFET's are operated in their linear region by adjusting the voltage. I would have thought that the power levels would have adjusted the duration of the pulses. i.e. their timing, not the voltage on the gate. But I don't really know. The auto mode already is turning on and off the welding so it just seemed likely that it was working in the MOSFET's current saturated region by timing the pulses.

[@lasersbee]

Spot on... Don't forget to also do the Capacitor and Positive Terminal Mods. Those mods will put even more reliability on your side. Great Info on the weld probes contact pressure...

[@321tryagain]

I'm familiar with "maker fabio"'s capacitor mod but not any "positive terminal mod". Can you give more information please?

[@lasersbee]

@@321tryagain Yeah... Put both Red wires (Bat and Probe) on the same Screw Terminal to not use the Positive PCB Trace.

[@thomasscott5227]

hi,and wish you all the best for the futur i made my own spot welder months ago, and like a lot in the comments it would,nt weld. i,ve watched all the advice on youtube and tried them all but nothing worked. today i came across your advice and thought i,ll try this as well as the others, and i have to say putting my welder on an angle makes a perfect spot weld on my replacement batteries in my cordless battery packs. i would like to thank you for the information you gave.

[@simonwhite699]

Thank you very much for the excellent information you explained it perfectly for me, really appreciate it!👍

[@vojtechborek8063]

Hi, thank you very much for your video, it was just first thing I did - just pushed more and more and more and welds weren't firm enough however I used good battery.. Good luck there :).

[@MaxReckless99]

sir you are amazing. and yes your right about everything you said. hats off to you

[@brainisfullofnonsense8183]

I am glad that you pointed out the problem that some other reviews have created. Spot welding is an incredibly current demanding application, and those 7.5ah lead acid batteries used for backup batteries and trail cameras just won't produce the number of "angry pixies" that are needed to run a device requiring 100 amps. The lawnmower battery is the best bang for the buck for about $20-25, where the car battery is more than capable of providing that current but at a much hight cost, say around $100. You can use bigger capacity batteries with no ill effects, so don't worry about using the larger car battery, or even a truck battery for what thats worth. It is only a concern if they are higher voltage or less current (Amperes) than demanded by the device. Some devices provide for overvoltage protection, others have undercurrent protection (to keep motors, etc. from being damaged), and others provide for both overvoltage and undercurrent protection. With spot welding, low voltage and high current are the name of the game, and that means big fat conductors from the battery all the way to the leads. Now here's where this enginerd is thankful that those other people ONLY had the $20 device let out the magic smoke: IF the MOSFETS did not get burned up and cut off the flow of current but instead failed in the closed position, the people could have had the battery they were using possibly "explode" like short circuiting a car battery or they could of had the battery they were welding tabs onto sink all that heat and then "explode" by getting them too hot for too long. Oh, I have a thought on how those backup batteries could be used with this welder (which is really just a programmable timer from 10 to 90 milliseconds), which is to have several of them wired in parallel (+ to +, - to -) so each battery only has to provide a part of the current required. Dependind on the size it could be six all the way up to 12 (possibly more if really small backup batteries are used). A capacitor bank could also be used. But I digress because either of these options is much more expensive than getting a $20 battery from Walrus-smart and just getting on with the welding. You got a new sub here. Well done.

[@tetradgroup]

Thanks for the clear explanation, you are spot on, just go get a lawn mower battery and happy welding. So many people try to over complicate this. Sounds like your a fellow aVe fan 👍

[@brainisfullofnonsense8183]

@@tetradgroup Yes Sir! One of the first 50k subsribers to his channel if I remember correctly. And just to let you know, after commenting I watched a 'capacitor fix' for these units and I have to say it looks like way more effort than just getting the garden tractor battery and using the leads provided, or using the same wire gauge or larger (smaller ga. number) to add short extensions as you did. That's the best options for a bench unit, and I think in the rare circumstances where you need to take the welder to the batteries instead of the other way around that lithium pack you have will be fine. The only reason that I wouldn't suggest using it all the time is because of their finite life measured in charge cycles combined with the higher cost of the pack. If you were using it full time out in the field and could justify the expense for the most compact form I would say get three of the 5000mah lithium cells (I have some that are the 2650 size cells, so 26mm diameter vs 18mm diameter for the 18650) tab them in series (3s1p) then shrink wrap them. Velcro them to the unit and done. If you went 3s2p you could more than double the expected life of the pack and cut the peak stress in half (which would lessen the butt-clench factor for me), but that's assuming they make it to end of life without being unintentionally 'decommissioned' by any of a million things that can (and do) go wrong when a tool is out in the field. Best wishes

[@crispy-k]

I bought one of the spot welders that have a battery on them. Cost 16$ i think. Works fine, i've rebuilt 2 complete ebike battery packs with it. No problem. Although it does have a tough time with thicker nickel strips. Nice vid ;)

[@tetradgroup]

Do you have a link to your welder?

[@ralphyrocket5770]

EXCELLENT Explanation!!

[@philiptaylor3262]

Thanks for the review

[@InssiAjaton]

I like to add a few more comments, although the practical aspects were already made very clear. My belief is that thew Energy setting is plain time. Higher number = longer time for the applied current (heat). The current is determined by the total loop resistance, which includes the battery internal resistance, the MOSFET resistances, the cable resistances and finally the contact resistance at the weld location. Now, a little of basic math. The current is = Battery voltage divided by the mentioned loop resistance. The same current is applied through the entire loop. And then the "secret" -- the heat at any location within the loop is the Current Squared times local resistance. So, this says, if the local resistance is Zero, no heat is generated at that place. Remember the demonstration with high probe pressures --> no weld! All the heat was generated in the cables, the MOSFETs and inside the battery. The destruction of the MOSFETs is likely to be caused by DROP of the Gate Drive, if the the battery voltage drops. That is where the Cranking Amperes come to play. Basically they tell what the battery internal resistance is. Bigger batteries tend to have lower resistances and higher cranking amperes, but the ampere-hour number is only a rough guidance. The cranking amperes is the most relevant figure. And one final point -- the gate drive for the MOSFETs is taken from the same voltage that remains for the control box after drops in the battery internal voltage as well as the input cables. If the weld location resistance is very low, with near zero drop there, more of the drop happens inside the battery and in general before the point where the gate drive voltage is picked. The typical MOSFETs operate best with 14 to 18 volt gate drive. The 12+ volts is OK, but under the cranking conditions the battery voltage and thereby the gate drive is likely to drop below 10 V or maybe even below 8 V. At that reduced gate drive the MOSFET resistance is much higher. And more of the desired heat for the welding is instead heating the MOSFETs, which blow up sooner rather than later!

[@carrtb]

Your assessment is correct. Technique is key, and there is a certain “bandwidth” the welder needs to be within to operate correctly (produce good welds) and not burning up MOSFETs/damaging battery cells. I’ve seen a schematic of this handy tool. There is no built-in current limiting in the welding circuit current loop. Once triggered by the control circuitry the MOSFETs close the remaining “open” in the current loop between the battery terminals and the welding probes (assuming the probes are making contact on the nickel strip). Assuming ideal MOSFETs and battery, the “high” resistances in the loop are the contact landing sites between each probe tip and nickel strip. Resistance causes heat with the passage of current (in this case it’s a heat spike) in each of the landing sites. That’s what we want as long as it is NOT TOO LITTLE OR TOO MUCH battery supply current. Hence, the published battery operating current range given in the instructions! If the current capacity of the battery source is within bounds: 1) Damage to the device won’t occur by pressing too lightly with the probes but the resistance will be too high and yield high visual sparks. Welds will also be inadequate. 2) Damage may occur to the device by pressing too firmly because making a circuit path with high pressure contacts reduces resistance of the contact points. This means inadequate heat is generated/no heat spike at the contact landing sites, no (or maybe very little) melting/welding AND you may damage a MOSFET or two if the higher allowed current (of your chosen battery) is beyond the limit of the MOSFET(s). I don’t know for certain but it may be the upper limit given in the instructions is what will save them in the event probe contact resistance is too low. This is why you won’t want a battery with higher op current as it may provide too easy an opportunity at too hot a heat spike or blowing a hole in your battery can (neither of which anybody wants!!!). If you have a battery with too high current capacity: See final statement above! If you have a battery with too low current capacity: Lack of adequate current will cause voltage droop. A droop in voltage is likely to cause a malfunction in the MOSFET control circuitry, the severity of which will cause improper control of the MOSTETs and one of them (or more) will likely blow. I’ve seen this lead to no more welding capability (MOSFETs blown “open”) to permanent current path closure (MOSFETs burned “closed”). This is extremely dangerous as the current path will not cut off until one of the welding probes is broken away from its landing site. By this time the nickel strip will be glowing orange or yellow and battery cell likely damaged if it didn’t already initiate signs of self destruction. Attempting another weld will immediately result in another burn. Disconnect the welder from the battery source. If one dares to return and test the welder again it should be done touching the probes to a 12V automotive lamp with tungsten filament. If it turns on immediately at least one MOSFET is burned closed.

[@tetradgroup]

Thanks for this explanation. There seems to be a lot of debate wether or not a 12vdc battery with extreamly high current can damage the mosfets. I plan on testing that theroy with some extra units I purchased.

[@carrtb]

@@tetradgroup I agree and look forward to your outcome! My hope is the current will prove to be appropriately limited by the welding site itself using adequate welding probe pressure/technique no matter the quantity being made available in excess. If true, providing higher available current will just be unnecessary overkill, no need to buy a bigger source battery. Still, if someone wasn’t careful and applied excessive pressure at the probe/contact landing sites, that overkill current could be destructive to the battery cell. This last remark is akin to using a sledge on a nail where a hammer would be plenty. The sledge would certainly drive in the nail but at what collateral cost to the surroundings! Thank you for studying this, sorry I tend to write too much.

[@stevelester6276]

In other words, he is saying that the source battery is sagging in voltage under load, and that puts the MOSFETS in the device into their linear region rather than saturated, and the heat dissipation kills them. Can be hack /solved.

[@Pops180]

Just needs more gate capacitance