Cheap Battery Spot Welder 18650, Yes its awesome!

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

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...

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.

This tutorial is dare I say it, spot on.

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!!

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.

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

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.

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

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

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.

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.

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!

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

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 !

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.

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.

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.

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

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!!