Realiable spot welder, need some advice

After going through 2 “Boss level spot welders”, 5 lipos over a year and a half, and a Sunkko 737G+ Ive had it enough Basically after less than 2 months of use another new boss level welder has failed on me or the lipos which i doubt because they are 2 5ah panther graphene in parallel I even heated up the lipos to room temperature at 25 celsius over night before trying again

I got 6 packs to build, deadlines are approaching and the welds I get are really weak, so weak that I can almost break them by hand. And lately the welders failing on me, and throwing lots money in thrash for customs has been really stressing me out

I usually would get welds stronger than the strip itself, the welds would stay “sticked” to the cell and the strip would just start ripping from them

Im desperate to find a welder that is reliable,does not overheat, yet strong enough to weld 0.15mm pure nickel or more All I found on the internet were sunkkos, which I find very sketchy, and sunstone welders with no pricing on their sites, and arduino based and lipo powered

I found the @aulakiria welder amazing, for a few batteries, but using it for regularly building packs its not so great, because even with a heatsink and a fan I menage to get it to 40celisus

What welders do you use guys use?

@pjotr47 @longhairedboy @Eboosted @barajabali @thisguyhere


U need an industrial welder. Which are pretty expensive. @Kaly has one he can probably give u some info

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Im willing to spend up to a 1000$ But would prefer something more budget friendly, since Im not in the best financial situation ATM


I would of suggested thw arduino spot welder but it doesnt seem to be so useful in ur situation since if u go “cheap” then its going to cost u more because that is what has happened so far? But im pretty sure there are some inexpensive industrial spot welders

Kweld is very robust. He sells a wall plug psu with a super capacitor bank so you don’t have to deal with lipos for welding all day with consistent power. But if you go at it like a madman it’ll still get hot. When I weld fast the elecrtodes get too hot to hold. Then the battery connections, then the wires. Will want several probe sets to swap if welding a crap-ton very fast.

(need a psu to go with the cap kit)

And germany so just VAT for you?


I had the EXACT same experience as you and went with the next level spot welder, it’s freaking amazing go for it, it’s build like a tank.

However I suggest you add a capacitor bank or use 2 lipos in parallel or they will build up heat really fast


your refering to the Kweld?

I used 3 second between automatic welds on my boss level welder, and it would overheat every 5min I have been considering this welder for a backup, just last week Im in Croatia, so yea just VAT

But still I would like something 220v powered, just for not having to replace the batteries every few months because a pair of graphenes is like 120$

Have you considered getting 2-3 welders with batteries and switching them out every 50 or so welds? That way they would stay cool and last longer plus you always have a spare if one breaks.

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The heat is probably the reason they keep dying on me, on a certain speed of welding the temperature on the sensor stays at 30celsius, but that is wrong for sure, the mosfets are at probably like 100c 3 boss level Welders would cost me around 700$, that is not really a solution to my problem but is my last choice

yeah Next Level == kweld. @Eboosted you pulled the trigger on it? haha.

Size comparison with the boss here. kweld is godzilla.

There’s a long thread on endless sphere and also on eevblog if you want to read up on it.

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Kweld = Next level. The electrodes are forever and you set the energy instead of time

Some builders are just using 2 sunkko 709a…

Thats great to hear, I would like to use capacitors but also I dont know how long would they last

I have made great experience with this good old spot welder. IMG_0391

Did several battery builds with it and it never failed me.

Maybe it is a cheap option until you collect enough money for something really professional!


Have you tried the Malectrics? It is cheaper compared to the boss welder.

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I use the sunkko 709a. But I see there is difference between each 709a welder. There are some good welders from a batch and some bad.

It is also important which circuit breaker your house have. I use a 30A type C circuit breaker. My house installation has a possibility to deliver (at peak) 80A @240v. A spotwelder is such like a big short-circuit for your home installation.

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I made an Welder out of an Microwave oven transformer, the welds are so awesome with this one. Even getting better results than the “better” one in my workplace… Oh and I have an Footpedal, which is great.

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Not sure what to tell you, my boss welder has been rock solid, probably approaching 10k welds at this point.

I do have three lipos in parallel, and welder is heatsinked with a fan.

If it appraches 40c, i just take a break for a few minutes, temps come down to 25c pretty quick.

I find the biggest factor in quality welds is how fast the battery is. Hence the three lipos in parallel. And keeping the thing cool.






What timing are you using on the boss welder?

I get solid nickel-steel welds at 3ms pulse, 3x