So, it turns out the spot welder I got is a piece of shit (I think)

Hey guys,

so yeah I got this spot welder cause it had decent reviews and a built in cell tester

i’m having trouble getting it to do good welds.
I have it set to 85A current, 2 pulse setting. When I go to 90 it basically just blows a hole in the nickel. The “pulse group” knob… i honestly don’t know what it does. I fucked with it a little but it doesn’t seem to change anything.

When I do the welds, they seem fine at first, but after i go back and give them a tug to test them, sometimes they come apart if i yank hard enough. If i put a lot of pressure on the top of it before I weld to stick the electrodes in, I can get it to stick decently and can’t really pull it back out, but if I go back and put one more layer of nickel on it, I can definitely pull the top layer off.

Anyone have any suggestions to make the welds stick a little better?

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What thickness nickel are you using?


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if the suggestion is that i should get a better welder, feel free to let me know that haha

Sunkko welders don’t really like nickel over .15mm…

yeah, that’s what i figured, even though it says in the name haha. it seems pretty weak.

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this one says it can do 0.3mm in the name. are these guys just lying?

wait… i found it. :sweat:

Try .15mm nickel at 40-45 amps, dual pulse and the pulse knob set at 8-9.

ok, but my last question then is ampacity. according to the nickel chart, 0.15mm is good for ~7A. so doesn’t that mean that you would need to do 4 layers for the samsung 40T (which is a ~30A battery)? Or am I not doing that math right?

That’s correct

Depends on what width nickel your using.

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I have a simular welder. 0.2mm nickle won’t work. 0.15mm does.

Better source

Yes, as @Athrx linked, there was an experiment done (you can see it somewhere in that thread) that led to those numbers being revised. I’d use those numbers in the top of the Conductor Current Ratings thread.

edit: it’s here

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For esk8 use, unless you really do run full speed 5kw down the highway for half an hour at a time, the numbers in red barely truly get warm.

Even on pneumatics, it takes me about 1000w to maintain 40km/hr. That’s 20 amps at 50v. I may use 60, 70 to get there fast though

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Those ratings are continuous, it’s designed that way. For instantaneous or peak, you can pretty much double all the numbers for a few seconds at a time. Like starting from a stop for example or climbing a steep hill.

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Make sure you’re not trying to weld a second layer of new nickel directly onto an existing spot where you’ve already welded - my experience has been that each weld needs a fresh spot. Also, I always give the strips of nickel a gentle sanding w 600 grit and then wipe them with isoprop.

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I got thinner nickel, and the pack is coming along nicely now. The welder can actually make a good weld on the 0.15mm nickel.

I changed the design to a 12s4p flat pack.

My question now is about making the whole pack structure. I don’t have much in the way of pcb or hard plastic.

This is probably a total noob question but can I use cardboard to give the pack a “skeleton”? Or is that asking for a fire?

after wrapping fish paper and shrink wrap around it, of course.