kWeld - "Next level" DIY battery spot welder

flippy · May 10, 2019

i am looking at the cases and some questions pop up.
how does the fan cooling work for the kCap? i see a fan header but i dont see a mount for a fan.
i am also missing a STL for 3d printing the kCap case, the kWeld does have one.
can you design a case that will fit a 12cm fan and completly covers the capacitors you nothing can get near the caps?

doesnt the kWeld need any cooling? a small fan at the top or rear of the STL version of the case might help in the lifespan of the diode(s) and heavy usage.
the acrylic version has millions of holes but the STL is completly closed. a option for a rear mounted fan and a small grill in the front to get some airflow inside the case should help offset the lack of holes.

tatus1969 · May 10, 2019

I finally made it! "kSupply" power supply module 0-12V 0-70A to charge the ultracapacitor modules are ordered and available in my shop for preorder. https://www.keenlab.de/index.php/product/ksupply/ 8)

tatus1969 · May 10, 2019

flippy said:
how does the fan cooling work for the kCap? i see a fan header but i dont see a mount for a fan.

You need four 50mm M4 standoffs and then you can do this:

flippy said:
i am also missing a STL for 3d printing the kCap case, the kWeld does have one.
can you design a case that will fit a 12cm fan and completly covers the capacitors you nothing can get near the caps?

I went away from 3D printing because print services for that were much more expensive than laser cutting services. But there is a community contribution. I've never put it online because I couldn't find the time to test it. If someone reports me that it works the I can do that.
View attachment kCap-case-3d-stl.zip

flippy said:
doesnt the kWeld need any cooling? a small fan at the top or rear of the STL version of the case might help in the lifespan of the diode(s) and heavy usage.

I'm afraid but I don't know for the 3D case. The laser cut case doesn't need a fan, I could never bring the unit into overtemp protection.

flippy said:
the acrylic version has millions of holes but the STL is completly closed.

I could supply the original Sketchup files, would you be interested in extending that to fit a fan?

flippy · May 10, 2019

sure, ill, help. might take a while for me to have actual time to do it proper but i'll tinker with it when i have free time.

if you have the original files i can see if i can make a better solution that does not include a fan that is just a magnet for stuff to drop into.
i got a massive 3d printer that can easely print these big things.
i will PM you my email adress to send them to.

BenjAZ · May 20, 2019

I'm so pleased with my kweld!
I cannot believe the difference between this great device compared to my previous chinese spot welder

However, to weld 0.2mm nickel strips for a whole 50cells battery I've noticed the wires (battery and electrodes) get quite hot.
I was wondering what is the best way to cool down the wires.

Last time I leaved the electrodes on a frozen gel bag from time to time and swapping between both identical batteries I've got.

What's the best way to cool down the wires?

flippy · May 20, 2019

i am working on active watercooling for each of the leads. especially with .3 nickel or copper shit gets hot real fast.

if i get my kweld i will make the cooling to fit and print some handles that have the cooling built in. but it has to be fully isolated dual cooling setup otherwise you would get 2000 amps tru the watercooling, no bueno.

tatus1969 · May 21, 2019

BenjAZ said:
I was wondering what is the best way to cool down the wires.

I use to have a glass of water and stick them in that briefly. They cool down rapidly when doing this.

Headrc · May 21, 2019

Has anyone welded 1.5mm nickel plated copper with the Kweld? If so ....what power rating do you use? And are you using the standard electrodes?

Merlin · May 21, 2019

1.5mm copper?

i havent.

but maybe ask these 2 guys. looks like they have the right tool for 1.5mm copper welds

tatus1969 · May 21, 2019

Headrc said:
Has anyone welded 1.5mm nickel plated copper with the Kweld? If so ....what power rating do you use? And are you using the standard electrodes?

Do you by chance mean 0.15mm?

BenjAZ · May 21, 2019

tatus1969 said:
I use to have a glass of water and stick them in that briefly. They cool down rapidly when doing this.

Ok, I'll try tomorrow as I have to weld a 14s33p battery pack :wink:

flippy · May 21, 2019

i see the power supply board on preorder.

would using a regular 500W-ish ATX PSU be a valid solution? i would really like to weld without having a plane take off on my workbench. would the PCB limit the current enough to prevent a OCP shutdown of a regular power supply?

tatus1969 · May 23, 2019

flippy said:
would using a regular 500W-ish ATX PSU be a valid solution? i would really like to weld without having a plane take off on my workbench. would the PCB limit the current enough to prevent a OCP shutdown of a regular power supply?

Any capable 12V supply will work, and the kSupply current limit is adjustable via a small potentiometer. You can tune it such that the 12V supply doesn't run into overcurrent protection.

BenjAZ · May 24, 2019

After nearly 6000 welds in the last two days, I can say I LOVE my kWeld!

I got about 1400 welds with one charge (Turnigy nano-tech 3s 5000mAh 65-130C), but perhaps I could get more because suddently the battery dropped 0.5V and I had to swap it by an identical battery.
At this moment I changed from manual mode (pedal) to auto, so my leg loves the auto mode! :lol:

Welding 0.15mm nickel strips does not generate that much heat (@15J), but I keep using my frozen gel bag to cool down the electrodes while I'm cutting the nickel strips.

Congrats to the kWeld maker!!

Headrc · May 24, 2019

My mistake ....LOL ...I meant .15mm copper of course. So has anyone successfully welded .15mm copper with their Kweld?

tatus1969 · May 24, 2019

BenjAZ said:
Congrats to the kWeld maker!!

Thanks 8)

ossivirt · May 24, 2019

Headrc said:
My mistake ....LOL ...I meant .15mm copper of course. So has anyone successfully welded .15mm copper with their Kweld?

It should be possible. I have only 0.1 and 0.2mm. I made one battery with 0.1mm and it welds ok at 50j and my battery amps are 1500A. 0.2mm I have only tried for a few welds and I probably need battery current closer to 2000A to get good welds. I wanted to test 0.15mm but could not find it easily.

ridethelightning · May 24, 2019

ossivirt said:
Headrc said:

My mistake ....LOL ...I meant .15mm copper of course. So has anyone successfully welded .15mm copper with their Kweld?

Click to expand...

It should be possible. I have only 0.1 and 0.2mm. I made one battery with 0.1mm and it welds ok at 50j and my battery amps are 1500A. 0.2mm I have only tried for a few welds and I probably need battery current closer to 2000A to get good welds. I wanted to test 0.15mm but could not find it easily.

this is good info. im going to modify a welder for copper welding. looks like i need to aim for 2000-3000amps to do any decent copper welding. btw did you use tungsten electrode tips? i have found that to be the key.
also, the highest possible energy in shortest possible time.

spinningmagnets · May 24, 2019

ride the lightning, I don't know if carbon tips would work, but I have some for experiments. PM me your address and I'll send you a couple.

ridethelightning · May 24, 2019

Thanks spinningmagnets,pm sent.

the other thing i will test is doing the spotwelding in an open topped tub, filled with argon.
as iv seen mentioned before, and can verify from experience is that after a while the tungsten tips get brittle and bits bust off and stick to the weld. this is due to oxidation, as the tips get cherry red every time you make a weld(thats how the copper fuses)
not a big issue but id like to fix it if pos.
argon is a heavy gas from memory, so as long as i dont stir up the gas, it should sit in the tub, over the cells.....reminds me of the 1st alien movie with the eggs sitting there :mrgreen:

eee291 · May 24, 2019

Just make sure you don't suffocate, do it in a well ventilated area :lol:

ridethelightning · May 24, 2019

yep, got that

ossivirt · May 25, 2019

ridethelightning said:
ossivirt said:

Headrc said:

My mistake ....LOL ...I meant .15mm copper of course. So has anyone successfully welded .15mm copper with their Kweld?

Click to expand...

It should be possible. I have only 0.1 and 0.2mm. I made one battery with 0.1mm and it welds ok at 50j and my battery amps are 1500A. 0.2mm I have only tried for a few welds and I probably need battery current closer to 2000A to get good welds. I wanted to test 0.15mm but could not find it easily.

Click to expand...

this is good info. im going to modify a welder for copper welding. looks like i need to aim for 2000-3000amps to do any decent copper welding. btw did you use tungsten electrode tips? i have found that to be the key.
also, the highest possible energy in shortest possible time.

Just original electrodes.

Compoundbike · May 26, 2019

how good are the welds compared to sunkko ? sorry for the dumb question.. but im tired of my sukko which delivers self releasing welds. :flame:

so im thinking about a k-Weld.

ossivirt · May 26, 2019

Compoundbike said:
how good are the welds compared to sunkko ? sorry for the dumb question.. but im tired of my sukko which delivers self releasing welds. so im thinking about a k-Weld.

How to best describe the difference :roll:

I did multiple welds to 0.15mm nickel with sunko and prayed afterwards that even one of then would hold. With kweld every single one is constantly strong and I need pliers to rip off the nickel and it tears of around the weld points leaving the welds and rest of the nickel still attached to the cell.

I have the cheapest possible sunko welder so I had it at maximum settings and kweld beats it even at very low energy levels. (10j)

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