kWeld - "Next level" DIY battery spot welder

[m3vuv]

looks like this guys some sort of pratt!!!

[tatus1969]

looks like this guys some sort of pratt!!!

I'm a fan of Chris Pratt too, especially when together with Jennifer Lawrence. Thanks for pointing this out 

[fudmuffin]

Hi. Is there a firmware changelog available for the kWeld? I'd like to know what has changed before upgrading my unit (from firmware 2.2) to the latest (firmware 2.4). Thanks!

[tatus1969]

Hi. Is there a firmware changelog available for the kWeld? I'd like to know what has changed before upgrading my unit (from firmware 2.2) to the latest (firmware 2.4). Thanks!

Just go to the kWeld product page https://www.keenlab.de/index.php/portfolio-item/kweld/, that has a firmware download link including the revision history.

[hsorbo]

Hello! I Just ordered a kWeld without assembled cables (was not available). The crimp tool depicted in the assembly-instructions looks a lot like HX50-B on aliexpress. (example: https://www.aliexpress.com/item/HX-50B-crimping-tool-crimping-plier-2-multi-tool-tools-hands-Copper-Tube-Terminal-Crimping-Tool/32649569297.html ) Has anybody used one of these or can recommend another crimp tool for assembling cables?

[tatus1969]

Hello! I Just ordered a kWeld without assembled cables (was not available). The crimp tool depicted in the assembly-instructions looks a lot like HX50-B on aliexpress. (example: https://www.aliexpress.com/item/HX-50B-crimping-tool-crimping-plier-2-multi-tool-tools-hands-Copper-Tube-Terminal-Crimping-Tool/32649569297.html ) Has anybody used one of these or can recommend another crimp tool for assembling cables?

I have been using exactly this one before having moved cable assembly to an external service provider. They create burrs and the surface isn't the best, but most importantly they create enough pressure.

[carracing111]

My Kweld and the KCap capacitors are already working!

The Chinese step-down in parallel has not worked, I adjusted the voltage and amperage separately exactly the same. Then I joined 4 step-down in parallel to the HP source and the capacitors. Result: 3 step-down broken. Only one has survived ...

Finally I decided to mount two groups of KCap capacitors in parallel fed by another step-down to 20A. In this way I have achieved a very acceptable welding speed and the capacitors do not get to discharge. Also, nothing heats up! I only managed to activate the fans by pointing to the condensers with a hair dryer.
I'm welding nickel from 0.15mm to 19J. Welding times between 9 and 12ms and 1600-1700A. The welds are very good!

I would like to investigate with other types of electrodes, since the ones I use now wear out pretty fast. Soldering directly to the cells very well, but when I nickel on nickel the electrodes sometimes stick and after 400-500 solders I must rectify the electrodes because they are no longer in good condition. My electrodes are 3mm, I'm thinking about ordering C14500 copper bars, I hope they work better!

Some photos and video of my tests:

https://www.youtube.com/watch?v=GP6wKORjo4c

[mzzj]

I would like to investigate with other types of electrodes, since the ones I use now wear out pretty fast. Soldering directly to the cells very well, but when I nickel on nickel the electrodes sometimes stick and after 400-500 solders I must rectify the electrodes because they are no longer in good condition. My electrodes are 3mm, I'm thinking about ordering C14500 copper bars, I hope they work better!

I would try Glidcop or RWMA 2
https://sunstonewelders.com/electrodes/
https://sunstonewelders.com/products/welding-electrodes/

[tatus1969]

The Chinese step-down in parallel has not worked, I adjusted the voltage and amperage separately exactly the same. Then I joined 4 step-down in parallel to the HP source and the capacitors. Result: 3 step-down broken. Only one has survived ...

Thats a really nice setup, thanks for sharing the pictures!

That's of course bad learning regarding the step-down's. I'll have to either investigate the root cause for that (currently I have only one module here), or finally get up to speed with my own solution.

[anishkgt]

So the joules is calculated with this formula if am not wrong
J=I2(I squared ) R X T


Www.Georgehobby.wordpress.com

Equipments: DSO104z, Hakko FX888D, Brymen BM869s

Sent from my iPhone using Tapatalk

[carracing111]

Mzzj, thanks for the suggestion, but Sunstone's Glidcop electrodes are very expensive, especially the shipping. A pair of electrodes cost about $120 !
I found Glidcop copper bars in China at a very reasonable price but I'm not sure it's really the same material. It will be a matter of performing some tests.

https://hosometal.en.made-in-china.com/product/goMEVBvrZepc/China-Tungsten-Copper-Copper-Tungsten-Glidcop-Resistance-Welding-Electrode-elkonite-.html
https://www.alibaba.com/product-detail/Glidcop_11036855.html?spm=a2700.7724838.2017115.2.1fa14c064ip15c

Tatus1969, I would be very happy if you finished the step-down specific to the HP Power supply !  I would commit to buying a couple units and another Kweld !

I have a question about the welder Kweld. When I turn off the HP power supply, both the Kweld and step-down continue to be on for a long time due to the charge contained in the capacitors.
There comes a time when the Kweld emits a very sharp and continuous sound and a little later emits another different sound (tick - tick - tick...) until finally everything is completely turned off. I'm not sure if this is completely normal or it may have some long-term negative consequence.
Perhaps it would be a good idea to mount a group of resistors to quickly discharge the capacitors when the power supply is turned off ?

Regards

[nvdheide]

carracing111 that's what I did with mine.

https://imgur.com/a/X6u4dWq



0.375 Ohms gets the capacitor bank to below 1V in just a couple minutes

[tatus1969]

So the joules is calculated with this formula if am not wrong
J=I2(I squared ) R X T

Almost, because that's not exactly what it is doing. It calculates the voltage across the electrode tips, and multiplies that with the current to get the instantaneous power. That is then integrated.

Tatus1969, I would be very happy if you finished the step-down specific to the HP Power supply !  I would commit to buying a couple units and another Kweld !

It's on my list, but I'll need approx 6-8 weeks to finish up the direct freelance design projects. There are a few other own designs that got on hold in favor of these as well.

I have a question about the welder Kweld. When I turn off the HP power supply, both the Kweld and step-down continue to be on for a long time due to the charge contained in the capacitors.
There comes a time when the Kweld emits a very sharp and continuous sound and a little later emits another different sound (tick - tick - tick...) until finally everything is completely turned off. I'm not sure if this is completely normal or it may have some long-term negative consequence.

That strange sound comes from the onboard SEPIC switching converter, the controller chip does not have an adjustable undervoltage lockout and starts hicking up at input voltages below 3V. It doesn't harm other than being annoying. I couldn't completely remove this when desigining it, and because my 3V to 30V design target is quite a large input voltage range for a SEPIC converter, I decided to live with that effect.

Perhaps it would be a good idea to mount a group of resistors to quickly discharge the capacitors when the power supply is turned off ?

I have plans for a kWeld2 that will have charger, capacitors and switch on one board, and that will also include an ideal diode to the 12V power supply to prevent backfeeding, and a 12V halogen bulb socket that will be turned on whenever the 12V is not present. But again, currently no time to start this.

[tatus1969]

Another video from a customer, if you like to support me please share:

[FredNuno]

Hi Frank, your device KeenLab spot welder is awesome .
I just received it, mount everything and made a 4S8P pack LiIon bateries 18650GA. I use 27,5 Joule, a 4S1P/25C LiPo batterie as power source and 0,15 m/m strep 8 m/m wide. All went good so far.
Thank you.
FredNuno.

[carracing111]

Hi, I would like to make a suggestion for the next software update.
The delay setting only affects the automatic mode, could it also work in manual mode? For my application with the welding head would be very good!

Another feature that I would like, would be to invert the polarity of the electrodes between welds. In this way the electrodes wear out equally. Approximately every 400-500 welds I must readjust the electrodes because one deteriorates much more. With this feature the electrodes should work well for at least 3 or 4 thousand solders without any problem! Maybe using two Kweld units ... it should not be too complicated, right  ?

[tatus1969]

Hi Frank, your device KeenLab spot welder is awesome .
I just received it, mount everything and made a 4S8P pack LiIon bateries 18650GA. I use 27,5 Joule, a 4S1P/25C LiPo batterie as power source and 0,15 m/m strep 8 m/m wide. All went good so far.

Thanks  By the way, keenlab is the name of my company 

Hi, I would like to make a suggestion for the next software update.
The delay setting only affects the automatic mode, could it also work in manual mode? For my application with the welding head would be very good!

You want to use one control signal for both pneumatic and pulse, right? I can add this if you like, do you have the firmware updater (sorry don't remember)?

Another feature that I would like, would be to invert the polarity of the electrodes between welds. In this way the electrodes wear out equally. Approximately every 400-500 welds I must readjust the electrodes because one deteriorates much more. With this feature the electrodes should work well for at least 3 or 4 thousand solders without any problem! Maybe using two Kweld units ... it should not be too complicated, right  ?

That's a good point, as arcing will always wear the positive electrode (if I my physics memory is right, the ions travel from - to + and collide there). Did you consider using an inert gas to prevent arcing? That should significantly increase electrode life. To switch polarity, I would need to use four power switches instead of one. Of course that is possible but that would be a quite expensive system. I don't think that this would be very reasonable.

[carracing111]

Yes, I have the cable for software updates. I would be very grateful if you can add this feature!

I had not thought about using inert gas. Is this a usual practice for this type of welding? I guess the solution will not be cheap either.

Regarding the system to invert the polarity of the electrodes, I would like to hear a quote if you are willing to build it.

I am evaluating the purchase of a 125-ADP equipment that has the characteristic of reversing the polarity between welds. but it's quite expensive!
http://www.amadamiyachi.com/products/resistance-welding/rw-power-supplies/adp-series

I am really happy with Kweld, the only problem is the premature wear of the electrodes and I have also tested the Sunstone Glidcop electrodes. The result has not improved as I expected.

Regards

[tatus1969]

Yes, I have the cable for software updates. I would be very grateful if you can add this feature!

I had not thought about using inert gas. Is this a usual practice for this type of welding? I guess the solution will not be cheap either.

Regarding the system to invert the polarity of the electrodes, I would like to hear a quote if you are willing to build it.

I am evaluating the purchase of a 125-ADP equipment that has the characteristic of reversing the polarity between welds. but it's quite expensive!
http://www.amadamiyachi.com/products/resistance-welding/rw-power-supplies/adp-series

I am really happy with Kweld, the only problem is the premature wear of the electrodes and I have also tested the Sunstone Glidcop electrodes. The result has not improved as I expected.

Regards

Sorry for not getting back on you earlier. Regarding inert gas, this is done by one of my customers because that prevents coloring of the weld. I think that he was using a simple nitrogen setup. As I haven't done own tests, this was just an idea that I wanted to share.

Regarding a custom unit, I would be happy to make a design for you. That's my main business model aside from making and selling own stuff. My standard hourly rate is 90€, and for larger projects I also make fixed price offers based on an agreed set of requirements. I also offer covering series production at any scale. The downside is that I am currently fully occupied with three active customer projects, and two new projects are already confirmed. This means that I cannot handle another project until roughly January next year. If you are interested anyway, please let me know. I'll then sit down and make a more detailed estimation of the involved work.


I would be happy to design a custom unit for you

[FredNuno]

Some days ago I made a mistake with my KWeld. I switched on my LiPo the wrong way (inverted polarity) and I had some smokes on the board. Some diodes went fried (D7, D8 and D19). I asked help from Frank and after some tests he gently send me those diodes for free. I soldered them to the board and now my KWeld comes to life again. What a support I have had from Frank!!!
I want to thank Frank for his patience and dedication to this community.
FredNuno

[carracing111]

Of course, I'm interested! I would like to know an approximate budget to assess if it is worth it or to opt for the purchase of a system like the 125-ADP. If it does not complicate things much, it would also be nice if my new custom Kweld was able to handle more amps, maybe 4000A? Thanks for the support !

[rx8pilot]

Some days ago I made a mistake with my KWeld. I switched on my LiPo the wrong way (inverted polarity) and I had some smokes on the board. Some diodes went fried (D7, D8 and D19). I asked help from Frank and after some tests he gently send me those diodes for free. I soldered them to the board and now my KWeld comes to life again. What a support I have had from Frank!!!
I want to thank Frank for his patience and dedication to this community.
FredNuno

Solid!

[tatus1969]

Of course, I'm interested! I would like to know an approximate budget to assess if it is worth it or to opt for the purchase of a system like the 125-ADP. If it does not complicate things much, it would also be nice if my new custom Kweld was able to handle more amps, maybe 4000A? Thanks for the support !

Cranking up the current is just a matter of the amount of silicon that you throw against it, 4000A is not a problem. We need to talk about the repetition rate though, as that determines the thermals. I need to sit down with a sharp pencil, but my rough estimate is
- component cost (40 MOSFETs, 8 TVS diodes): 150€
- PCB and assembly (I have a semi professional manual reflow process here): 100€
- design and layout work (approximately two weeks): 7200€

EDIT: this is for the power switch module, you'll need a suitable capacitor bank and a charger for them on top.

[carracing111]

Thank you very much for your time, I did not think the redesign could be so expensive. I understand all the work you can have, but that is almost the price of a new 125 ADP (8021€), so it's not worth it.

I will keep you in mind for other projects that can not be obtained directly in the market!

Regards.

[yngndrw]

€7,200 for 2 weeks ? I'm in the wrong business !