I just tried Kweld with the supplied electrodes.
Everything seems to work fine, the calibration was successful although I believe that my capacitors are not able to supply the adequate power.
When I exceed 25J, after each welding Kweld restarts. It seems that the voltage falls below a minimum for a brief moment and this causes the restart.
With my old spot welder I do not have this problem since it uses an independent power supply. How can I solve this with Kweld? Is it possible to add an independent power supply?
I hope that with the supercapacitors works better.
I also need to set a power of 100J to get acceptable welds in pure nickel 0.15mm.
I have a feeling that Kweld needs a more powerful power supply.
Maybe the problem is in the added cable. My old welder connects directly to the capacitors and uses a much thicker electrode wire.
It is assumed that with 100J I could weld nickel of 0.3mm and this power is the one I need to weld nickel of 0.15. It seems that the capacitors deliver enough power (1370A), or not?
At the moment I do not intend to weld thicker nickel and the solderings to 100J in nickel of 0.15mm serve me.
The problem is that if I add Kweld in my welding head and restart it to each solder, then the power will be mismatched again, and I would have to reconfigure the soldering iron after each solder! That's why I've thought about adding a small independent source of energy.
Can you think of a better solution?
When will the supercapacitors be ready?
What I do not quite understand is because my Arduino Spot Welder works well with my capacitors. I can make good welds in 0.15mm nickel between 10-12ms. Maybe shorter pulses would be better but I think 10-12ms is within an acceptable range.
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Thanks It is performing extremely well. Even when doing a full pull (1kA for 200ms) the MOSFETs don't get even slightly warm. I am considering doing a test row by removing one after another to see how much I overdid it. ...
Perfect, thanks for the quick response.
I will order two boards without condensers plus a full board.
I could try 4S3P with my capacitors. I guess I can make some kind of adapter, so that the pins of my capacitors match.
I attach a couple of photos of my current capacitor configuration and with the welding head that will inherit my new Kweld!
If someone is interested in a head like mine, I can send detailed photos, explain how it works and offer a good price.
Regards
https://preview.ibb.co/hZaJ4x/20180330_122252.png
Hi, looks nice. Did you ever try removing some MOSFETs
Just wanted to let you know that the capacitor module is now available for pre-orders at https://www.keenlab.de/index.php/product/kweld-ultracapacitor-module/! I expect to be able to deliver by beginning of June. The production batch size for this first round is not too big, and I expect not to be able to build up regular stock yet.
Here is my power bank setup, 100pcs of 10000uf cheap capacitors, provide perfect weld at 12.6V...
That is 1F in total, and when you charge them to 12.6V and allow them to discharge to 8V (I won't recommend to go lower, because current drops proportionally, hence output power drops quadratically), this corresponds to an energy delivery of 47 joules. I typically calculate a ballpark system efficiency number of 15% (the remaining 85% is lost in capacitor ESR, cabling, fuse, and welder switch), this allows you to weld with a pulse energy of up to 7.1 joules. This is just enough for 0.1mm nickel, but I doubt that you can do 0.2mm or 0.3mm with your setup.
That is 1F in total, and when you charge them to 12.6V and allow them to discharge to 8V (I won't recommend to go lower, because current drops proportionally, hence output power drops quadratically), this corresponds to an energy delivery of 47 joules. I typically calculate a ballpark system efficiency number of 15% (the remaining 85% is lost in capacitor ESR, cabling, fuse, and welder switch), this allows you to weld with a pulse energy of up to 7.1 joules. This is just enough for 0.1mm nickel, but I doubt that you can do 0.2mm or 0.3mm with your setup.
Sure you are right in your calculations, I just shared my experience and it serves me well. Having 100 caps helps greatly to reduce the ESR and operate with safe currents on individual capacitors. In the attempt to minimise the losses, I use quality awg6 welding cables and no fuse. Instead, I do charge the bank by using automotive bulb which provide quick recharge (about 5-7 sec, just enough time to prepare next welding position) and safety in case of any eventual FET failures and power sourse shorts.
The bank is dischaged to about 5V and provide robust and repeated result with 0.15mm I have used for my battery. I did not try thicker nickel since did not have it, however the way out is quite simple, or more capacitance or little bit more voltage, there is some room for it with 16V capacitors.
The calculations result from my experiments, and findings that I came to with a customer here in Germany who was using 5 x 1F (huge) electrolytic audio capacitors. Even they don't provide enough energy for one 50 joulse pulse to weld 0.3mm nickel.
If you use 6AWG and no fuse, then this helps improving the efficiency and explains why you can do 0.15mm nickel.
Please don't get me wrong, I don't want to critizise your impressive design, just want to share my experience with smaller capacitors.
Just wanted to let you know that the capacitor module is now available for pre-orders at https://www.keenlab.de/index.php/product/kweld-ultracapacitor-module/! I expect to be able to deliver by beginning of June. The production batch size for this first round is not too big, and I expect not to be able to build up regular stock yet.
Using audio caps may be the answer for poor performance
impressive report by Toorbough ULL-Zeveigh about their real quality: https://endless-sphere.com/forums/viewtopic.php?f=2&t=2633&start=825
Question: The module available is a redesign of the pcb shown or the version with bodge wires? How do you charge the capacitor bank? Are there plans to offer a charger in near future as well as a complete welding system?
Perfect, thanks for the quick response.
I will order two boards without condensers plus a full board.
I could try 4S3P with my capacitors. I guess I can make some kind of adapter, so that the pins of my capacitors match.
I attach a couple of photos of my current capacitor configuration and with the welding head that will inherit my new Kweld!
If someone is interested in a head like mine, I can send detailed photos, explain how it works and offer a good price.
Regards
https://preview.ibb.co/hZaJ4x/20180330_122252.png
Where did you get the pneumatic head? And price?