kWeld - "Next level" DIY battery spot welder

Carracing111 said:
When your welders are available, I will buy one!
I just shipped out the last batch today, and the next batch is already in progress. I have some work to do on the website (the shipping rate system is very annoying, I will replace it with a better one) and plan to accept pre-orders for another batch of 200 kits.

Carracing111 said:
I guess that by simply lengthening the electrodes enough I can get an adequate ESR.
Yes, but that also increases the losses, and more importantly, the loop inductance. At current levels like this, the stored magnetic energy in this short piece of wire is so high that it is difficulty to get rid of it when the power switch has to get rid of it when opening the circuit. When current is too high, I would prefer lowering the voltage by reducing the number of cells put in series.

Carracing111 said:
If I understood correctly ... to get the capacitors recharged in 1 second, I think I could use the 60V and 20A source, since it has 1500W, but I would need a constant voltage and current converter, of about 10-15V and up 50A?
Exactly. I am developing a solution (including a capacitor bank) for this purpose, it is a number of posts above. The power source is alrerady working on my desk and can deliver 12V / 70A reliably.
 
A quick update: I had time to test the Turnigy graphene 3S / 6000mAh / 65C. It delivers about the same current as the smaller and cheaper nanotech 3S / 5000mAh / 65-130C battery. The only weakness is that the leads are only AWG10. Does anyone know of affordable Lipos that have AWG8 and XT150 connectors?
 
tatus1969 said:
A quick update: I had time to test the Turnigy graphene 3S / 6000mAh / 65C. It delivers about the same current as the smaller and cheaper nanotech 3S / 5000mAh / 65-130C battery. The only weakness is that the leads are only AWG10. Does anyone know of affordable Lipos that have AWG8 and XT150 connectors?

I didn't find any when I was looking. Part of the reason I went with two smaller ones in parallel, as each one had 10ga wires. Not sure it will really make a noticeable difference.

What kind of weld current did you see?
 
Maybe you could use these type of Turnigy Graphene ? Notice the missing wires, make your own as rugged as you wanna be, and use the plug you want for it.

90c discharge. 6Ah 2s

 
macribs said:
Maybe you could use these type of Turnigy Graphene ? Notice the missing wires, make your own as rugged as you wanna be, and use the plug you want for it.

90c discharge. 6Ah 2s

Why haven't thought of this before? :shock:
 
macribs said:
Maybe you could use these type of Turnigy Graphene ? Notice the missing wires, make your own as rugged as you wanna be, and use the plug you want for it.

90c discharge. 6Ah 2s


That is a hard case 2S RC car battery. See the holes? Those are female "tube" or bullet connectors. Here is another one. https://vortexhobbies.com/orion-carbon-max-38v-7500-110c-tubes-ori14069-p-169436.html They are more expensive and unfortunately they do not come in 3S but they can be seriesed and they are rated 110C continuous. These are the highest C lipos I could find.
 
Any advantage to using Sunstone copper alloy electrodes?
 
tomjasz said:
Any advantage to using Sunstone copper alloy electrodes?
Thanks for the hint, the price point is similar to mine. But I don't see much wear on my probes, they only wear whenever you make bad contact. And there is quite some metal to wear, you can sharpen them a number of times.

Their feed looks similar to that of a Dremel, so that would result in a more complex electrode holder for kWeld.
 
I have just received my welder, looks absolutely fantastic. Very impressed with the design, quality of the supplied hardware and components, the leads and probe tips look great. In addition the documentation is fantastic. This is an area often overlooked, but great doco is essential for a product of this type with wildly varying levels of ability across the customer base. Communication throughout the order process was excellent, thank you Frank for your email updates.

Now I just need to machine a suitable enclosure and complete assembly.

For anybody on the fence about ordering one of these, this is definitely a superior kit to all others I have seen. It's certainly a LOT nicer than my very agricultural early efforts a couple of years ago :)
 
thanks for your great feedback!

In the meantime, I have received pictures of this beautiful case from a customer. It is laser cut material from 3mm panels, which should also be more cost effective than 3D printed parts.



I've made his design available here for you to download: https://www.kicksurfer.de/index.php/product/kweld-lasercut-housing/
 
If I had the space for a laser cutter and a 3D printer I would definitely be thinking about getting them. Especially a laser cutter. They really take up a large amount of space. Unfortunately the people who run the local maker space are a bit... weird?
 
tatus1969 said:
kweld-case-lasercut.jpg

I've made his design available here for you to download: https://www.kicksurfer.de/index.php/product/kweld-lasercut-housing/

WOW! SO nice and generous!
 
new stock is coming, and I've just opened for pre-orders at the shop! --> https://www.keenlab.de/index.php/product-category/kspot-welder-kit/
 
tatus1969 said:
new stock is coming, and I've just opened for pre-orders at the shop! --> https://www.keenlab.de/index.php/product-category/kspot-welder-kit/

Can previous kits be upgraded?
 
tomjasz said:
tatus1969 said:
new stock is coming, and I've just opened for pre-orders at the shop! --> https://www.keenlab.de/index.php/product-category/kspot-welder-kit/

Can previous kits be upgraded?
if you have the firmware update tool (or can make your own as described in the user manual), then you can upload the latest firmware that I have made available on the website (https://www.keenlab.de/index.php/portfolio-item/kweld/). This enables all new features including the menu, except for the extended input voltage range of the new unit of course. You can also upgrade the welder with a rotary encoder, but that is a quite tricky soldering task. I have attached the document here. Last but not least, I highly recommend to upgrade the extended protection components, especially as the voltage regulator of the previous (rev.2) kits has occasionally failed. This is described in the attached doc as well, and I supply component kits for small money.
 

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My welder arrived too and everything is a step ahead from other similar spot welder! Waiting for some spare time to take care of it :D
In the meantime looking at the laser cut case I tough to modify the 3D model of the case before printing. Isn't it a good idea to have the little holes to allow air flow in the 3D printed case also?

Edit: tatus1969 Is possible to have a IGES or STEP file of the case? STL is useless in CREO and that's what I've been using from many time.
 
tatus1969 said:
I highly recommend to upgrade the extended protection components, especially as the voltage regulator of the previous (rev.2) kits has occasionally failed. This is described in the attached doc as well, and I supply component kits for small money.
OK Thanks for that. Unfortunately it is beyond my skill level. I manage basic, very basic, wire and connector soldering but worry about this level. I guess I should have been less anxious to own a second welder. Perhaps someone with skills is interested enough to pay a fair price and make the upgrades. I can then purchase a new welder. Thanks for the quick response.
 
tomjasz said:
tatus1969 said:
I highly recommend to upgrade the extended protection components, especially as the voltage regulator of the previous (rev.2) kits has occasionally failed. This is described in the attached doc as well, and I supply component kits for small money.
OK Thanks for that. Unfortunately it is beyond my skill level. I manage basic, very basic, wire and connector soldering but worry about this level. I guess I should have been less anxious to own a second welder. Perhaps someone with skills is interested enough to pay a fair price and make the upgrades. I can then purchase a new welder. Thanks for the quick response.
If you would pay the shipping cost for one direction and the upgrade parts, then I'll be happy to upgrade the protection components for you.
 
tatus1969 said:
If you would pay the shipping cost for one direction and the upgrade parts, then I'll be happy to upgrade the protection components for you.

Wow! Why yes! How very generous!
 
Got my k weld put together and a laser cut case made locally today, assembled tested and operational.

I made a bit of a mess with the glue but here it is.

344FB8D5-E30F-4347-9625-DC05BDC5F2E5.jpeg


2BDC91F6-4742-44FE-8A03-1B23FE4354EC.jpeg


22 seems the ticket the top 4

Middle 4 30

Bottom 4 10

Thanks Frank
 

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that looks great! Have fun with your new tool, if you've got any issues please let know!
 
Has anyone tried EC8 connectors on their kWeld? They look like they could handle quite a bit of current so possibly have low contact resistance.
 
The Lightning Stalker said:
Has anyone tried EC8 connectors on their kWeld? They look like they could handle quite a bit of current so possibly have low contact resistance.
I am using XT90 with one of my batteries. Sadly that Lipo has only AWG10 wires, so the connector is *not* the bottleneck. EC8 should be better than that.
 
I don't know what's ec8 rated for but when you re on a "good run" the wires and connectors get that hot you can't touch it.
Remember they passing 1200 amps.

I have build 300 cells now and it works really well.
Except of the small welding sticks. It stops your work quick and often because of heat. Even with gloves.
Welding with "good pressure" with the small stick makes a bit pain in your thumbs. 3 days later I still can feel I made "some" welds. Work should be easier when they are 3 times thicker. (whatever it makes possible to beef them up)

I have sharpened the copper tips twice yet.

The graphene 3s5000 is good for completing 50cells. (discharge to 3.75v)
Nice. Recharging in a short break and go on with your work.

Very happy with the package.

4,99 stars rating ;p
 
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