kWeld - "Next level" DIY battery spot welder

[leffex]

Battery is new.

Did calibrate the system.

At least I can't see any faulty connection.

What about the material on the tips and the sparks? I assume this is user error?

Tips shouldn't be sparking to much if you aren't using nickel plated metal. Then it will spark a lot.

You can try cleaning with alcohol. It will remove the non-conducting oil as well as smoke (coal / carbon) that will populate the tips after a while.

What thickness are you using and what power levels? I think I only used 100J around for 0,3mm pure nickel and for 0,2 50J-->80J but to my knowledge after experience even those power levels I used was way too high!

So pulling down the power to when the nickel fastens correctly is something you need to learn and go from there.

I don't think "ONE" lipo can do 1200 amps+... but I may be wrong so in a sense that may be an easy answer to a tricky problem here.

Is the kweld newly build? I have had a ONE nut lose on it on the copper bar row and it acted weird. Also ONE time it has been a little lose on the positive or negative INPUT or if it was OUTPUT. It is sure worth a double check here. Be careful not to short or drop metal into the kweld, allthough mine survived a short once I don't expect luck to be on my side always.

 

[sameh.d]

hi, new to kweld.
recently salvaged 21700 tesla model 3 cells. their positive side is aluminium and challenging to spotwelding.

any confirmation kweld can spot weld positive side on those cells? no puncturing? read some claim it can be spotwelded with kweld immediately after sanding positive side before oxidation happens again.

what setup? jowls?

what setup for negative side spotwelding? (welding at bottom?)

thanks

 

[brone]

Can anyone recommend what is the best series configuration for kweld? I'd like to have 2S (for higher parallel set) since their website lists the kweld from 4 to 30V. I see most recommended batteries listed as 3S - is there any downside of using 2S?

 

[fechter]

With 2S, your maximum weld current will be a bit lower so may have trouble welding thicker material.

 

[brone]

With 2S, your maximum weld current will be a bit lower so may have trouble welding thicker material.

How can the current be lower if i will parallel 5p 400A burst capable prismatic cells?

 

[riba2233]

because higher voltage can overcome contact resistance more easily

 

[brone]

because higher voltage can overcome contact resistance more easily

Alright, thanks

 

[Zambam]

Will this A123 LiFePo4 36V 20 Ah battery be suitable for a KWeld? The tag on it says short circuit current is 2250 Amps.

A123 LFP 36V 20Ah 720Wh High Current Battery Modules with 96 Cells | Greentec Auto

BAE Systems 36V rechargeable battery with A123 LiFePO4 battery M1B Cells. | Shipping included in the cost of the battery | DIY Battery Storage solutions

www.greentecauto.com

 

[gromike]

I don't think the KWeld is meant to be powered by a 36v battery. I use a bank of 12v batteries for mine.

 

[Zambam]

I don't think the KWeld is meant to be powered by a 36v battery. I use a bank of 12v batteries for mine.

The pack is 12S 8P. There are screw terminals for each parallel group which allow it to be reconfigured from 1S to 12S.

4S will give 14.4 V

 

[gromike]

So 4S/24P? That's something like 1,200 plus amps at the cells 50a current rating. One would think that will work!

 

[Zambam]

So 4S/24P? That's something like 1,200 plus amps at the cells 50a current rating. One would think that will work!

4S 8P is easy, just tap off a screw terminal. 4S 24P will need cutting it into 3 sections and wiring them in parallel.

 

[gromike]

8P would be something like 20ah. I wonder what power the KWeld draws per weld, at some average value?
It's your experiment, sounds like you got it figured out.

 

[Zambam]

No, I don't have it figured out! That's why I am asking questions.

 

[j bjork]

I tried a 4s lifepo4, i got an overcurrent problem I think (warning in the welder). I wasnt able to run it anyway, and just went with a 12v car battery.

 

[Zambam]

I tried a 4s lifepo4, i got an overcurrent problem I think (warning in the welder). I wasnt able to run it anyway, and just went with a 12v car battery.

Can you post the specs of the 4s lifepo4 you used?

edit: This was helpfull on power options for Kweld How to choose a suitable power source for kWeld Spot Welder

I have a H8 (group 49) 900 CCA battery in my car that I could use. One negative is I have to remove it from the car so it can be used on the bench. It's a heavy battery!

 

[j bjork]

It is 40Ah, the label says 660CCA (EN/SAE/GS)
So according to the label it doesent sound that powerful, but I think the amps went over 2000 when testing if I remember correctly.

 

[nbtesh]

not yet, but we are making a first batch of 20 right now. I hope to be able to open up for preorders before Christmas. The first units will be kits, and I might have a price point in one or two weeks from now. Software will be limited when they get released, but we are and will remain working heavily on that thereafter. My plan is to reach at least kWeld status, with proper energy metering and of course capacitor voltage control.

And to your question: it has already done stress testing with full steam 13ms / 3300 ampere pulses, once every two seconds. Sock solid after 100,000 cycles That amount of current is definitely by far enough for 0.3mm nickel, and also solid copper sheets should be possible. But I havent been able to test many variants yet, rather concenrating on development. I'm curious to read what you guys will achieve with it.

Hi Frank, almost a year later, we are waiting for some updates. when can we purchase the Kweld Pro?

 

[No_Shorty]

So I had a project from almost 2 years ago that I finally got around to doing.

I managed to do about 50-60 welds before my Turnigy Nanotech 3s let out the magic smoke... Maybe it didn't fare so well being in storage for so long.

Eager to continue with the new lease of life in the project I popped out and picked up a second hand lead acid battery - a 920CCA battery apparently... However at about 70-80% SoC it's just giving me undercurrent.

It is a bit chilly at the moment (about 9-10deg c) and the battery did come out of a garage. But given the CCA is 920 (which I understand to be a measurement at 0F (-18c)) it seems surprising to get undercurrent from the system (set at 800I).

Just wondering if I am doing anything wrong here. Or if this is a fairly common experience?

Edit: I think it may just be a low quality battery.. and/or might just need an overnight charge to 'get it going'. After charging for 2 hours the voltage didn't change much but I did finally get enough current to do a weld. I'll report back tomorrow.

Edit2: So yes, looks like I was just being impatient. After a night of charging, the battery happily delivered consistent 1100A welds over the whole 14s9p pack. So think the battery just needed a bit of love.

 

[julian.koenig87]

Hi.

Im Julian and Im new to spot welding. I will build some batteries for my mower (easy) and some Dewalt high current packs for my tools (21700 5s2p). So I bought a kweld few days ago.

Im planning to use 0.1 copperfoil under 0.15/0.2 nickel-steel or maybe pure nickel as a sandwich. I think this is the usual way and will be suitable. Powersupply will be a car battery and I also have 2x 3s 4.200mAh Lipos laying around.

I found this material:

1 Meter Schweißband auf Rolle aus Kupfer / Lötbrücken / Lötfahnen 0,18 x 11mm | eBay

<p>Wir sind ein Unternehmen, was sich auf den Verkauf und den Zellentausch von Akku´s spezialisiert hat. Durch ein gutes Preis/Leistungsverhältnis und optimaler Kundenzufriedenheit wollen wir uns am Markt weiter etablieren. Besuchen Sie unsere Seite oder kommen Sie persönlich vorbei. Wir freuen...

www.ebay.de

It is a 11x0.18 copper strip. Plated with nickel and zinc. I guess for better soldering behavoir. The question I have is. Is this material maybe also suitable for spot welding? 60% copper of 0.18 sounds like 0.1 copper. So this would work. But is the zinc a problem?

Best regards
Julian

 

[ganzey]

Hi.

Im Julian and Im new to spot welding. I will build some batteries for my mower (easy) and some Dewalt high current packs for my tools (21700 5s2p). So I bought a kweld few days ago.

Im planning to use 0.1 copperfoil under 0.15/0.2 nickel-steel or maybe pure nickel as a sandwich. I think this is the usual way and will be suitable. Powersupply will be a car battery and I also have 2x 3s 4.200mAh Lipos laying around.

I found this material:

1 Meter Schweißband auf Rolle aus Kupfer / Lötbrücken / Lötfahnen 0,18 x 11mm | eBay

<p>Wir sind ein Unternehmen, was sich auf den Verkauf und den Zellentausch von Akku´s spezialisiert hat. Durch ein gutes Preis/Leistungsverhältnis und optimaler Kundenzufriedenheit wollen wir uns am Markt weiter etablieren. Besuchen Sie unsere Seite oder kommen Sie persönlich vorbei. Wir freuen...

www.ebay.de

It is a 11x0.18 copper strip. Plated with nickel and zinc. I guess for better soldering behavoir. The question I have is. Is this material maybe also suitable for spot welding? 60% copper of 0.18 sounds like 0.1 copper. So this would work. But is the zinc a problem?

Best regards
Julian

Ive tried several suppliers and varying thicknesses of cupronickel, and they all welded like crap. Just use copper foil and NICKEL not nickel plated steel, that stuff will start rusting in no time at all

 

[Zambam]

I have this 1940's spot welder that's been in my possession for a long time. It weighs around 30 lbs! Primary of the transformer input is 120 VAC, secondary is 1.35 VAC- wound with 4 layers of 1 mm thick x 13 mm wide copper strips (insulated with black cotton fabric?). Anyone try spot welding 1 mm thick copper with the Kweld? Will it handle it? I have no use for this spot welder and intend to break it apart to harvest the copper components (bars, braid, strips, rod tips).

edit: I think the bars for the jaws are brass, not copper, needed for strength. You can see the color difference in the cleaned off spots.

 

[Diggs]

I have this 1940's spot welder

Interesting piece of hardware. (I worked manufacturing that used water-cooled industrial spot welders so this piques my curiosity.) Seems a shame to cannibalize it but without its contactor and control module there's not much to be done with it. I'm guessing there's a possibility the alignment guides may contain asbestos (unless they are stone?).

 

[Zambam]

Interesting piece of hardware. (I worked manufacturing that used water-cooled industrial spot welders so this piques my curiosity.) Seems a shame to cannibalize it but without its contactor and control module there's not much to be done with it. I'm guessing there's a possibility the alignment guides may contain asbestos (unless they are stone?).

 

[Zambam]

1940's was just a guess. Just finished breaking it up. There was not a single Phillips screw, all slotted, that may give an idea of its age. There's no control module. It's operated by a foot pedal which bring the jaws together and activates a switch at the same time that provides 120 VAC to the primary (which draws only 3 A, not much power). I tried spot welding a few thin strips of iron after cleaning up the oxidized contacts. The welds were crap, maybe I did a poor job cleaning. The insulations are cotton braid dipped in (I think) black shellac. I can upload a few pics of it disassembled if you are interested.

edit: This spot welder was in a heavy thick sheet metal case that had a metal tag marked "Cole radio works model 83 instan solder, Caldwell NJ". I was not able to find any info on it..