kWeld - "Next level" DIY battery spot welder

[Merlin]

I don't understand. The manual say clearly how to calibrate.
Is this the "don't put your pet in your microwave to dry it" thing?

 

[Compoundbike]

I didn't get a manual, the only source is in the internet download page. Didn't see the Calibration sentence.
To defend my stupid mistakes.

Whatever, the Welds are great now.

 

[spinningmagnets]

Compoudbike, would you please post a paragraph that you feel would adequately explain this? Doing so would help kWeld upgrade their instruction manual for new users.

 

[Merlin]

i didnt get either a manual. but ...eh....we re doing "diy" business. its the ground level of diy things. research, reading, asking, checking twice, doing, learning, burning money...but at least.....we step up our knowledge and have way more fun as "closed system" riders

in germany mostly everything is restricted by law to protect us dumb arse (sometimes just full of shit ppl)
russia is the opponent side of germany they dont ask. they do first and see what happens of course w/o russia we havent some stunning videos

anyway. happy to hear that you are able now to weld your cells =)
Maybe some red -big- letters right in the shop description of the welder will prevent this in the future.

*Please download -here- the manual for your Kweld. If not setup/calibrate right you can damage your cells*

 

[tatus1969]

Just came back from a hiking tour with my son over the long weekend that we had here in Germany.

I've collected a few important notes regarding kWeld use for the next manual revision, like don't apply external voltage to the electrodes, and a few tips for proper calibration. But this rises a question for me: the links to the manuals are right at the start of the product description, but at the moment I don't put an additional sheet of paper with info/warnings in the parcels. I think I'll better start doing this.

 

[tatus1969]

*Please download -here- the manual for your Kweld. If not setup/calibrate right you can damage your cells*

Thanks, added. But doesn't help buyers who don't even read the item description at all. For example, I get quite a few questions via email whether I have a US reseller. Or customers who are surprised of having received a kit for self assembly instead of a finished unit.

 

[Merlin]

The hard truth about "humans"that's why the planet will die...
They come right after a full hour of consulting in a store and after that going home to buy it 20 bugs cheaper

 

[tatus1969]

That makes me think of a prominent example of this kind (can someone tell him that it is called import duty because the importer has to pay it, and not the foreign country that sells the goods...) But I shoudln't get political here, just wanted to share this. I have recently upgraded the kWeld production tester 8)

 

[flippy]

Looking at the pivot design you have to be a engineer.

No way that would pass a cost focused manager

 

[tatus1969]

Looking at the pivot design you have to be a engineer.

No way that would pass a cost focused manager

:lol: that's the advantage being both in persona. Although the manager in me had to struggle quite a while, because that (off the shelf) component alone was 450€. But still this is a very cost effective solution, if you buy a turnkey production test solution from a specialized company then you can easily pay 20,000€ instead. Don't ask me how many hours I spent for design and making though :wink:

 

[DogDipstick]

But I shoudln't get political here, just wanted to share this. I have recently upgraded the kWeld production tester 8)

IMG_20190523_121819.jpg

Hello again friend... I have to ask... excuse me if this is superfluous... but being an engineers son, and laboring for his small establishment... I have to ask.... Whle I see how the board testing machine works....

How does one test the testing machine? Conundrums being what they are... All things being equal...


( lol just a joke my friend... I figured you would like the humor... )

Can not wait for more news on your future projects.

 

[tatus1969]

How does one test the testing machine?

That's actaully a very good question and worth more than a joke. That's why tester development is always an evolutionary process, you make a first attempt and run DUT's over it while a) observing it statistically and b) permanently asking for feedback from the operator. You then use that to make necessary additions (test coverage) and improvements (like in this case the nice lever). In other words, it is always bananaware (matures at the "customer") no matter how hard you try with your first attempt.

EDIT: I can proudly say that nothing escaped the first version, other than a past reliability problem of the rotary encoder. And that could not have been caught by the tester anyway, because most of them failed only after wiggling their shaft for a while. The new all-metal encoder appears to be much better.

 

[Acido]

I keep blowing my lipos, will i reduce the time required to make the weld by increasing their voltage?
And there by reducing the heat and stress on the thin aluminum terminals

Im currently at 3s and can make a 5s batters from the cells I have left that are not broken (all the same 5ah 75c panther)

 

[bigbore]

I keep blowing my lipos, will i reduce the time required to make the weld by increasing their voltage?
And there by reducing the heat and stress on the thin aluminum terminals

Im currently at 3s and can make a 5s batters from the cells I have left that are not broken (all the same 5ah 75c panther)

My old LiPos are still working pretty well .... did you see what I made?
Those batteries worked for some years on a e-scooter and then I rebuilt them in that configuration.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=89039&start=275#p1359933

 

[Merlin]

no problems with graphene lipos also here. at 0.3 nickel and +100J they had hard times. 10 welds 70° @ wires. but iR stays ok after some thousand welds. =)

 

[tatus1969]

I keep blowing my lipos, will i reduce the time required to make the weld by increasing their voltage?
And there by reducing the heat and stress on the thin aluminum terminals

Im currently at 3s and can make a 5s batters from the cells I have left that are not broken (all the same 5ah 75c panther)

I'd rather suggest to use only one of the models that I have tested in the past. Lipo manufacturers like to overrate their products, which is why I ended up doing this in the first place.

Increasing the voltage does not help, because it is the current that breaks the cell interconnects and you don't want to change that. But you could put more of them in parallel (same type and condition) to lower their stress. For example, make a 2S 10AH pack. The lower voltage will also lower the current, but that might still be enough unless you are mainly doing 0.3mm pure nickel.

 

[Acido]

I keep blowing my lipos, will i reduce the time required to make the weld by increasing their voltage?
And there by reducing the heat and stress on the thin aluminum terminals

Im currently at 3s and can make a 5s batters from the cells I have left that are not broken (all the same 5ah 75c panther)

I'd rather suggest to use only one of the models that I have tested in the past. Lipo manufacturers like to overrate their products, which is why I ended up doing this in the first place.

Increasing the voltage does not help, because it is the current that breaks the cell interconnects and you don't want to change that. But you could put more of them in parallel (same type and condition) to lower their stress. For example, make a 2S 10AH pack. The lower voltage will also lower the current, but that might still be enough unless you are mainly doing 0.3mm pure nickel.

I actually bought the ones you recommended, calibrated the welder and the 2nd day of welding they broke beyond repair

Then I took apart a new 5ah 75c panther and soldered 8awg wire from one terminal to the other and connected it in series and they still keep blowing the terminals up

I'm welding at 85J max and the time required to do that is i think 25-30ms and there's 3 seconds between welds
Im getting tired of this happening as I have a small custom battery side business and when time is crucial some crap like this always happens and I end up late

 

[Acido]

I keep blowing my lipos, will i reduce the time required to make the weld by increasing their voltage?
And there by reducing the heat and stress on the thin aluminum terminals

Im currently at 3s and can make a 5s batters from the cells I have left that are not broken (all the same 5ah 75c panther)

My old LiPos are still working pretty well .... did you see what I made?
Those batteries worked for some years on a e-scooter and then I rebuilt them in that configuration.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=89039&start=275#p1359933

This is what i have done, similar to your setup but the solder unsticks probably from heat and then on the next weld a big spark happens and blows the terminal
I used the proper flux for aluminum terminals and the solder and wire sticked really well
https://imgur.com/a/s7h18lx

 

[Merlin]

but the solder unsticks probably from heat and then ...

if this happens you see any problems on the welders site?
crazy setup for a tool doing side business.

 

[Acido]

but the solder unsticks probably from heat and then ...

if this happens you see any problems on the welders site?
crazy setup for a tool doing side business.

Yes the welder turns off, and sometimes I get a low voltage error when (when there the wire is barely making a connection to the terminal )

 

[tatus1969]

I actually bought the ones you recommended, calibrated the welder and the 2nd day of welding they broke beyond repair

Which exact battery model is that? For example, I know from other customers, that the green Hobbyking Graphene cannot be recommended as the cell interconnects seem to be too weak. I have the black model and it is still in good condition.

I'm welding at 85J max and the time required to do that is i think 25-30ms and there's 3 seconds between welds
Im getting tired of this happening as I have a small custom battery side business and when time is crucial some crap like this always happens and I end up late

Would an ultracapacitor based solution then be better for you? I have a few components for sale that could fit. The kCap module is good for up to 0.2mm pure nickel (~1100A current), and for thicker material you could use two of them in parallel (~1700A).

This is what i have done, similar to your setup but the solder unsticks probably from heat and then on the next weld a big spark happens and blows the terminal.

Which battery model was that?

 

[Acido]

I actually bought the ones you recommended, calibrated the welder and the 2nd day of welding they broke beyond repair

Which exact battery model is that? For example, I know from other customers, that the green Hobbyking Graphene cannot be recommended as the cell interconnects seem to be too weak. I have the black model and it is still in good condition.
Turnigy nano-tech 3S/5000mAh/130C broken connections within 2 days, and I also can confirm that the green graphenes break faster than the red in my case

I'm welding at 85J max and the time required to do that is i think 25-30ms and there's 3 seconds between welds
Im getting tired of this happening as I have a small custom battery side business and when time is crucial some crap like this always happens and I end up late

Would an ultracapacitor based solution then be better for you? I have a few components for sale that could fit. The kCap module is good for up to 0.2mm pure nickel (~1100A current), and for thicker material you could use two of them in parallel (~1700A).

I have been considering this solution but sometimes i weld up to 4 layers of 0.2mm nickel strip and Im not sure if one kCap would be enough, and buying 2 is a little out of my budget at the moment, Im considering going with a huge lead battery because the high performance ones cost around 200$, will never overheat or get empty

This is what i have done, similar to your setup but the solder unsticks probably from heat and then on the next weld a big spark happens and blows the terminal.

Which battery model was that?

I did that to both green and red graphenes, and the problem is the same, usually only one out of 6 gets unsticked, but that is probably from the heat, I once put my finger on the terminal and did a weld and it got hot for a really short time

 

[tatus1969]

I did that to both green and red graphenes, and the problem is the same, usually only one out of 6 gets unsticked, but that is probably from the heat, I once put my finger on the terminal and did a weld and it got hot for a really short time

If you have disassembled one of the red ones on your desk, can you measure the cell interconnect tab widths and thicknesses (separately plus and minus), and also tell me which material they are made from? I suspect that Hobbyking doesn't have a very consistent manufacturing process.

 

[Acido]

I did that to both green and red graphenes, and the problem is the same, usually only one out of 6 gets unsticked, but that is probably from the heat, I once put my finger on the terminal and did a weld and it got hot for a really short time

If you have disassembled one of the red ones on your desk, can you measure the cell interconnect tab widths and thicknesses (separately plus and minus), and also tell me which material they are made from? I suspect that Hobbyking doesn't have a very consistent manufacturing process.

I think I already measured either green or the red one and sent the measurements to your email, the terminals have some solder on them so i can not give you the exact thickness of the terminal, but its too thin to be able to carry those currents reliably anyways imo..

 

[Headrc]

What Joule setting are folks needing to use to spot weld .3mm nickel with their Kweld?