kWeld - "Next level" DIY battery spot welder

Batteries, Chargers, and Battery Management Systems.
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tatus1969
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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 14, 2017 11:45 am

A first lot of 25 PCBs is ordered, and I have the system part list and pricing complete. I will add articles to my web shop today, stay tuned!

And I have changed the electrode design like this now. The cable will be soldered to the electrode holder. The tip will be held into place with one screw/nut. The (brass) nut will be soldered to the tube to ease electrode replacement.

Please tell me what you think about it? The construction is much simpler now and can be machined quicker.
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Re: low cost DIY battery spot welder

Post by parabellum » Jul 14, 2017 4:00 pm

Very nice, slim solution. I did something similar, but took copper tube and crimped it on both sides, not very replaceable but no screw in the way. :)

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Re: low cost DIY battery spot welder

Post by spinningmagnets » Jul 14, 2017 4:01 pm

I like those electrodes very much. Well done!

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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 14, 2017 5:48 pm

parabellum wrote:Very nice, slim solution. I did something similar, but took copper tube and crimped it on both sides, not very replaceable but no screw in the way. :)
What crimp tool do you use for that? Would that be able to handle 6mm diameter, and does it apply evenly distributed force? I mean something that is better than squeezing it in a vice :wink:
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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 14, 2017 6:12 pm

Just a quick update: the first items are online on https://www.kicksurfer.de/index.php/shop/
I will add more tomorrow, as it is late here.

The first batch of electronic sets is ordered and I estimate that I can add them to the stock by mid August. It will not be possible to place an order for that before, but as I appreciate your help here I want to respect the order in that you registered interest. If you want to buy an electronics set, then please register as a customer on my site and give me a PM here that you actuall plan to purchase an electronics set. I will reserve one set for you for the duration of one week after stock arrival.

All the other items will not be that problematic, as I can source them quickly. However, I will not build up a large stock of them because I think that most of you will want to source as much as possible locally and do the machining/soldering/crimping/assembling work by yourself.
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Re: low cost DIY battery spot welder

Post by parabellum » Jul 14, 2017 7:49 pm

tatus1969 wrote:What crimp tool do you use for that? Would that be able to handle 6mm diameter, and does it apply evenly distributed force? I mean something that is better than squeezing it in a vice :wink:
I think, yes. https://www.amazon.com/gp/product/B01I3 ... UTF8&psc=1
But it is for resistance welder and electrodes are 6mmD SS
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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 15, 2017 4:52 am

parabellum wrote: I think, yes.
Thanks, I will go for that. Much quicker than soldering, more robust result, and I can use it to replace my crimp multi tool that doesn't like crimping AWG8 well.

*cough* it's not what I think what it is on the other end, is it? 8)
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Re: low cost DIY battery spot welder

Post by parabellum » Jul 15, 2017 8:44 am

tatus1969 wrote:
parabellum wrote: *cough* it's not what I think what it is on the other end, is it? 8)
:oops: Yes it is. Transformer got those "contrary" terminals mounted on the secondary, half wrapped under copper shielding . But it will see <72A RMS for short 2-5 sec bursts. May add a solder blob over connection if they make some heating issue.
P.S. The purchase links are still under maintenance, right?

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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 15, 2017 11:04 am

tatus1969 wrote: It will not be possible to place an order for that before
I'll have to take that back, I just wasn't familiar enough with that system.

Sorry for the confusion!!!

WOW, that's an endless world of possibilities there! If someone needs a guide to setting up a Wordpress + Wocommerce server, here is another expert :wink:

Okay, no more products added there yet, but I managed to set up the full chain for the electronics module, including
- accepting pre-orders now - I'll serve them in the order that they come in
- the option whether you want me to complete it (solder LCD and dial pot), or you want to do that
- world wide automatic shipping rate calculator
- safe credit card payment via stripe

I'll add Paypal as well, but my business account there needs verification and they told me that this would take 2-3 weeks :shock:

I've set the limit to 20 copies now, to accomodate the possibility that not all of the 25 ordered are good.

Please order only one per person for now, in order to allow others receiving one. I need to refuse larger orders for the first batch. No problem of course later, after successful ramp up!

If you plan to purchase other options that are not in the store yet, please wait and you'll be offered a combined shipping rate. So you don't need to pay shipping twice.

I've activated the website again and do accept orders 8)
Last edited by tatus1969 on Jul 15, 2017 1:52 pm, edited 1 time in total.
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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 15, 2017 11:10 am

parabellum wrote: :oops: Yes it is. Transformer got those "contrary" terminals mounted on the secondary, half wrapped under copper shielding . But it will see <72A RMS for short 2-5 sec bursts. May add a solder blob over connection if they make some heating issue.
Just joking, I've done more silly things these days :wink:
parabellum wrote: P.S. The purchase links are still under maintenance, right?
That was quite an effort to pull all the strings together on the shop system, but also very exciting. It is amazing what kind of services are out there these days...
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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 15, 2017 4:06 pm

The remaining items are online as well. As I will be doing all the soldering, machining, and assembly work by myself for the time being, I need to set the prices for that relatively high. When this product is ramping up nicely, then this may change in the future.
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Re: low cost DIY battery spot welder

Post by mxer » Jul 15, 2017 4:45 pm

I hope I'm not going to be priced out of this one, what drew me to the thread was "low cost" hope there will be options to buy raw materials, I feel half the fun is customising you own units sourcing parts and commissioning the build 8) ...

What are you planning to add to the shop? full builds, raw materials package, options to purchase items separately?..

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Re: low cost DIY battery spot welder

Post by mxer » Jul 15, 2017 5:26 pm

https://www.kicksurfer.de/index.php/shop/


Found it, lol.

And answered my own questions
, excellent!!! I like it..

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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 15, 2017 5:35 pm

mxer wrote:I hope I'm not going to be priced out of this one, what drew me to the thread was "low cost" hope there will be options to buy raw materials, I feel half the fun is customising you own units sourcing parts and commissioning the build 8) ...
I know that I don't exactly meet the thread title anymore. I made several design decisions towards robustness, accepting a higher price. And it is not high volume (yet?) that would allow sourcing parts more economically. Just check how much one of these MOSFETs cost...

Also, the small parts are currently all collected together here and there. Only a higher volume would allow me to use a better supplier. If this project develops, then I will definitely do that and achieve much lower cost.

It is a spot welder for people who make their own batteries, possibly for custom designed ebikes or similar, and I guess that most people have the required machining tools available and can source components like bolts and nuts easily locally, if they don't have them in their drawers already.
mxer wrote: What are you planning to add to the shop? full builds, raw materials package, options to purchase items separately?..
Have you checked the shop most recently? I just did that.

I don't want to sell bare PCBs for people who want to solder themselves, because I am afraid of illegal copies of certain far eastern countries, and therefore want to protect the firmware.
Last edited by tatus1969 on Jul 15, 2017 6:53 pm, edited 1 time in total.
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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 15, 2017 5:36 pm

mxer wrote:https://www.kicksurfer.de/index.php/shop/


Found it, lol.

And answered my own questions
, excellent!!! I like it..
message overlap :D
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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 16, 2017 7:51 am

I just learned something very interesting from an idea of someone at EEVBlog.

Some welds of 0.1mm nickel strip using 30J of energy, showing little coloring.

Image

Some welds of 0.2mm nickel strip with 60J, showing strong coloring of all welds - except the leftmost pair per cell.

Image

The leftmost welds were achieved by adding a drop of solder flux (Chipquik SMD291 in my case). Please forgive me if that is common knowledge, but I was quite impressed :D
Last edited by tatus1969 on Jul 16, 2017 8:58 am, edited 1 time in total.
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Re: low cost DIY battery spot welder

Post by tomjasz » Jul 16, 2017 8:43 am

Why the need for coloring, or am I not understanding ?
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 16, 2017 8:57 am

tomjasz wrote:Why the need for coloring, or am I not understanding ?
The flux prevents the coloring.
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Re: low cost DIY battery spot welder

Post by spinningmagnets » Jul 16, 2017 9:25 am

Okashira has tried just about everything under the sun, and he recommends the Sunkko 709A. Right now it is on Banggood for $290 USD, plus shipping https://www.banggood.com/SUNKKO-709A-1_ ... 08660.html

That being said, there is a discussion about how to repair it when it sometimes fries a component on the inside. The failed internal components had died when they were being used for exactly what they sere designed to do. I would say that...if you have one of those units, you should upgrade the guts before you really need to, so it doesn't fail right in the middle of the job.

This kWeld unit, on the other hand...does not use generic components. All the electronics are high quality, and have a safety margin for the the job that each one of them is chosen for. Rather than being designed to accomplish a wide variety of jobs, the kWeld was specifically designed to spot-weld 0.10mm-0.20mm nickel strips to 18650 cells.

It is a bargain at the prices he is charging. In a year or so, he will be copied by someone in China, but the Chinese clone will have counterfeit components on it. It will perform poorly, and it will fail occasionally.

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Re: low cost DIY battery spot welder

Post by parabellum » Jul 16, 2017 10:05 am

Cool option set in your shop! Will be nice to my lady for a while, so she may let me put one of Kwelders in to buy list by August. :D
Keep up the good work!
https://www.kicksurfer.de/index.php/pro ... ectronics/

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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 16, 2017 5:00 pm

parabellum wrote:Cool option set in your shop! Will be nice to my lady for a while, so she may let me put one of Kwelders in to buy list by August. :D
Keep up the good work!
https://www.kicksurfer.de/index.php/pro ... ectronics/
Thanks, and good luck :wink:
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Re: low cost DIY battery spot welder

Post by 12-C » Jul 17, 2017 11:32 am

tatus1969 wrote:
tomjasz wrote:Why the need for coloring, or am I not understanding ?
The flux prevents the coloring.

Isn't the use of flux a risk of future corrosion and weld deterioration? I recall from reading about soldering in general that not all fluxes are the same but should be washed from the surface to prevent future deterioration. Are you able to wash the flux from the joint on the battery? Or is this flux not a concern with regard to corrosion?

Have you tired to use flux with any other weld thickness/materials?

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Re: low cost DIY battery spot welder

Post by tatus1969 » Jul 17, 2017 3:14 pm

12-C wrote:
tatus1969 wrote:
tomjasz wrote:Why the need for coloring, or am I not understanding ?
The flux prevents the coloring.
Isn't the use of flux a risk of future corrosion and weld deterioration?
No, not in this case. I used so-called no-clean flux, which does not contain corrisive components and does normally remain on soldered circuit boards. That's standard since a long time in the electronics manufacturing industry, corrosive fluxes are not used anymore except in special cases, for example soldering nickel strips.
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Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Jul 17, 2017 3:57 pm

It was again exaggerated complexity that kept me from getting where I want. There is Paypal, Paypal Express, Paypal PLUS, then they tell you something about different APIs, bank account authorization, and so on. To summarize this: Paypal is now available in the shop, it was again easier/quicker than expected!
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Re: kWeld - "Next level" DIY battery spot welder

Post by liveforphysics » Jul 17, 2017 4:07 pm

Nice board and nice idea leveraging the burst current of a hobby pack.

In my limited experience, spot weld quality and repeatability seems to hinge greatly on consistent electrode angle and pressures, as well as surface prep.

The same electrical pulse delivered can make a tidy weld or just burn holes or not make a weld depending on the above mentioned factors.
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