kWeld - "Next level" DIY battery spot welder

Batteries, Chargers, and Battery Management Systems.

Re: low cost DIY battery spot welder

Postby tatus1969 » Sun Jul 09, 2017 10:54 am

This started as a one-off, but my solution has some unique features (apart from being very robust - I will explain those in the upcoming video), so I am planning to sell it in form of a kit. It depends on you makers and builders how that kit should look like. My idea is to only sell assembled/tested/programmed PCBs and the mechanical parts in raw form. This means (apart from things like bolts, nuts, cable lugs, ...) brass blocks cut to length, copper rod, and enough AWG8 wire. You would need to drill and cut the brass pieces, cut and form the copper rod into electrodes, and cut / crimp the cables. The other extreme would be supplying complete systems, but this involves considerable machining work and would make everything much more expensive. I need some feedback from you folks... And if someone is interested in a kit, just send me a PM.
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Re: low cost DIY battery spot welder

Postby mxer » Sun Jul 09, 2017 1:47 pm

Pm'ed definitely interested in the raw materials to have a play, great project and thanks for sharing.

:D
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Re: low cost DIY battery spot welder

Postby spinningmagnets » Sun Jul 09, 2017 6:44 pm

I can't speak for anyone else, but...here's what I would want the seller to do at a minimum.

Image

I like the board in the pic above, all of the tiny electronic components are all in one place (instead of me needing to order them from three different vendors), and they are all soldered in the proper location on the board.

What I most want is for the brain-chip to be pre-programmed by the seller before I get it. It may be quick and easy for you, but I will pay for someone else to make sure that it is done right.

What I can easily do without screwing it up:
Cut square bar into proper lengths, drill seven holes in each, bolt bars to their proper place.
Make the four cables (I can source all the components for the cables locally)
Attach fuse
solder-in the large single capacitor (too easy, just make sure the positive hole is clearly marked?)
Make all the tube standoffs (brass, plastic?...either is easy). I can also source stand-off tubes locally without any wait
Attach screen read-out
solder-in the adjustment dial into place
plug-in and solder that 6-pin "segger" device

If you add the raw square bar to the kit, that's fine, I can finish it off. However, you can make the shipping a little lighter because I can source the square bar from a local metals supplier (since you are shipping around the world). I just need the dimensions, and I can be working on it while I wait for your kit to arrive...You can have the cables as a purchase option, either a loose-part kit or complete, but...I can make those too, quite easily.

Sooo...is that all I have to do to take the kit from the first pic to end up like the second pic below?

[edit: I now think I would definitely recommend that you make the square-bars and cables available on your website as a completed product (cut and drilled), separate from the basic kit. However, charge a high price for those, because most DIY guys can buy those by themselves using local materials...no need for you to try to be competitive and get headaches over the easy-to-get stuff. The square bar can be found at onlinemetals.com, and you need to focus on the tech stuff, not brass bars and cables. I just bought a 3/4-inch diameter copper rod a foot long for $20, arrived in four days.]

Image
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Re: low cost DIY battery spot welder

Postby 12-C » Sun Jul 09, 2017 10:44 pm

+1 spinning magments

The reflow work for SMT is well beyond another project that I want to undertake. And forget about programming.

soldering through hole components is simple enough and rather fun...

It would be great if it was a "all components included- build most yourself" type product.

Looks really impressive!

Any idea if you anticipate it handling thicker ribbon, aluminum or copper?

Thanks!
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Re: low cost DIY battery spot welder

Postby tatus1969 » Mon Jul 10, 2017 1:11 am

The video is online!

If you like it, you can help me by sharing the video via Facebook etc.

https://youtu.be/Ceos88VO6p4
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Re: low cost DIY battery spot welder

Postby spinningmagnets » Mon Jul 10, 2017 1:26 am

All I can say is...WOW!

I like it even more now that I have seen the video. Please save one for me, and PM me your paypal email address.

As I stated above, I do not need the cables, the probes or the square bars, but I will need everything else.
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Re: low cost DIY battery spot welder

Postby mxer » Mon Jul 10, 2017 4:00 am

+1 above

Video is great! Thanks. Pm me your details, cheers
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Re: low cost DIY battery spot welder

Postby TheBeastie » Mon Jul 10, 2017 1:06 pm

Wow amazing job. Really looks awesome.
That really is a truly next-gen DIY spot welder. We can't ever have enough projects like this.
I really like the LCD display with a joule output reading with the variable knob.
And the auto-mode without footswitch is cool.
But then I saw the self-calibration and auto milliohm resistance reporting,
just wow.
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Re: low cost DIY battery spot welder

Postby fechter » Mon Jul 10, 2017 2:10 pm

Gets my seal of approval. Nice work.
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Re: low cost DIY battery spot welder

Postby mauimart » Mon Jul 10, 2017 2:39 pm

Simple sophistication. Brilliant! Have you tried to weld 0.2mm nickel strip with the 5Ah battery?
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Re: low cost DIY battery spot welder

Postby tatus1969 » Mon Jul 10, 2017 4:50 pm

spinningmagnets wrote:

Thanks a lot for your helpful thoughts. (No, you haven't forgotten anything.)

I will go ahead and make these items available:
1) PCB with all SMT components soldered and microcontroller programmed
2) set of through-hole components like capacitor, connectors, LCD, potentiometer, etc
3) fully assembled and programmed PCB
4) cable assembly for those who don't have a suitable crimp tool
5) set of mechanical components like bolts and nuts, excluding the parts that need machining
5a) the foot switch
6) set of raw brass and copper parts, cut to length
7) set of finished brass and copper parts
8 ) programmer for firmware updates that plugs into USB (the Segger tool is a full debugger and too costly), plus an update tool (Windows)
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Re: low cost DIY battery spot welder

Postby tatus1969 » Mon Jul 10, 2017 4:51 pm

spinningmagnets wrote:All I can say is...WOW!

I like it even more now that I have seen the video. Please save one for me, and PM me your paypal email address.

As I stated above, I do not need the cables, the probes or the square bars, but I will need everything else.

Thanks :D Did you receive my last PM's?
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Re: low cost DIY battery spot welder

Postby tatus1969 » Mon Jul 10, 2017 5:00 pm

mauimart wrote:Simple sophistication. Brilliant!

Thanks, usability was my first priority. This made me opt against fancy push buttons as well, even tough they are cheaper. I recently had to work with a Weller WX2 soldering station. Setting the temperature with its touch keys takes ages and is a real headache.

mauimart wrote:Have you tried to weld 0.2mm nickel strip with the 5Ah battery?

I've just tried to weld five layers of 0.1mm nickel strip. The two bottom layers are welded but can easily be separated. The top three layers stick together. Just yesterday I have ordered 0.1mm copper foil and some of these, these are 0.3mm nickel.

Image
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Re: low cost DIY battery spot welder

Postby spinningmagnets » Mon Jul 10, 2017 6:41 pm

I like how long the slots are on those nickel strips. I believe that those slots will help make the spot-welds more consistent.
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Re: low cost DIY battery spot welder

Postby 12-C » Mon Jul 10, 2017 11:04 pm

Great product!

Can you quote a price and how long until delivery? I sent a PM.

I really liked the video.

Do you anticipate it being able to weld copper, aluminum, or any others?

Thanks!
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Re: low cost DIY battery spot welder

Postby tomjasz » Mon Jul 10, 2017 11:11 pm

Website listed at end of video..
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

Postby tatus1969 » Tue Jul 11, 2017 2:16 am

12-C wrote:Can you quote a price and how long until delivery?

I am busy doing the calculations, but that is not yet finished (almost). I will order assembled PCBs from a professional service, expect around 3 wks for that. Then give me a few days for testing/programming/packing/shipping.

12-C wrote:Do you anticipate it being able to weld copper, aluminum, or any others?

It certainly does 0.3mm nickel, but a lot depends on the power source. The welder circuit contributes only 140 micro (!) ohms. The MOSFETs are rated 40V and I have programmed a current limit of 2000A for 200ms, so there should be enough headroom for thicker materials.
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Re: low cost DIY battery spot welder

Postby tatus1969 » Tue Jul 11, 2017 2:19 am

I made a video where I am doing robustnes testing:

edit: this time the correct link:
https://youtu.be/fWXphoDE_H8
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Re: low cost DIY battery spot welder

Postby tatus1969 » Tue Jul 11, 2017 2:53 pm

Okay, I'll continue finishing the release design and send an RFQ to my PCB assembly company, but I wanted to share this one with you first. It's rather crazy (and educational?), please don't take it too seriously - I am a quality minded professional EE despite of what you see there :wink:

https://youtu.be/JR3GJYScquc
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Re: low cost DIY battery spot welder

Postby 12-C » Tue Jul 11, 2017 11:20 pm

tatus1969 wrote:Okay, I'll continue finishing the release design and send an RFQ to my PCB assembly company, but I wanted to share this one with you first. It's rather crazy (and educational?), please don't take it too seriously - I am a quality minded professional EE despite of what you see there :wink:

https://youtu.be/JR3GJYScquc


hahaha that was great, I actually jumped lol scared me as much as you lol

would it be possible to program a sensing feature to prevent autofire if the electrodes are in contact?
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Re: low cost DIY battery spot welder

Postby mxer » Wed Jul 12, 2017 5:23 am

HaHaha, very educational.

Made me jump too, interesting to see the extreme :D
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Re: low cost DIY battery spot welder

Postby fechter » Wed Jul 12, 2017 10:32 am

Maybe some heat-shrink tubing around the electrodes with only the tip exposed might help with the accidental firing. :wink: I could imagine using a foot pedal in conjunction with the auto fire as well. Use the foot pedal to disable firing when not pressed. I didn't really like using a foot pedal for firing as the thing had a bad tendency to move around on the floor, but I could see just holding it down to enable auto-fire.

Pretty impressive it welds those slotted tabs with the electrodes on the same side of the slot. With the electrodes on opposite sides of the slot, it should take much less current to get a good weld.
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Re: low cost DIY battery spot welder

Postby tatus1969 » Wed Jul 12, 2017 2:39 pm

12-C wrote:would it be possible to program a sensing feature to prevent autofire if the electrodes are in contact?

That is not easily possible. I need to fire a pulse in order to measure the resistance between the electrodes, it cannot distinguish a dead short from a nickel strip before that. If what I did in the video were a dead short. But I had a different idea, the video showing it is already rendering 8)

What would probably be convenient is to integrate the switch into one of the electrode holder, and make it spring loaded, but that definitely exceeds my mechanical skills. Not to speak of how to maintain low resistance...

fechter wrote:Maybe some heat-shrink tubing around the electrodes with only the tip exposed might help with the accidental firing. :wink:

You bet what I did right after the video :wink:

fechter wrote:I could imagine using a foot pedal in conjunction with the auto fire as well. Use the foot pedal to disable firing when not pressed. I didn't really like using a foot pedal for firing as the thing had a bad tendency to move around on the floor, but I could see just holding it down to enable auto-fire.

Me too, for the same reason. But that is an interesting idea, I will keep that in mind. Please watch my next video and tell me what you think about my improvement idea.

fechter wrote:Pretty impressive it welds those slotted tabs with the electrodes on the same side of the slot.

You probably don't believe me that I already knew how to use these tabs before making that video...
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Re: low cost DIY battery spot welder

Postby tatus1969 » Wed Jul 12, 2017 3:06 pm

There goes the next video, showing some improvements:
https://youtu.be/9-CQd02EDIs
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Re: low cost DIY battery spot welder

Postby 12-C » Thu Jul 13, 2017 11:52 pm

Nice features!
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