Author Topic: kWeld - "Next level" DIY battery spot welder  (Read 88889 times)

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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #500 on: January 02, 2018, 09:32:34 pm »
if you sell them directly.
I am currently working on the next batch kWeld, and on a customer project (a motor controller), so I didn't have time to continue the stationery kWeld power supply. I think that I can continue this in three weeks, as it is already almost mature. I plan to sell the capacitor balancer board with and without capacitors.
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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #501 on: January 02, 2018, 09:36:32 pm »
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?
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Offline Derriell

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #502 on: January 05, 2018, 05:53:59 am »
It has arrived today   :-+

How many mOhms (approximately) will it lose when using thicker cables and solder the cables (partly) directly to the board?
 

Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #503 on: January 05, 2018, 09:45:41 pm »
It has arrived today   :-+

How many mOhms (approximately) will it lose when using thicker cables and solder the cables (partly) directly to the board?
Great!

You can estimate this directly from the AWG relationship, I use to use Wikipedia. The table is for solid cores, you can add maybe 15% to the numbers for fine stranded cores. https://en.wikipedia.org/wiki/American_wire_gauge

The standard setup is AWG8, total length 0.8m.

I don't recommend soldering the excess strands to the PCB, just cut them. The cable lugs have negligible resistance.
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Offline LuboN

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #504 on: January 06, 2018, 09:08:18 am »
Try to use two or three smaller capacity LiPos parallel, that way the resistance of leads and connectors divide  ;)
 

Online Kjelt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #505 on: January 06, 2018, 09:24:18 am »
I plan to sell the capacitor balancer board with and without capacitors.
Please sent me a pm if these are for sale in your shop  :-+
 

Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #506 on: January 07, 2018, 10:59:04 pm »
I plan to sell the capacitor balancer board with and without capacitors.
Please sent me a pm if these are for sale in your shop  :-+
Can I ask you to subscribe to the website newsletter? It's because I'm likely to forget doing that when it's time. I know myself better ;-)
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Online Kjelt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #507 on: January 07, 2018, 11:57:05 pm »
I plan to sell the capacitor balancer board with and without capacitors.
Please sent me a pm if these are for sale in your shop  :-+
Can I ask you to subscribe to the website newsletter? It's because I'm likely to forget doing that when it's time. I know myself better ;-)
Done, i think..........
I press the subscribe button but nothing further happens?
 

Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #508 on: January 09, 2018, 12:33:46 am »
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/
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Offline arcol

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #509 on: January 09, 2018, 09:24:25 pm »
Bear with me, if it is slightly offtopic question.

I would like to build some battery pack for power tools (different brand, so I want to unify them).
I'm looking for these type of connectors not really important which type I end up with,
only want to have pairs. Please see the attached picture.
 
So I can build adapters. I don't know the proper english term, or I'm really unlucky, but can not find
anywhere (ebay, mouser, lcsc.com).

Can somebody tell me how could I source such connectors?
These is the only obstacle between me and a spot welder... :)
 

Offline anishkgt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #510 on: January 09, 2018, 09:32:23 pm »
Those seem like some lithium battery pack connectors. I suggest you start another thread for this. You would get more response add more pics mention where this is taken from like what device and what it originally connects to.
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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #511 on: January 10, 2018, 09:30:53 am »
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/
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Offline anishkgt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #512 on: January 12, 2018, 06:32:03 am »
Hey frank since your high power designs for this project, thought I’d share this article that I came across

https://www.allaboutcircuits.com/news/how-mosfet-arrays-balance-supercapacitor-cells/?utm_source=All+About+Circuits+Members&utm_campaign=80d6eb1df1-EMAIL_CAMPAIGN_2017_12_22&utm_medium=email&utm_term=0_2565529c4b-80d6eb1df1-272670005/


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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #513 on: January 12, 2018, 10:35:06 pm »
Hey frank since your high power designs for this project, thought I’d share this article that I came across

[url=https://www.allaboutcircuits.com/news/how-mosfet-arrays-balance-supercapacitor-cells/?utm_source=All+About+Circuits+Members&utm_campaign=80d6eb1df1-EMAIL_CAMPAIGN_2017_12_22&utm_medium=email&utm_term=0_2565529c4b-80d6eb1df1-272670005/]https://www.allaboutcircuits.com/news/how-mosfet-arrays-balance-supercapacitor-cells/?utm_source=All+About+Circuits+Members&utm_campaign=80d6eb1df1-EMAIL_CAMPAIGN_2017_12_22&utm_medium=email&utm_term=0_2565529c4b-80d6eb1df1-272670005/[/URL]


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That is an interesting idea, they juse use matched MOSFETs with precise gate threshold voltages. The circuit complexity cannot get lower than that.

As I will use the capacitors under extreme conditions, I expect them to start drifting quicker than if they were used for some kind of backup. This is why my balancer is a bit more complex and uses some comparators. It is a kind of intelligent balancing technique that decides which cells to discharge based on the average voltage from the pack. This way it is only reducing voltage of those cells that are a certain delta above the others. The circuit is still cheap because it doesn`t use anything else than jellybean comparators, some MOSFETs and shunt resistors.
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Offline anishkgt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #514 on: January 12, 2018, 10:47:22 pm »
Good to know.


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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #515 on: February 04, 2018, 01:57:21 am »
I have received the first batch of laser-cut housing parts for kWeld. Here is a picture of the first build, they will be available in my shop soon. These are much more affordable than 3D printed housings (unless you have a printer yourself), so I stopped the development of those.

« Last Edit: February 04, 2018, 02:00:26 am by tatus1969 »
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Offline anishkgt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #516 on: February 04, 2018, 02:02:08 am »
I would have it colored solid black or a different shade with just two or three holes and a tiny fan for cooling. Adds that pro look to it frank.

Don’t get me wrong but this is kinda childish to me.


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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #517 on: February 04, 2018, 09:42:21 pm »
I would have it colored solid black or a different shade with just two or three holes and a tiny fan for cooling. Adds that pro look to it frank.
Thanks for your suggestion. I think that I will make it available in two colors, transparent and white. But this mainly because acrylic glass is just beautiful (therefore I started with that) but you can see every tiny scratch. I don`t think that the welder needs as fan, as the module does not produce lots of heat. The only part that heats up significantly is the fuse. I have never managed to heat the MOSFETs above ~ 50°C. The weakest parts of the system are the Lipo battery and the electrodes.
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Offline branadic

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #518 on: February 16, 2018, 06:18:45 am »
Hi all,

I've already ordered the kWeld kit and wait for it to arrive. Nevertheless I'm interested in what is possible with it and do have questions that are worth to discuss here. Some of the questions were already asked and answered by Frank, but I will ask them here again.

Is butt welding possible with kWeld as shown here or what is necessary to make kWeld able to butt weld?



One possible solution is to use a second microcontroller that controls a cinematic as well as kWeld. The foot switch is a simple 3.3V digital input with a 100k pullup and a 1k/1nF low pass filter on the input, as Frank wrote me.

How to spot weld a (resistance) wire with kWeld to a rod or similar?

I've seen the picture on kWeld website and would like to know more about how this has been done. It looks like some electrode has been used.



minute 12 ff.

I think it would be helpful for all of us to share the knowledge and experience with kWeld as well as modifications done to realize specialties.

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Offline anishkgt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #519 on: February 16, 2018, 06:33:45 am »
Its all about mastering the weld time and energy. I've made one but they are meant to be used with a MOT (Microwave Oven Transformer). The project is explained here  (https://georgehobby.wordpress.com/2018/01/27/maxweldv2/) Basically a dual pulse spot welder, unlike KWeld. Max weld works on time delay ranging from 0 (being disabled) to 1000ms.


Edit:
Am sure this would be achievable in kWeld as well.
« Last Edit: February 16, 2018, 06:56:43 am by anishkgt »
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Offline branadic

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #520 on: February 17, 2018, 09:46:57 am »
Thanks for your response, even though I hoped that those guys with a kWeld would have shared their experience here.

-branadic-
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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #521 on: April 05, 2018, 07:52:02 am »
The most recent batch of 150 kWeld's is shipped out, and I have now time to make some progress. Next will be the ultracapacitor module that will be part of the stationery kWeld supply (but can be used for a lot of other purposes, of course :-). The design is finished and ordered, and here are some first pictures.

The specifications are:
- using Maxwell BCAP0310 cells in a 3S2P configuration
- 8.1V / 206F / 6780Ws
- balancing circuit that actually does what it is supposed to: keep the cells balanced within +-50mV (most far-east modules only have overvoltage limiters)
- temperature monitoring and control of optional 120mm fan
- separate input and output terminals
- series diode for charger to protect it from inductive kickback when welding
- dimensions 110x110x47mm (bare module), 120x120x105mm (with fan and standoffs)
- most important: the output current with kWeld is approximately 1000A
- maximum repetition rate (50J pulses) is once every 4 seconds without fan cooling, which can be lowered significantly with a decent fan

I plan to sell them at www.keenlab.de in three different fashions:
- as fully assembled board for 100€ (the module comes without a fan and the needed standoffs)
- as assembled board, but without the capacitors for 25€

If you are interested, then please leave me a message or check out https://www.keenlab.de/index.php/product/kweld-ultracapacitor-module/



« Last Edit: April 05, 2018, 07:57:05 am by tatus1969 »
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Online Kjelt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #522 on: April 05, 2018, 03:10:41 pm »
 :-+ on the waitinglist  :)
 

Offline all_repair

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #523 on: April 05, 2018, 03:47:12 pm »
Waiting for assembled board without capacitor here.
 

Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #524 on: April 07, 2018, 08:35:55 am »
Thanks guys :-+
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