Which spot welder control board to use?

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Oz18650

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I have recently obtained a 240v 1100w microwave oven transformer to make myself a spot welder for battery packs.

There are a few different controller boards available and I am looking for some pointers on selecting which control board to use.

There seem to be 3 main ones available

The cheapest one seems to be
Geekcreit NY-D01 40A/100A Digital Display Spot Welding Module Time and Current Controller Panel Timing Ammeter Spot Welders Control Board - 100A
I think this is single pulse and comes in "40A" for AU$14.89 or "100A" for $19.36
https://www.banggood.com/Geekcreit-....html?rmmds=search&ID=517855&cur_warehouse=CN

Then there is this one
100A LCD Display Digital Double Pulse Encoder Spot Welder Welding Machine Transformer Controller Board Time Control Module
for AU$40.24
https://www.banggood.com/100A-LCD-D...-p-1380038.html?rmmds=search&cur_warehouse=CN

Or this one:
NY-D08 100A Spot Welder Controller Welding Machine Pneumatic Color LCD Display Multi-point Personalization with Temperature Sensor
also $40.24
https://www.banggood.com/NY-D08-100...-p-1569035.html?rmmds=search&cur_warehouse=CN
This one has a colour screen.
It alsoseems to add a temperature control - but I am not sure how that works with the rest of it?
It also talks about "no external power supply', but the diagram shows a 9-12v AC transformer?
It also says "pneumatic control", but I am not sure what that is for?

Then there is
https://www.ebay.com.au/itm/220V-Sp...attery-welder-includ-transformer/283114770145
Which seems to add a heatsink and transformer

Has anyone used any of there these?
Does anyone have some ideas on which to choose?
 
I used a JST41-1200 Battery spot welding control board, 16 single chip microcomputer control, 1602 MCU LCD, encoder double pulse pcb to control the pulse duration. https://www.aliexpress.com/item/32810563725.html

Striped out an old 230V 850W microwave oven i had kicking around to salvage the transformer, cut out the secondary windings and removed the magnetic shims i replaced the windings with two turns of 16mm2 flexible battery cable with approx 1M of spare cable to exit through the case for each of the spark electrodes.

I mounted the MOT in the case along with the pcb and used a small 230V to 12V transformer for the pcb power supply. Cut the end of the case out and fitted an old PC fan on the end to keep everything cool, not that anything gets hot, I probably didn't need the fan. Pushed the battery cable out through a couple of holes drilled into the front of the case and cut holes for the display board and adjustment knob.

I soldered a couple of soldering iron tips into the ends of the battery cable for the electrodes and covered the ends with a few layers of heat shrink.

Used an old sewing machine peddle switch to operate the welder.

It works very well for welding fuses to cells with pulse power set to about 80% but I do need to have the pulse power set to 100% if I'm welding nickel strip otherwise the weld isn't strong enough.

I have now obtained a 1000W MOT that I'm going to fit in at some stage. I will take a few build photos when I get around to doing it.

I haven't measured the output amperage but I would imagine it's around the 450A mark, the voltage at the electrodes around 1.8V

I found that a two pulse weld works well on the fuses, P1 set to 65% for 70ms (to pre-warm the metal) a 25ms delay and P2 set to 80% for 90ms (for the weld).

The only purchases i made was for the JST41-1200, 230V-12V transformer and 2.5m of 16mm2 battery cable, the build cost was around 35 and a few hours of my time.
 
Thank you for the comprehensive reply chuckp!
It was actually a post of yours elsewhere on the forum that inpired me to go down the DIY spot welder path - so thank you for that too.
I definitely want to weld nickel strip. Do you think the bigger transformer will make a difference to how well that works?
I have not seen the JST41-1200 on either eBay or banggood (I have used these 2 marketplaces) and the ad you linked to says
"There are slight welding marks on the circuit board, which do not affect the use of the product. Please don't buy it if you mind"
Which makes me a bit wary that it might be used?
 
Oz18650 said:
Thank you for the comprehensive reply chuckp!
It was actually a post of yours elsewhere on the forum that inpired me to go down the DIY spot welder path - so thank you for that too.
I definitely want to weld nickel strip. Do you think the bigger transformer will make a difference to how well that works?
Click to expand...

Most defiantly I'd go with the larger MOT, mine is prefect on my fuses but it does struggle with nickel strip sometimes.
I think pure nickel strip vs the nickel plated steal makes a massive difference too.

Oz18650 said:
"There are slight welding marks on the circuit board, which do not affect the use of the product. Please don't buy it if you mind"
Which makes me a bit wary that it might be used?
Click to expand...

I've had a fair bit of stuff from Ailexpress and so for everything has been great.
The board i received was defiantly new not used.
I think they are marks made during manufacturing so not A grade then they sell them off a litter cheaper
 
It wasn't my original idea, I had help from old timers who figured I could try building a spot welder out of a microwave the same way they build them commercially. But, 12 or so years ago I popularized MOT-based spot welders. Almost everyone on the net who's heard of them, has heard of them because of me. Either because of my written tutorials, or later my Youtube tutorials, or later, the tutorials of bigger Youtubers who asked me for help. :p. The idea came about because I wanted to create a welder that welded chainmaille rings, and the existing welders were terrible (also because of my design, there's now chainamaille ring welders sold by the big supply companies.. I know this, because they told me they made them because of me :) ).

It's awesome to see that there are companies manufacturing spot welder timers for the DIY community, because MOT-based spot welders are so popular that there's actual demand for that.

Back in the day, this was not a thing you could buy. So I made my own out of the TRIAC from a microwave oven, a 555-timer chip, some junk components I pulled out of old VCRs, a cell phone charger, and some old amplifiers. Stuffed it all into a CD-ROM case and gave it a cover from the fake wood on the front of an old record player.

So, I technically built it for free, from junk :D

I have pictures of it around somewhere... *digs*...


image_tpxrsv.jpg


- I knew how to create circuit boards, but didn't have any copper blanks or etchant.

- I forget what it all does, I know there was a pushbutton that overrode the timer circuit and just acted like a switch. The speaker terminals in the back were so that you could swap out the timing components (resistors and capacitors that determined the bulk timing scale). One pair was to add a foot pedal trigger instead of the trigger button. I think there were three sets of timing triggers on the front, the two small knobs and the big precise knob and a selector switch to switch among them (in chainmaille, it's common to rotate between 2-3 different wire sizes back and forth when making jewellery, so instead of having to crank the knob every single weld to set it up for the next wire size, I just gave it 3 knobs you would set correctly at the start of a project, and then switches to jump around to which knob was active).

- Yes that's hot glue, not silicone. I'd never used silicone, but I did have hot glue.

- Yes, that heatsink on the TRIAC is comically undersized, meant for a TO-220, not a 15A TRIAC. And yes I didn't have any small bolts, so it's afixed with copper wire like it's a hay bale.

Really the whole thing was just as ghetto as could be. But I had zero budget and online electronic suppliers were just starting to appear (as in, I found a good deal on LEDs on eBay, bought 2000 of them and split them among 20 guys all around the world... for LEDs, something anyone can order in any quantity they want nowadays, for nearly free).

There was an ugly period between the death of Radioshack and the creation of the online small-scale electronic suppliers.


image_pxrzhv.jpg



image_mxuoop.jpg


I luckily realized, "A tutorial using a 555 timer chip is going to be obsolete as soon as it's made, don't write one" and never did :p

$15 for something that shows up at your door sounds like heaven. Do that. Don't do what I did.
 
Just curious, why go this route vs a malectrics or Kweld? It seems like it's not worth the effort considering how the other options are basically plug and play - and with a large community with lots of useful info about both units.

As for the DC welders you linked - the malectrics or Kweld units look like a much better option. They look seriously under powered for what they are doing, with not nearly enough heat sinking. Also, they don't seem to be adjustable in any useful way. You will need to adjust current depending on what you are welding, and to what. Different cells will respond differently - another reason I would go with the german units
 
The main reason I chose this path is price.
Yes it will be more effort, but I don't think too much.
I am also hoping to contribute my experience with this to the community and give some insight into what works or does not work.
I did look at the malectrics and kweld and they seemed like good products, but I would need to buy the welders and a high current battery to power them.
I think this way should be significantly cheaper. Hopefully the results are still good.
The controller board was cheap (AU$30) and the microwave oven transformer was free from a discarded microwave oven (I even have another as a spare)
I still need a few bits:
-secondary winding wire, which will be recycled
-9-12v transformer - I think I should be able to find one of these.
- flexible leads - not sure where these will come from
- tips - not sure where these will come from
There is probably very little cost in those other parts, so it should end up very low cost.
My controller board finally arrived yesterday!
I am still a fair way off from spot welding packs together. I still have to wait to check for self discharging cells, then capacity test, so I have plenty of time to get the spotwelder set up.
 
I still need a few bits:
-secondary winding wire, which will be recycled
- flexible leads - not sure where these will come from
Click to expand...


You can make these from the existing secondary.

First, you have to unwind your secondary. This'll take a long time, since it's 2000 turns. Wrap cardboard around the leg of a chair, and then spear the leg of the chair through the secondary so that it uses the leg like an axle.

You can clamp a steel bar into a power drill, use an end-stop (so you're not holding it with your muscles) and run the drill so that it yanks the secondary wire and slowly re-spools it onto the steel bar. It'll be tough at first until it breaks through the outer layer of enamel. It'll break a bunch of times, that's okay.

Once you have a spool, you can re-spool it the right length. Place two pieces of wood the distance apart that you want the length of your secondary to be (~1 foot per turn, howevermany turns, plus two feet for leads). Then just wrap it around and around those two wooden pegs until you've used up all the wire.

Then twist the cable you just made so it doesn't unwind, ziptie it at the ends, and then cut, flux, and solder them.

Now you've got a flexible copper cable you can use as wire for your new secondary.

Spot welders are the hardest to do this with, since you won't have much extra wire to work with (you took material that was tightly wrapped around the core, and stretched it out an extra 2 feet, probably cutting the cross section to 1/2 or 1/3). But it works.
 
Thanks for the suggestion Matt, however I cut the secondary wire, then hammered the remains out, so there is no way that wire is being reused...
I will be giving that copper to my electrician friend to take to the recycler.
 
Oz18650 said:
Thanks for the suggestion Matt, however I cut the secondary wire, then hammered the remains out, so there is no way that wire is being reused...
I will be giving that copper to my electrician friend to take to the recycler.
Click to expand...

I personally prefer to work with a DC based welder for safety reasons.
I don't trust the AC method and a cheap non-Certified Chinese board with my life or that of my cat :angel:

So I am looking at the DC route. This board --> https://www.aliexpress.com/item/400...&terminal_id=27b4a549ae9f4e8d8d9a25f00bc64e8a

comes with everything you need and has an adjustable power level (so it says).
The FETS on the board are 300A capable each. Although there are more of them on other boards like what was said.... the others don't appear to have weld power control. Just automated pulse timing.

I have contacted a seller and am waiting for a response. The one seller said they have a version with programmable pulse width along with auto pulse. They were checking on if it was available to me still.
 
Bubba said:
Oz18650 said:
Thanks for the suggestion Matt, however I cut the secondary wire, then hammered the remains out, so there is no way that wire is being reused...
I will be giving that copper to my electrician friend to take to the recycler.
Click to expand...

I personally prefer to work with a DC based welder for safety reasons.
I don't trust the AC method and a cheap non-Certified Chinese board with my life or that of my cat :angel:

So I am looking at the DC route. This board --> https://www.aliexpress.com/item/400...&terminal_id=27b4a549ae9f4e8d8d9a25f00bc64e8a

comes with everything you need and has an adjustable power level (so it says).
The FETS on the board are 300A capable each. Although there are more of them on other boards like what was said.... the others don't appear to have weld power control. Just automated pulse timing.

I have contacted a seller and am waiting for a response. The one seller said they have a version with programmable pulse width along with auto pulse. They were checking on if it was available to me still.
Click to expand...
Cool.
That could be another good option for people to use.
Please let us know how your spot welder turns out.
 
Oz said:
however I cut the secondary wire, then hammered the remains out, so there is no way that wire is being reused...
Click to expand...

Ahh, this is the one bit of advice of mine that many people didn't take, so just about all the tutorials out there say to just cut it off :p. A shame. When I first made my tutorials, I said to remove the secondary intact, but didn't say why. It was supposed to be revealed in later project-specific videos that I only ever half-filmed and never finished.

Bubbs said:
I don't trust the AC method and a cheap non-Certified Chinese board with my life or that of my cat
Click to expand...

It's all done on the primary side. The worst thing that can happen is that the spot welder locks on. The output of a transformer based spot welder is still lower voltage than an AAA battery.

Meanwhile, I presume you trust your toaster with your life? Because that's made in China for as cheap as possible, and it's 120vac unshielded right next to where you stick your hand. So is a space heater. And a blow drier. And a light switch for that matter.

...

That said, for $42 including the Lipo that powers it... that ain't a bad deal. You're not going to be welding sheet metal with it, but for 18650s, you should be set.
 
Spot Welding machine control panel time relay adjustment time of current transformer spot welder 100A SCR Item specifics Dimensions:77 mm*50 mm Model Number:YTD-SPOT-100 A Rated Duty Cycle:60%Usage:Spot welding machine DIY Product Description The control panel of the spot welding machine is a controller which is independently developed for the DIY or the simple resistance welding. The principle of silicon controlled phase shifting triggering is adopted to adjust the time and the current to achieve the purpose of welding.
 
Hi all.
I got myselfe a transformer out of a microwave from the junk yard, cut it open with an angle grinder and removed the secondary coil.
My secondary side is now 3 windings of a 20mm jumpstart cable wich should give me around 3V.
I did not weld it together and wanted to test it.
The transformer gives me a very loud humming noise
and an output of 0V
Is that because I did not weld it together or is the primary side shorted?

Thanks for advice.
Andy

edit: stupid me got scared of the humming and turned off my brain.
I forgot to switch the meter to AC :idea:
 
JST41-1200 Battery is good. I also use other tools like oscillating tool from protoolsadviser whichactually perform a wide variety of functions from cutting to cleaning to sanding. Also needed tool during metalworking and welding
 
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