Help with Capacitive Spot welder

diggler

1 kW
Joined
Mar 24, 2014
Messages
308
Location
Twin Cities, Minnesota, USA
I got this kit from someone who built it himself. He said it worked and he had used it to spot weld cells together when he replaced power tool batteries for people as a side gig.
I'm a noob to this sort of thing. I was hoping someone might be able to help me get this spot welder going.
As far as I know all I need to get it up and running is a capacitor (but not sure how big I should get), 1 or 2 power supplies, a foot switch, a fan and a speaker. O and a project box.
He included a mess of parts and the three 10k pots are in there, but I don't see any of the others.
Here are a bunch of pics. If anybody needs better or closer pics let me know.
Thanks
 

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Looks like a nice toy!

Have you checked out Fritz's website?

The Rockford Fosgate RFC1 is a popular choice on the ES $100 CD Welder thread.
I just bought two of these to play with shipped for $85 each.
And this foot switch has a nice solid click, and seems OK for the money.
 
great links! thank you!
looks like I got some reading to do. :D
 
So 1f is enough for lion laptop cells? and will work with my set up?
One of these will work? http://www.ebay.com/itm/Rockford-Fosgate-RFC1-1-0-Farad-Capacitor-/321612863556?hash=item4ae19ed844&vxp=mtr
I ordered that foot switch. but paid more so I didn't have to wait 3 weeks. should have it mon.
 
I'm still confused.
Here are some closer picks. The diagram sais 3f. and two ac power supplies? and what is D20?
20150128_163504.jpg
20150128_163545.jpg
 

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Hope you got this for a good price because the cap and the transformer will still be the big $$$ items after the FETs.

D20 is a 50A bridge rectifier diode turning the AC to DC to charge the caps.

The transformer is a single unit with a centre tap/toroid with two windings allowing two AC voltage outputs. But that may be hard to source something so specific.
Like this toroid, 4A would be a minimum else the caps will take longer to charge :( Does Fritz specify anything? Other guys who have built this will have websites too.
A meanwell DC power supply with current limiting may be cheaper, but I'm not sure if recommended.

Can't hurt to just start with the RFC1 1F cap, but remember a 20V audio cap will limit you to lower voltages <18V, which should be fine for most welds to 18650's.
 
How ironic.....I just purchased all the parts and instructions on Momday. Should have it all by the first of the week. Hopefully we can help each other along the way to get these up and going. I have over 400 cells to spot weld....

I doubt that he had it working and then took it all apart, that doesn't make any sort of logical sense but such is life sometimes.

Look forward to your progress.

Tom
 
Hope you got this for a good price because the cap and the transformer will still be the big $$$ items after the FETs.
Yah he gave it to me like 8 months ago and I still haven't paid him for it yet. :oops: But he said 100 buck would be fine.
D20 is a 50A bridge rectifier diode turning the AC to DC to charge the caps.
Okay thanks. That's what this must be.
20150128_223457.jpg
20150128_223503.jpg
The transformer is a single unit with a centre tap/toroid with two windings allowing two AC voltage outputs. But that may be hard to source something so specific.
Like this toroid, 4A would be a minimum else the caps will take longer to charge :( Does Fritz specify anything? Other guys who have built this will have websites too.
A meanwell DC power supply with current limiting may be cheaper, but I'm not sure if recommended.
Okay so the toroid would be all I need for the psu? Or should I get a stronger one?
I have a 150 meanwell but it's modded for 18650's so I can only get 4.33V out of it now.
Also I think this need AC volts too.
20150128_225214.jpg
Can't hurt to just start with the RFC1 1F cap, but remember a 20V audio cap will limit you to lower voltages <18V, which should be fine for most welds to 18650's
Cool. I can always parallel another one in if need be right? It sais 25V 3 farad in the diagram. I would need the higher voltages for aluminum or thicker welding right?

And it looks like he included the resistors for Resistor Bank Discharge.
20150128_230121.jpg

I'm not afraid to drop some money down to get this thing running right the first time. I just don't want to order the wrong parts or have to double order because I cheeped out on something.

So It looks like after the psu and cap all I need is a fan, a 8 ohm speaker, some beefy cables and the electrodes.
I have some 12 and 10 awg wire for the cap and rectifier. I'll have to get some 14 or 16 for the other stuff.

litespeed

Nice! your building one from scratch? Feel free to post stuff up here! And yah I don't know how much help I'm going to be, but I can use all the help I can get. :roll:
Yah he had it workin when he lived in cali, but it was just taking up space now. And I think he's got another one. He travels around laying fiber optics.
I'm looking forward to my progress too. I've had these 1000 used cell almost a year now and now that I finally got them all tested I'd like to actually put them to use. I plan on a 60V 40ah pack for my commuter. And a 12V for lights n stuff on my SIKK fat bike.

Here is a pick of the spare parts.
 
diggler said:
Okay so the toroid would be all I need for the psu? Or should I get a stronger one?

Yes the toroidal transformer plus rectifier is the PSU.
That was just a quick google and I'm not making any recommendations because I haven't read any of the documentation.
But an Ebay search has this one looks massive and these guys sell many different ones. What is specified? 200VA?

A single 1F cap wouldn't supply the full 600Ws (which by my maths calculates out to 4F but I assume the caps continue to charge during discharge?) this welder is rated for, but may be enough for nickel on 18650's. You can always add a second.
 
This is what the diagram sais.
20150129_025231.jpg
Thanks a lot for you help so far.
 
http://astore.amazon.com/capacitowelde-20 This is what Fritz recommends for the spotwelder.

You need to know if your going to run 2.1 or 2.5. 2.1 runs at 20 volts where 2.5 runs at 23 volts pushing the output to 800watts. I'm a firm believer in more is more when watts are concerned. Bad thing about the 2.5 version is you should use a bit better components (which you may already have!) and a higher voltage cap which is not the typical car audio variety, read-> mo-money!

Tom
 
http://astore.amazon.com/capacitowelde-20 This is what Fritz recommends for the spotwelder.
This is what he recommend for my welder? or his welder?
My diagram sais 24volt and these are 25 volt. I don't know if the 1 volt matters.
You need to know if your going to run 2.1 or 2.5. 2.1 runs at 20 volts where 2.5 runs at 23 volts pushing the output to 800watts.
I don't know what 2.1 and 2.5 are but since the welder sais 600w all over it I'm guessing I should run 2.1 so 20 volts then.
Maybe they say 25 volt 3 farad capacitor in the diagram because it's a good Idea to have a bigger cap then you need for reliability reasons.
I'm a firm believer in more is more when watts are concerned.
haha what do you mean by this? More watts is better, right? or more watts mo problems.
Bad thing about the 2.5 version is you should use a bit better components (which you may already have!) and a higher voltage cap which is not the typical car audio variety, read-> mo-money!
Yah it's seem like a bit of a gamble. I really only need this for 18650's. I don't know if I have the better components, and if I run it at 2.1 then I can get by with the car audio ones.

So as of right now I'm thinking 2.1 is what I will do.
So I think I'll get 2 of the Rockford caps. I'll try it with 1 and if I need 2 then I'll use 2.
And as far as the transformer I'm still a bit confused. I'll have to do some research. Unless someone can tell me for sure what I need.
 
That transformer is the one you need. Look here, http://frikkieg.blogspot.com/p/welder-photos.html and browse through the photos. You may just want to read this whole site, http://frikkieg.blogspot.com I did and maybe that will shed some light on your questions.

Let me know how it goes,

Tom
 
Okay thank you for the links.
:lol: You guy's have been trying to get me to read fritz's website this hole time and I should have listened! :oops: I just glanced at it the first time.
I read the hole thing and I'm unsure about a couple things. He sais if you got the V2.5 chip and you want to run 25v 800w than you have to change diode D10, otherwise it wont charge the cap higher than 20v. Also if you got the V2.5 chip and the diode D10 has been changed to the 25v one and you have a car audio cap you wont have over voltage protection on your cap if the chip fails!
Now my diode D10 doesn't look anything like the one in fritz's link for the the 25v one.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MMSZ5253BT1GOSCT-ND
Can anybody tell me if I got the 25v diode?

Also the update sais you have to change the D4 diode and my D4 diode sais 730 on it and the updated one appears to be 735. (the last 3 digits on it are 735) http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=1N4735AFSCT-ND
So it appears that my board is built for V2.1 use.

What I gathered from fritz's site is that if it has the V2.5 chip than it will display V2.5 when you power it up but if you don't connect a 100 Ohm resistor in series between pin 15 and 5v than it will not charge past 20 volts.
So could I just power it up without the capacitor hooked up to see what the display sais. Before I bought the capacitor.
But I guess this still wont tell me what diode is at D10 if the display sais v2.5. :?
:idea: Can I test the diode by giving it 21v off a quickly strung together 18650 battery with a resistor, without frying something on the board? How much current does it take to turn it on?

I seems like chances are there wont be a failure in the chip and I probably have V2.1 diodes and I can run lower volts on the V2.5 chip if I have that.
So I should just get a couple of those Rockford caps off fritz's amazon store, and that smaller $87 transformer since I'm only running 600w?
Or what do you think?

Also thanks for the link to his amazon store because on his blog it just sais typesetting where the bill of materials are.
Maybe I should just email fritz and get his recommendation.
 
Okay I emailed him and he told me it was the V2.1.
He told me to get the $87 500VA 25+25 transformer from his amazon store.
And he suggested that I get computer grade capacitors. He said there expensive but worth it.
The only 1 farad computer cap I found so far were $200 bucks! http://www.electronicplus.com/search-return.asp?search=1+farad&Submit=Search
Does anybody know where I can get them cheaper?
I do want to go 3F to get the full 600w out of this welder but I think 2f 400w would be plenty for what I need it for at the moment.
Do you guys agree with fritz about the caps or do you think I should just get the Rockford ones?
Thanks again for all the help so far.
Hopefully I will have this up and running in a couple weeks when I get all the parts in.
 
Sorry I didn't wait for any replies I just ordered two of those computer caps.
And I believe I have all the other parts I need coming too.
 
fritz had emailed me back with a link to caps that were 1f 25vdc and under $100. So I quick canceled my order then when I tried to order from his link there was only one left. But I just found two more for a little over $100 a piece so I ordered those. I got the fan and speaker and 4 awg cables with copper connections for the board coming and some wire for everything ells. So now I just have to figure out the case.
I have a big sheet of aluminum diamond plate from a pick up tail gate that I got from the guy I shovel snow for, $10. But I was going to polish that up and use it for a battery box on my ebike. I like the idea of using a craftsmen tool box but he had an iron core transformer so I don't think mine will fit.
litespeed
how are you going to build your case?
 
Ill buy a pre built case. Either this one, http://www.mouser.com/ProductDetail/Bud-Industries/WA-1543/?qs=UQ5vIheBPd7AWL9FF%252b%2FJ%2Fg%3D%3D or this one which is super heavy, http://www.hammondmfg.com/1453.htm

Heck I might even try a tool box since these others are so expensive.

Tom
 
I got a tool box today for mine. $20
The two other caps aren't coming any more they said they were out of stock.
I hope the one will do the job. I'll keep looking on ebay...
 
well there was one more on there.
The guy must just be selling one at a time?
So now I have two coming. I'll keep looking but I'm thinking 400w will do it.
I should probably get some nickel strips coming eh?
 
ordered one more cap so I will have the full 600w. guy said he will send them out together.
I got all the parts except for the caps now but I have been working on my SIKK fat tire bike lately.
Once I get the caps I'll switch back to focusing on this.

litespeed how's your build goin?
 
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