Build your own CD battery tab welder for about $100.00+-

[texaspyro]

Uses 220V power input... not good if you are in the US.

Welding current 50-800A... might be able to do thin foil onto a AA battery.

 

[fortisi876]

Uses 220V power input... not good if you are in the US.

Welding current 50-800A... might be able to do thin foil onto a AA battery.

Thanks for the quick reply texaspyro!

If it's not too much of a pain, can you clarify for me what you meant about the 220V, how's it not good in the US?

Regarding the welding current, if 50-800A is insufficient what would you consider a minimum for doing, say, RC battery packs and power tool battery packs?

Thanks in advance!

 

[amberwolf]

Typically 220VAC isn't wired up in many (most?) houses in the USA except to a dryer outlet and a stove outlet, assuming you have electric versions of those. I've lived in some older houses that don't even have any 220VAC outlets at all, so to use it you'd possibly have to add a sub-panel from your main panel and run wiring/etc from there.

 

[fortisi876]

Typically 220VAC isn't wired up in many (most?) houses in the USA except to a dryer outlet and a stove outlet, assuming you have electric versions of those. I've lived in some older houses that don't even have any 220VAC outlets at all, so to use it you'd possibly have to add a sub-panel from your main panel and run wiring/etc from there.

Oh...is that how he meant it??? LOL!

Ok, I thought I was missing something or it had to do with the electronics end of the unit itself. I was an electrician for several yrs many moons ago so that's not a problem. Currently, I have 220/240V hooked up in my garage for my stand up air compressor so it'd work out perfect cuz the plug is located on top of my workbench out there. BTW- AFAIK, all homes are equipped with 220/240V at the panel, it's just a matter of running a line and receptacle to your desired location that becomes a pain.

If I can just get some confirmation that this lil unit has enough juice to weld the specific gauge thickness needed for battery packs in power tools and r/c use then I'm gonna go ahead and give it a try.

 

[amberwolf]

Regarding 220 at the panel, some of the older houses I've lived in did not have that; just a single phase from the overhead lines, and only one bus in the box. No breakers, either, just fuses. (if they had two phases from the overhead, they didn't have them bussed out like normal in the box; only 110V was available from any point in the box to any other point).


Regarding energy capacity of that unit: If it can only do 50-800A peak, I doubt it will do what you want. Back in this thread I think there were some currents of various things listed, which my poor memory doesn't recall exactly, but seemed much higher than that.

I can only find this post that has any info on it, in a quick search:
http://endless-sphere.com/forums/viewtopic.php?p=394606#p394606

 

[fortisi876]

Thanks for your advice Amber!


Here's another one I found that MIGHT be a more powerful unit???
http://www.aliexpress.com/product-fm/511023772-MCU-Spot-Soldering-Station-XC-10-welder-battery-welder-duble-pulse-18650-welder-wholesalers.html

 

[texaspyro]

It says output power is 1KVA (basically a kilowatt). My peak welder output power is around half a megawatt...

 

[fortisi876]

....

 

[texaspyro]

Yes, you need some way of varying the voltage on the caps. Energy is 0.5 * C * V * V so a little voltage change at the high end makes a big difference in the weld energy. My welder is driven by a simple constant voltage power supply, but the caps are charged through a FET. By varying the pulses that drive the FET, the cap voltage is regulated to within a few millivolts. Simple SCR welders are usually driven by a variable voltage power supply (it should have current limiting because a drained cap looks like a dead short).

 

[fortisi876]

Thnx TP!

Do you think this SCR would be ok??? IR 50RIA20

 

[texaspyro]

Do you think this SCR would be ok??? IR 50RIA20

That's a 200V 50A SCR... it will vaporize with a satisfying BANG! You need something that can handle 1000's of amps for a welder. (my welder can crank out over 20,000 amps).

The motorcycle charger does not allow you to vary the output voltage to tune the weld current. You need a variable lab type supply with current limiting in order to do it properly

 

[fortisi876]

You wouldn't happen to have a part number handy, would ya?

 

[The Electrician]

Here are my test results of various car audio caps (the good ones are at the end):


Model XCP-1 by XXX (a division of NIPPONAMERICA.COM):
1195 N.W. 97th Ave
Miami FL 33172
Advertised as: 1.5F, less than 2 milliohms ESR.
Measures:
@20 Hz 0.097F 6.450 miilohms
@120 Hz 0.097F 5.066 milliohms
@DC 0.106F
(note: a second sample had an ESR in the 3 milliohm range)

texaspyro, what instrument are you using to measure capacitance and ESR? Does this same instrument give a value for DC capacitance? If not, how do you measure DC capacitance?

 

[texaspyro]

My welder has a capacitance measurement function built in that measures capacitance at DC. It charges the caps to a known voltage and times the discharge through a known resistance to calculate the R*C time constant from which you get C. It is accurate to under 1%

I also use an ESI 2600 VideoBridge LRC meter to measure capacitance and ESR with AC... it's a wicked ass tool that cost over $20,000 when new.

 

[texaspyro]

You wouldn't happen to have a part number handy, would ya?

Nope, I gave up on SCRs a long time ago...

 

[fortisi876]

So, basically, this thread turned into a "look at what I built, its the beeeest!".....instead of what it was intended to be......wonderful.

Enjoy ur holiday folks.

 

[diaz]

So, basically, this thread turned into a "look at what I built, its the beeeest!".....instead of what it was intended to be......wonderful.

Enjoy ur holiday folks.

Totally uncalled for. This thread is possibly the best internet source of information on this subject. Texaspyro (I am guessing that's who you were digging at) may not be going open with his design but he has given masses of information to this thread, and was no end of help when I PM'ed him. Pretty much all the information to make a similar welder is in this thread. Even if you don't want a FET welder the information in this thread is massive. Get your self the autopager plugin for Firefox though, makes it much easier to search, which does become a problem with big threads like this.

 

[texaspyro]

The specs and numbers I'm quoting for the welder that I built are what is required for a welder than can do the job of making decent welds on anything more than small flashlight and coin cell type batteries. You need to design with those numbers in mind (scale them up or down to match your requirements). I did not just build a welder with some random parts and those specs fell out after the machine was built... the requirements were determined beforehand and a machine that could meet them was designed and built.

I'm not in the position to release the design because I know that that will elicit WAY more requests for assistance than I am able to provide at this time... just ask Fritz about what releasing a welder design unleashes (http://frikkieg.blogspot.com/). The people with the skills to build the welder without assistance could design and build their own. Those that don't, always need endless hand holding... I've already been down that road way too many times with other projects.

As far as suitable SCR part numbers, I just don't have any. SCRs that can handle 10000+ amp pulses are few and far between, and as I mentioned way back in this thread, SCR welders are rude and crude and socially unacceptable. They can be made to work, but I want real, consistent, controllable, reproducible, reliable welds... something that you won't get from an SCR welder. All the SCR's that I played with were surplus units with custom part numbers and no published specs. And they all made very satisfying BANGs vaporizing themselves when asked to weld heavy tabs onto he-man batteries.

 

[amberwolf]

The p/n on the one I have here (not yet built into a welder) is 034976 (0220 Italy), 175A 300V. It has an IR logo, but is a Miller welder part, so it may not be the IR p/n.

A search on similar body styles and ratings finds a 2N3887 by Powerex
http://html.alldatasheet.com/html-pdf/20551/POWEREX/2N3887/245/1/2N3887.html
but I think it's physically smaller than the one I have. IR doesn't seem to make SCRs anymore? Or I am totally missing them on their site.

The Powerex site shows a list of some high-current SCRs, but they only go up to maybe 5000A or so:
http://www.pwrx.com/Grids.aspx?g=140&m=25
a 600V 5000A version is only a bit over 14cm across and almost 3cm thick.
Everywhere I can actually find them for sale, there is no price, only an RFQ link, so they are probably so expensive individually you couldn't afford one, even if they would sell you just one.

I did about 10 minutes of googling for various SCRs, and looking at various manufacturers of them, and under 100A is fairly common. After that they get rare, and over 1000A there is almost nothing. I found zero over 5000A. I'm sure there are some, but you'd have to know where to look, apparently (and I'm usually fairly good at searching for things).

The one I have is larger diameter than a quarter for the body, wieghs a pound or two, with a threaded bolt-end that's larger than any of my hubmotor axles or the NuVinci axle. :lol: Almost as large a threaded section diameter as my Fusin's axle nut. Nto sure what gauge wire it has pre-mounted on the end, but it is as large as my pinky finger.

I haven't built my welder yet, but based on size and the prices found in a quick google search ($150-$300 and up) for just the low-end one I have, it would probably be a lot cheaper to use lots of paralleled FETs to do the job. If I didn't already have this one, that's probably what I would do, and if (when?) I blow this up, that's almost certainly what I *will* do. :lol:

 

[The Mighty Volt]

I just built a battery tab welder from plans at ledhacks.com. It uses two 2.2 farad capacitors firing through a thrystor. I just tried it for the first time and it doesn't have enough power to weld the tab. It will just barely stick. The capacitors are car stereo capacitors Did I make a mistake getting these capacitors or could something else be the problem??

99% of card audio caps are fradulent crapassators... Their true values are usually around 10-20% of what they are labeled as, and they have high ESRs. The only ones that I can recommend are Monster Cable and Rockford 1 farad caps. Also the Scosche 1F cap measures OK, but I have not used them much in welding. The Volfenhag ZX-3 and ZX-4 are usable. The ZX-3's are only 1.0F . The ZX-4's are 1.5F (not 4F) (avoid the other Volfenhags).

I use 4 Rockford 0.5 Farad caps with 1 Rockford 1F cap. Does the business. Its even welding cupro-nickel tab which is beautiful stuff, very soft and easy to work.

 

[fortisi876]

Totally uncalled for. This thread is possibly the best internet source of information on this subject. Texaspyro (I am guessing that's who you were digging at) may not be going open with his design but he has given masses of information to this thread, and was no end of help when I PM'ed him. Pretty much all the information to make a similar welder is in this thread. Even if you don't want a FET welder the information in this thread is massive. Get your self the autopager plugin for Firefox though, makes it much easier to search, which does become a problem with big threads like this.

Let me clear something up. My remark wasn't directed at any one person but more so what the entire thread has turned into. So I apologize if it came off rude but holy crap the entire process of trying to gather a material list has become frustrating because it doesn't really matter which forum you go to it's always the same thing, non answers. For whatever reason, this topic seems to only draw secretive types who enjoy showing off their fancy accomplishment all while tearing down the original purpose of the thread, making an affordable tab welder that a layman can build. Damn, some of you should be working at NASA not playing with FET tab welders.

It'd be like going to a DIY site, starting a thread asking for help on tiling your bathroom, including a list of intended tools and materials only to have people chime in and pick your list apart without really ever giving better examples of what works better and why. Then to boot, they show off their handy work! LOL!

In a nutshell, just about everything that was used a few yrs ago, with success, is pretty much useless today, NOT making my project any easier folks!
Rant over.

 

[texaspyro]

For welder use, the SCR current spec that you are interested in is the single-pulse current rating, no the continuous rating. The pulse rating is usually around 5-10 times the continuous rating.

 

[diaz]

If you want to weld and build a welder and save money all at the same time then be prepared that it might not turn out that way. For the time and money I have spent on my little project I could easy have bought a welder, especially one from China. But I like to tinker If you just want to weld then buy a welder (as you started asking), or farm the job out.

If you want to build then there is a ton of information out there:

If you can't find a big enough SCR then make one, image attached, and taken from here http://205.243.100.155/frames/shrinkergallery.html Will it work I don't know, might be to slow at the voltages we are using, just an idea, try it and let us know.

Quick eBay search lands me here http://www.ebay.co.uk/itm/250811161959 then Google lands me here http://www.galco.com/techdoc/wesb/n280ch_cp.pdf for a datasheet that suggests a none repetitive peak ability of 9000A ish.

There are lots of people doing very naughty things with silicon, see this page http://tesladownunder.com/CanCrushing.htm using an SCR bank as a reverse blocking diode. He managed to get 12.5 kA before popping them.

Look at posts early on in this thread by Jeremy Harris, he seemed to have success. Part numbers included.

Look at the link in the very first post.

Build a microwave transformer welder.

Build one like this http://www.imsolidstate.com/archives/590

If that's not enough to go on........

 

[texaspyro]

The main problem with honkin' big SCRs is that they usually come with a honkin' big price (even surplus)... more than a stack of FETs. Also mounting and hooking up to a hocky-puck SCR is a non-trivial task.

 

[diaz]

Granted, that SCR I found on eBay is the same price as my bank of MOSFETS cost me. Good argument for going the MOSFET route, check Jiri's page here http://www.pittnerovi.com/jiri/hobby/electronics/welder/ it works, and this link (a new one to me) http://www.turtlesarehere.com/html/cd_welder.html

(Really want an excuse to make a switch like the one I pictured above, (might also be a bit bouncy for welder work))