Spot welding question.

Seen a video the other day of someone spot welding tabs on Nicad batteries to put them in a battery pack. Is there any way to make a welder into a spot welder??? I have a 200DX TIG All I could see in the video was they had 2 insulated copper rods the size of a pencil that they would make the spot welds with. I am guessing using a foot pedal. Maybe the TIG with custom leads.

Ideas where to start. Might be able to dig up some copper rods and get a couple extra cables for the 200DX. AC or DC polarity???

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Originally Posted by Brian Ski

Seen a video the other day of someone spot welding tabs on Nicad batteries to put them in a battery pack. Is there any way to make a welder into a spot welder??? I have a 200DX TIG All I could see in the video was they had 2 insulated copper rods the size of a pencil that they would make the spot welds with. I am guessing using a foot pedal. Maybe the TIG with custom leads.

Ideas where to start. Might be able to dig up some copper rods and get a couple extra cables for the 200DX. AC or DC polarity???

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Plenty of people have made them from microwave oven transformers, running AC, so that would work, not sure what the commercial units use. Having a spot timer would be ideal, but you could make that part up, yourself. Just connect it to the torch switch pins. You can find a bunch of how to guides on the web and places to buy the battery tabs. I have a stack of old batteries that I want to re-cell, so that project is also on my list. However, I am not sure I will ever get to it...

I'm curious about that myself. I have a bunch of 18650 li-ion cells I need to put tabs on.

Looks like the current required is a bit more than what a normal TIG welder will do. Probably best just to make a complete unit.

http://www.avdweb.nl/tech-tips/spot-welder.html

Another option is to use DC and a capacitive discharge type welder. That you could charge with a TIG power supply, but that is overkill, and a much lower DC supply would do the job.

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Originally Posted by Rambozo

Looks like the current required is a bit more than what a normal TIG welder will do. Probably best just to make a complete unit.

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Not sure on his numbers... 1100 amps may be to spot weld thick metal.

I found this one on Ebay 221464732210 made for batteries. 100 amp max and for batteries it said about 25-29 amps. Still hate to drop $150 for something that may be used a few times.

A couple new battery packs are going to cost me $90 a pop. Depends on what I can get new batteries for. I found a place that had some brand new bastard battery packs for $3 a piece. (they fit some really odd stuff) I think they had a dozen new batteries in them. Pretty good price!!!

Ya know,,, you don't have to spot weld them...

I routinely solder those tabs ;)

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Originally Posted by Blaster

Ya know,,, you don't have to spot weld them...

I routinely solder those tabs ;)

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I worry about putting too much heat into my batteries. What's your method ?

Big Iron, good thin solder (Kester), and be QUICK ;)

I've been doing this for a very long time, started in the electric RC (planes,cars,boats) hobby. I've done a lot of it, never had a problem...

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Originally Posted by Blaster

Big Iron, good thin solder (Kester), and be QUICK ;)

I've been doing this for a very long time, started in the electric RC (planes,cars,boats) hobby. I've done a lot of it, never had a problem...

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What size iron are you using ?

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Originally Posted by Blaster

Ya know,,, you don't have to spot weld them...

I routinely solder those tabs ;)

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Yea I have done that before. They are not as secure and if you use a wire to solder them they don't lay as flat. Plus you use a lower heat for a lot longer time. I never had a problem either, but heard they can explode. The Lithium ion batteries are a lot more dangerous to solder. When you are soldering a dozen batteries together, never fails I get a weak connection in one of them.

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Originally Posted by zoama

What size iron are you using ?

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Just like 40W on the soldering station...

And again, I've done this 100's of times, I never buy "Battery Packs", just assemble them into packs and haven't ever found any problems with connections. If there are no Tabs at all, just bare cells, I use copper "solder wick" for the bridge connections.

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Originally Posted by Blaster

Just like 40W on the soldering station...

And again, I've done this 100's of times, I never buy "Battery Packs", just assemble them into packs and haven't ever found any problems with connections. If there are no Tabs at all, just bare cells, I use copper "solder wick" for the bridge connections.

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Have you done this on 18650 cells ?

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Originally Posted by zoama

Have you done this on 16850 cells ?

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Iv'e soldered plenty if Ni-Cd and NiMH packs and while I've never measured it exactly, I feel it shortens the life of the cells. Very hard to quantify since there is an extreme range of cell performance anyway. Then there is the whole time/temp debate. I tried one Li-Ion pack, and found that it self discharged at a rate over double what a new pack did. That was a pair of 16850s running with a Ti controller chip. Again even though I was using the same brand of cells, it was not the same lot, and as all the Li-Ion battery recalls can attest to, even the major manufacturers like SONY can get it wrong from time to time. A lot depends on the application, too. Some things need long shelf life while others just need high current output. Big difference between an RC car, a cell phone, and a watch. I figured I would just put that project on hold until I made the right tool for the job.

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Originally Posted by zoama

Have you done this on 18650 cells ?

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Sure, many times.

Here's what I do;

Tin all the ends first quickly (40w iron, "scratching" and that really thin Kester flux core). This is the most heat the cell sees and I don't think it's enough to make any difference....

Go back to the first end you tinned, it's cool now, and place a "blob" of solder (be sure it wets). This takes very little heat & time as the tinned surface so readily accepts the new solder.

Go back to the first one you blobbed, put the wick on top of the solder. Then heat the wick from the top until it wets & sinks in. Again, takes just a second.

Cut the wick a tiny bit Long to bridge to the next cell and finish the series connections. The nice thing about using the braid is that you can now align the cells and it will flatten-out as they are tightened together. Then, once positioned properly, run the iron with the solder in front of it over the braid to fill & stiffen them.

I really don't believe I've effected the integrity of any of the cells, but as Rambozo says, it would be difficult to quantify that exactly ;)

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Originally Posted by Blaster

Tin all the ends first quickly (40w iron, "scratching" and that really thin Kester flux core). This is the most heat the cell sees and I don't think it's enough to make any difference....

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Maybe I have had older batteries. I have been soldering for decades, but I could not get a good connection to the battery with solder. Maybe need to rough the surface or maybe the nicads I was using had stainless ends. Sometimes it would hit right off, other times a lot of heat and no solder flow.

Every try the lithium quarter batteries???

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Originally Posted by Brian Ski

Maybe I have had older batteries. I have been soldering for decades, but I could not get a good connection to the battery with solder. Maybe need to rough the surface or maybe the nicads I was using had stainless ends. Sometimes it would hit right off, other times a lot of heat and no solder flow.

Every try the lithium quarter batteries???

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I think it's all about the solder....

I learned about soldering from HeathKit stuff (like the Large 27" color console TV ;)) and they always supplied the solder. When I used anything else it never worked as well. That's why I specified Kester 66 (thin, like .040). Also I specified "scratching". I learned this from getting solder to stick to steel. I found out about Tinning Fluid and how, on bare steel, you use a steel brush and a torch to get the liquid solder to adhere.

On batteries I don't use tinning fluid, just the good Kester, then take the flattest side of the iron and "work" in on the steel ends by Scratching with the iron with some downforce. It works!

And yes, those button batteries, the 3032's for memory back-up in many electronic boards, I put leads on them too :D

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Originally Posted by Blaster

I think it's all about the solder....

I learned about soldering from HeathKit stuff (like the Large 27" color console TV ;)) and they always supplied the solder. When I used anything else it never worked as well. That's why I specified Kester 66 (thin, like .040). Also I specified "scratching". I learned this from getting solder to stick to steel. I found out about Tinning Fluid and how, on bare steel, you use a steel brush and a torch to get the liquid solder to adhere.

On batteries I don't use tinning fluid, just the good Kester, then take the flattest side of the iron and "work" in on the steel ends by Scratching with the iron with some downforce. It works!

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Sounds like both of us have been around for a while. I always use a decent electrical solder. One of my first major projects was a LNW80 expansion interface for the TRS-80 model I. Still have it packed up in the garage. I was one of the guy on the internet before there was one. Old BBS systems.

Back to the topic, sounds like a neat idea to use the solder wick. I have used stranded wire before but it left the batteries a little taller and they did not fit into the pack as well.

I do have most of the stuff to try the spot welding so I will give it a try when I get the chance.

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Originally Posted by Brian Ski

Sounds like both of us have been around for a while. I always use a decent electrical solder. One of my first major projects was a LNW80 expansion interface for the TRS-80 model I. Still have it packed up in the garage. I was one of the guy on the internet before there was one. Old BBS systems.

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So, was that the little cigarette pack size box on the ribbon cable, between the CPU & Keyboard, that doubled the RAM by adding another 2K :D

Compuserve, TheSource, I was there too ...

My buddies and I broke Apple][ sw and traded it all over the place, calling ourselves "Mr.Xerox"

I had a TRS-80 16k extended basic.

I recall piggy-backing RAM and soldering a wire to an address line on all the chips to gain some more memory on my Model I. Also, the first BBS I wrote for my Model I, I recall buzzing a relay when someone wanted to chat since it had no sound, just a cassette to backup programs. And all on floppy disc.

Had a tymnet engine also when I worked for the GOV, was on the internet before it was the internet as well.