Micro spot welder? For Battery packs.

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Well, I have 5 old 18V NiCad battery packs.  Only 1 is holding enough voltage.  Replacements are about $70 from Home Depot.Each has 15 cells in it.  I can buy a cell for a shade over $1 from Ebay (in quantity and reportidly better quality than factory - who knows for sure).So, I can solder a whole bunch batteries together, or, it seems the recommended way is spot welding.I have 4 welders and a couple big DC power supplies.  Can I build my own.  I'm thinking two tungsten electrodes - probably eacg in a TIG torch (so I can re-sharpen as necessary).The DIY people tend to use capacitors, going for low voltage, high current.  The seem to suggest short burst of current as high as 800Amps.  I personally doubt that.  Requires very low induction to get that.  So I'm thinking I can just use my TIG welder and acheive pretty much the same thing.  Set it up for DC stick etc.Can anyone comment on this?Might just give it a try.ThanksCon Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:I've built small (low current) packs using soldered tabs but wished I had a spot welder for bigger jobs.Try your ideas on some old cells first and see how hot they get.  Overheating rechargeable cells is a sure way to kill them.Many of the commercial battery spot welders seem to use two contacts less than 1/4 inch apart.  Hold the tab to the battery, then press the electrodes on the tab, then turn on the power very briefly.  The tab may have small holes melted in it, but the edges of the hole are permanently attached to the battery terminal.
Reply:Try to find cells with tabs already attached. Simpler to just solder the tabs together with eachother.