Happy New Years to everyone!
What a way to spend New Years Eve....
Most people would consider the way I spent the last five hours a waste of a New Years Eve, but I'm pretty satisfied, nonetheless.
Sorry Nemo, but I beat you to welding copper, aluminum and several other metals, (including a few kind of exotic ones
) with a homebuilt Capacitive Discharge welder.
Ok, Here's the setup I used:
The Tab Welder II ( http://www.ledhacks.com/power/tab_welder%20ii.htm
) '5F audio cap at 14.5V
in parallel with the higher voltage welder ( http://www.ledhacks.com/power/higher%20V%20welder.htm
with the reed switch near the negative electrode (as described up above a few posts
) to activate the SCR of the 30V 432,000uF 'real' caps.
All the welds above are what I'd call 'serviceable' ; some aren't quite as good as I would like, but should hold up under normal use.
On the ones that look like copper on 'non'-copper metals; That is residue from the electrodes that 'burned off' the tips.
It is just too hot for 'pure' copper electrodes... I think with Cr-Cu or Zr-Cu or maybe Tungsten electrodes, things will work a lot better.
If you are planning to weld batteries using copper tabbing material with a homebuilt welder, it would be wise to use .008 to .012 inch thick strip. I had no luck at all welding .024 thick copper to anything; The .016 inch thick stuff produces marginal strength welds at 30V with the 'pure' copper electrodes (although at 40V with better electrodes it would probably work, OK, I'm guessing.)
and the .004 copper is pretty flimsy, although it will weld nicely to steel at 22V, rather than 30V.
Watch the pressure on the tips of your electrodes!! The higher the voltage, the more pressure you need. 15 to 20 pounds on each electrode seems to be about right for around 30V.
I darn near burned a hole all the way through the copper coin above when I got a little careless and only had a couple of pounds pressure on the electrode.
Another thing I noticed... Using Fechter's idea of the ferrite 'C' around the reed switch makes the second pulse happen lots faster than just taping or gluing the reed switch to the welding cable. I can no longer actually feel the second pulse.. (That's probably
a GOOD thing... More in line with the milliseconds delay on Pro dual pulse welders.