On Mon, 02 Jan 2006 12:07:02 -0500, Joseph Gwinn
wrote:

In article ,
Don Foreman wrote:

On Sun, 1 Jan 2006 22:21:57 -0600, "Ron Moore"
wrote:

I was thinking of the welder mech that is used to link batteries into packs.
Don't know why I was thinking that. I'm sorry, I not sure what you were
referring to that is not DC output, unless it is the resistance welder and
not the charger.

Right, it's the resistance soldering device, soldering guns and
otherwise. The Wassco I mentioned is also AC. Capacitive discharge
DC works great for spotwelding batteries.

Gunner has mentioned soldering heavy wires by pressing a 250-watt gun
(sans tip) up against the splice and pulling the trigger, using the
current to heat the wires. I've never tried that, but it sounds
neat. The tip on a 250 watt gun is a few inches of about 1/8"
square copper and it get real hot right quick.

I recently measured the voltage across the tip of my 250-watt Wen
soldering gun - it's 0.175 volts rms or so (starts lower, then rises as
the copper tip heats and increases in resistance). To achieve the
stated 250 watts, the current will be 250/0.175= 1,429 amps. This could
almost be used for spot welding (where 4,000 amps is more common), and
the resulting magnetic field can pick up small pieces of iron (~50
grams).

For the record, the Wen Soldering Gun (Model 250, bought in 1963)
consists of a big AC power transformer with a one-turn secondary made of
3/8 inch brass rod. The open-circuit voltage (with tip removed) is
0.275 volts rms, for 118.9 volts rms in, so the transformer winding
ratio is 435:1. The gun was manufactured under US patents 2,701,835 and
2,680,187. Go to http://www.pat2pdf.org/ to get copies.

The Weller soldering gun is almost identical, although the tip of the
Wen is instead made of 0.164" diameter (~AWG #6) plated round copper
wire.

Joe Gwinn

Joe is right. I'd assumed 1.5 volts because it illuminates the
little penlight bulbs, but my measurement just now agrees with Joe's.
They must have another winding for the light bulbs.

Thanks, Joe!

Rather than buy a battery charger, I suggest the two courses most
likely to work a

1: Dan Caster's suggestion of putting a new secondary on a
discarded microwave oven. If the size and weight aren't a problem,
that would certainly work. (Be sure to strip the high voltage
secondary off completely. ) Make that 1 or 2 turn secondary out of
insulated heavy braid or copper strip, or several (half a dozen)
bits of #12 copper wire in parallel.

2: buy two or three HF soldering guns at $9.99 each, connect them in
series. 0.175 volts may not be enough to push much current thru thin
brass.

Neither of these courses will cost half as much as the battery
charger, and both are much more likely to work.