The Edsyn will work. Didn't we just have a thread
on soldering to batteries?

Yes. But I like to double-check.

Maybe that was on a.h.r. Clean surfaces. Scuff with
sandpaper. Use liquid flux. Crank Edsyn up to 800F.
Tin wire. Tin battery. Use more flux and reflow wire
to battery.

Pretty much what I thought. Thanks.