I turned up a special hammer head tip (see the post above) for my Weller WES50 soldering station to solder F size (D on steroids) NiMH cells end to end. It worked really well and I am happy with the results. My iron was set to around 780 degrees F. The tip, being made from uncoated copper, would have to be thoroughly cleaned, quite often, as resin and oxidation took over and insulated the end pads. This worked well for applying the battery tabs too. It does hold a good deal of heat.
Each battery pole was lightly roughed up with a fine grit drum on a dremel tool, and then cleaned with isopropyl alcohol prior to tinning. After each solder joint, I would rapidly cool the cell with compressed air to minimize the chances of over heating them.