I noticed with my screw-on tips, they didn't transfer heat that well. Then I saw somewhere that you need to use pliers to really screw them on there. After trying this, it seemed to help a lot with heating. Scoob, if you have screw-on tips, you might want to try using some pliers and tighten it down for better contact and heat transfer. Make sure you don't over-do-it, else you might strip the threads. Just tight enough so you can't easily unscrew it with your fingers.
macfjej, like I said before, I have that exact soldering iron. It has worked fine for me and will probably work fine for you. I do, however, suggest at least a 60w iron for soldering batterys together so it will melt the solder faster and not heat up the battery. I just had to take my batteries to my LHS to get them soldered, but I may just get a stronger iron next time because one of the cells blew up after a few runs:035: and I don't want to blame them, but I think it was due to incorrect soldering. I think you can get a pretty cheap 60w iron from Tower Hobbies for about $6.
Clicky!
Good Luck,
Brijar!!!