I'm having trouble soldering the battery pack to the fuse, the solder I have just beads up and falls off when I remove the heat. I'm not a soldering expert so I don't know if there are certain types of solder I should be using. Any help is appreciated.
You're soldering to the fuse? Why not get a fuse holder?
The solder probably isn't sticking because the fuse isn't hot enough. It takes a fairly powerful iron and some patience to solder to large pieces of metal.