One solenoid stud terminal is connected by a large wire directly to battery "+" and the other goes to the starter motor. The battery side is a common place to pick up power for electrical stuff. Some models get the main fuse power from there. It should never be used to connect to anything except a fuse, or to long wires leading around the bike even if they lead to a fuse. I've worked on many bikes with melted and burned wiring from unfused wiring that shorted to ground somewhere.