Small wire connected to positive battery terminal

[jcevans2]

I have a 1999 Explorer SOHC V6. There is a small wire connected to the positive battery cable at the terminal using an extra hex nut. What is this wire for?

 

[jcevans2]

I have a 1999 Explorer SOHC V6. There is a small wire connected to the positive battery cable at the terminal using an extra hex nut. What is this wire for?

I finally found what this wire is for - nothing. It seems a previous owner tried to do some wiring and started with a black wire from the positive battery terminal. It was routed through the firewall, under the seats and carpet, then spliced to a red wire somewhere along the way. The end was left exposed inside the plastic interior panel on the passenger side of the cargo area (below the window which happens to be leaky). There was also a yellow wire hooked around one blade of a fuse and jammed into the fuse panel. It followed the same path to the cargo area and was also left exposed inside the plastic interior panel. This seems very dangerous to me. I'm removing these wires.