Cleaning under the hood of the '05 roadster I discovered this wire and connector at the battery.
Red wire connected to the + and black wire to the - post. Not jury-rigged, there is a nut on both posts
specifically for this whatever-it-is. No inline fuse, just the male/female connector on the end.
Its too short to reach just about anything so apparently its just a tap on the battery, but for what?

 

That's a connector that was installed to hook up a battery tender (maintainer / charger).

 

Thanks. That makes sense. The original owner of this low mileage beauty left it in his Florida garage
for months at a time.

 

Often times that wire/connector is extended enough to get to it in the cowl area.
That way you can plug up the battery tender without having to open the hood.
( also handy if you make up another cord with a 12v LED trouble light )

 

Call me a prude BUT I would take that 12V wire off the battery terminal (after first taking the complete NEG cable off the battery) and put a fuse on the line going to the tender if you get one. If not, I would remove that set of wires by first removing the complete NEG cable off the battery. If anything touches that positive wire to ground it'll cause quite the spark, possibly hurt someone, and possibly ruin sensitive electronics. Just my experienced opinion (experience in preservation of self, others, and property).

 

SELF DESTRUCT WIRE ...GO AHEAD AND CUT IT