was looking for the source of some whining/hissing noise I’ve began to notice after removing my stock air box cover one day just to inspect , and honestly I some how noticed this wire connected to my battery that I’ve seen to never notice before . Had the car about 3 months drove it about 3k miles no problems I just never noticed this wire..

 

looks like a connector for a battery charger

 

It allows you to easily connect a battery tender without removing the battery from the car. The cable running from the battery tender has a connector that plugs into the connector on the cable connected to the battery. The cable connected to your battery is just missing the cap that covers the connector when not in use.

Battery Tender connector cable

 

I can keep the battery topped off and still close the hood and have the car covered. I use the paint stir stick as a reminder not to drive away with the charger connected. I leave the stick on the drivers seat so I cannot miss it.

 

...and it uses a trailer hitch connector. So if you have a different charger, you can easily adapt it to this cable attached to your battery. You can buy a trailer hitch connector from any auto parts store or Amazon.

 

The cable from the battery tender is thin enough that I route it up through the front inside of the passenger door (my battery tender sits on the floor near where yours is located) and then underneath the front fender near the windshield. I like the reminder stick.

 

I just close the hood but dont fully latch it.

 

My variation on the: “Remove Before Flight” flags.

 

That’s what I figured from a pilot. My brother was a pilot in the Air Force and for American Airlines.