The OBDII connector is a standard connection point to the battery on all new vehicles that will allow you to set the 5 watt panel on your dash and charge / maintain your vehicle battery from inside the vehicle.
My Honda Civic Si, like many vehicles, disconnects the DC auxiliary port (cigarette lighter port) from the battery when the car is off. This cable lets you hook your battery maintainer, in my case a small solar panel, through the OBDII port. This cable does the job. I have found it is a little tight on the port but so far it is making good contact.
I keep my Class B motorhome engine battery fully charged year round even though I don't drive it much in the winter. I use it on my other car also to top off the charge. It is great as a battery memory device when changing batteries. I like it so much that I made a You Tube video on how to use it: https://www.youtube.com/watch?v=Toq1e8UguEk
Easily connects to the OBD II port & connects to the Solar Battery panel. My vehicle is always ready to start. Worth the money.