Not enough info. The only "12 volt outlet" that is remotely standard is the lighter socket in a car. Most if not all cars have the negative side of the battery at ground, which is the outer shell of a lighter socket. So the center contact is positive. If you are asking about any other 12 volt outlet, you need to check it out with a meter, or get a diagram for the system.
The 12V auxiliary power outlet used to be called a cigarette lighter with a covering device that could get hot enough to light a cigarette. Since smoking is no longer popular, the lighter was replaced with a plastic cover and it was renamed a "12V auxiliary power outlet".You can plug 12v devices into it for power such as search lights phone chargers etc
1st - check clip underdash on reverse side of outlet 2nd - check fuse underhood - top left corner under plastic moldings
The owners manual list fuse numbers: 1. Power Outlet (Front) 16. Power Outlet (Rear) 31. Cigar Lighter
The 2014 Infiniti QX80 is 6 ft. 7.9 in. (79.9 in.)12V front, 12V rear and 12V cargo area power outlet(s) wide.
drill hole in dashboard, install outlet in hole, and run two wires to the battery
The 2013 Audi TTS is 6 ft. 0.5 in. (72.5 in.)12V front power outlet(s) wide.
The 2012 Audi TT is 6 ft. 0.5 in. (72.5 in.)12V front power outlet(s) wide.
The 2010 Audi TTS is 6 ft. 0.5 in. (72.5 in.)12V front power outlet(s) wide.
The 2009 Audi TT is 6 ft. 0.5 in. (72.5 in.)12V front power outlet(s) wide.
The 2011 Audi TT is 6 ft. 0.5 in. (72.5 in.)12V front power outlet(s) wide.
The 2007 BMW X3 is 6 ft. 1 in. (73 in.)12V front, 12V rear and 12V cargo area power outlet(s) wide.
The 2012 Toyota Sequoia is 6 ft. 7.9 in. (79.9 in.)12V front, 12V rear and 12V cargo area power outlet(s) wide.