Hi all. We've been tenting for years and just bought a project popup this fall. The usual wood rot from leaks but overall a great deal for $200. We just too two back to back short trips this week. 1st had electric hookups and the second didn't. When on shore power, the centurion cs 1200 had power to 120v plugs and fridge and 12v lights and heater. Second trip run in off battery, we had no 120v power. Does the inverter only change 120 to 12v, or should it also convert 12v to 120v? Let's just say our first luxury let down was a non functioning Keurig. Thanks for the help!