Many of the newer LED tvs I've seen in the stores the past year actually run on 12V. Internally, they all run on 12V or less with the only difference being whether the manufacturer decides to build the power supply into the unit or have a separate wall wart power supply. Units with an internal converter (110AC to 12VDC) require UL approval but if the unit takes 12VDC, only the wall wart needs approval, a potential cost savings. This also removes the AC power supply from the cabinet, reducing internal heat, the bane of electronics.
I'd shop around for an LED tv that uses a separate wall wart power supply. Verify that it's 12V out and all you'll need is a cord with a matching plug or you could use my solution. I cut the power cord and install polarized connectors (PowerPole) on the cut ends then make up another patch cord to connect to a battery or cigarette lighter socket. I now have a choice of pwoer sources for the tv.