I did that on a 22-inch VIZIO flatscreen with no problems.. The they went with 120VAC cords coming out of the TV and it was hard to find one with an external transformer Brick.
The alternative would be to just get a small power inverter to produce 120VAC PURE SINE wave power. The flatscreen wattage is low like between 50 and 75WATTS...
I run all of my OFF-ROAD POPUP electronics and other small wattage items with a 600WATT Power Inverter. I could very easy get away with a 300WATT Model but always like to have some extra power available if needed...
I always found something that I wanted to run from the Power Inverter everytime I turned around haha...
Roy Ken