Re: 12 Volt of 120 Volt TV
The size of the inverter has nothing to do with the current draw. If you only had a 50W load on it, a 100W inverter and a 300W inverter would be drawing the same current from the battery. Just because the inverter is 300W doesn't mean its drawing 300W when your load is lower.
I don't believe I did imply that it would, but it has to do with what it could be used for by the wattage rating of each.
For the OP use it wouldn't be feasible for the usage of an inverter.
It would be easier to just get a 12v TV for his/her use.
BTW, try using a 100w inverter on a laptop and see if it'll fire up and for how long
Then try a 300w inverter and see the difference, if you don't believe it matters, I have, it matters..
Along with the size of battery, wiring used and fuze rating required.
Most battery backup units for computers will only give about 20 minutes of power max with the small battery supplied with those units, they all use a form of an inverter to supply 110v of power.
It gets more complicated from there for inverters. And none are advisable for use on a boat for an add-on..