assuming this battery is 100AmHr at the 20Hr rate of 5amps
using 17-18 amps, 6hrs to total dead if inverter has extreme low voltage shut down, maybe 3.5 hrs to 11.x volts
TV won't use that much, neither will a fan
seems like you might be trying to use a small electric heater
now you have to recharge a dead battery, all day generator or engine run
NOT the best of ideas
good thing to ask questions first
you could try it one time 'at home' in driveway and find out for real then charge battery to full could take 2 days reach full charge zero amps
keeps us posted
