newbie inverter question - Event Date: 15 Nov 2015

Thanks again to everyone that offered replies and explanations!  I have learned a lot from this discussion and appreciate the expertise in this forum.  I feel like I can make an informed decision on what will be right for my situation.  

+1

My original reason to post was “Rockin the Pod” asked should he replace his TV with a 12 volt one or buy and inverter. My choice is to buy a TV that will run on 12 volt DC because of the requirement to run a inverter you need 11 amps of DC to make 1 amp of AC. I went out and measured the current to run my TV to get the actual numbers. On the back of the TV it says Power Supply 12V, 3A, 24W and on the AC Adapter it has input 100-240 VAC 50/60 hz, 1.8 A, Output 12 VDC-3 amps. So at 24 watts that is 2 amps of DC to run the TV. The actual measurements, using a current clamp, was with the TV on battery power it drew .72 amps, with a DVD playing it drew .98 amps (.98A x 12.7V = 12.5 watts). (Turns out to be much lower than the manufacture says). The measurements with the 120 AC adapter with the TV running the current measurement was .11 amps and with a DVD playing .15 amps (.15A x 120V = 18 W). The difference in wattage between the DC and AC I think is because the AC Adapter is a small inverter. So if I wanted to play a DVD and run the TV thru an inverter it would draw from the battery .15 amps x 11 = 1.65 amps. If I ran it with just the battery it’s only drawing 1 amp.

The one thing that I find kind of interesting is that my combo radio/dvd/cd player and my HD antenna amplifier all run on 12 volts.  Wonder why they put a 120 Volt tv in.  Scratching my head a little bit on that one.

Originally posted by JandL The measurements with the 120 AC adapter with the TV running the current measurement was .11 amps and with a DVD playing .15 amps (.15A x 120V = 18 W). The difference in wattage between the DC and AC I think is because the AC Adapter is a small inverter. So if I wanted to play a DVD and run the TV thru an inverter it would draw from the battery .15 amps x 11 = 1.65 amps. If I ran it with just the battery it’s only drawing 1 amp.

I was with you until the last sentence. I'm not sure where the number 11 came from. The 18 watts seems reasonabe at 120V. Producing that from 12V with an 80% efficient inverter would take

18/0.8/12 = 1.875A

That said, the 12V TV is still the best option.