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TropicGuy · 04-02-2010, 10:25 PM

I am going to add a Television in the bedroom area. From what I have read, it seems a 12v unit is the best choice. Or is it? I am wondering how long you can realistically power a 19" LCD TV from the batteries. It seems almost like the two balance out in the end. If I wanted to watch the tv couldnt I get an inverter? I have read several posts here on the forums, and have googled 12V Televisions. The selection is not very good. And they are pricey for what you get. What is the current general consensus on this?

bryanl · 04-03-2010, 09:09 AM

Consider that the efficiency of an inverter runs about 90% and, if wired properly, nearly makes up for that in line losses in many cases. Contrast that to the nominal battery variations of 10% or more from factors such as temperature, cycle to cycle variation, use profile, and other things.

What will get you is the continuous drain at rather significant levels. For instance, watching a DVD movie in the evening requires the energy from about 50 pounds of battery (500 watt hours).

The fact is that you just can't get much battery energy storage in a TT. Worrying about a few percent here or there is like using a tin cup to prevent the Titanic from sinking - may make you feel good but isn't going to make much difference in the final result.

OB Bambi · 04-03-2010, 09:44 AM

I have written about this before in other threads...I bought a Polaroid 19" television with DVD player from Target. It runs on 12 volts. It works great, doesn't use much juice (I've never done any scientific experiments on this) and it cost me $329 about two years ago. I think they have come down in price since then.

Randy Bowman

TropicGuy · 04-03-2010, 06:00 PM

Randy thanks for the reply. If I can buy it at walk in retail then thats a little different. I will check out that tip. I searched all over the forums and for some reason I never saw your post so thanks for re-pointing it out! What is the model number of your Polaroid tv? Target does not carry them anymore but I thought I would search around and see who does.

Jim Foster · 04-03-2010, 07:19 PM

We sometimes watch TV from bed while dry camping. We use a 350 watt inverter to power our 22" Vizio flat panel TV. We set the sleep timer to prevent the TV from running all night and taking down the batteries. The inverter will continue to run, but it draws very little when not running something.

A 12v TV sounds like a good idea, however, I would get one with a sleep timer, otherwise, if you fall asleep, you may run your batteries down overnight.

Not to say you will fall asleep watching TV from bed, just because we always do.

OB Bambi · 04-04-2010, 02:37 PM

The Polaroid TV is Model # TDX-01930B

It is: 19" HD LCD, TV?/DVD Combo

The thing that makes this work in the Airstream is: The television came with a in-line transformer very much like the transformer for my laptop. (Three prong plug into the wall-120v. and 12 volt coming out of the transformer to the television). As it turned out I didn't even use the transformer...I bought a connector plug and a cigarette lighter plug from Radio Shack and used it directly. That way I use the trailer batteries directly without a invertor running using power just to run. I take it that Target doesn't carry this unit anymore. It seems like I saw one at Walmart about a year ago that was, I think, another brand but a 12volt unit.

I hope that the photo shows below. It is the transformer and how it plugs in to the television.

Randy

TropicGuy · 04-04-2010, 04:27 PM

No kidding. I was moving an LCD monitor this morning, and it suddenly dawned on me that maybe MANY TV's can be DC powered, and alot of the smaller ones have this "brick" that you show above. I cant believe it took me this long to realize this.
Thanks!

eharv · 04-04-2010, 04:51 PM

Randy and you are correct. Many of the smaller TV's are DC powered and have a "brick" for AC power. I just recently purchased a new Vizio 23". They make a 19" for under $200 (at Sams Club).
I would also suggest that you consider the new LED LCD TV's. The picture is powered by LED's which use much less electricity. The two Vizio's that I mentioned above are LED LCD TV's.
Good luck.

AirsDream · 04-04-2010, 05:32 PM

Quote:

Originally Posted by bryanl

For instance, watching a DVD movie in the evening requires the energy from about 50 pounds of battery (500 watt hours).

Well, not quite. The Polaroid unit I have (discussed in this thread) draws 55W max. (and of course, it's not drawing at max. rate unless the screenis at full brightness all the time and the sound is all the way up to clipping all the time!), but assuming it's run that way ... a 120 minute movie would run 110 Watt hours, and at 12 Volts, that's less than 10 amp hours ... on a sunny day, I get more than that out of my solar panels in an hour.

Or did I miss something in EE 101?

OB Bambi · 04-04-2010, 07:07 PM

http://www.airforums.com/forums/f450...-up-61942.html

I hope this helps you.

Randy

bryanl · 04-05-2010, 10:37 AM

re: "Well, not quite." -- yeah, that's rather typical in these discussions, start nitpicking a generality as if it means anything.

If you really want to go this direction, why not get one or two of those DVD players they have for kids in the backseat? They aren't expensive and can run on their own batteries. Then you can leave all lights off (even LED's or flourescents) and save a bit more. Then you can shut down the furnace and the fridge and alarms and whatever else and save a bit more. Then you can make sure that you only watch 90 minute movies and so on.

It is always possible to adapt to the limitations and constraints of an RV off grid and figuring out the best way is often a personal preference matter.

re: " Or did I miss something in EE 101?" -- what they don't teach in EE 101 is client relationships and the problems encountered in figuring out the real problem in real world situations for arbitrary clients who aren't really sure what they are asking for. (another thing rarely found in the entire EE curriculum is lead acid battery technology and how use involves available energy capacity, which are major factors in this consideration)

What I tried to provide was based on real world experience in trying to help a number of folks who get rather surprised by low batteries in the morning.

Pardon the snark, but sometimes it gets really frustrating trying to get across that idea one person's experience and choice is not necessarily the same as another's.

BTW: the 'LED' hype these days is about the backlight and not the LCD. The TV is basically the same except that it uses LED's rather than cold cathode fluorescents as the light source to shine through the LCD to create the picture. This might or might not make a difference in power efficiency depending upon compromises in the TV design. The backlight is the major power hog in TV's which is why smaller (and/or darker) screens often use significantly less power.

GetOutDoors · 04-05-2010, 12:10 PM

I bought one of these . . . JENSEN LCD TVs

They are built for the temp swings and vibration of RV's.

TropicGuy · 04-08-2010, 06:13 PM

bryanl you are correct on every point in your post. I havent seen any studies that prove or disprove the LED is more power efficient than CC, however I would think the LED would run much hotter, which may or may not be a good thing. My quest was to get the "right" tv, and not a piece of junk. I think I can get a high quality tv with an external ac power supply, connect it to the 12V rail, and that way I can get a good tv and not break the bank. Im hoping Samsung will have one that will fit the bill

snake · 05-17-2010, 08:59 AM

I just replaced an analog 14" LCD TV with a digital (Insignia brand from Best Buy) 19" HD LED TV. Both units have 12 volt converters and will run directly on 12 volt DC.

The new LED TV cost $199 plus they offered a 4 year warranty for $24, (plus tax, of course, for our poor State) I don't normally pay for extended warranties, but considering the vibration and temperature extremes in the travel trailer I thought it was a good investment.

I did a test using both TV's on 110 volt AC and a Kill-A-Watt meter. The 14" LCD consumed about 35 watts, compared with 23 watts for the 19" LED TV.

That's pretty impressive, 23 watts is about 2 amps at 12 volts, at that rate you could run the TV all day and night before discharging a normal 100 AH battery 50%!

AirsDream · 05-17-2010, 09:15 AM

That sounds about right. And so watching a DVD movie, assuming you also hook up a DVD player, will NOT consume "the energy from about 50 pounds of battery (500 watt hours." Enjoy.

snake · 05-17-2010, 11:10 AM

I use a portable Sony DVD player when I watch movies, it will run for hours on it's own battery with the screen turned off and just providing signal to the trailer's television.

I can recharge it when I'm driving around in the Tow Vehicle.

tfmkevin · 05-17-2010, 08:03 PM

I researched this quite a bit, and ended up buying two of these 22" Skyworth 12V flat screens (from Roadtrucker.com... I know, I know, but they gave VERY good service)

22" (21.6") Skyworth 12 Volt TV DVD Combo Digital Tuner SLC-2269A

They have a fantastic picture - HDTV with up to 1080p, lots of inputs, built-in DVD, run on 12V (or 120V) and have a very flexible supply requirement - they can operate down to 10.1V DC. That means that even when the rest of your trailer is rolling over in its last death rattle of power starvation, you can still be enjoying the latest episode of "Cash Cab".

The power draw is very low - even with DVD operation. I haven't measured it yet, but plan to soon.

This is the largest-screen 12V TV I've found, the lowest power consumption, and the most forgiving supply requirement.

bryanl · 05-18-2010, 07:57 AM

re: "will NOT consume "the energy from about 50 pounds of battery (500 watt hours." -- interesting how this rule of thumb tends to irk some folks (and how they handle their ire). Perhaps that is why so many just lurk and don't offer their experience or insight.

Nobody is contesting the idea that you can squeeze your energy consumption or that you can spend a lot of capital to reduce your consumption or increase your input.

It is sad that a general guideline that has proven useful in helping folks avoid the dreaded 'dead battery in the morning' syndrome seems to be something to attack rather than to understand.

Another component in this is the high precision psuedo engineering being done. That also seems common when it comes to off grid energy planning. The real world is a bit more complicated and less predictable than some are trying to convince themselves, I think. Available battery capacity has a wide variance over such variables as temperature, age, use patterns, and cycle to cycle variances. Use of energy is not restricted to just one particular well defined set of devices.

It might well explain why so many have to learn via experience no matter their 'engineering.' That tends to have a high cost and often leads to disappointments in unrealized expectations. The mind is a wonderful thing, though, and can often set aside the unpleasant memories.

A hint for those trying to reduce monitor power consumption: turn down the brightness as far as you can. With a bit of imagination (as much as thinking 1080 resolution makes a difference with small monitors), you can really turn down the power consumption.

TouringDan · 09-28-2010, 07:00 AM

To All:

I think that I may have stumbled across the perfect small TV for small RV's. It is a Vizio M220MV. It has the following features:

22", 1080p, 41 watts, 12v dc or 120v ac with power cord, LED lighting, 2.37" thick, 7.6 lbs., one year warranty, 2 HDMI connections, $248 at Sams. I like

the fact that it can be connected directly to a 12v dc power source. I plan to purchase a 12v portable dvd player for watching movies.

I used a VideoSecu Wall mount ($25 at Amazon) and secure it for travel using a couple of small bungee cords (see photos). This is a nice wall mount and works well.

Here is the url for the photos:http://picasaweb.google.com/adventur...ioTradewindTV#

Here is the link to the photos:

Lumatic · 09-28-2010, 07:31 AM

I had a few 12v combo units and the dvd mechanics didn't last. I now have a Sharp which is a better made unit but 110 only and works great on shore power or my Honda eu 2000. The Sharp draws 60 watts. I have a generic 400 watt modified sine wave inverter. It won't run my TV but will run a 100 watt light bulb. Anybody know why not?