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Old 27-01-2011, 11:25   #1
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12vdc Appliances

Dear Folks, my wife and I, after a bit of searching, are a couple of days away from becoming owners of a Cheoy Lee 42'. We are excited. We need to add a few items to the vessel since we will be living on her for several months per year. The items that we need are:

1. 19" diagonal flat panel HD TV with DVD player
2. microwave

We have read an article that stated that it is better to purchase 120 AC appliances as compared to 12 volt appliances. The reason given was that 12 volt appliances are not as ruggedly built as 120 AC appliances. Having no background on this subject I have no idea if this article is correct. I do know that using 120 AC appliances will engage the inverter with about a 10-20% energy loss while cruising. In any case, I want reliable appliances and if 120 AC is the way to go - - so be it. Many thanks, bill brown

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Old 27-01-2011, 11:45   #2
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Which design? I have a Cheoy Lee built, Bob Perry designed Golden Wave 42 which I love. Owned and cruised her for the past 20 years.

Re: appliances, I'd go with a 12V LCD if you can find one...the "more reliable" impreachment doesn't really apply to this type of "appliance". I have both on my boat: a 12VDC LCD TV for TV and videos, and a 120VAC LCD at the nav station for chart display (runs off my sine wave inverter which is usually on when I'm away from the dock). Most LCD monitors/TV run on low DC voltage anyway, and just have either internal or external power supplies to convert 120VAC to the needed DC voltage.

RE: the microwave, I'd get a standard 120VAC model. Lots more to choose from, and you'll only use the microwave sparingly anyway. The inverter should handle that nicely.



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Old 27-01-2011, 12:04   #3
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My ac microwave uses 100amps tru the inverter but as Bill says It si used only for short burts I do have the 12v tv much to chose from
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Old 27-01-2011, 12:54   #4
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My wife is addicted to watching old DVDs of Law and Order...The TV/DVD through the inverter uses more power each night than our 3 Kycera 135 watt solar panels produce during the day in the Carribbean! It may be due to the 3000 watt inverter.

However, the microwave never blips the energy curve.

"Remember, experience only means that you screw-up less often."
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Old 27-01-2011, 12:57   #5
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I have written too much in the past about the advantages, (amps wise) of avoiding the inverter's use when you can, they are SOO inefficient! BUT...

With a Microwave you just have to run the inverter, although we just don't use one while cruising, and never missed it.

As previously said, most modern electronics that have a wall socket "black box", are running on lower voltage DC anyway. The requirements are on the black box, as well as the TV, computer, printer, etc. If it is 12 or 13V DC you can run it directly off of the boat's 12V system and skip the black box that came with the TV. If it is say... 19V DC that the TV or computer unit uses, and the accompanying AC socket "black box" provides, rather than turn on the inverter, try this: Get a mobile / car power supply from mostly laptop computer catalogs. They have a cigarette lighter plug on one end of the wire, and if you order correctly, the perfect appliance "IN" plug on the other end. In the middle of the wire is a small box that boosts your boat's 12V DC to the 19V DC that your appliance uses. (there are hundreds of plug, amperage, and voltage combinations available) Get the right one! If it is more than about 3 amps draw, be sure that your lighter socket is rated for that, or hard wire it in. Also be sure that the polarity on both ends is correct. 99% are C = + on the appliance end plug, and their is a clear symbol that confirms this on the back of the appliance, usually next to the plug hole.

We have compared... to watch a movie using our small DC to AC inverter, running the flat screen TV with the black box, (that came with it), takes about 6 Amp/Hours. If I leave off the inverter and watch the same movie, directly off of the boat's system, with a 12V DC to 19V DC booster cord, it only consumes 3 Amp/Hours! It's a nobrainer...

In both houses and ESPECIALLY boats, money spent on clever ways to conserve energy is many times over cheaper than money spent on producing more energy. We use The above power supply practice, built a a small 2 cu/ft fridge with vacuum panel insulation, fluorescent or LED lighting, etc, and run it 100% on our solar panels, because we get by on about 40 amp/hours a day. This was expensive, but in the long run, when you figure in the alternatives, like a larger less reliable alternator, extra diesel, shorter engine life from running it to charge batteries, etc the conservation route just makes more sense. At least from my point of view...

Hope this helps, Mark
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Old 27-01-2011, 12:59   #6
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The flat panel screens are DC. Most used to have the brick power supply which is easy to convert to running off ships power. Newer TV's have gone to internal power conversion which is a problem for all but the most technically skilled. Look for a tv with a brick power supply that converts 110 to 12v DC. All you have to do is cut the brick off and run the wires to a chosen DC power source. There may be issues with voltage so wouldn't run the tv while the engine is running and charging the batteries.

Inverters have pretty high losses converting DC to AC except when the draw is near their max rated output. A low drain item like a TV run off a 1500 watt inverter will be wasting a lot of energy. Don't know how efficient the smaller inverters are but cheap doesn't usually transfer into high efficiency or quality. Might want to do a bit of research into real life current draw of the inverter you chose at low loads. From experience know that the claims of efficiency for inverters don't translate to real world.
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Old 27-01-2011, 13:11   #7
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In the case of a microwave oven, I don’t think you can avoid the inverter, because the magnetron in a microwave needs ±1200V, obtained from a transformer in AC models, or an internal inverter in DC units.

Old style CRT televisions also require a high voltage supply to the flyback coil, though new LCD models probably don’t.
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Old 27-01-2011, 13:12   #8

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the 'black box' thing that plugs into the wall is nothing more then an transformer/inverter...

it is usually referred to a low voltage appliance transformer, or a 'wall wart'....
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Old 04-02-2011, 11:18   #9
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Check out a truck stop. May seem a strange place to get apliances, but they have most kitchen appliances available in 12 volt. They have toasters, small ovens, TVs DVD players and they are all compact so they are easy to store. Though I have heard that the 12 volt coffee makers are so slow that you are better off boiling water and using a pour through filter. Heck my local Pilot even has a 12 volt pizza oven. They are much cheaper than the ones you get at the marine stores, and likely the same ones as they basically are all disposable cheap stuff. Same as the 110 volt stuff. I don't see most 110 volt stuff as being dependable at all unless you spend a lot of money. Almost all LCD TVs are made in just a few factories, and different labels thrown on them.
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Old 04-02-2011, 11:38   #10
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Originally Posted by bill brown View Post
if 120 AC is the way to go - - so be it
120 is not the way to go -- 230 is. Half the current for the same power, smaller wires, less heating.

But seriously, as others have said, the microwave works perfectly off the inverter. Inverters are perfect for things used intermittently.

As others have said, the native voltage of most LCD TVs is 12v. Just find one with a separate wall wart, chop it off, wire it up directly. That way you won't be incurring the power overhead of the inverter for hours at a time.
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Old 04-02-2011, 12:21   #11
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Seems to me most new common flat panel TVs (in the US) have the AC to DC circuit in the tv itself. The AC cord going in the back of the TV like typical.

CVS Pharmacy in the US has a Craig brand DC TV. Two sizes, 13 and ? inches, $150 and $200. It's HDTV but sorta dumpy looking. Probably what would be found in the truck stops as well.

However, based on a single line tip from a member here, Target has a nice Visio LED flat panel that is 12v. I did a Google map search for the nearest store and headed over to look. I looked at the smaller Visio's and found one that was DC input to the back of the TV. It was a good looking 19 inch model that was easy to spot with the "brick" laying behind it and a white cord to the TV. For $200 dollars I couldn't resist, it's on my boat now.

The new M series LED TVs, model number M190MV. The brick output is 3.85 amps at 12V. I suppose real world current draw would be somewhat less.

If 19 inches is big enough I think you would like it.
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Old 04-02-2011, 12:24   #12
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not a transformer/inverter,
it's a transformer/rectifier/regulator.
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Old 04-02-2011, 12:27   #13

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thank you...

I stand technically corrected again...
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Old 04-02-2011, 13:26   #14
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There other sites like this one:

Buy 12 Volt Color LCD TV's - 12 Volt Refrigerators - 12 Volt Appliances - Trucker GPS Supplies & Accessories
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Old 04-02-2011, 14:28   #15
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Several choices there with DVD built in. I missed that requirement by the OP.

I wonder why the models with DVD commonly come from lesser known manufacturers. Not saying they are of lower quality, with VGA, HDMI, 1080p, etc, they seem to be up to date with a good price, too.

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