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Old 03-29-2003, 11:31 PM   #1
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Question Voltage Inverters

I wonder if I could get some advice on voltage inverters? Is there an inverter available that has minimal inefficiency (power loss to heat). I want to power a tv/vcr combo when dry camping, and have only found AC/DC units available in 9" screens. I would like a 13" unit, which would require use of an inverter. Or is the whole inverter approach a "battery burner" no matter what?

Thanks in advance.

Mike Costanzo
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Old 03-30-2003, 01:32 AM   #2
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Inverters

The efficiency of any device is based on .............money. With an increase in investment, quality and power are increased. The sine wave units cost more than common inverters. Inverter size should be decided by power needed.......now and the future. Used units work as well as new units. There is a load comparison between battery load and ac output. The battery must output 10 times the ac draw. If a device requires 10 amps at 120 volts ac, then the load on a battery will be 100amps at 12volts dc. Important factors for inverters is intended load and battery bank capacity. For our Airstream, we use a 2kw and have a 1.5kw spare unit. Some times the refer is powered by the inverter. There are also 3 solar panel that provide 36amps at 13 volts in the direct sunlite. Using an inverter for just a tv, check the tv power in watts, and buy as required....
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Old 03-30-2003, 06:24 AM   #3
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12 volt tv

mike

welcome to the forum,

here is a thread i started a while back about tv's.

http://www.airforums.com/forum...ght=12+volt+tv

john
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Old 03-30-2003, 07:41 AM   #4
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we bought our 13" Broksonic tv/vcr ac/dc on ebay last year from the distributor who sells excess poduct. Just over 100 dollars.
I also got a Jensen inverter 300watt 2 input , on there for 20 bucks, I use it when on the road and not using the generator, for my kids video game console, or lap tops. Works great.
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Old 03-30-2003, 08:23 AM   #5
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Wal-Mart, Auto Zone....

carry the Vector line of inverters. I bought a nice 400 watt/800 watt peak for $59 last year. I think they dropped the price on that one to $49. They have larger and smaller sizes available.
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Old 03-30-2003, 09:24 AM   #6
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First, we've pretty much decided against bothering to have VCR capability in the trailer. Today, that's almost to the point of taking along a record player for vinyl albums.

So far, the best 12V capable DVD player we've found is the Phillips DVD580MT sold at Target. You have to buy a 12V cord for it at Radio Shack, etc. It can be mounted horizontal or vertical, and is a slot rather than tray load. It's the only 12V player I've found that has component video outputs in addition to the others. Most just have composite video, but a few have S-Video.

The little Phillips 9" TV we have draws an average of .25A at 120VAC. To translate that to 12V battery power, multiply the current by 10, then divide that by inverter efficiency, i.e. .85 which comes out to about 2.9A at 12V. I use a homemade outlet box with a multimeter that reads up to 10A DC, to determine appliance loads.

One might assume it only needs a .25 X 120 = 30A inverter, but that would be wrong. The degaussing coil, not very large in a 9" TV, takes more than that at startup, however, it happens too quickly to measure.

You have to be careful with inverters. For example, the 12V plug on the Winegard antenna panel is only rated at 8A, meaning about the most inverter you'd want to continuously support at rated output from there is 110W. I've read where Winegard says melting the panel with greater load is a common problem. There's nothing wrong with using a larger inverter, such as a 200W not putting out more than about 100W, but I'd probably want to fuse it at 8-10A (that circuit is on a 20A breaker in our trailer).

We're probably gonna wind up with a 15" LCD TV that works off 12V. But we're still gonna need an inverter for the satellite receiver, which draws about .11A continously and as much as .17A when searching for a signal.

Hope this helps!
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Old 03-30-2003, 11:34 PM   #7
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Thanks to all of you for your thoughtful replies. I now have a much clearer idea of what will suit my needs. I must say that this forum is remarkable. I belong to two others (for one of my cars and my motorcycle) and I've never seen a more engaged, commited, and knowledgeable community.

Mike
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Old 03-31-2003, 08:46 AM   #8
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one additional comment on the vcr. My tv/vcr gets a lot of use, we still own many tapes and tape movies and shows for the road. I also bought an inexpensive DVD player from Walmart, the Apex brand, and I plug it into the TV when we want to watch the DVD's. Its small enough to stow ina a cabinet.
Total cost 150 for tv/vcr/dvd and ac/dc. Add 20 for the inverter if we need to use that.
By the way I love my record albums too- I have a great 1970 turntable and 300-400 rockin and jazzin' lps.
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Old 03-31-2003, 11:17 AM   #9
 
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Weakness of TV/VCR combos

We had been taking on the road a simple small TV. We considered next season taking along a 9" TV/VCR combo that we owned: the other day it died (very little use). The VCR does not want to stop ejecting an inexisting tape.

Had inherited a bigger one. A few weeks after: without warning it developed a different but similar non stop dance with the VCR. ( one day will open both of them and try to fix them)

We looked at a lot of reviews and discussions about TV & VCR before buying a new unit.
Result: we bought a TV & a VCR. More money, but when the VCR dies, you still have a TV. The readings we did pointed that this was a serious concern about combos, and talking to repair outfits confirmed it.
We now will use this small TV and a good Panasonic VCR, very light, we found in a thriftshop for $25: it seemed not to want to read tapes and we couln't clean the head. Just opend it and cleaned with alcohol. Best buy I ever found. It looked like it had never been used ($300 new 5 years ago)
What I read led me to believe that the VCR in a combo is not as well made as a separate VCR. At least in combos under $200.
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Old 08-01-2006, 09:51 AM   #10
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still having trouble with this

I have the Sony 19" LCD TV as included in the entertainment package from AS. I see if it is rated too high I could melt the Winegard 12 volt plug (higher than 8a) I also read I need a pure sinewave. Now with that in mind can someone give me a recommendation as to a particular inverter I could purchase? In other words, while you can try to teach me the science and math, and I will really try to understand it, I would love for someone to say, "get this." I haven't "got" it yet, in my head or in my trailer so if I am ever to watch tv without shore power, I need help! I have stood before the various units and asked questions at the stores, but in the end I don't want to risk either the outlet or the lcd so I have passed them by.
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Old 08-01-2006, 11:22 AM   #11
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Quote:
Originally Posted by wheel interested
I have the Sony 19" LCD TV as included in the entertainment package from AS. I see if it is rated too high I could melt the Winegard 12 volt plug (higher than 8a) I also read I need a pure sinewave. Now with that in mind can someone give me a recommendation as to a particular inverter I could purchase? In other words, while you can try to teach me the science and math, and I will really try to understand it, I would love for someone to say, "get this." I haven't "got" it yet, in my head or in my trailer so if I am ever to watch tv without shore power, I need help! I have stood before the various units and asked questions at the stores, but in the end I don't want to risk either the outlet or the lcd so I have passed them by.
Hi Carol,

Most pure sine wave inverters retail for about $1/watt. They start at around $250 for a 300 watt model and go up to the stratosphere! The typical rule of thumb is to get an inverter with double the capacity that you need, so you need to figure the requirements of your TV/Stereo and anything else that you want to run and then double it to cover the start-up power surge.

If you need a 600 watt inverter, it will draw 50 amps for each hour of operation. You then have to figure how long you will be using the inverter to calculate the amp-hours that the batteries will need to produce, keeping in mind that you should not draw down a deep cycle battery much past 50%.

Say that you will watch TV for 2 hours and the TV/VCR will use 300 watts. Divide this number by 12 (volts) to get 25 amps/hour. The batteries will need to have 25 X 2 hours or 50amp-hour capacity X 2 or a minimum of 100 amp-hour capacity.

Just be sure that your equipment requires a pure sine wave inverter. A lot of stuff will work on a modified sine inverter, which are way cheaper.
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Old 08-01-2006, 11:30 AM   #12
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I am not for positive about this but I thought I found out somewhere that I need 95 range for the monitor, don't know if that is misinformation, and don't know if the energy saving feature would help.

I know the draw will be steep, but considered flicking it on for news or a short time while on the road. Maybe it's better I don't have one. I will try to see what the 2 24s 1/2 discharge would add up to.

I definitely want to get 2 27 AGMs and a new converter and a battery monitor eventually.
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Old 08-01-2006, 11:37 PM   #13
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Quote:
Originally Posted by wheel interested
I am not for positive about this but I thought I found out somewhere that I need 95 range for the monitor, don't know if that is misinformation, and don't know if the energy saving feature would help.

I know the draw will be steep, but considered flicking it on for news or a short time while on the road. Maybe it's better I don't have one. I will try to see what the 2 24s 1/2 discharge would add up to.

I definitely want to get 2 27 AGMs and a new converter and a battery monitor eventually.
Carol,

Look into the Lifeline 6 volt AGM golf cart batteries. They have a HUGE reserve of amp-hours compared to the gp24 or gp27's. 2 in series will give you the 12 volts that you need.
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