Portable power source as inverter

[garbonz]

Originally Posted by Kaadk

I haven't worked the numbers so you might be right. I just know that there's inherently loss whenever you do conversions. I always try to minimize the number of conversions if I can.

Looking up those Jensen's, I agree. They are expensive. I wasn't referring to something like that. I was thinking more along the lines of a regular 12v TV, like you'd find for tailgating. Not one marketed for RV's specifically.

I have not seen any cheapish 12 volt TV in the 27-32 in size I was looking for, so I got a Samsung. It doesn't seem to draw much power. Many of us are stuck with the stock 110 volt units that come with the camper, and would have to switch them out.

If you know of a $200 32 in 12volt TV, I'd would have bought it, but I would still need the inverter for the blueray player and soundbar so it would have changed things.

[Rmack]

Originally Posted by Kaadk

Why not just get a 12v TV? This is the way I'd go if I ever did dry camping.

Inverters might sound like a good idea, but I'd only use them for things that must use AC. You're going to use more power converting from DC to AC back to DC (in the TV) then you would directly providing DC to a TV that can take it.

I hear ya, but I have a pretty small trailer, and I'm pretty much maxed out on carrying any large-ish devices.

And, I need all of my other three components powered by 110 to get any channels. I suppose the 12v TV would have some sort of antenna, right? Even if I could hook it up to my trailer's antenna, I seldom get many, if any channels with that where I camp.

[Rmack]

I've been doing more research on this subject, and someone made a suggestion.

I can't believe I didn't think of this before. Apparently, I can buy a small inverter, say a 400 watt unit, that has a 12v cigarette lighter-type plug on it. I could just plug this unit in the 12v near my TV, and run my four devices off of it.

The only down side is it would be a fair distance from the batteries, as my TV is about three quarters of the length of my 22' trailer away from the front where the batteries are, and I understand that is undesirable. Anyone know how big of a problem this would be?

There is a 12v receptacle that is closer to the front -say one third back- and I could us that one and run a short 110 extension cord. Would this be worth it?

I only want the capability to watch a couple hours of TV or so at night when I can't run my generators.

[Kaadk]

Well, that plug should be coming off the distro panel, so it's more a matter of how far from there then it is from the batteries. Unless it's for some reason wired directly that I don't know.

Either way, the line loss should be minimal. Like I've said before, I'd be more worried about conversion loss, but even that would be minimal.

There's two ways to look at this.

1) Scrimp and save on every electron and maximize your boondock time before you need to recharge.
2) Don't care, I'd rather have connivence.

Myself? I would fall under category #1. Except that I don't boondock. The wife won't camp without AC. If I did though I'd be here, trying to get through a weekend on batteries on a single charge.

Most people fall under #2. They have generators to recharge, so they don't need to be misers.

For those people, I wouldn't bother analyzing too much at first and go with trial and error. Go pick up a cheap inverter (I got one at XS Cargo for like $40 bucks back in '03) and try it out. If it gets you through a movie, great. Now you can consider a permanent install. Maybe pick one up a little larger, look for better features, better warranty, etc...

If it doesn't work, you should be able to figure out what it'll take to get you there. Do you need to cut back on how much you're running? Do you need a larger inverter? These kinds of things should identify themselves once you've tried it out.

PS. No, I don't know where to get a cheap 12v 32". I haven't needed to look. If I did, I'd be going with something smaller anyways, depending on what I can find at the local car audio shop.

[Rmack]

Originally Posted by Kaadk

Well, that plug should be coming off the distro panel, so it's more a matter of how far from there then it is from the batteries. Unless it's for some reason wired directly that I don't know.

Oh.

Well, It's right across the trailer from the distribution center, If it's where I think it is. Fuses and circuit breakers, right?

Originally Posted by Kaadk

Either way, the line loss should be minimal. Like I've said before, I'd be more worried about conversion loss, but even that would be minimal.

As long as it's minimal, I can live with it. The bottom line is how long can I go on a full charge.

I think I could extend the time by plugging one of my four devices, most likely the one with the least power requirment, into my Power Dome. Should give me a little more time.

Originally Posted by Kaadk

There's two ways to look at this.

1) Scrimp and save on every electron and maximize your boondock time before you need to recharge.
2) Don't care, I'd rather have connivence.

I'm definitely a two. There are enough chores to RV'ing already. If I can just pull off a couple of hours or so at night with the gennies off, and still run the furnace all night, I'll be happy.

And, if I can get a 12v plug, and don't have to monkey around with the wiring, that's a big plus.

[RPAspey]

Originally Posted by Rmack

I've been doing more research on this subject, and someone made a suggestion.

I can't believe I didn't think of this before. Apparently, I can buy a small inverter, say a 400 watt unit, that has a 12v cigarette lighter-type plug on it. I could just plug this unit in the 12v near my TV, and run my four devices off of it.

The only down side is it would be a fair distance from the batteries, as my TV is about three quarters of the length of my 22' trailer away from the front where the batteries are, and I understand that is undesirable. Anyone know how big of a problem this would be?

There is a 12v receptacle that is closer to the front -say one third back- and I could us that one and run a short 110 extension cord. Would this be worth it?

I only want the capability to watch a couple hours of TV or so at night when I can't run my generators.

....there might be some problems. Most 12v outlets are only good for a few amps... better check yours. I tried the lighter plug. Once. The plug and outlet got hot after a 2 hour movie.

Next, if you use even part of that 400 watts, say 200 watts, you'll be pulling a lot of amps, that would be around 16 amps. The voltage loss from the batteries will be pretty big even at 15' of #12 wire, which would be nearly 6%. Better inverters have a low voltage cutoff that could be around 10.5 volts. At 6% loss that's like starting with 11.5 volts.

Those cheap inverters won't likely be a pure sine wave. If so, you will likely have noise/grain problems with the image and sound. Been there done that, my pure sine wave really made a difference.

Anyway, there will also be a noisy fan that will likely irritate you as well especially during a quiet scene in a movie. You'd be surprised how loud a fan the size of a silver dollar gets in a quiet trailer.

Please listen the advice from people who've been where you are now, you'll save money and time.


2000 Cherokee, LEDs, solar, inverter, etc. '07 Tundra 5.7L DC-LB, modded as well.

[garbonz]

Originally Posted by RPAspey

....there might be some problems. Most 12v outlets are only good for a few amps... better check yours. I tried the lighter plug. Once. The plug and outlet got hot after a 2 hour movie.

Next, if you use even part of that 400 watts, say 200 watts, you'll be pulling a lot of amps, that would be around 16 amps. The voltage loss from the batteries will be pretty big even at 15' of #12 wire, which would be nearly 6%. Better inverters have a low voltage cutoff that could be around 10.5 volts. At 6% loss that's like starting with 11.5 volts.

Those cheap inverters won't likely be a pure sine wave. If so, you will likely have noise/grain problems with the image and sound. Been there done that, my pure sine wave really made a difference.

Anyway, there will also be a noisy fan that will likely irritate you as well especially during a quiet scene in a movie. You'd be surprised how loud a fan the size of a silver dollar gets in a quiet trailer.

Please listen the advice from people who've been where you are now, you'll save money and time.


2000 Cherokee, LEDs, solar, inverter, etc. '07 Tundra 5.7L DC-LB, modded as well.

32in Samsung TV - 33 watts AC
32in Jensen 12 volt - 90w (7.5 amps) DC
Sony blueray player - 5 watts AC
Phillips sound bar - 20 watts AC

Total AC watts = 60 watts AC which is .5 amps AC or about 5 amps (not including the inverter conversion efficiency) In my application this system uses 7.1 amps of DC running the TV, DVD and Soundbar.

The 12 volt TV gets you NOWHERE and is $700 bucks.

The Samsung is $350 plus a 200 watt inverter (PSW) for $80.

You can check your cigarette lighter and they make some that are better than others and may carry 7 amps for a long time...

Priceless

[Rmack]

Originally Posted by garbonz

32in Samsung TV - 33 watts AC
32in Jensen 12 volt - 90w (7.5 amps) DC
Sony blueray player - 5 watts AC
Phillips sound bar - 20 watts AC

Total AC watts = 60 watts AC which is .5 amps AC or about 5 amps (not including the inverter conversion efficiency) In my application this system uses 7.1 amps of DC running the TV, DVD and Soundbar.

A 32" Samsung TV only draws 33 watts, huh? I wonder how much my other three componts need;

Direct TV receiver, one of the latest, able to record five channels at once in HD

Winegard 'Traveler' auto satellite dish. (the electric motors might be rather power-hungry, but stop after the dish is aligned.)

Direct TV 'SWM' system that allows my receiver to work with the sat dish

Originally Posted by garbonz

The 12 volt TV gets you NOWHERE and is $700 bucks.

The Samsung is $350 plus a 200 watt inverter (PSW) for $80.

You can check your cigarette lighter and they make some that are better than others and may carry 7 amps for a long time...

I'm clear on the PSW inverter only, but how do you tell the better ones, price?

Here's another question for you gurus; Does it make any difference if the inverter is just within it's wattage limits, or is it more efficient in any way to have a little overkill.