110V vs 12V Appliance Usage - Pros & Cons

[Sky_Boss]

OK...I have an open question for discussion...

I am reading a lot about 12V devices such as TVs and such. From a power management standpoint, is there a reason to prefer 12V devices over 110V devices?

What factors should be considered when making that choice?

Does boon docking dictate leaning in one direction or another?

Do inverter/convert/solar charger configurations come into play? (I assume more and bigger batteries and use of lower power lights (LEDs) will always help. LOL)

I suppose my purpose it to decide whether I need to look into my true needs for my expected uses. I currently don't see us spending a lot of time boon docking but at the same time, we want to have systems to support overnight boon docking such as in Walmart lots.

I would suppose that the end state would be to have the ability to run fans, lights, TV-satellite-audio equipment, and such for a night. Obviously AC would not fit into that equation.

The floor is open.

[Ramblin]

This is a topic that interests me as well. I will soon embark on a project to replace my old CRT TV's with flat panels. I intend to use 12V models because I want to be able to run them while boondocking and not have to run my genny or use an inverter.

My thinking is, there has to be lots of inefficiency in the conversion from 12V to 120V, then back to 12V internally in the TV. I have no supporting data, but common sense seems to indicate that 1 hour of TV watching will cost more (from a DC consumption point of view) if I invert it to 120V than if I just use a 12V TV and power it directly.

I boondock about 1/2 the time. If I never boondocked, I'd have a different view. If I always had shore power, everything 120V would be the ticket, I would think.

[daveshan]

Any time you convert power you have a loss so using a device that operates at your native 12v would give longer battery life than using an inverter to power a device that draws the same wattage but uses 120v and requires you to use an inverter to power it.

That being said I bought the TVs I wanted (32" & 22") and will live with the small loss. Smaller items are run off of a small inverter so the big one can stay off.

[John Hilley]

For the most part, if you have an inverter you don't need 12 volt appliances. Most of them are inferior to 120 ac appliances or are a lot more expensive. I use 12 volt chargers for cell phones, Nook, Kindle and notebook computers. Every thing else runs off the inverter. If you plan on running off the inverter while camped with out shore power, you will have to add to your battery capacity and charge with either solar, generator or both. going down the road, you can use the inverter with 120 volt devices with out depleting the battery as the alternator can provide the necessary power.

[BryanL]

re: "there has to be lots of inefficiency in the conversion from 12V to 120V, then back to 12V internally in the TV"

Many electronic doodads use a 12v power feed that they then convert to 5v or whatever their circuits need.

The conversion efficiency in modern switching power supplies is really rather good (90% or so).

Wiring efficiency is another factor to consider. Upping the voltage by a factor of ten reduces power loss in the wiring by a factor of a hundred (one tenth the current and the wiring power loss is by current squared).

Another factor is power regulation and cleanliness. I have been worried that my 12v TV was not equipped for the sort of power an RV low voltage system provides but, so far, it seems able to handle it. A device designed to be powered by a 12v power brick may not have the power conditioning circuits or input component tolerances to handle RV charging voltages or line spikes due to such things as pumps and fans on the line.

I think John also has a point. There is a lot more available for 110VAC than for 12VDC so you have more options about quality, style, and capability to suit your needs.

Your batteries are rated for a draw of about a watt per pound (the 20 hour capacity specification). Loads larger than this (such as for larger inverters) need special attention to wiring and connections to the battery. Also note that you only have about 12 watt hours per pound that you should use from your batteries - they don't store much energy so it is easy to run them down.

[Midniteoyl]

The solar guys claim 15%-20% loss during each conversion..

And dont forget the internal ac to dc conversion already taking place inside stereos and tv's .

[BryanL]

Homepower magazine did a look at Off-Grid Inverter Efficiency that would be a good resource for someone looking to figure out what is best for them.

A lot depends upon matching your inverter to your load and only having it on when you need it.

If you check the top ten, you'll see the peak efficiency for all of them is about 98% -- that gives you an idea of what can be done.

Many solar, off grid applications tend to use the inverter as their only power source so it is on all the time. That tends to emphasize the idle power draw of the inverter and lowers overall average effective efficiency. They also tend to size the inverter for peak loads yet run them most of the time at a small percentage of their capacity. That also reduces efficiency.

This topic can get into the weeds in a big hurry because power factor, inverter output waveform, load consistency, input lead impedance and all sorts of nifty technical stuff can come up.

[clyon51]

Lots of info here for you to digest. Rather than adding or agreeing, I'll just tell what I did and how it worked out.

Upgraded CRTs to LEDs. You'll find most LEDs are actually 12vdc with a 110v WART. I cut the WARTS off and directly wired the TVs to 12v. Don't have and don't want a DVR. If I did, I would have got a 12v or got the TVs with them built in.

Upgraded all interior lights to LED, including flouresents with LED strip lights. Probably not relevent, but Clare uses a CPAP (Came as 110v with WART), so just got 12v cord.

We don't dry camp much, usually just enroute to our destination. I have 2 6v GC batteries (Trojan T 105s) under my steps too.

While in Fl this spring, I un-pluged the converter/charger just to know how I could do. Warm but not hot enough for AC, so ran Fantastic vent fan most of the day. Clare used CPAP 8 hrs at night, watched TV about 5 hrs a day. Normal water pump use as well as lights.

After 55 hrs, batteries were at 12.0 volts...which is my limit...about 50% discharged. In the morning I ran the genny 10mins for coffee. If Clare needed the micro, genny again for 10 mins or so. I did and still have a small portable inverter I use for the computer.

The bottom line for us and our RV use, we have NO need for a large inverter. I did replace a factory solar panel with a 20 watt...useless in Mich even for batt maintenance. If I do any more upgrades to elec, I'd put up 200 watt or so solar panels.

Maybe for you, maybe not, just passing on real world experience.

[Ramblin]

Originally Posted by clyon51

Lots of info here for you to digest. Rather than adding or agreeing, I'll just tell what I did and how it worked out.

<snip lots of great info>

Maybe for you, maybe not, just passing on real world experience.

Thanks for that. I have a very similar coach to yours, and very similar goals. I just put two new GC batteries under my steps and so, after I upgrade my TVs and my lights (also on my list) I should be able to get similar results. Thanks again.

[JimM68]

Our rig has 2 U2200's, and a 2000 watt inverter. Without a heating or cooling load, 24 hours is easy, with zero effort in conservation, running the tv's, satelite, icemaker, lighting, no problem.

[clyon51]

[QUOTE="Ramblin"]

Thanks for that. I have a very similar coach to yours, and very similar goals. I just put two new GC batteries under my steps and 9so, after I upgrade my TVs and my lights (also on my list) I should be able to get similar results. Thanks again./QUOTE]

Hey you'er welcome Ramblin! I generally would rather report real world experience that what I've read or or heard, or what I've read on some website someplace

Hey, it all depends on individual goals and needs.

[jspande]

I'll add one thing to CYLON's list (I've mentioned it before but it's worth repeating).

With LED or LCD TVs, you can usually improve picture quality and save power (up to around 50% as I recall) at the same time by simply adjusting the video settings, primarily contrast and brightness. They're typically set way too high initially to "grab" customers in the store.

Do a Google search for your make and model (and the word "calibrate") and you may be able to find recommended settings, otherwise just reduce contrast and brightness to minimum that you're happy with.

[JC2]

Originally Posted by jspande

I'll add one thing to CYLON's list (I've mentioned it before but it's worth repeating).

With LED or LCD TVs, you can usually improve picture quality and save power (up to around 50% as I recall) at the same time by simply adjusting the video settings, primarily contrast and brightness. They're typically set way too high initially to "grab" customers in the store.

Do a Google search for your make and model (and the word "calibrate") and you may be able to find recommended settings, otherwise just reduce contrast and brightness to minimum that you're happy with.

One thing worth mentioning also is that most TV's in a store will have been set to demo mode which will result in a brighter video screen that you mentioned. Most setups will allow the end user to reset this to normal mode" which is not as bright.

[clyon51]

One more thing I should have clarified, I chose LED over LCD TVs because they are lighter, run cooler and use less electricity. Actually the only difference in the two is how they are backlit. LCD uses floresent and LEDs uses, well I'll ya guess that one

LED use 90% less elec than CRT and 40% less than LCD. LCDs may also not be 12v.