12V to 120V Inverter/Changer or solar... my brain hurts

[John Ayers]

First... here is my build thread. http://www.mikenchell.com/forums/viewtopic.php?p=815156#815156 It has the necessary calculations for the questions I'm asking. Second, I've not finished my electrical diagram because I hit a wall and need to see around it to finish. Third, I've wired residential houses, but never anything like this so talk slow it might take a few mins but I'll catch it at some point.

OK, So I'm looking at inverters. The reason it easy... I'm not getting a converter. I see no reason to. My lights are 12V LED's and have transformers with them and everything else has bigger draws... I thought it would be simpler and cheaper to just wire everything of a 120V inverter.

But then I saw an inverter/charger. Looks cool, but it's no longer available from Norther Tool. I know I want to pull a wire from my car's alternator to the battery's to charge while running... but I'm not certain if the inverter will switch to shore power automatically or if there are switches needed. And this one had a charger to start charging batteries when shore power is available.

Is the 'all in one' idea best or separate components better? I usually think separate because WHEN something fails your not totally screwed, only half screwed... but how do you guys do your inverters? How are switches from shore power to battery handled, and how about chargers... separate or built in.

Lastly, there are TONS of new solar products replacing inverters right now. They don't do stepped charging but are "trickle" and that does not sound good for my 'El-Cheap-O' brand battery, but would a solar kit be fine if the switches from shore power to battery are expensive or just plane difficult. The solar options bug me because you need a 15AMP panel and that's just pricy...

I'm just about to spend money and having second thoughts about how to best do this. Just need some reinforcement.

Thanks!

[Lgboro]

I've got all of the above sitting around and nothing installed yet ao I'm sure I'm no help.... . I do intend to wire mine for all possibilities since I have them at hand.

[John Ayers]

I've got all of the above sitting around and nothing installed yet ao I'm sure I'm no help.... . I do intend to wire mine for all possibilities since I have them at hand.

Nice! Let me know how things go

[bdosborn]

Is there a reason you don't want a 12V system? You'll pay a big efficiency penalty going 120V. A lightly loaded inverter is less than 80% efficient. Converting from 120V to 12V is even worse if you use little wall warts to do it. You could be wasting half your battery power in voltage conversions. Inverter/chargers are real spendy as well.

Here's a link to an electrical sticky with a basic trailer wiring diagram. It has fuse and wire sizes so its pretty easy to follow.

Trailer Wiring Diagram

You'd get a lot better battery life if you went with a 12V system. Finally, don't worry about a solar system *yet*, get your basic electrical system figured out first. PV systems are really easy, you can design it in later after you get your basic system figured out.

Bruce

[John Ayers]

Hu?
Well... I was not honestly aware that I could run my fridge on a 12V system... or the TV or DVD player. I thought that would have to be 120V... and like electricity I was trying to follow the path of least resistance. I looked at the link, and I can run the lights and fans on a 12V converter/charger... but won't I still need the 120V inverter to run the three power hogs?

[GuitarPhotog]

You may well not be able to run your fridge, TV, or DVD player on 12 VDC, but there are 12 VDC units available. And converting the appliance end might be cheaper and more energy efficient in the end.

For what it's worth, the Tin Tent uses 12 VDC throughout, with no 120 VAC, unless it's plugged into shore power. It's not an uncommon configuration for a small trailer.

<Chas>

[Ratkity]

Hu?
Well... I was not honestly aware that I could run my fridge on a 12V system... or the TV or DVD player. I thought that would have to be 120V... and like electricity I was trying to follow the path of least resistance. I looked at the link, and I can run the lights and fans on a 12V converter/charger... but won't I still need the 120V inverter to run the three power hogs?

I have a 12v/120AC 13" HDTV TV/DVD combo in my tear that I ordered through Target. It doesn't use any more voltage than my fantastic fan. I only use it to check weather (if my fractal hdtv antenna picks up any stations) or to watch a movie at night if I'm too keyed up to sleep. You can check out several tv and dvd combos (or separate 12v systems) if you look at a lot of trucker RV appliance websites. Just keep in mind that truckers run with a big bank of batteries! I'd never try to run a frig or AC off batteries unless I had something else supplementing the power (generator, solar or 120 AC).

Good luck on whatever you decide to do! These folks here know their stuff.

Hugs,
Ratkity

edit: spelling

[Wimperdink]

How I did it suggestion....

http://www.mikenchell.com/forums/viewtopic.php?p=466525#466525

if your tv/dvd is 120v a/c then my method will only operate that and the refridgerator while plugged into shore power but all 12v will work plugged in or not.


You could still run an inverter for your fridge & tv but those things will kill your battery pretty fast no matter how you look at it.

[Engineer Guy]

I've lived 'The Good Life' on +12 VDC in this new House I wired - before it was Grid wired - and in a Tuff Shed and in an Avion 'Land Yacht' Trailer. Anything you want is out there, especially from the off-Grid, Alt Energy folks. Trucker Sites are another good resource, although some things like +12 VDC Coffee Pots get 'so so' Reviews.

We're about to fire up a nice lil new/used TT I picked up, and it'll be geared to Boondocking off-Grid. My initial mods will be to add a few Terminal Blocks for ease of adding 'things', and upgrade some key Wire Gauge sizes. K.I.S.S.. There's nice Fuse Blocks out there, and even nifty Circuit Breakers that fit into Auto Fuse Blade form factors.

My $0.02 worth is to go +12 VDC and get out there first and 'do it'. Then, you'll see what you REALLY need to go 120 VAC for. Likely, little or nothing. I got by Boondocking in my SUV with a 400 Watt 120 VAC Inverter [your actual size may vary!] used occasionally. When I ran the SUV Engine VERY occasionally, I used an Outlet Strip to multi-task and charge every 120 VAC gadget I had.

I'm also cutting over to powering 'stuff' off of +5 VDC USB where possible. The newest protocol is to be able to draw up to 1 Amp via USB, and it'll really cut down on my Adapters and Cordage laying about. A Cig Lighter-style +12 VDC -> +5 VDC Receptacle is at Wally World for cheap. +6 VDC Radios using 4 x 1.5 VDC Batteries will typically run from USB just fine, and so on. There's even USB-based 1.5 VDC Battery Chargers. Me, I like the USB-powered, Desktop 'Hula Girl' available on one Website!

The 12 Volt Side Of Life

Roadtrucker Catalog

Real Goods

USB Accessories Search Results

Cobra 400 Watt Inverter -> Amazon

[bdosborn]

but won't I still need the 120V inverter to run the three power hogs?

Unfortunately, you'll probably only be able to run your 120V fridge for around 6 hours or so off your single battery. That's why most people run a 12V system and don't use an electric refrigerator; it takes too much battery to support a 120V fridge. No fridge and 12V loads is more efficient and will give you longer run times off the battery before you have to recharge.

Do a search on Engle or Waeco if you really want an electric fridge. They make super efficient 12V models but hold on to your hat when you see the price; they're expensive.

Bruce

[bdosborn]

but won't I still need the 120V inverter to run the three power hogs?

Unfortunately, you'll probably only be able to run your 120V fridge for around 6 hours or so off your single battery. That's why most people run a 12V system and don't use an electric refrigerator; it takes too much battery to support a 120V fridge. No fridge and 12V loads is more efficient and will give you longer run times off the battery before you have to recharge.

Do a search on Engle or Waeco if you really want an electric fridge. They make super efficient 12V models but hold on to your hat when you see the price; they're expensive.

Bruce

[bdosborn]

but won't I still need the 120V inverter to run the three power hogs?

Unfortunately, you'll probably only be able to run your 120V fridge for around 6 hours or so off your single battery. That's why most people run a 12V system and don't use an electric refrigerator; it takes too much battery to support a 120V fridge. No fridge and 12V loads is more efficient and will give you longer run times off the battery before you have to recharge.

Do a search on Engle or Waeco if you really want an electric fridge. They make super efficient 12V models but hold on to your hat when you see the price; they're expensive.

Bruce

[bdosborn]

but won't I still need the 120V inverter to run the three power hogs?

Unfortunately, you'll probably only be able to run your 120V fridge for around 6 hours or so off your single battery. That's why most people run a 12V system and don't use an electric refrigerator; it takes too much battery to support a 120V fridge. No fridge and 12V loads is more efficient and will give you longer run times off the battery before you have to recharge.

Do a search on Engle or Waeco if you really want an electric fridge. They make super efficient 12V models but hold on to your hat when you see the price; they're expensive.

Bruce

[terryjones1]

but won't I still need the 120V inverter to run the three power hogs?

Unfortunately, you'll probably only be able to run your 120V fridge for around 6 hours or so off your single battery. That's why most people run a 12V system and don't use an electric refrigerator; it takes too much battery to support a 120V fridge. No fridge and 12V loads is more efficient and will give you longer run times off the battery before you have to recharge.

Do a search on Engle or Waeco if you really want an electric fridge. They make super efficient 12V models but hold on to your hat when you see the price; they're expensive.

Bruce

You can add the Norcold DC0051 to the list of super efficient 12 DCV refrigerators. Mine cost approximately $590.

[Richard A.]

Many folks do know know just how much current an inverter draws off the 12v system.

These are rough numbers .. but close enough .. for every 100 watts of 120vac you are using ... you suck 10 AMPS of 12 vdc power.

In addition, if you have the inverter ON but are not using any AC it still draws 12v current at idle. So turn OFF the inverter when not using it.