Searching for the nebuchadnezzar

[The Nebuchadnezzar]

Hi again all,

So I am sitting here asking myself a question: If I have an electrical system consisting of shore power, genset and house batteries and inverter (solar panels for charging are a possibility) do I need 12v available for anything? Will 2-way/ 3-way appliances run in gas mode without 12v?

Thanks again guys

[Docsgsxr]

If you have a 3 way fridge and no power to it, with only gas on it, it will run on gas.

As far as 12 v power is concerned, remember, led lighting is mostly 12v. You can buy some with converters you plug into a wall but lose energy efficiency that way. Most of your water pumps are designed to run on 12v too. Not to mention ceiling mounted exhaust fans. (If you build a battery bank inside, you may want to consider 12v computer fans for ventilation of the space.

viewtopic.php?f=9&t=12834&start=570 read here.....



http://www.ehow.com/how-does_5631807_co ... work_.html

a little read on how gas works on a fridge.


-Doc

[Locutus]

Not sure about the 2-way appliances but I think they do need electricity to operate in propane mode, probably 12VDC. Your solar panels themselves will deliver either 12VDC or 24VDC depending on the panels and how they're set up. When using your batteries for power, DC appliances and lighting will be more efficient because you won't have conversion losses, assuming your DC wiring is of sufficient gauge to minimize voltage drop.

If you haven't already done so, read Handy Bob's blog thoroughly and re-read until you have a good understanding of the subject matter.

http://handybobsolar.wordpress.com/

[The Nebuchadnezzar]

Thank you Doc

[The Nebuchadnezzar]

Handy Bob's article is great! there is one thing that keeps confusing me though. If using an converter that gets installed in a sub panel in front of shore power/ generator. So for connecting 12v appliances are there two 12v distribution panels one for the converter and one that would run directly from the batteries?

[Docsgsxr]

No. Shore power to converter which charges batteries and runs 12v items. I am sure there is some sort of transfer switch from converter to battery when shore power is disconnected.

Only time you'd need two boxes is if you ran 110v AND 12v throughout.

I am going to try to sketch out my plan and post it here for you. Brb........

[Docsgsxr]

I tried to design one but I am awful with photoshop and paint, so I borrowed one,

very simple diagram,



as you can see, only one breaker box, but to hook into the battery some people use bus bars with inline fuses. I prefer the route that comes on most cars and trucks, one power line to a fuse box, and ground everything else to the body of the bus via the negative post of the battery. Like so,



Am I as clear as Alabama clay mud?

-Doc

[The Nebuchadnezzar]

Thank you Doc

[Docsgsxr]

You got it!

[Locutus]

In addition to Handy Bob's blog, I've found this book very helpful:

http://www.amazon.com/Electrical-System ... al+systems

[jazty]

Originally Posted by Locutus

When using your batteries for power, DC appliances and lighting will be more efficient because you won't have conversion losses, assuming your DC wiring is of sufficient gauge to minimize voltage drop.

While on the topic of wire gauge and voltage loss, here is a nice calculator to figure out wire gauge. Try to keep your voltage loss within 1-3% and you'll be doing great!

http://www.solar-wind.co.uk/cable-sizing-DC-cables.html

As if you needed another resource right now

[The Nebuchadnezzar]

Thanks guys, I actually have that book its excellent, it was that 12v thing that had me confused. So I've been scouting for a generator, I'm thinking diesel would be the best way to go, but they are not as plentiful used as gas. Propane genset seems to be a good option too. There is also quite a bit of room under the bus, I suppose I could install a marine gas tank. What do you use, if you use one?

[The Nebuchadnezzar]

The nebuchadnezzar finally came up up on the First Student sale list, will hopefully have him home soon

[sojourner]

A 2 or 2-way fridge does require 12VDC to power the control board. Without it the fridge will not work normally (it can be "hot wired to test though).

[The Nebuchadnezzar]

Thank you

[Docsgsxr]

Good luck on your hunt!

[The Nebuchadnezzar]

Thanks Doc.
I've been learning about RV electrical systems for my build and there seems to be disagreement regarding pure sine wave and modified sine wave inverters and what you can run using them. The pure is considerably more expensive though probably worth the cost if modified is going to ruin expensive appliances and such. Some folks say that there are very few things that actually need pure sine wave? Any advise would be appreciated.
Thank you

[Timelord]

Modified sine wave is murder on AC motors. It is not the easiest on switching power supplies either. In short, use nothing you love on modified sine wave inverters.

[claydbal]

Originally Posted by Timelord

Modified sine wave is murder on AC motors. It is not the easiest on switching power supplies either. In short, use nothing you love on modified sine wave inverters.

other than fans,and water pump, what else would be considered A/C motor?

[bansil]

actually any electronic digital timers is effected, like microwaves, clocks and coffee pots...never really effected us in the last few years.

turn coffee pot on when we need coffee (don't use timer feature)

really don't care what time it is (microwave clock never gets set)

and the clock we use (very seldom is normally running on invertor)

I always use my laptop while driving off an invertor never a problem (also has the older "brick" charger this makes a difference the internet told me )

the laptop thing I have been doing for years in multiple vehicles and always used invertors (cheap ones also like the B&D 500 watt is a tank and 5 years old probably)

Also have an old aluminum cased no name ~$15 400wt that we run a small crockpot for dip with, it's an antique

and our fridge runs 10 hr days while traveling off the invertor

I have had good luck with modified sine wave invertors, I just never had the extra cash when an invertor was needed, so I always got mod. sine

True sine wave are a lot cleaner in power (I have read)

Also their is an unwritten rule about using 85% of an electronic devices rated output for max life...seems to work that way

I have 2 cobra 3000 watt (1500 nominal) and biggest load it see's is 930 watts (microwave and fridge while on the road)

don't forget to power invertors you need enough 12v amps and the correct wire size to run them, I only use microwave while bus is running (this lets me also use the alt to help power it)

Keep invertors close to batteries (separate compartments) to minimize the big cables you need to feed them 12V