Adding Inverter for dry camping

I'll step aside and let those with more experience chime in. But I can provide a basic overview.

With two batteries, you can't power a very big inverter. Not big enough to do what you are proposing. Would you be happy with an outlet or two? The best thing at this point would be for you to list the items you must be able to plug in and run, those things that would be nice but not absolutely necessary, and those that would truly be a luxury to have 110v to run.

you don't say what type of RV you have but factory inverters are usually only come on the bigger motorhomes.
so not sure why you'd think that the 120v AC outlets should run on 12v DC power.

i installed a 400w inverter in my 24' HTT.
connected it straight to the batteries, routing the wires through cabinets and out the front of the trailer, where the other wires come out. it has an on/off toggle switch on it.
can run the tv and dvd on it and also recharge electronic devices.

for dry camping, that's all i need. don't need to have all the 120v outlets usable on 12v battery power.
not sure what other things you'd need them for, if you're dry camping.

You need to do a lot more research into what you plan.

This is a link to an excellent discussion of 12 Volt systems; part 2 of the discussion goes into inverters. You need to thoroughly read and understand this before you go further.

http://www.marxrv.com/12volt/12volt.htm

With 2 #27 batteries, you can't run more than the entertainment center for a few hours at a time. Maybe a SMALL microwave for a few minutes to warm up things, not to cook.

300 watts or so of solar would be enough to keep the 2 #27's charged for most uses.

Regards,
Doug

We use a regular cell phone charger that plugs into a 12- volt system. It came with our phone.

If your inverter is "whole house" running everything 120v in the RV, then the converter must be turned off (various ways to do that) or it will use more battery juice than it can put back in, and your batteries will go flat--this takes a while so you do get a chance to notice the converter is still on and shut it off :)

You will want your fridge on gas, not auto, or else it will see 120v and run on that. Water heater on propane whenever you have that on. Air conditioner off. DW trained in use of microwave and hairdryer (you too :) )

Then for whole house, just plug the shore cord into the inverter.

Another way is to have just certain things run off inverter which runs a sub-panel (which does NOT include the converter!)

Another way is to have an inverter with a transfer switch so you can be whole or part house on inverter and the rest (or all of it) on shore power or gen

You can do anything you want really. Here is what I do as an example only, not recommending it unless it suits you too. In this case one inverter is whole house with shore cord into it and the other does only certain items that have been displaced from whole house for when off-grid (they usually go back to whole house when we have shore power but don't have to be--can still use the inverter method for them)

http://forums.trailerlife.com/Index.cfm/fuseaction/thread/tid/26237237.cfm

If all you are wanting to do is charge a cell phone or two, then just add a 12v plug (cigarette lighter socket) and use a car charger.

For me, I may occasionally run my netbook, charge my cell phone and/or kindle, and run my mp3 docking station with speakers. I found it was easier to do one of the following:

1. use a 12v plug inverter

2. use a portable power pack/jumper box

or

3. use a small battery operated charger

For the mp3 and netbook, I usually use 1 or 2. For the cell phone and kindle I usually use 3, sometimes 1 or the "car charger" into the house 12v plug. #1 and car chargers power directly off the house battery via the 12v plug. #2 gets recharged when I plug into shore power. #3 is still on its first set of D batteries into the 2nd year of use. I've never run low on power yet.

If you're wanting to run hair dryers, microwaves, etc., then you're looking at more than a 2nd battery can do.

Hi,

All RV's come from the factory with a 12 volt battery charger. So if you where to plug in the RV to a inverter, it would turn on the charger, and quickly discharge the battery while the inverter might use 60 amps to run the 40 amp charger, and both will stop about 1 hour later.

What I would recommend, and it is very simple is buy a 500 watt inveter that plugs into a cigarette lighter. You can use a car charger to charge your cell phone, it will use barely 1 amp per hour from your RV battery, it is very energy efficient. Plugging in your inverter and turn it on, with no load the inverter will consume about 10 - 15 watts, or about 1 amp hour per hour it is on. Add a load, such as the 50 watt TV set, and the total load might be 60 watts or so, about 5 amp hours per hour.

Your group 27 battery is good for about 100 amp hours "Lab rating" but real world, you can draw out about 50 amp hours every day, without damage to the battery. Then need to recharge about 60 amp hours to make up for the lost amount in the charge cycle.

Your RV will consume about 35 amp hours to just run the CO meter, propane leak detector, and refrigerator, about what one 120 watt solar panel will collect in one day. So to get through a long weekend, a single 120 watt panel will recharge the batteries just enough to give you some additional power for the next day. But if you are consuming 70 AH daily, your batteries will be depleted in about 3 nights.

So I would recommend a pair of 100 - 150 watt solar panels. Panels larger than 150 watts might not fit on the roof, between the antenna, RV Roof vents, refrigerator or A/C covers. Shading is bad on the panels. You do want them elevated by about 1" above the roof surface, so they will get good air circulation under it, and keep it cooler.

I make my solar roof mounts out of 2" angle aluminum. I cut off 6" length, and drill three holes 3/16" for #10 screws into the roof, and a 5/16" hole for a 1/4-20 bolt into the solar panel framework. Rubber roof sealant between the mount and roof keeps out the water.

I ran my wires down through the refrigerator roof vent into the closet next to my refrigerator. I put the controller there. I would recommend a PWM controller.

SunElec.com They sell solar panels near $1 per rated watt!

I used grey direct burial UV rated # 10 Romex wire to run from the panels to the controller. It is good for about 15 amps max. Home Depot.

I installed a couple of cigarette lighter receptacles in my RV so I can use portable inverters in several locations. I used #10 wire to them, and used a 20 amp fuse. Most of the time I will never exceed 20 amps through the inverter (about 200 watts load).

You can plug in your cell car charger in the same locations.

Good luck on your installation.

Fred.

Just go buy a small portable inverter that will plug into a 12 V outlet, if all you need to do is charge electronics. I have one for my car, to charge camera batteries, bluetooth devices, phones, laptop computer, whatever.

When I was a partner in a travel trailer, we had 2 extra 12 V outlets added, one in the bedside wardrobe and one near the dinette. Very handy for charging all kinds of things, or using the laptop.