Curt, the experts will weigh in soon, I'm sure, but a few general concepts make sense to me. The battery bank you have will allow you to run things in your RV (except for the air conditioner and the microwave oven) for a certain period of time. The more battery capacity, the long you can run devices before it's time to recharge the batteries. As you probably already know, you can recharge the batteries in three common ways: by hooking up to a power pedestal at an RV park, by running your generator, and by using solar panels. So, while you can get by with one deep cycle battery, you will be running it down frequently, requiring more frequent recharging cycles. So, folks add batteries until they reach a point that they are happy with. Of course, this also depends on the electricity usage habits you practice. Some folks are very frugal and can go a long time on a small battery bank, while others use a bit more, in order to run things like televisions, satellite boxes, etc. To more directly answer your question: I would say that boondockers usually have at least two batteries, but many have 4, 6, or 8. As for the AGM batteries, they are preferred by many, but are certainly not required.

One method used by folks it to start out with, say, two batteries, and see how they do. Reserving the ability to add batteries is smart, if they are needed. I intend to equip my fulltime RV with as many batteries as it will conveniently hold (the diesel pusher motorhome we are looking at comes with 8 AGM batteries, which should be just enough for us.) Most fifth wheels are a bit more weight and space conscious, so you usually only see 2 to 4 batteries. The method you use to recharge the battery bank is up to you. Many, many, folks use one or two Honda or Yamaha portable generators of around 2000 watts each to recharge their battery bank each morning for a couple of hours when boondocking.

As you mention, there is a ton of information available on this topic on the Internet and the RV forums. We'll see what the more experienced RVers offer up, but doing some online research may be smart so that you make good choices. The bottom line is that your RV is set up to boondock to some degree right from the factory. If you choose to enhance that capability, it will allow you to go longer between battery recharging sessions. Some people are cool with running a genset twice per day, and others want to add solar to reduce the need to run a fuel-powered generator, decreasing noise, smell, and carbon-footprint. You will need to decide what type of RV user you are, and what you prefer.

Your mileage may vary, and I hope you find all the information you are looking for. It is certainly out there for you!

Roy

Yes indeed, as Bill J said and as I begin a lot of my posts, “It depends.”  One just has to analyze the power requirements of the rig and your lifestyle.  Rigs with RV fridges require less battery power and less solar.  Are you going to boondock a couple of days – or weeks?  Do you have a generator – how big and how much do you plan to use the generator to do the bulk battery charging with the solar “topping off” the last 15-20% for the battery charging? (Generators really aren’t a good idea to finish the charging of the batteries due to the long time it take to get the last 15-20% in the batteries as they sort of trickle charge the last amount to top them off.  They do the initial “bulk” charging.)

Assuming you don’t have a residential refrigerator, I can tell you that a 300AH bank along with 400 watts of solar is about the minimum in our experience IF you have an RV (gas) refrigerator and use little to no power to cook except maybe coffee in the morning.  This, with a 2,000 watt full sinewave inverter allows for some TV / DVR usage and naturally lights and water pump usage, etc. without undue concern.

We find 600AH, with RV (gas) appliances pretty well give us the freedom to do pretty much whatever we want as long as we have good sun during the day and maybe an hour of generator time in the AM to bulk up the batteries with the solar finishing the job.  Naturally all of this is dependent on your lifestyle.

Recall that, for example, with a 300AH bank only 150AH should be used.  Discharging more than 50% of a battery bank will, over time, significantly shorten battery life. So you need twice the Amp Hours you plan to use.

With a residential refrigerator, IMO, we would need 900AH and 800 watts of solar to do what we now do with 600AH, 400watts of solar and a big generator when we boondock.

Everyone is different.  But that’s us for a reference point.

Go here:

http://www.jackdanmayer.com/rv_electrical_and_solar.htm

and you will get a lot of useful and accurate information.  A lot.

If you do not have room for 8D batteries or other larger 12 volt batteries, 6 volt golf cart batteries are your best bet. The reason is for a normal size, automotive, the 6 volts are the only ones with thick, deep cycle, plates.  There is not enough room for thick enough plates in 12 volt to be true deep cycle. That is why most go with 6 volts in series, they are just a bit better.  But, if an odd number of batteries is best, 12 volts will do the job better.  
Lifeline makes extra tall 6 volt AGMs, that are wonderful if your battery compartment is tall enough. I wish we could have used them.
You mentioned gel cells, forget them since they have no advantages over AGM and some disadvantages like taking longer to charge. AGMs do not need to be vented and there is less issue putting them in the same compartment as your charger, though it is still better to keep them separate.
As to the converter vs. inverter/charger, it depends. Many find the converter that is installed is not a good fit for a large battery bank, so they need to upgrade anyway. Converters come in different sizes, about the largest has a 70 amp charger. Most inverter/chargers have 100 to 150 amp chargers, so they will charge a large battery bank faster, and that includes a 4 battery system. Most inverter/chargers have more sophisticated and programmable chargers than converters. Some find it better to install more than one inverter and use a high end converter, since it gives them flexibility on what is using the battery. Converters are also good when your shore power is weak or flaky, like Mexico or Yukon, they will charge your batteries when the voltage is at 90 or 140, while most inverter/chargers will not. If you change to an inverter/charger and have the room, you can leave your old converter in with its own plug, as long as it has a decent charger, and use it when on weak (1000 watt generator or over a 100' of 15amp extension cord) or flaky power.
To also address the residential fridge issue, a 12 cuft RV fridge uses around 40AH of battery a day (Norcold 1200), a big residential uses 90 to 120, so the real additional usage is 50 to 80AH per day. A friend who moved from an 8 cuft RV fridge to a top freezer residential, I think around 11 cu ft, found it used 40AH more per day.

-- Edited by bjoyce on Tuesday 20th of January 2015 07:20:39 AM

Curt:

A comment about the inverter/converter (charger) combination:  I carry a good quality, but far less expensive, converter only (charger) in addition to the big 3,000 watt combo unit.  If that big box full of technology were to fail the backup charger would at least keep you going and you can move the slides, etc.  The combination units are very reliable, but just remember, no 12 volts - essentially no rig.  Almost everything requires 12 volts.  Even the RV refrigerator when it is running on gas needs 12 volts to run the computer.

A thought . . .

Great comments from everyone....much appreciated. If I have limited funds and would like to boondock...a little right now or future....What would be the combination of components that I might need to accomplish that? Would 2-4 6V batteries and an inverter be sufficient with a portable generator? If I'm going that far would it be better to just go ahead and invest in solar? From what NWescapee said I might be able to just go with a couple of 6V batteries and an inverter to be off grid for a few days with a portable generator since I don't have one on my 5th wheel. Who would you recommend contacting to recommend, purchase and install the components? Maybe I need to take a class to better understand my needs for this type of venture?

Curt:

Working on a budget: Actually, you can do a lot with 4 - 6volt “golf cart” batteries and a ~1.800 watt inverter plus a small generator if you don’t run hair dryers and microwaves.  Naturally the battery charger that would come with the trailer would take care of the charging, but there is no need to go spend a lot of dollars on big inverters/converters, 3,000+ watts like we have, with a limited size battery bank.  With a smaller bank you can’t run anything that requires that kind of inverting power for any length of time without killing the batteries in very short order.

I used one of these – the 1,800 watt continuous version – for years in our rig.  Still have it on the bench. It is full sinewave and they are simple and work great.  Two smaller sizes, full sinewave which you do want, are also available with a simple on/off remote switch. 

http://www.xantrex.com/power-products/power-inverters/prowatt-sw.aspx

Also found this, FWIW as to first check for pricing:

http://www.toolfetch.com/catalog/product/view/id/70230/s/xantrex-8061220-prowatt-tm-true-sine-wave-12-volt-power-inverter-2000-watt-max-3000-watt-surge/category/33956/

This is a high quality product for relatively modest cost that is safe to run TV / entertainment stuff and computers, etc.

You can do a lot if you monitor power usage even without solar but with a small generator for relatively short stays.  For longer stays solar becomes more of a requirement along with the small generator.  But you don’t have to install solar day one.

PM me if you want to chat about specifics.

Bill