RV Electric Power for Dry Camping


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RV Electric Power for Dry Camping

Read This Disclaimer First   I've written what I personally did, and my opinions.  Don't assume what I did was safe, and don't assume it will work for you.  Do more research, and make your own choices.  I'm not responsible for your outcomes! :-) 

 

Contents of this page

1. Introduction

2. Why Dry Camping

3. Dry Camping Electric Overview

 

Introduction

 

If you visit the Technical section of any RV forum on the internet you'll soon see these questions

  • How many solar panels do I need to charge my batteries?

  • What size inverter do I need to run my microwave?

  • How many batteries do we need to dry camp?

  • Etc.

After replying to several dozen of these, and similar questions, I decided to write a "how to" guide for this topic.  So, here goes...

 

One problem is that most people would like a simple answer, but it just isn't simple.  I'll try to write this as concisely as possible, but there are many variables, and you'll need some minor technical knowledge.  So fair warning, this isn't a short topic.  I'll use links to additional information on some topics.  That way you can keep reading for the basics, but you can click on the link if you want more detail.

 

Budget

I assume you have budget constraints -- you're not rich.  You need to learn as much as possible about the subject so you can save money by doing most of the modifications yourself.  Some things you may not be comfortable doing yourself, but at least you'll understand them and be able to evaluate quotes given to you by professionals.

 

Intended Use -- Frequency and Duration of Dry Camping

If you plan to dry camp only 2 or 3 days at a time you probably don't need any modifications.  Most RV's are designed to do this.  However, if you'd like to dry camp more you'll probably want to make some changes. 

 

Lifestyle
You may have already thought of some lifestyle changes you'll have to make to dry camp.  One  example is water consumption.  I imagine you've already accepted quick showers or sponge baths as a necessary evil.  Can't take those long hot showers with only 100 gallons of fresh water onboard. 

 

In the same way, you may need to make some concessions on the use of electrical conveniences, because they require a lot of power.  Appliances that generate heat or cold are the top users of electricity in any RV.  Among the worst is the air conditioner system.  If you plan to run an air conditioner, plan to run a generator!  One exception is the "swamp cooler", used in dry climates.  We have one of these that only draws 5 amps DC.

 

Other big energy users are microwave, toaster, hair dryer, curling iron, soldering iron, space heater, coffee maker, etc.  To use these items on DC power requires a large battery bank and a large inverter.  Otherwise, you really need a generator running any time you're using these. 

Overall Principal: 

The more you conserve electricity,

the less you have to worry about generating it,

and the less it will cost you in equipment. 

So, how often you dry camp, for how long, and how much power you use, will determine how extensive your modifications need to be.  I'll outline three "levels" of dry camping and give some general comments on each.  Later we'll get more detailed.

 

 

Why Dry Camping?

 

Why would you want to dry camp?  There are many reasons.  For one, it's the only way to "Boondock".  That is, to camp away from everyone in the remote parts of the country. 

 

Another reason is for economy.  I'll use our own budget for 2005 as an example.  We've been fulltiming since September of 2004 and dry camping nearly 50% of the time.  At our current rate we believe our solar and other equipment will have paid for itself sometime in early 2006.

 

How we saved $2272.05 by dry camping in 2005

  • In 2005 we paid $3493.66 for campsites.

  • Out of 365 nights, 184 nights were DRY camping, and of those 184 nights, 113 were FREE

  • On average, we paid $15.80 per night for sites that were Full Hookup

  • So, if we had paid for a FHU site every night, we'd have paid 365 X $15.80 = $5765.71 for camping

  • By dry camping, we saved $2272.05 in 2005 (and a similar amount in 2006, etc.)

 

Dry Camping Electric Overview

 

CAUTION:  If you own a newer, high-end motorhome, you may have advanced monitoring systems, generator auto-start, etc.  Be sure to consult owners manuals and/or your manufacturer before making any changes that might void your warranty or damage your equipment.

 

 

Basic Dry Camping

Duration:  2 to 7 days at a time.

Generator and Batteries:  If you have a motorhome or other RV with a built in generator you may not require any changes at all.  Many people dry camp with only the equipment that came with their RV.

 

At most, you'll need only a few things.  The most common modification will be to increase the number of batteries.  For example, if your RV has 2, add 2 more.  This will probably cost under $200.  The  benefit is that you'll reduce the frequency of generator runs for charging.  Note that if your batteries are old they'll pull down the new batteries, so you may want to replace them all at once. 

 

With this setup, you won't have enough battery power to use the microwave, hairdryer, toaster, or other high wattage appliance, so you'll need to run the generator to use these.  But that's OK because whenever the generator is running the batteries will be charging too. 

 

Your RV probably has a device called a "Converter" that uses 120 Volt AC electricity to make 12 Volt DC.  This 12 Volt DC powers all your 12v lights, and 12v appliances like TV, radio, etc.  It also charges your batteries.  It does this whenever you're plugged in at an RV park, and also when the generator is running; however, the standard RV converter is a poor battery charger and takes a long time to fully charge them.  For this reason, you may consider a dedicated battery charger that will charge the batteries faster.  Another alternative is an inverter/charger.  Some of you will already have one of these, especially in newer and higher-end coaches. 

 

If you don't have a generator, or if yours is loud and you hate to hear it run, you could buy a quiet, efficient generator like the Honda or Yamaha models.  We'll figure out later what size you should buy.  Cost starts around $500 and goes up.

 

Solar:  For this amount of dry camping solar energy is not cost effective; however, if you really hate the sound of a generator, even the super-quiet Hondas, you might consider a couple of solar panels (200 to 250 watts total) and a good charge controller.  Still, without a generator you still can't run your high wattage appliances.  Also, you'll need to remember that the panels have to be in the sun, so your home will be in the sun too, unless you have the panels on remote mounts.  This basic solar setup would cost around $1100 to $1500.  That's a lot to spend if you're only dry camping a few days or a week at a time.

 

Inverter:  An inverter is similar to a converter, but it does the reverse.  It takes battery power and turns it into 120 Volts AC for running standard household appliances like vacuum cleaners, TVs, computers, etc.  Most newer motor homes come standard with an inverter, so you may already have one.  If you don't, you may not even need one.  It depends on your lifestyle choices and how your rig is equipped to use DC voltage.  If your TV, radio, lights, etc. are all 12 Volt DC, and you don't plan on using any other appliances, then you can get by without an Inverter.

 

$$  Total cost for basic dry camping: $0 to $2000. 

Moderate Dry Camping  Updated

Duration:  Multiple 5 to 7 day trips each year, or up to 30 days or more at one time.

Generator:  A generator is almost a must at this level of dry camping.  Normally, a balanced system including a generator and solar is preferred.  Even with solar power, you'll still probably need a generator from time to time but maybe not if you're very frugal or only camp in sunny places, or have lots and lots of panels.

 

Batteries are very important for this much dry camping.  Most people will consider the minimum to be 420 Amp Hours of battery power.  You'll get this with four golf-cart sized 6 volt batteries (wired to make 12 volts).  More batteries are better if you can afford the space and weight.

 

Solar Panels can start becoming cost effective at this level.  A typical system (like ours) will have three 120watt panels (360 Watts total) and a charge controller that maximizes panel output (called an MPPT controller.  This setup will cost between $1700 and $2200 if you do it yourself.

 

Inverter:  It depends on your lifestyle, but most people dry camping this much need an inverter.  A pure sine wave inverter with 1000 to 2000 watts output is typical.  Some of these will also have a built in battery charger, and this can be a plus.

 

Adaptations to save power:  You can do with less capacity, if you can save power to start with.  Replacing incandescent lights with fluorescent is one way - almost a must do.  Choosing more efficient appliances, and using more 12 volt appliances to avoid the inefficiency of the inverter (generally you lose 10%).

Here's the update: 

 

The Importance of Batteries and Adequate Charging

 

After three years of dry camping, and watching others do it, I've come to the conclusion that the lack of an adequate battery bank is the #1 deterrent to successful (i.e. frugal, fun, and quiet) dry camping.   Your batteries are the heart of your system, and if they are too small, or if you're not fully utilizing them, you'll be a slave to your generator and the bane of neighbors who would like to enjoy a little quiet from time to time.

 

Without the ability to store sufficient power to meet your daily needs you're going to have to run your generator most of the time, and that's costly, noisy, and totally unnecessary.  We've seen people who run a generator 8 to 12 and even 16 hours a day.  There's just no reason for that.   With an adequate battery bank, a good inverter/charger, and a little conservation, you should be able to meet all your energy needs by running the generator just a few hours a day, even without solar power. 

 

Your situation will vary, but here are the basics for a non-solar RV:

 

Preparation:

  1. Do the energy survey (in the next chapter "Determining your Needs") and determine how much power you'll need

  2. Buy more batteries so you have enough to meet your needs. 

  3. Ensure your charger will charge your battery bank at the highest level allowed by the manufacturer (see the chapter on Battery Chargers for details)

  4. Install an efficient pure-sine wave inverter to meet your basic AC power needs for TV, Computer, etc.  No need to power the microwave, toaster, hair dryer, etc.  You can start the generator for these.

Implementation:

  1. Plan your battery charging. 

    • First thing in the morning, note your batteries state of charge.  If they are below 50% write down how far below (let's say they're down 20 amp hours below 50%). 

    • Start the generator first-thing in the morning (as soon as quiet hours are over) and start charging your batteries.  Also, use this time to run other appliances as needed - coffee maker, microwave, toaster, etc..  Don't turn off the generator until the batteries are at 100%.  This might take 2 or 3 hours, maybe more. It's also OK to take them up to 95% 3 out of 4 days, then 100% on the 4th day.

  2. Be frugal with power use all day.  Turn off anything not needed.  Remove phantom loads.  See Conserving Power and other chapters for more tips.

  3. During the day/evening, any time you run the generator to power the microwave, etc. be sure to charge batteries too (assuming your generator will do both at the same time)

  4. Re-start your generator when your batteries reach 50%, or when they reach 50% plus the previous morning deficit (see item 1 above).  Be sure to charge your batteries enough in the evening so they will NOT be below 50% the next morning when you wake up.

  5. Start over at #1 and repeat every day. 

$$  Total cost $400 to $5000 if you do it yourself.  Add $400 to $2500 to have it done.  A lot depends on what you start out with in the RV.

Extensive Dry Camping

Duration:  Up to full-time dry camping 24/7/365; totally off-the-grid.

If you're planning on this you should have some experience dry camping so you know what you're getting into.   Depending on your energy needs the same equipment used for "moderate" dry camping could work for you, but often you'll want more reserve capacity and greater flexibility.  Our personal system is "Moderate Level" and we get by OK, but as Tim Allen says, there's no such thing as too much power

 

Most long-term dry campers have larger battery banks because it gives them more reserve capacity.  It's also more economical in the long run, because you're not draining the batteries as deeply in between charges and they last longer.  Some with high cargo capacity (like bus conversions) have over 1000 pounds of batteries.

 

Some dedicated dry campers have gone to 24 volt systems and industrial batteries.  Higher voltage systems lose less voltage in cable.  Solar power is utilized as much as possible -- 700 to 1000 Watts or more isn't uncommon.  Much of this equipment is intended for home and industrial applications, and inverters, chargers, solar panels, etc. are all 24 volt (or even 48 volt).

 

Depending on the geography, you'll sometimes see wind power generators.  These have advantages and disadvantages.  They work day and night, and it doesn't matter if it's cloudy.  Of course, they do need a stiff breeze to work well.  They're also a little noisy, some more than others, and they sometimes kill flying birds. 

 

$$  The total cost of a setup like this can easily reach $10,000 DIY and more if done by a professional.

OK, that's the overview of dry camping power levels.  Think about where your plans fit in and let's figure out how much power you'll need to reach your dry camping goals

 

Continue on to Determining Your Needs -- or choose another topic from the menu in the left sidebar at the top of this page.