RV Electric Power for Dry Camping


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Conserving Electric Power 

 

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! :-) 

 

Remember this 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. 

 

If you're serious about dry camping,  and you don't want to spend a fortune on MAKING electricity, then you should consider spending a little to SAVE electricity.  Remember, a watt saved is a watt made!  Wow, does that sound corny or what!?

 

1.  Just like at home, turn some things off!

 

At one time we were horrible energy wasters.  This is when we lived in a regular house -- a buddy drove up one night and knocked on the door.  "Mac, you've got a light bulb burned out in that 2nd floor bedroom on the left".  Puzzled, I asked how he knew this, and he said; "Because that's the only light in the house that isn't on!".  LOL. If this sounds like you, you'll really have to make some changes for frugal dry camping.

 

2.  Replace Lighting to Improve Efficiency

 

New Fixtures:  Our RV came with standard, cheap incandescent light fixtures on the ceiling.  Like he ones in  the photo on the left below.  Ours were the two bulb variety, and used the fairly common 1141 bulb.  This is an 18 w bulb, and draws 1.5 amps.  So you turn two of them on you're using 3 amps.  We had three of these fixtures, two in the living room and one in the kitchen.  We replaced them with compact fluorescent (CF) lights from Thin-Light.  See photo on the right.  These use two 8w fluorescent tubes, so they draw about the same current as a single 1141 bulb!  However, they put out about 800 lumens, about as bright as a standard 60w bulb.

 

 

Typical low efficiency RV lighting on the left, and high-efficiency fluorescent on the right

 

Simple bulb change:  In the rest of the RV we didn't want to go to fluorescents yet.  The are a little expensive to buy, and we don't use the lights very long in the bathroom, bedroom, etc.  So in these rooms we changed one of the two bulbs to a lower wattage bulb that fits the same socket.  We installed a 97 in the socket that turns on first.  It's only 0.7 amps, a little over 9 watts, so about half the draw of an 1141.

 

How about LED lights?  We had bad results with them.  We're going to try again in the future, but it's hard to find high quality lights at a good price.  Another year, and maybe the prices will be reasonable.  Here's a link to our experience with LEDs.

 

3.  Plan Your Generator Run Time

 

This may seem obvious to you, but it's not to many people.  If you have a small, efficient generator this isn't as important, but it still maters.  If you have a large built-in generator like our Onan 5000 then you're wasting a lot of gas if you don't plan your generator runs for battery charging.

 

A 5000 Watt generator is very inefficient to use for battery charging.  For this reason, you should run it when it will do the most good, and that's when the batteries are lowest.  A battery can take a charge much faster when it's at 50% charge than when it's at 80% charge.  So here's what to do:

  • Run the generator in the morning, to give the batteries a big boost

  • Remember to turn on your charger (if it's manual like mine) any time you run the generator for other reasons, like microwave use, etc.

4.  Adequate Size Wiring

 

This is important for all 12vdc wiring, but especially important for inverter power cables and solar charger wiring.  Solar panels cost a lot of money, using wire that's too small can waste it by dropping voltage.  Ditto the cables from Battery to inverter.

 

In both cases, you should use the largest wire that's convenient to work with.  It's almost impossible to use too large a wire, but you do start loosing benefit on most solar chargers beyond #6 or #4 AWG -- unless you have a really huge array, or very long run.  On the battery to inverter run, keep the wiring as short as possible, and use 0000 (4/0) cable when possible for inverters 1500W or larger.

 

Here's a very useful web tool to figure wire sizes and calculate voltage drop:  www.powerstream.com/Wire_Size.htm  At the bottom of the page is the voltage drop calculator.  The percentage drop is the important number.  You want to keep voltage drops to less than 3% to the inverter if possible.  For high amp use you'd prefer even less.  For the solar controller to the batteries you want this to be under 1.5%

 

Why is larger wire required for lower voltage applications?  It's because you have to pull more amps at low voltages to get the same wattage output.  This is why many large solar and wind systems in homes are 24v or 48v.

 

5. Finding Phantom Loads

 

A "phantom load" is electricity being used accidentally with no benefit.  For example; your AC powered television probably uses a small amount of electricity all the time, so it's ready to turn "on" instantly when you push the button.  The same goes for your satellite TV receiver.  By unplugging these you can save that power.  Here's a list of some other common phantom loads:

  • Microwave clock, clock on other appliances

  • AC/DC power adapters.  Those little black plastic cubes.  Also known as "Vampire Wall Warts"

  • Refrigerator "climate control" or similar function, uses DC power to heat coils that minimize outside condensation.  Switchable on/off

  • Computers (both desktop and laptop) and monitors, when plugged in and not in use

All these are easy to see.  Some loads may not be obvious.  One way to find them is with an amp meter.  Start with all DC and AC power turned off.  Put the amp meter on your battery bank (or observe reading if it's built in like a Link or Trimetric).  One by one, enable DC circuits.  When a circuit shows power drain find out what is powered by that circuit and determine if it can be turned off or un plugged.  After you finish with the DC side, turn on the inverter and check each AC circuit (turn breakers on one by one).  This may take some time, and you may need to repeat it to get them all. 

 

Be sure to NOT disable any safety items like propane or CO sensors, fire alarms, etc. 

 

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