The Junk Sicence 12volt Guide.

 

As you read through this information, we will talk about all the different parts of this system and discuss some of the very useful additions and improvements that you can make yourself. Also included will be some highly technical info that you can bypass if it doesn't interest you. So, let's get started by talking about batteries. The battery is the heart of the 12 volt system. No other single component is as critical to the system's functioning as your battery system! That's why a lot of time needs to be spent talking about the care and feeding of your battery(s).

Batteries

Discovering the Battery:
Sure, we all know what a battery is.... it's that thing that goes dead when you leave the headlights on overnight! But, in reality there's a little more to it than that, so a review of battery basics is in order here..

• A battery is an electrical storage device. Batteries do not make electricity; they store it, just as a water tank stores water for future use. As chemicals in the battery change, electrical energy is stored or released. In rechargeable batteries this process can be repeated many times. Batteries are not 100% efficient - some energy is lost as heat and chemical reactions when charging and discharging. If you use 1000 watts from a battery, it might take 1200 watts or more to fully recharge it. Slower charging and discharging rates are more efficient. Practically all batteries used in 12V applications are Lead-Acid type batteries. Even after over a century of use, they still offer the best price to power ratio.

  Batteries are categorized in two ways:

• by application (what they are used for)

• and by construction (how they are built). The major applications are automotive, marine, and deep-cycle. Deep-cycle batteries include solar electric (PV), backup power, and RV and boat "house" batteries. The major construction types are flooded (wet), gelled, and AGM (absorbed glass mat). AGM batteries are also sometimes called "starved electrolyte", because the fiberglass mat is only 90% saturated with Sulfuric acid. Flooded may be standard, with removable caps, or the so-called "maintenance free" (without caps). All gelled are sealed and a few are "valve regulated", which means that a small valve keeps a slight positive pressure in each cell. Most AGM batteries are sealed and valve regulated. Sealed gell and AGM batteries offer the convenience of no maintenance and produce less gas, so at first glance, they may appear more attractive than standard flooded cell batteries. There is a down side here, tho.... These batteries, especially the gell cell type, require precise control of the charging process to prevent permanent damage by overcharging. They also tend to be significantly more expensive and have a somewhat shorter lifespan. It all depends on what premium you put on the maintenance free aspect of it. In my opinion, the standard flooded cell battery offers better overall performance for the price and will probably last a lot longer in most common 12V applications. The need to add water periodically is a small price to pay for the advantages you get. I strongly suggest that you avoid the "maintenance free" flooded cell batteries... they truly aren't a good design: they are simply a standard flooded cell battery with sealed cells. Each cell has a small valve to release excessive pressure. They still can be run low on electrolyte with heavy usage and fast charging, and there's no way to add water, so the batteries often die young.

  It's important to understand the differences in battery types...

  Starting batteries are normally used to start and run engines. Engine starters need a very large starting current for a very short time. Starting batteries have a large number of thin plates for maximum surface area. The plates are composed of a Lead "sponge", similar in appearance to a very fine foam sponge. This gives a very large surface area, but if deep cycled, this sponge will quickly be damaged and will fall to the bottom of the cells. Automotive batteries will generally fail after 30 or more deep cycles.

  Deep cycle batteries are designed to be discharged down as much as 80% repeatedly, and have much thicker plates. The major difference between a true deep cycle battery and others is that the plates are solid Lead plates - not sponge. Unfortunately, it is often  impossible to tell what kind of battery you are really buying in some of the discount stores or places that specialize in automotive batteries.

  Many Marine batteries are actually "hybrid", and fall between the starting  and deep-cycle batteries, while a few are true deep cycle. In the hybrid, the plates may be composed of Lead sponge, but it is coarser and  heavier than that used in starting batteries. It is often hard to tell what you are getting in a "marine" battery, but most are a hybrid. "Hybrid" types should not be discharged more than 50%.

  A battery's capacity for storing energy is rated in several different ways, depending on the battery type. Starting batteries are often rated in Cold Cranking Amps or CCA. CCA is the discharge load in amps which a battery can sustain for 30 seconds at 0 degrees F. and not fall below 1.2 volts per cell (7.2V on 12V battery). This battery rating measures a burst of energy that a car needs to start on a cold morning.

  Deep cycle batteries are often rated in Amp/Hours. Amp/Hour rating of battery capacity is calculated by multiplying the current (in amperes) by time (in hours) the current is drawn. For example: A battery which can deliver 4 amperes for 20 hours before being discharged would have a 80 amp-hour battery rating (4 X 20= 80).

  You may also see batteries rated with a Reserve Capacity.  RC is the number of minutes a new, fully charged battery at 80 degrees F. will sustain a discharge load of 25 amps to a cut-off voltage of 1.75 volts per cell (10.5V on 12V battery). This battery rating measures more of a continuous load on the battery. For 12V use, this rating is a little less useful, as the common loads that 12V use puts on a battery are a lot less than that 25 amp load used to determine RC.

  I feel that the best bet is to consider batteries by their amp/hour rating, so that is the rating method used throughout this article.
   

• Selecting batteries
  Now that we know a little more about batteries, it becomes obvious what we should be using in our 12V system: Deep cycle batteries! When you unplug from the A/C line, you are using only your batteries to provide power for your home. It's therefore necessary to have a reliable recharging system, and to avoid heavy discharge conditions when you can. If possible, use only deep cycle batteries!

  Selecting the correct batteries is all about lifespan.... The right batteries will last a lot longer, leaving you with more money for the finer things in life! The lifespan of a battery will vary considerably with how it is used, how it is maintained and charged, temperature, and other factors. We'll talk more about maximizing the lifespan of your batteries later, but for now, here are some typical expectations for batteries used in deep cycle service:
             Starting: 3-12 months
             Marine: 1-6 years
             Golf cart: 2-8 years
             Deep cycle (L-16 type etc.): 4-8 years

   AGM deep cycle: 4-10 years
   Gelled deep cycle: 2-5 years
  From this list, you can see a couple of things... First, if you have the money to purchase the batteries you want, then the Deep Cycle battery is by far the best investment. However, if you're short on cash, but have a source of good used starting batteries for low cost, you can actually save money by putting up with a little extra work (changing them out as needed).

  Your battery bank will consist of two or more batteries run in parallel. This means that, although you may have a dozen 12V batteries hooked together in your bank, you're still drawing only 12 Volts from the bank all the time.

  

  When replacing your batteries, remove the negative cable first because this will minimize the possibility of shorting the battery  when you remove the other cable. Next remove the positive cable and then any hold-down bracket or clamp you may have installed. Dispose of the old battery by exchanging it when you buy your new one or by taking it to a recycling center.  Please remember that batteries contain large amounts of harmful lead and acid.

  After removing the old battery(s), be sure that the battery tray and cable terminals or connectors are clean.  Auto parts stores sell a cheap wire brush that will allow you to clean the inside of a terminal clamps and the terminals.  If the terminals, cables or hold down brackets are severely corroded, replace them. Keep track of the markings you made on the cables before replacing them!

  Thinly coat the terminals and terminal clamps with a high temperature grease or petroleum jelly (like Vaseline) to prevent corrosion. Place the replacement battery(s) so that the cables will connect to the correct terminals. Be extra careful here, as reversing the polarity of the battery when connecting it may severely damage or destroy some parts of your electrical system. Replace the hold-down brackets or straps to secure the batteries in place, then reconnect the cables in reverse order, i.e., attach the positive cable first and then the negative cable last.

  Before using the battery(s), check the electrolyte levels and state-of-charge.  Refill or recharge as required.

  A word of Caution: If you have decided to add additional batteries to your system, be sure to build and use a battery bank room or compartment specially designed and vented for batteries. Never place batteries in an unvented compartment as potentially explosive hydrogen gas will build up. Never place batteries in any compartment where electrical sparks or other ignition sources may exist. ( a simple 12 volt light with a switch on it is an excellent source of ignition spark!!) Also, be sure to secure batteries with straps or brackets to prevent them from moving about if the shelves are bumped. An unsecured battery may tip over and spill acid, or worse, may short out against any metal objects and cause a fire. If you are setting up a new battery bank, don't do a half-assed job!
   

• Care of your batteries
  Now that you have made the choice of what kind of batteries you will use, and have successfully installed them, it's time to talk about maintenance. In order to get the most from your new batteries, you can't just forget them now and expect them to work for you forever. It is very important to take good care of your new batteries and treat them right.

  You must keep an eye on the electrolyte level in the batteries. Most premature failures are caused by low electrolyte levels, and there's just no excuse for it, as it's simple and cheap to keep the batteries filled to the top. Electrolyte is lost whenever the batteries are charged and also when the batteries are discharged heavily. You should check the level in each cell of your batteries regularly. I recommend at least once a month, but it may be necessary to check and top off your batteries more often, depending on usage and how you charge them. At all costs, you must keep the electrolyte level above the plates at all times. In the warmer climates and during the summer, check the electrolyte levels more frequently. To replenish the electrolyte, add distilled water as required.  Never add acid-- just distilled water and do not overfill. Never use anything except distilled water! Tap water contains a lot of chemical and mineral impurities and will kill your battery before its time.

  A word of Caution: Batteries contain a sulfuric acid electrolyte which is a highly corrosive liquid. Don't get any on you! In case of a spill or splash, immediately flush the affected area with lots of cold water to dilute the acid. A mixture of baking soda and water can also be used to neutralize the acid, but watch out for the foam that will be generated! Be careful and pay attention to what you are doing! Also, avoid generating sparks, smoking or open flames in the vicinity of batteries.... batteries produce flammable hydrogen gas (remember the Hindenburg?) and can explode violently if the gas is ignited. This is especially important when batteries are housed inside any sort of compartment. Again, protective clothing and safety glasses are recommended to protect you in case of accident. Please treat batteries with the respect they deserve.

  Maintaining the correct electrolyte levels, tightening loose hold-down clamps and terminals, and removing corrosion is normally the only preventative maintenance required for a battery. However, you can extend your battery's life by keeping your battery charged properly and avoid deep discharges. Let me explain:

  A battery "cycle" is one complete discharge and recharge cycle. It is usually considered to be discharging from 100% to some point not lower than 20%, and then charging back up to 100%. Battery life is directly related to how deep the battery is cycled each time. If a battery is discharged to only 50% each cycle, it will last about twice as long as if it is cycled to 20%. Running the battery down totally flat will have a very negative effect on the lifespan of the battery. See the table below for voltages as related to depth of discharge. This chart is designed to be used when monitoring a battery under load. This chart is a little more useful to the average 12Ver, as we are most interested in monitoring the state of charge of our battery bank while it is actually in use. See the Testing your batteries section below for information on determining open circuit state of charge using either a volt meter or a specific gravity tester.

  Voltage	State of Charge
  12.6+	100%
  12.5	90%
  12.42	80%
  12.32	70%
  12.20	60%
  12.06	50%
  11.9	40%
  11.75	30%
  11.58	20%
  11.31	10%
  10.5	0%

  Avoid discharging the battery below the 40% level whenever possible.

  If the battery has been charging, then it's important to let the battery set for 2 to 3 hours without a load or charger connected to stabilize before testing. Otherwise, your reading will be high, caused by a phenomenon called "surface charge"  It is also necessary to invest in a good digital voltmeter.... it's the only meter that will offer the necessary accuracy to properly test your battery system. It's possible to install your own panel mount digital voltmeter... I'll tell you more about that in the section on monitoring. For now, it's important that you understand that your battery's life is adversely affected by too deep a discharge.

  At this point, it's also important to note that the battery voltage will be affected by temperature.... The chart above, and most other ratings applied to Lead/Acid batteries assume that the battery is at room temperature: 21 degrees C or about 70 degrees F. As the temperature of the battery drops, so will the fully-charged voltage reading. I have found a lot of conflicting information about this phenomenon, but it seems to be safe to say that for each 10 degrees F drop in temp, you can expect to see the voltage drop about a tenth of a volt. (.10 volt) That means that a battery at 32 degrees F with a no-load voltage reading of  12.35 volts is fully charged. It's therefore a very good idea to maintain room temperature in your battery compartment.
  
  Battery capacity (how many amp-hours it can hold) is reduced as temperature goes down, and increased as temperature goes up. This is why your car battery dies on a cold winter morning, even though it worked fine the previous afternoon. At freezing, the battery's capacity is reduced by 20%. At approximately -22 degrees F (-27 C), battery AH capacity drops to 50%. Capacity is increased at higher temperatures - at 122 degrees F, battery capacity would be about 12% higher. Even though battery capacity at high temperatures is higher,  battery life is shortened. Battery capacity is reduced by 50% at -22 degrees F - but battery LIFE increases by about 60%. Battery life is reduced at higher temperatures - for every 15 degrees F over 77, battery life is cut in half. In reality, this is fascinating information, but isn't really terribly important.

You should recharge a deep cycle battery as soon as possible after each heavy use. It is very hard on a deep cycle battery to sit for extended periods in a partially charged state. To charge the battery, you can use a wide variety of methods. Most 12Vers use some sort of mechanical charging system, such as a wind or solar system, or a small generator such as the one described later. In any event, the charging system should be run or operated regularly, if it is not one that is constantly charging your batteries.

 

Charging your batteries
OK, for you techie types, here are the specs for charging deep cycle flooded cell batteries:

Most flooded batteries should be charged at no more than the "C/10" rate for any sustained period. "C/10" is the battery capacity in amp/hours divided by 10. For a 220 AH battery, this would equal 22 Amps. Charging at 15.5 volts will give you a 100% charge on Lead-Acid batteries. Note that flooded batteries MUST bubble (gas) somewhat to ensure a full charge, and to mix the electrolyte. Float voltage for Lead-Acid batteries should be about 2.15 to 2.23 volts per cell, or about 12.9-13.4 volts for a 12 volt battery. Flooded battery life can be extended if an equalizing charge is applied every 10 to 40 days. This is a charge that is about 10% higher than normal full charge voltage, and is applied for about 2 to 16 hours. This makes sure that all the cells are equally charged, and the gas bubbles mix the electrolyte. If the liquid in standard wet cells is not mixed, the electrolyte becomes "stratified". You can have very strong solution at the top, and very weak at the bottom of the cell.

Testing your batteries
This section gets a bit technical, but is included to help you diagnose battery problems. If your 12 volt system isn't performing as well as you expect, it's time for some tests to determine what's wrong...

First off, visually inspect for obvious problems.... for example; damaged cases, corroded terminals or cables, loose hold-down clamps or cable terminals, or low electrolyte.

 If you have just recharged your battery, then a phenomenon known as "surface charge" will cause the battery voltage to be higher than normal. To insure accurate readings, you must eliminate any surface charge before testing. Use one of the following methods;

          1.  Allow the battery to sit for six hours with no load or charger connected, or...
          2.  Apply a 25 amp load for three minutes and wait five minutes, or...
          3.  With a battery load tester, apply a 150 amp load for 10-15 seconds.

The battery under test must be disconnected from any load or charger when testing. This is referred to as "Open Circuit". Use the following table, determine the battery's state-of-charge. The best way to measure the state-of-charge is to check the specific gravity in each cell with a hydrometer.  A temperature compensating hydrometer will cost approximately five dollars at an auto parts store. If the battery is sealed, then the correct procedure to test it is to measure the battery's voltage with a good quality digital DC voltmeter with an accuracy of .5% or better. Voltages are shown for both 12 volt and 6 volt batteries.

Check both the specific gravity in each cell with a external hydrometer AND the battery terminal voltage with a digital voltmeter without the engine or converter/charger running.  If the state-of-charge is BELOW 75% using either the specific gravity or voltage test then the battery needs to be recharged BEFORE proceeding.
Replace the battery, if one or more of the following conditions occur:
 
• If there is a .050 or more difference in the specific gravity reading between the highest and lowest cell, you have a weak or dead cell(s),
• If the battery will not recharge to a 75% or more state-of-charge level.
• If digital voltmeter connected to the battery terminals indicates 0 volts, you have an open cell, or if the digital voltmeter indicates 10.45 to 10.65 volts (5.2 to 5.35 volts for a 6 volt battery), you have a shorted cell.  [A shorted cell is caused by plates touching, sediment build-up or "treeing" between plates.
   
   
• The bottom line....
  • Pay attention to safety when working with or near batteries.
  • Buy only good quality Deep Cycle batteries for your system, if possible. Golf cart batteries offer excellent capacity and lifespan at a reasonable cost, btw.
  • Keep up with battery maintenance... check electrolyte levels regularly and pay attention to charging and discharging protocols to increase lifespan.
  • Invest in a good digital voltmeter and use it.
     
• Battery manufacturers
  Here is a list of links to battery manufacturers home pages for your convenience. Many of these pages contain battery specifications, application charts and technical data. Enjoy!
  • Lifeline Batteries Inc.
  • AC Delco
  • Trojan Batteries
  • Interstate Batteries of America
  • Optima Batteries Inc.
  • GNB Technologies Inc.

Electricity:

Ladies, and Gentlemen! Step right up and learn about the newest idea to come from old ideas! You’ve heard about the industrial revolution, you’ve heard about the sexual revolution, you’ve heard about the political revolution… well, welcome, one and all to the 12-Volt Revolution!

That’s right, ladies and gents, you can join the 12-volt revolution today, and get rid of those annoying electric bills forever! With the simple implementation of a few inexpensive devices, you can be providing your own electricity, at a tiny fraction of the cost you’re paying now!

Okay, enough theatrics… here’s how:

Thanks largely to America’s “melting pot” philosophy, most of us have some amount of Gypsy Blood… which is another way of saying we love to travel! However, we’ve also been spoiled by modern conveniences, which run on electricity… and in order to allow these two facts to co-exist in our space-time continuum, it was absolutely necessary that we therefore invent… the motor home!

A motor home is really nothing but an automobile with comfortable living and sleeping quarters designed into it. And since automobiles in the modern world produce their own electricity, in 12-volt DC, is it any wonder that a whole plethora of devices were then designed to use that form of power while mimicking the operation of common household appliances? Televisions, microwaves, dishwashers, washing machines, hair dryers, toasters, you name it… the list is absolutely endless! And, for those few devices that just don’t adapt easily enough… there is the inverter, which converts 12-volt DC power to 110-volt AC in a flash… so you can run those devices as well!

Now, you don’t live in a motor home, but the cost of electricity and the dependence on a centralized system are both putting you at serious risk. So, a conversion to 12-volt DC might be in order!

There are many ways to produce 12-volt DC in sufficient quantities to power a home that’s adapted to it… Photovoltaics are probably the most expensive, converting sunlight to electricity, and it’s a great system… if you can afford several thousand dollars! But I naturally assume that you can’t, so here’s my suggestions:

First, we’ll start with the small home generator. This machine can run about three hours a day on half a gallon of gasoline (or alcohol, if necessary), and will charge a bank of a dozen 12-volt batteries in that time. A dozen batteries should provide all the power you’ll need for a day, so starting this generator and letting it run for a few hours every day can take care of your electricity needs… and if you do run low on power, during and weather for instance, you can fire it up for an emergency boost, something you can’t do with a photovoltaic system!

All it is, as you can see from the photo, is an old three horsepower lawnmower that drives an automotive alternator instead of a grass-cutting blade. The alternator charges the batteries just as it would in a car, and the simple wiring diagram that makes it work is shown in the figure below. Even if you don’t have the parts, you should be able to get them and build this… or have one built… for under $100.00. The battery mounted on the generator provides a source of portable power when you need it, as well.

The wiring diagram to the right shows how to connect the alternator so that it charges the battery. On the back of the alternator, you’ll find three posts, and they’re marked A, G and F. Wire them as shown in the diagram.   The hot wire running to the field post will provide the initial startup charge that energizes the field when the engine is running, producing electricity.

While the diagram does not show it, a simple toggle switch should be placed somewhere between the positive post of the battery, and the field post of the alternator. Turn this switch on to charge your batteries, and off when the engine is not running, to prevent any drain of your power by the alternator itself.

If you have large AC-powered devices that you absolutely cannot live without, such as washers and dryers, well pumps, or air conditioners, you can still use this method, but you’ll have to make two adaptations… first, use a larger engine, at least eight horsepower, and second, locate a five horsepower (or larger) single-phase, 220 volt AC electric motor. Run both the auto alternator and the AC motor with the engine. When you want AC power, you’ll have to start this engine, and idle it so that the motor is driven at its rated RPM. At this speed, it will produce about 90% of the electricity it would normally consume. The wires that lead from it can be fed into your breaker box… but be absolutely certain that you know what you’re doing, and that you have the main incoming power disconnected before you do it! With this system, you can run large appliances or tools… but you’ll be burning gas all the time you’re running them, so I strongly recommend looking into 12-volt or other alternatives (for instance, did you know you can still buy a gasoline powered washing machine???)

Batteries: A battery bank is the next part of your home power system. As any DC electrician will tell you, the biggest problem most 12-volters run into is excessive battery drain. Using automotive batteries is possible, and if you have a source for them at little or no cost, then by all means go for it! But what you really need is marine or golf-cart batteries, and here’s why!

Marine and cart batteries are designed to be run dead, then take a charge again! An automotive battery isn’t, and if you run it completely dead a few times, it’s gonna reach a point where it won’t come back! Deep-cycle batteries can be bought at most boat supply stores, golf pro shops, even Wal-Mart, and if you’re going to be using this for your primary power system, they’re well worth the investment.

Your battery bank should be set up in a location that can be ventilated! Many batteries give off hydrogen and sulfuric acid fumes, and this can be an explosive mixture when it meets oxygen! I’d store the battery bank in a small ventilated shed (which can be built from pallets, like our OFS  in the last section), on a porch, or in a garage with a vent opening just over the racks that hold the batteries.

Wiring: Your household wiring will carry 12-volt current, but you’ll need to change outlets and light fixtures. There are 12-volt light bulbs that can screw directly into your normal sockets, but they are expensive, and we’ll be going over a much cheaper alternative in a few moments. If you’re going to a full 12-volt system, then you can adapt your existing wiring by replacing outlets with automotive cigarette lighter plugs, which you can gather up at a junkyard, or buy from auto supply stores or department stores. If, on the other hand, you plan to keep grid power for backup, you may want to run separate wiring for your DC fixtures and appliances, or you can merely select which circuits from your breaker box will become DC-only, and wire accordingly. WARNING: unless you really know what you’re doing, don’t even attempt to mess with your household circuits! Call an electrician and get it done right!

If alternating current is an absolute necessity, for instance to power a welder or other necessary device, I suggest you look into a small diesel engine. If you’re mechanically inclined, you’ll find that a 3-53 or 3-71 Detroit engine is fairly simple to repair and maintain, and being diesel, it has an advantage that few people will tell you about: it can run on just about any kind of oil! Diesel fuel, kerosene, soybean oil, used motor oil (filtered, of course), even waste cooking oil… it may take a little work to collect and filter the fuel, but it will make that old motor tick right on over!

However, there is more energy there that you can harness! Connect the cooling system to your OFS, running the water that cools the engine through coils in your hot water storage tank before it goes to a radiator for cooling, and you’ll be able to capture all that heat, too. Hook up a water pump to draw water from your well and pump it to an elevated storage tank, to bring water to your home. An air conditioning compressor can provide a boost to your home refrigeration system, or maintain a freezer for meat storage in the hottest part of the year. And don’t forget… the alternator can keep your battery bank fully charged!

OK, now that you know all about batteries and charging, let's put some of that stored energy to use. There are a lot of things that you can do to make your RV home more comfortable and energy efficient. There are even a few projects illustrated to spur your creative urges.

 
• Inverters
   One of the most useful items that you can add to your system is an inverter. Inverters make 110 volt AC power from your 12 volt battery system. This will allow you to operate many of your appliances and accessories that require AC power, so that you can use standard appliances and accessories that don't cost extra. Inverters range from simple portable units that plug into a cigarette lighter to larger, hard wired units that are permanently installed. AC wattage ratings are available from 100 watts up to 4000 watts or more. Most 110V AC appliances are fair game.
  
  Picking the right inverter isn't difficult. You need to decide just what it is that you wish to accomplish and how much battery capacity you have available.

  Sizing. Let's start by determining what it is that you want to operate. Here's a table listing some of the more common appliances and their wattage requirements.
   

  Appliance	Wattage (approx.)	Appliance	Wattage (approx.)
  13" color TV	50	Computer	70
  19" color TV	120	Computer monitor	55
  Stereo	50	Computer printer	20
  VCR	25	Hand mixer	100
  Satellite Receiver	20	Blender	350
  Heating pad	50	Toaster	1250
  Electric blanket	150	Microwave	650-1500
  Electric drill	500	Coffee maker	1250 brew, 200 warm

  It's obvious that  your microwave requires quite a lot of power. Most ovens will draw 650 - 1500 watts. Starting surges can be as high as 1750 watts. If you want to be able to use your microwave with your inverter, your inverter should be capable of producing at least 1500 watts and be rated for a 1750 watt surge. If you want to be able to use resistance heated appliances, like a toaster oven or electric coffee maker, be sure that the inverter you choose has a high enough rating. Most of these appliances will require 1200 to 1500 watts. They don't have a starting surge, like motors or microwaves, but are hungry for watts. When in doubt, consult the owners manual for the appliance or check the ratings plate for wattage requirements.

  Now is a good time to discuss just what these wattage numbers really mean in terms of 12 volt battery power, which requires some simple calculations. What we need to do first is figure out how many DC amps the inverter will draw when it's making that AC power for your appliances. To put it simply, for every 100 watts of AC power that your inverter is producing, it needs to draw about 10 amps from your 12 volt battery system. For inverters rated at 90% efficiency, the number is closer to 9.25 amps per 100 watts, but for ease of calculation, just figure on trading 10 amps DC for each 100 watts AC... it's easier to figure that way and errs on the side of safety. For those of you who just MUST have the math, here it is:    Watts = Volts x Amps, so Amps = Watts / Volts. For an inverter, operating at 90% efficiency, the conversion can be represented thus: AC watts / 12 volts X 1.11  = DC amps
  Example... television drawing 100 watts operating on an inverter will draw about 9.25 amps from your batteries..
  100 / 12 X 1.11 = 9.25
  The reason that this is important is that you only have a fixed capacity in amp/hours available from your battery bank. A pair of 6v deep cycle batteries or a pair of group 24 RV batteries will have a capacity of about 200 amp hours. That means that if you run that TV from the previous example for about 20 hours, your batteries will be flat! 9.25A X 20 hours = 185 amp/hours.

  Still with me? Good! Using the chart on wattage requirements and adding our new-found knowledge of amp hours, lets take a shot at how many amp hours of battery bank we need to supply us for a standard days use.
   

  Appliance	Watts	Use Time	Watt Hours	Amp Hours
  19" color TV	120	3 hr.	360	36
  Satellite Receiver	20	3 hr.	60	6
  Computer/monitor	125	2 hr.	250	25
  Coffee Maker	1250	20 min	417	41.7
  Microwave	1000	15 min.	250	25
  		Totals >	1127	133.7

  Don't forget that you are also using power from your batteries to run 12 Volt lighting, fans, etc.

  You begin to see that putting in a larger inverter to run bigger loads will require you to have an appropriately sized battery bank and an adequate method for recharging it! You can't hook a 2000 watt inverter to a single battery and cook the Thanksgiving turkey in the microwave! You should get a feel for your intended inverter usage and take into account the size of your battery bank before selecting an inverter. For instance, I chose a 3750 watt inverter to go with my 20 battery bank. It runs all my electronics, charges power tools, runs kitchen tools, supports my microwave, computer, televison, VCR, etc. My inverter cost about $700. And that brings us to the next topic:

  Hybrid Systems.  Often, it is more cost effective to purchase a smaller inverter to run the small appliances that you have and use a generator to power the more watt-hungry larger appliances, like electric dryers and ranges. This will give you quiet power for most uses and minimize the wear and tear on your generator. If you can't manage a full sized battery bank and large inverter, this hybrid approach may work better for you. It does require that you start your generator when you need to run one of those appliances, though.

  Inverter types  There are 3 main types of inverters. Square Wave, Modified Sine Wave and True Sine Wave. Let's look at the differences:
      Square Wave inverters are the cheapest. They also are usually the least efficient and will not run any of your electronic equipment. The reason for this is that the AC waveform they produce is very different from what you get at a standard wall outlet. Instead of being a sine wave it is a square wave. These inverters are usually functional for power tools and motors, but will not work with your TV or stereo. Definitely not recommended!
      Modified Sine Wave inverters are the middle of the road. They produce an output wave form that is close to a true sine wave and will work adequately with most devices, including TVs and computers. You may be able to see some slight distortion lines on the TV or hear a slight buzz on the stereo, but for the most part, these inverters provide quite acceptable performance. One noted exception is that most laser printers won't work properly with a Modified Sine Wave inverter. They are also middle-of-the-road as far as cost goes.
      True Sine Wave inverters are exactly that. They produce a practically perfect sine wave output. These units will operate even the fussiest electronic device, but they are much more expensive than their cousins, the Modified Sine Wave inverters. Do you need one? Probably not, unless you simply MUST have the best, or need it for a highly sensitive piece of equipment.

  Costs. You can expect to pay about $50 to $100 for a small portable MSW unit. RV designed units start at about $300 for a 750 watt w/charger and go all the way up to units rated at more than 5000 watts and costing over a thousand dollars. Price increases with wattage ratings and capabilities. The best thing I can suggest is to do some research. Check the links listed below for inverter manufacturers and remember to size the inverter based on your real needs.

  Project: Installing an inverter.  I'm going to take you through the inverter installation that I did for my RV. Your needs and situation will be different, but this should give you some ideas. A word of Caution: Always follow the inverter manufacturer's installation guidelines, paying close attention to proper wire sizing. Installing an inverter requires understanding of safe electrical practices and electrical safety code. If you don't have the necessary skills, get a qualified electrician to do the wiring. Don't take chances with safety!
  
  Mount the inverter away from your battery bank, in a place where it will be accessible and safe from moisture and flammable items or gases. Inverters utilize some components that can create a spark, so never install an inverter in the same space as the batteries! Ideally, it should be located near the main breaker panel for the house, with the battery bank in an adjacent or nearby room or compartment.
  
  The next step was to wire the AC side of the inverter to my electrical system. One of the advantages of an installed inverter is the availability of AC power at the same outlets that you were used to using when plugged into the grid. I simply chose the wall outlet circuits that I wanted the inverter to power and connected through the breaker panel to accommodate my choices. I used standard 12-2 w/gnd Romex and fittings to wire up the AC side of my inverter. This is really simpler than it sounds, so don't worry. Your inverter installation manual will give you some basic examples of installation wiring.
  
  The wiring to the battery bank is done next. I installed heavy duty battery cable to connect the inverter directly to the batteries. It's important to use heavy enough wire here, as some larger inverters can draw several hundred amps when under full load! My inverter required 6 ga. wire. I also twisted the heavy wire to help eliminate any electrical interference when operating the unit. A fuse was used to protect the system from meltdown. I used a 100A fuse connected directly to the positive terminal of the battery.
  
  
  Some of the larger and more expensive inverters offer very sophisticated control panels that will tell you battery voltage, charge/discharge rate, amp hours used, you name it. Very handy, but somewhat expensive. A little further on I will share some tips about constructing your own monitor panel, like I did. In use, the inverter is almost like being back on the grid! I can charge my laptop batteries, watch TV or a movie on the VCR, run my kitchen appliances, and all without an actual electric bill! And while it can be expensive to set up, you can shave a lot of costs with some simple thought.

• Sources. Here are some links to Inverter manufacturers and retailers. In particular, RV Solar Electric's website is well worth a look. They are a very knowledgeable company and have been doing RV systems like these for years. Their prices are very competitive as well. I bought my inverter there and they were very prompt and helpful... give them a look!
  Trace Engineering. (360) 435-8826. http://www.traceengineering.com/
  Heart Interface. (800) 446-6180. In WA (206) 872-7225. http://www.heartinterface.com/
  EXELTECH.  (800) 886-4683. http://www.exeltech.com/
  STATPOWER.  (800) 670-0707. http://www.statpower.com/

  RV Solar Electric. 14415 No. 73d St., Scottsdale, AZ 85260. (800) 999-8520. http://www.rvsolarelectric.com/
  West Marine. Box 50050, Watsonville, CA 95077. (800) 538-0775. http://www.westmarine.com/
  Wrangler Power Products. These folks don't sell inverters, but carry a huge selection of the wiring products you'll need to install one... 4444 S.E. 27th Ave., Portland, OR 97202. (800)962-2616. http://www.wranglernw.com/

  Solar
   Solar panels will provide power to charge your batteries whenever you have sunlight. This can extend a charge period almost indefinitely and solar is quiet and non-polluting. Even a single panel will help a lot. A single 55 watt panel provides almost 6 amps of charge current when in direct sunlight. That doesn't sound like much, but multiply that 6 amps by 10 hours and you're doing some serious battery charging! Several solar panels, a good sized battery bank and an inverter will provide you with many of the luxuries of living on-grid, and will be silent and reliable. The only drawback to solar is it's cost. A single 50 or 60 watt panel can cost you as much as $400 and larger panels are really pricey... still, it's an attractive option for those who can afford it. A solar system consists of one or more solar panels connected through a charge controller to your 12 volt system. Sunlight striking the panels generates power and the charge controller monitors the battery voltage to prevent overcharging. These systems are extremely reliable and maintenance free.

• Sizing. The number and size of solar panels may be determined more by your pocket book than any other factor. For all it's advantages, solar remains very expensive. It is definitely worthwhile to have at least a single panel, at least 30 or 40 watts, just to keep your batteries in top shape. A single 50 or 60 watt panel will, in the summer, provide you with as much as 60 or 70 amp hours of charge per day. For those who want to be truly independent, a number of larger panels coupled to a larger battery bank will provide you with plenty of power, even when you have an occasional cloudy day. Cloudy days are the bane of solar charging! Even a high thin cloud layer will cut your charge current by 50% or more, and you'll only get 10-20% of rated power on an overcast day. This is when more panels will help. Most authorities agree that if you calculate your daily average energy usage and then provide enough solar capacity to exceed your daily use by 25%, you'll be all set. Let's think about that a little... If you take that daily usage table that I did for the inverter section and add the calculated additional 12 volt appliance and lighting use, we can come up with a figure to work with... see below

  Appliance	Watts	Use Time	Watt Hours	Amp Hours
  19" color TV	120	3 hr.	360	36
  Satellite Receiver	20	3 hr.	60	6
  Computer/monitor	125	2 hr.	250	25
  Coffee Maker	1250	20 min	417	41.7
  Microwave	1000	15 min.	250	25
  			Total >	133.7
  Appliance	Amperage	Use Time	Amp Hours
  12 Volt lighting	6A (4 ea. 1.5A bulbs)	3 hr.	18
  12 Volt fan	3A	2 hr..	6
  		Total >	24	24
  			Grand Total AH >	157.7

  Looks like we'll need to replace about 160 amp hours (AH) of usage every day. If we figure that a 60-75 watt panel can produce 60 to 70 AH per day under perfect conditions, then it's reasonable to assume that the same panel will produce an average of about 35 AH per day, due to adverse weather conditions, time of year and other factors. Some days are sunny, some are cloudy..... For planning purposes, we can figure on that average output, per panel, of about 35 AH a day. Looks like we'll need at least 5 panels up there, and probably would be better off with 6 panels. There is always some loss of efficiency when recharging a lead acid battery and a couple of cloudy days will really hurt your overall charge capability! Looks like we will either have to conserve power a bit better, or do some serious investing in solar panels. The truth is, the above example is a bit on the energy extravagant side, but illustrates that it's easier to use power than it is to replace it! A small system, consisting of a single 55 watt panel, would provide adequate power to keep me in business for a week, provided that I am conservative and don't have cloudy weather. If it's cloudy, or I have poor exposure to the sun, I'll have to run the generator for a couple of hours every few days to charge the batteries.
      There are a number of very good sizing guides available on the web... RV Solar Electric has one you should look at... click here to check it out.

  Hybrid Systems. Again, sometimes the best answer is a compromise... a small solar system to save $$ on panels and a small generator to take up the slack when needed can be the most cost effective way to go. The JS Portable Power Company Homemade Generator, with a 100 Amp Alternator, will keep those batteries fully charged with only a couple of hours of run time a day..
  
  
  

• Wiring.  Now that your panels are mounted on your roof, it is necessary to get all those electrons from the panel to the battery. The best way is to use as heavy a gauge of wire as possible to reduce losses on the line over distance. Even though my panel maxes out at under 6 amps, I use 10 ga. wire to connect it. Bigger (within reason..) is better! Another problem is how to route the wires into the house. Drilling holes in the roof is always to be avoided when possible, so the best bet is to run it over the side and bring it in through a drilled hole under the eaves, sealing the hole around the wire with good silcone sealer (like WalMart's Shoe Goo). Once inside the house, the wire can be routed to the location of the battery bank and connected to the charge controller.

• Controllers.  Although it is possible to directly connect the solar panel(s) to the batteries, it is much better to use a charge controller. This device protects against overcharging of the batteries and also provides a diode to prevent reverse current flow to the panel at night. These controllers can be as fancy as your pocketbook can handle, or very simple. The simple ones will usually cost in the $50-$75 range and do the same job as the fancy ones with the meters and computer monitoring. The controller simply hooks into the charge wiring between the panel and the batteries.

  Sources.  Here are some links to a number of suppliers of alternative energy systems. Browse some of these sites to get a feel for what's available, costs and applications. Several of these sites have guides to help you design and size your own solar electrical system.
  Home Power Magazine: PO Box 520, Ashland, OR 97520. (800) 707-6585. http://www.homepower.com/
  RV Solar Electric: 14415 N. 73d St., Scottsdale, AZ 85260  (800) 999-8520. http://www.rvsolarelectric.com/
  Real Goods: 555 Leslie St., Ukiah, CA 95482-5507. (800) 762-7325. http://www.realgoods.com/
  Backwoods Solar Electric Systems: 1395 Rolling Thunder Ridge, Sandpoint, ID 83864 (208) 263-4290. http://www.backwoodssolar.com/
  Alternative Energy Engineering: Box 339, Redway, CA 95560 (800) 777-6609. http://www.alt-energy.com/
  Sierra Solar Systems: 109 Argall Way, Nevada City, CA 95959 (800) 517-6527. http://www.sierrasolar.com/
   

• Monitoring
  Most RVs come standard with a little analog battery meter or a small LED display. RV enthusiastists learn quicjly that these meters aren't very accurate and aren't much use if you really want to know what's going on in your 12 Volt system. One possibility is to purchase a good quality hand held digital volt meter and use it to monitor the voltage from your batteries. The drawback to this method is that you have to hook it up to your batteries whenever you want to take a reading. A better solution is to install a small digital panel meter and permanently connect it to your batteries. This way, the information is right there at your fingertips. There are a number of these battery monitors available. One place you can look to see some examples of what's available is at the Backwoods Solar Electric Systems website. Click HERE for a look at one of their catalog pages featuring meters. Most of the solar equipment retailers offer a variety of meters to suit your needs, but they can be a little pricey. Still, for an out-of-the-box solution complete with installation instructions, they're hard to beat. You can expect to pay $40-$50 for a simple panel voltmeter and as much as several hundred bucks for a really sophisticated system monitor. At the bare minimum, you should have an accurate voltmeter... even better is to have a voltmeter to monitor your battery's state of charge and an ammeter to see what kind of current is going to or from your batteries.
      Some of you may be thinking: "Why should I have to pay such close attention to my batteries? Can't I just sort of ignore them and hope for the best?" Well, sure you can! The problem is that when you're dependent on your batteries for all of life's little conveniences, it's real easy to use more juice than you put back in... sort of like overdrawing your checking account. The addition of a volt and amp meter will allow you to see how much current you're taking out of the batteries and how much you are putting back in via solar or generator charging. When I installed an ammeter, I was amazed at how much current just a few lights draw, not to mention other 12 Volt items like the furnace and water pump. It's definitely better to know for sure what's going on.
      If you plan to install, or have already installed an inverter, you may be able to purchase a very nice monitoring panel as an accessory to your inverter. Most of the major brands designed for RVs have this option available. It can tell you all you need to know and some even have provisions for outside source charge monitoring, from solar panels, for instance. It's worth checking into and will save you having to install your own monitoring system. See the links above in the inverter section and check out some of the manufacturers' webpages.
      One alternative for you tinkerers out there is to build your own! Simple, battery operated DC panel meters are available for under $10 and with a little work, you can have a very nice 12 Volt panel meter for cheap! A little more work and you can cobble up a very functional volt/amp meter. Let's see how:

  Project. Build a simple DC Voltmeter for your system.

  This is a simple volt meter that is easy and cheap. The meter runs off a single 9 Volt battery and is very easy to build and install. You can connect it to just about ant wiring in the system that carries unswitched 12 volts and it's small enough to fit just about anywhere. The parts as listed are available from All Electronics Corp. They have a website at http://www.allelectronics.com/ and you can download their catalog in PDF format and view it.
   

  • Parts list
  • 3 1/2 digit digital voltmeter, panel mount, battery operated, 200mv full scale. Can be purchased for about $10 from All Electronics Corp. 1-800-825-5432  Part # PM-128
  • Small toggle switch, SPST, pick up anywhere, Radio Shack, your junk drawer, etc. All Electronics Corp. Part # MTS-4 will do just fine.
  • 9 Volt Transistor radio battery.
  • 9 Volt battery connector. All Electronics Corp. Part # BST-8
  • 1 100 Kohm resistor 1/2 watt 0.5%
  • 1 9.99 Mohm resistor 1/2 watt 0.5 %

  
  Follow the directions included with the panel meter. The resistor values listed above are the correct ones for the meter available from All Electronics Corp., but your meter may specify different values to use. The resistors are installed in holes provided on the meter circuit board to form a voltage divider to set the range of the meter to 0-20 Volts. The meter instructions will explain how to do this. Attach the battery connector as specified in the meter instructions. Install the small toggle switch on the battery connector + lead... this is used to turn the meter on and off. You can omit this switch and have the meter on all the time, but it will run down the 9 Volt battery in about 6 months. I chose to use the on/off switch on mine. Mount the meter in your rig in a convenient location, preferably near a 12 volt source. Closer to the battery is better, but not super critical. Connect the meter input leads to the 12 volt source. A fuse would be a good idea if the circuit that you connect the meter to isn't already fused. A 1 amp fuse will be way more than enough, as the meter draws practically no current. See below for a diagram.

  
    Project. Build a DC Amp meter for your system.

  This is a little more difficult, but worth the effort. The same meter as was used above can also be used to measure DC current if a device called a Shunt is used. Put simply, a shunt is a very accurate, very low Ohm resistor that is placed in the DC positive line directly off the battery. By measuring the voltage drop across the shunt, we can determine the amperage flowing thru it.

  
     We will be using the same panel voltmeter as above to build our amp meter. Some basic wiring ingenuity and the use of a suitable switch will allow you to use a single panel meter for both functions... more on that later. First, the shunt must be built or purchased. You will need a .01 ohm shunt, one that's rated 10 mvolt / amp. Shunts are available from a variety of sources, but you can also build your own! I constructed mine from a set of 10 .1 ohm 10 watt precision resistors wired in parallel to produce the desired .01 ohm resistance. The resisters are connected by bus bars made of 4 strands of 12 ga. solid copper wire and the whole thing is connected using 8 ga. wire. .     .
                                                               
    The Block diagram for the ammeter looks like this: The meter, set up to it's 200mv full-scale range will measure up to 20 amps using this setup. A change in the meter resistor voltage divider will give you a range to 200 amps, but less resolution. I wouldn't recommend passing 200 amps through this homemade shunt, but it's capable of carrying 50 or 60 amps without frying. The 20 amp scale works well for me, but the one downfall is that this shunt and meter combo isn't large enough to allow the inverter to be hooked up through it. I originally designed this setup long before I had installed the inverter. It's still a very useful setup and may give some of you tinkerers out there some ideas for a design of your own....
    Here's a wiring diagram that I used to build my volt/amp meter for my rig. This allows you to use the one panel meter to monitor both amps and volts.

  When I designed my monitor panel, I wanted to have everything in one location. The panel has controls for the generator, the volt/amp meter, controls and indicators for the solar panel and a handy 20A cigarette lighter socket with a circuit breaker for heavy duty 12 volt loads. Whether you buy one or build one, it's really worth your while to have at least an accurate voltmeter in your rig to allow you to keep tabs on your battery condition while dry camping. It will extend the life of your batteries by preventing too deep a discharge and will give you the ability to see just how much power you are using and putting back in. Prevent those "bounced" energy checks!! ;-)
   

• Wiring
  Most of the 12 Volt wiring is done using 12 or 14 ga. twinlead. The most common seems to be red insulation to denote the positive wire. When in doubt, check with a meter to determine which is positive and which is ground. Many systems also use a crimp style connector to tap into these 12 volt wires to hook up lights and other low current devices. I don't personally care for these crimp connectors as they can fail over time, so any time I make a new connection, I use either wire nuts or solder and heat shrink to make secure connections.
      If you intend to install 12 Volt equipment, it's important to be sure that you use adequately sized wire to meet the amperage requirements of whatever it is that you're installing. Here's a table of wire sizes and amperage ratings that will provide some basic guidelines. This table leans a bit towards heavier wire than is absolutely necessary, but that's actually safer in the long run. Always provide fuse protection of any new wiring that you install. The fuse should be sized so as to protect the wiring from meltdown. Don't put a 20 amp fuse on a circuit wired with 16 ga. wire.

  Total Amperage  Draw	Up to 4'	4' to 7'	7' to 10'	10' to 13'	13' to 16'	16' to 19'	19' to 22 '	22' to 28'
  0 - 10	16 Gauge	14 Gauge	14 Gauge	12 Gauge	12 Gauge	12 Gauge	10 Gauge	10 Gauge
  10 - 20	14 Gauge	12 Gauge	12 Gauge	10 Gauge	10 Gauge	8 Gauge	8 Gauge	8 Gauge
  20 - 35	12 Gauge	10 Gauge	8 Gauge	8 Gauge	6 Gauge	6 Gauge	6 Gauge	4 Gauge
  35 - 50	10 Gauge	8 Gauge	8 Gauge	6 Gauge	4 Gauge	4 Gauge	4 Gauge	4 Gauge
  50 - 65	8 Gauge	8 Gauge	6 Gauge	4 Gauge	4 Gauge	4 Gauge	4 Gauge	2 Gauge
  65 - 85	6 Gauge	6 Gauge	4 Gauge	4 Gauge	2 Gauge	2 Gauge	2 Gauge	0 Gauge
  85 - 105	6 Gauge	6 Gauge	4 Gauge	2 Gauge	2 Gauge	2 Gauge	2 Gauge	0 Gauge
  105 - 125	4 Gauge	4 Gauge	4 Gauge	2 Gauge	0 Gauge	0 Gauge	0 Gauge	0 Gauge
  125 - 150	2 Gauge	2 Gauge	2 Gauge	0 Gauge	0 Gauge	0 Gauge	0 Gauge	00 Gauge

   

• Lighting
  RVs commonly use simple incandescent light fixtures. These work fairly well, but draw quite a bit of current per bulb. The most common bulbs used are 1073 or 1141 automotive bulbs and they draw about 1.5 amps a piece. These work well, as do the simple taillight rigs I use myself. Incandescent fixtures are inexpensive and can be found in any RV supply store or catalog. However, even they are inexpensive, it is worthwhile to consider alternatives to those standard incandescent fixtures.
      Fluorescent lights are excellent for producing large amounts of light for less current. Sunray and Thinlite both make high quality 12 Volt fluorescent lights in a variety of sizes and configurations. These make great kitchen and workspace lighting. They are a little pricey, at $30 - $40 a piece, but work well and last a long time. Avoid those really inexpensive fluorescent fixtures found in some automotive catalogs... they produce rather bluish light and tend to use up tubes at an alarming rate.
      For more efficient use of power, consider adding halogen lamps where possible. These fixtures deliver excellent white light for reading or detail work and use about 1/2 the power of standard incandescent lamps. You can easily construct one from the halogen headlamp unit out of any late model wreck.
   
• Appliances
  There are many 12 Volt appliances and accessories that can add a lot of pleasure without heavy expense or high power consumption. Some work very well and others are basically a waste of time. In my experience, anything that uses resistance heating to accomplish it's goal is a pretty sure bet to be a loser. A good example are the 12 Volt coffee pots you will see advertised in some RV catalogs. Trust me on this one.. they don't work. You will use up lots of battery power for very little result. The main reason is that these items were designed to be used in a vehicle with the motor running, so they are real energy wasters. Ditto on things like 12 volt frying pans and 12 volt toaster ovens. Just don't waste your money. On the other hand, there are a number of 12 Volt devices that will actually improve your quality of life. Here are a few of my personal favorites:
   

  	Definitely a great addition ... a "Fantastic Fan". This is a high volume 12 Volt fan that you install as a roof vent. It draws very little current and can really help keep your home cool without using A/C. On low, it only draws a couple of amps and on high, it will exchange the air in a room for cooler outside air in a minute or two. Find them at any camping retailer... Try: http://www.camperschoice.com/ http://www.campingworld.com/ Adohen Supply Co.
  	These are great little fans as well... they run on 12 volts and move a lot of air for only about a 1.5 amp current draw. A few of these, strategically placed around your home will keep you a lot cooler! Find them at camping stores or lots of automotive parts stores.
  	If you build in some 12 Volt Cigarette lighter outlets around your house, these small automotive map lights are handy additions! I use one to light my computer desk and it's great for providing light to type by without a big battery drain. They are also handy to use as night lights and can be removed and stowed when not needed.

• Power saving suggestions.
  All right... we've got our battery bank squared away, figured out our charging sources, installed an inverter and are all ready to belly up to Life Off The Grid! Great! Here are a few tips on how to make life easier for you and your "own private power company". The whole trick to successful off-gridding is conservation. I don't mean huddling around a single flashlight to save battery power... I mean fully utilizing all the functionality of your 12V home without running out of energy. Practice makes perfect, and as you get used to how your system works, you'll feel more confident being electrically independent.
  • First off, start out with fully charged batteries.
  • Turn off lights when you don't need them.
  • Turn the radio off when you go outside.
  • Pay attention to those things that draw power and shut them down when you're not actually using them.
  • Watch the battery meter and get a feel for how healthy your batteries are. Refer to the tables from the beginning of this ebook. If possible, recharge your batteries before they get down to 50% of capacity, as this will extend their life.
  • If you are using solar panels, pay attention to what's overhead. Mount them so as to take the best advantage of the sun.
  • Take advantage of the current that your solar system generates during the day and run high current devices then... charge your laptop batteries with the inverter for later use, take showers and such , etc.
  • When operating on the inverter, beware of phantom loads!  Here's a possible scenario: You turn on the inverter to run your computer. That's fine, but if your TV set and satellite receiver are still plugged in from last night, chances are they are still drawing power. This increases the amperage draw of the inverter and can run down your batteries much faster. My Satellite receiver draws exactly the same amount of power whether it's on or "off". My 19" TV draws about 120 watts when it's on and about 20 watts when it's "off". Pretty sneaky, huh? One answer is to put inline switches in the power cords of offending devices. Or, you can simply unplug them.
     
• The bottom line....
  • Pay attention to your batteries. Maintenance and proper selection pay off in long life.
  • Provide for adequate charging and monitoring. Don't just "plug it in and forget it".
  • Make an intelligent inverter choice, based on your needs and battery capacity.
  • Consider adding some solar charging capability to your system. Do your homework and remember: the best thing about solar is that it's modular. Buy some now, expand the system later; you don't have to buy everything all at once.
  • A good monitor panel will make your life much easier. Plus, they're fun to play with! Whether you make your own or buy a fancy one, it will give you total control over your own power company.
  • If you choose to add new accessories, follow good wiring practices. Just because it's only 12 volts doesn't mean that you can do a half-assed job. Use proper wire, of the proper size, and fuse new circuits to protect against overloads.
  • After all this work, take time enjoy the freedom that electrical independence can bring.
  • And most of all, don't ever let that 12 Volt electrical system intimidate you again.... Knowledge is Power, and with your knowledge, you should have plenty of power, no matter where you park!