New Energy Watch

Getting Into 12-Volt Power

 If you want to save the world from global warming and help your own bank account in the process, there’s no better way to do it than through conservation. It doesn't matter how many MPG your car gets  --  you can’t do better than leaving it parked and taking public transportation or riding a bike. It’s good if you’ve switched to compact fluorescent lamps for half of your lighting, but it’s better if you just  leave off every light that you’re not using (giving yourself a bit of leeway for cheeriness).

Until you get used to the habits of conservation, the practice isn't very exciting. Even then a lot of us feel the need to quantify what we’re doing and see the tangible results of our efforts. Thus, gadgets like the Blueline PowerMonitor  come in handy.

It can also be fun to take a hands-on approach, tapping into wind power, solar energy, water power, and so on. One of the best reasons to get involved is that it gives you direct understanding of how much energy it takes to accomplish things, and one of the most direct paths to that understanding is through 12-volt power systems. Yes, the 12-volt world can get technical and complicated, but the basics of DC volts, amps, watts, and ohms are fairly simple. Once you get a grip on these things, you'll view the uses and misuses of energy in a different light.

Can you get involved with 12-volt power enough to make a positive difference, have fun, and see the results of your efforts, without incurring much expense? Absolutely, and you’ll be following the well-traveled path of thousands of boaters and RVers who rely on 12-volt DC electrical systems to do much more than manage engines and instruments. Check out the other posts on 12-volt power here, and make this a conversation by posting your comments and ideas. 

~ Doug Logan, New Energy Watch

A Simple Solar Panel

There are some great  statistics about the amount of energy we could harvest from the sun if we were able to harness solar power efficiently and on a wide-scale basis. As the National Renewable Energy Lab  reports, “Every day, more energy falls on the U.S. than we use in an entire year.” An interesting point, and doubly interesting when considered in relation to another NREL factoid: “Every day  more solar energy falls to the Earth than the total amount of energy the planet's 5.9 billion inhabitants would consume in 27 years.” (That tells us something about the disproportionate use of energy in the U.S. Granted, we get a lot done with that energy, but we also waste enormous amounts of it.)   

Solar power is clean, quiet, and surprisingly inexpensive after clean-energy rebates have been reaped and the remaining cost of equipment has been amortized. A lot of us aren’t in a position, either physically or financially, where we can do much with solar power. On the other hand, a lot of us are perfectly solar-capable, but the notion of “going solar” is daunting in terms of research, paperwork, initial investment, construction hassles, and so on. So we do nothing.

Well, it doesn’t have to be all or nothing. You can get involved in solar energy in a meaningful way for about $300. In other posts we describe deep-cycle batteries that store energy derived from the sun,  and inverters that turn 12-volt DC power into AC.

The heart of the system is the solar panel. For less than  $150 you can get a small, plug-and-play panel with an output of 15-18 watts, giving a current flow of a bit over one ampere (at 12 volts). With a decent amount of sunlight, that’s enough to keep a 12-volt deep-cycle battery topped up between regular discharges of, say, 8 to 10 amp-hours. At least that’s been our experience over about eight years of experimentation with just such a system. See our 12-Volt Basics post for more information on watts, volts, and amps.

With that amount of replenishment available, you can do a host of small electrical chores, including running lights, making your morning coffee, and recharging power tools and hand-held vacuum cleaners. This accomplishes two things. First, it gets you familiar with solar energy combined with 12-volt DC power. Second, it takes a fraction of the load off the power grid. When millions of people contribute a bit, day after day, big things happen.

For solid information on how photovoltaics work, visit the U.S. Department of Energy’s Photovoltaics Basics page.

For a review of a small panel we can recommend, see Product Review: ICP Sunsei Solarcharger 1200.

~ Doug Logan, New Energy Watch

Product Review: ICP Sunsei Solarcharger 1200

For most of our experiments with trickle-charging and maintaining batteries over the years we’ve used a simple 15-watt panel from ICP Solar,  usually in conjunction with a charge controller, but often by just keeping an eye on things and a multimeter handy. That panel has withstood baking sun, snow and ice, scratches, drops, short-circuits, and even a fracture of the glass in the back of the case (from being stepped on). It’s still going strong. Meanwhile, ICP has put out a updated panel under the Sunsei brand name, an 18-watt module called the Solarcharger 1200. We ordered one and have had it outside the workshop for a while, topping up a battery used for various chores, including recharging other batteries and running a small TV. We also ordered the optional but highly recommended Sunsei charge controller, so that we can more or less forget about monitoring the battery.

While the glass area of the panel seems about the same as its predecessor, it’s better protected on the new model, and ICP has made big progress with weatherproofing, connectors, and accessories. Shown in the photo here is a “what’s in the box” selection that came with the Solarcharger 1200. From left to right, 1) 10-foot extension power cable with male and end connections, 2) 1.5-foot connector with O-terminals, 3) 1.5-foot connector with female 12-volt socket., 4) 1.5-foot connector with male 12-volt plug, 5) 1.5-foot connector with heavy-duty battery clamps, 6) double-ended cable to connect two panels together 7) connector with bare wires for connecting to charge controller. At bottom is the supplied mounting hardware.

We can recommend this panel for several reasons. First, it does what it’s supposed to do. (Whether it can survive the trials and tribulations suffered by its forebear remains to be seen.) More importantly, it’s completely simple to set up. The ICP engineers have done a great job of making the whole process --  including the ability to add more panels and greater capacity -- completely plug-and-play. There's also a 10-year warranty on the product.

For those who don't even want to contemplate wiring a charge controller between the panel and the battery, ICP makes the same panel in Model 1201, which has an integral charge controller. We haven't tested that one. The links below are to the Model 1200 (note that the Amazon photo is wrong and there's a typo in the headline -- "120-volt" instead of "12-volt") and the optional Sunsei charge controller, which can handle up to a 10-amp current.

Simple 12-Volt Solar: Every kWh Counts

With a few bits and pieces -- a battery, a solar panel and charge controller, and either a 12-volt socket (cigarette lighter adaptor) or an inverter to change DC power into AC -- you can get involved with solar energy in a basic, inexpensive way, and gather enough energy from the sun to power quite a few small appliances, as well as recharge batteries that run everything from vacuum cleaners to power drills and flashlights.

Every watt of energy saved helps break our disgraceful dependence on OPEC (for a quarter to a fifth of our daily oil needs). What helps the most is developing the habit of looking for ways to conserve, and using alternative sources of power whenever possible. Running most of your handheld power tools on energy gathered from the sun is a great way to start. And it’s fun.

Most of us who run boats and RVs, and who tinker a bit under the hoods of our cars, are familiar with 12-volt batteries, at least the type used to start engines, as opposed to deep-cycle 12-volt batteries, which are designed and built somewhat differently, and for different purposes. If you’re new to 12-volt systems, read 12-Volt DC Basics, then 12-Volt Safety Issues. After that, if you’re interested in getting involved, read more fundamentals in the other posts in our 12-Volt Power category. If you're not a tinkerer, and would prefer to jump into solar power with both feet, consult www.findsolar.com for professional installers in your area.

Doug Logan, New Energy Watch

12-Volt DC Basics

DC means Direct Current. It's the kind of electrical current produced by batteries. 12-volt DC batteries are the kind found in cars, trucks, RVs, and boats.

AC means Alternating Current, the kind of electrical current found in wall sockets in buildings.

In buildings, we can replace any amount of AC electricity, from a small fraction to 100 percent, with energy collected by solar panels and stored in 12-volt DC batteries. Direct current from the batteries can be changed to AC by means of an inverter, or it can be used directly to run equipment designed for DC; for example, a car vacuum that plugs into a cigarette lighter socket.

On this website we talk about very basic 12-volt concepts and systems. If you would like to replace a bit of your AC requirement with energy derived from the sun -- get your toe in the water for a minimal investment -- this will be a good place to start. If you'd like to get involved with solar energy in a serious way, try www.findsolar.com.

Now, on to more basics. Note that these are utterly rudimentary definitions. There's much more to know, but you don't need to know much more in order to get involved.

Voltage/Volts = the amount of potential energy available to push electrical current. Think of it as pressure in a water system. For a battery-powered system, think of a water tower with a big tank on top. It's drained by gravity, and the way water flows out of it depends on the diameter of the pipe, the length of the pipe, and the weight of the water in the tank at any given time.

Amperage/Amps = the flow of electrical current through conductors like wires. Think of it as the amount of water current flowing through a pipe.

Wattage/Watts = the amount of energy expended, or used. Think of it as the water that fills a glass (a few watts) or a swimming pool (lots of watts).

Ampere-hours (Ah) = the current in amperes multiplied by the amount of time it flows. Deep-cycle batteries, the kind used for solar-power storage, have ampere-hour capacity ratings that give a general idea of how many amps can be drawn from the battery for how long. In a perfect world, a battery rated for 90 amp-hours would be able to give you 90 amps for one hour, 45 amps for two hours, one amp for 90 hours, and so on. In reality, you can and would use only a portion of those amp-hours before the battery should be charged again.

Ohm = a measure of resistance in a wire or other conductor. Resistance is determined both by the wire's length and its thickness, or gauge. The thicker the wire, the more easily current will flow through it. In a
simple 12-volt solar panel arrangement, resistance can exist between the solar panel and the battery, and between the battery and whatever it's supplying power to. Resistance always creates heat, and the greater the resistance, the more heat. Try to put too much current through too small a wire, and you can create enough resistance to start melting things and causing fires. This can happen even in a simple 12-volt system, so always use common sense and generous wire gauges. See 12-Volt Safety for more.

Now, here are some of the easiest equations you'll ever have to use:

• Volts x Amps = Watts
• Watts / Amps = Volts
• Watts / Volts = Amps

If you read the owner's manual for any electrical appliance, or the stamped electrical infomation on the appliance itself, you can usually discover what it needs for energy input and how much energy it uses. Then it's a matter of arithmetic to find out if your 12-volt system can handle the task. Bear in mind, though, that sometimes there's more to the story than simple volts, amps, watts, and ohms. For example, an inexpensive automotive-grade DC-to-AC inverter can be used for a myriad of tasks that are electrically simple, like running an incandescent light bulb, but some appliances that are sensitive to interference, like TVs, often need to be run through a better, more expensive inverter.

For starters, we'd recommend one of the simpler inverters. A 400-watt model from an auto-parts store or online retailer will cost about $35. If you find that you need a more sophisticated inverter later, you won't have too much of an investment in the simpler ones. See our Inverters section for more detailed information.

~ Doug Logan, New Energy Watch

12-Volt Safety Issues

Working with 12-volt systems is easy, and relatively safe, compared to 120-volt AC. You can create 12-volt potential by linking together just eight 1.5-volt flashlight batteries – AA, C, or D (1.5 x 8 = 12). The danger of shock is minimal. But 12-volt systems are far from benign, for several reasons.

First, even if a 12-volt battery can’t give you a significant direct shock, it can deliver a whopping big discharge of current. That’s how a 12-volt battery can run a starter motor to get cars and trucks running. That discharge of current can be violent, as you’ve noticed if you’ve managed to bridge the the terminals with a wrench or a wire. If you have a metal watch strap or a ring on, and that metal becomes part of the short circuit, you can get hurt. If you’ve used jumper cables, you’ve probably seen a good-sized spark as a clamp comes in contact with a terminal. So be alert to the danger of short circuits and sparking.

Second, when you produce a spark in the wrong environment, you can cause an explosion. Batteries produce hydrogen and oxygen when they’re charging  -- no problem if the battery is well-ventilated, but a potentially explosive mixture if the battery is in an enclosed, poorly ventilated space or container.

Third, inadequate wiring, unfused wires, poor connections, and corrosion can cause electrical fires, which in turn can catch other flammable material like cloth or paper on fire. If you get involved in a simple solar project with a 12-volt battery, follow the instructions, use big enough wire with short enough wiring runs; use fuses where necessary, and never run wiring under a rug or through any flammable material.

Fourth, the liquid electrolyte in flooded-cell batteries is mostly sulfuric acid, which will eat your clothes and burn your skin, and can blind you if you get it in your eyes. When inspecting and testing the flooded cells in your battery, wear glasses or other eye protection. Wear rubber gloves. When you pry off the cell covers with a flat-bladed screwdriver, do it gently and carefully, and make sure the battery is on a stable surface. If you do get electrolyte on you, rinse thoroughly with fresh water.

These warnings aren't meant to scare you off -- far from it. As we said at the top, working with 12-volt batteries is relatively safe, but you must read the directions, use common sense, and be alert. That's a pretty good combination of habits for any project.

~ Doug Logan, New Energy Watch

Deep-Cycle Batteries

We're all familiar with the kind of 12-volt batteries that start vehicles and are then charged by the alternator when the vehicle is running. These starting batteries are designed to deliver a lot of amps -- a very powerful current -- in a short time. Deep-cycle batteries can perform starting duties, too, but they're built with thicker plates that are designed to withstand numerous  cycles of deep discharging and charging. They're more expensive than starting batteries, but, properly cared for, last for years of service.

Deep-cycle batteries like the one pictured here are available in three basic types -- flooded, gel-cell, and absorbed glass mat (AGM). Each type has its advantages, but for the simple purposes we're discussing here, we'd recommend plain old flooded-cell batteries. These are less expensive and more forgiving of charging foibles than the others kinds, and they work just as well -- again, given periodic inspection and maintenance. See 12-Volt DC Basics for a bit more information on amps and amp-hour ratings.

We hesitate to recommend an online purchase of deep-cycle 12-volt batteries, for a few reasons. First, they do have a shelf life. All else being equal, a battery that was manufactured six months ago will be healthier and last longer than one made 18 months ago. Second, shippers and handers have been known to leave shipments in freezing or very hot conditions for long periods before before delivery to the store. Third, the suckers are heavy and expensive to ship. Save the UPS guy's back and make sure you get a good battery by going to the store yourself.

Check the date of manufacture, check the battery's standing voltage, and if possible have the storekeeper apply a load test to it. If it passes with flying colors, as is likely, then all you have to do is check the condition of the cells once in a while (wearing eye protection), and add a bit of distilled water if necessary.

Deep-cycle batteries are available at all sorts of hardware and department stores, as well as places that supply RV-ers and boaters.

Inverters

Inverters change DC current from a battery into AC current that can be used to power any light or appliance that demands no more than the rated wattage of the inverter. Small inverters have one or two grounded receptacles and can plug into a cigarette lighter socket. Larger ones have two or more receptacles and need to be clamped directly to the battery terminals. Inverters almost always have cooling fans, and demand a portion of the battery’s power for their own operations. This is why it’s always more efficient to use 12-volt appliances, or take DC power directly from the battery. Nevertheless, inverters let us run all sorts of gear and gizmos.

There are three levels of sophistication in inverters, according to the shape of the electrical wave form they deliver. The highest level is the true sine wave inverter, which will power pretty much anything that runs on AC without interference, interruption, or trouble. These are the most expensive inverters. At the other end of the scale are inverters that put out a “square” wave form. These can cause interference in some sensitive appliances like TVs and other receivers, and devices with rheostats/dimmers, but are fine for incandescent lights, pumps, and other “dumb” equipment. In the middle are “modified sine wave” inverters, which can often bridge the gap in wave form performance. Most inverters on the market today are modified sine wave models, and true sine wave models are coming down in price.

An inverter’s rated wattage should probably be matched to a battery’s amp-hour rating. Some experts say that a ratio of about 5:1 is best – so for a battery rated at 100 amp-hours, don’t use an inverter rated above 500 watts. A good combination of common elements would be a 90-Ah deep-cycle battery and a 400-watt inverter.

For the projects we’re covering here, we'd recommend a simple, modified sine-wave or square wave inverter. A 400-watt model from an auto-parts store or online retailer will cost about $35, and in most cases will run everything from a light to a TV. If it turns out later that you need a more sophisticated inverter, you won't have too much invested already.

Light Chooser from EnvironmentalDefense.org

Here's an excellent click-by-click locator for energy-saving, long-life bulbs/lamps for pretty much all applications -- inside, outside, ceiling fans, dimmable, etc. It's available on the website of Environmental Defense.org.

Energy-Saving Light Bulb Chooser

Hydrogen vehicles versus plug-in electrics

Nothing will make a bigger difference in global warming than transportation tranformation. Below is a link to a New York Times article that outlines where the major car companies are today on development of hydrogen vehicles. They're come a long way. In fact, if the fueling infrastructure were in place today, there would be viable cars to buy. And they would be bought.

On the Road, Hope for a Zero-Pollution Car

The Toyota Prius modified by ECD Ovonics, and the Honda FCX look particularly promising, but credit is also due to Ford and GM. Their engineers have been hard at work for years, despite being undercut by old tech, old business allegiances, workforce inertia, and oblivious marketing managers.

Meanwhile, we have Lee Iacocca placing his bet on the plug-in electric car in his new book, Where Have All the Leaders Gone. It's worth quoting a couple of questions and answers from CNN Money's recent interview of the author:

What do you think of global warming?

I campaigned for George W. Bush in 2000 and against Gore because I thought Gore was a little nutty when he was talking global warming. Now I think it's a serious problem. As I said in my book, I never thought I'd pay $8 to go see Al give a PowerPoint presentation. There has to be a solution that everybody's got to join - the whole planet, not one country - and so I've become a believer. I didn't get too enlightened until years after I left the auto business.

What can the auto industry do?

Plug-in hybrids. I think they're virtually here now. We've still got to get better batteries, of course, but hybrids are good. Expensive and complex, but they do the job and get good gas mileage. That's the wave of the future.

Some people are betting on hydrogen-powered fuel cells.

I think that's way off. Where are you going to get all that hydrogen? How are you going to store it in the car? How are you going to distribute it? That's a long-term problem.

We wonder whether Iacocca would have modified his view if the Times article had been out before he finished his manuscript, which would have been at least six months ago. NEW's view is that both technologies are desirable and necessary. Bring 'em on.

Here's a link to the full Iacocca interview at CNNMoney.com.