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Portable 12 Volt 17 Watt Wind Generator with Automatic Furling

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Portable 12 Volt 17 Watt Wind Generator with Automatic Furling I've just designed and built a practical, portable 12 Volt 17 Watt wind generator that is ideal (and appropriate) for setting up in campgrounds, parks, Earth Day exhibitions, research stations, and third world homesteads. On "light breeze" days (5mph) when most wind generators are becalmed, this light-and-nimble unit reliably generates power, at charging levels, fully taking advantage of the erratic, gusting winds that are so common in near-ground conditions. A 48VDC, 1,600 rpm brushed permanent magnet motor (#370-350-00 / PE24113G -from a medical centrifuge), with a standard keyed 5/16 inch diameter steel shaft, was used to serve as the generator. A shaft arbor, 3/8-24 right hand (Grainger Item# 3ZN05 / Dayton Item# 3ZN05) was fitted on the shaft, to use as a 12 Volt generator, @ 550 rpm, when turned clockwise. The motor, weighing in at just under 3 pounds, has permanently lubricated bearings, but is not weatherproof. Note: If you plan to use a counter-clockwise set of blades, the timing of the "generator" brushes (2 carbon brushes) and internal commutator is such that the same amount of power (Amps and Volts) is also generated when turned counter-clockwise, but be aware that the shaft arbor manufacturer's suggestion as to "right-hand" and left-hand" thread pertains to motors only, and not wind generators, where the just the opposite thread is required. Note that the Grainger Shaft Arbor requires a thin, soft metal shim inserted against the flat face of the standard keyed generator shaft, for the allen set screw (which has a knurled cup point) to bite into and firmly hold the arbor in place. I used 2 layers, fashioned from an aluminum beer can. Or, use a replacement allen set screw with a soft brass core. Also, two, 1-1/4" thin neoprene washers are needed to pad (and grip) the 1-1/4" steel washers that come with the shaft arbor. The original shaft arbor nut was also replaced, with a nut

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Portable 12 Volt 17 Watt Wind Generator with Automatic Furling
by shastalore on April 12, 2009 Table of Contents intro: Portable 12 Volt 17 Watt Wind Generator with Automatic Furling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . step 1: Stock High-Speed Blades for the Wind Generator: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . step 2: Simple Furling Device for the Wind Generator: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . File Downloads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . step 3: Shortening the Length of the Blades for a Safer, More Portable Device: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . step 4: Tower and Rigging for the Portable Wind Generator: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . step 5: Physical Limits of the Portable Wind Generator: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Related Instructables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Advertisements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 3 5 5 6 7 8 8 8

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

intro: Portable 12 Volt 17 Watt Wind Generator with Automatic Furling
I've just designed and built a practical, portable 12 Volt 17 Watt wind generator that is ideal (and appropriate) for setting up in campgrounds, parks, Earth Day exhibitions, research stations, and third world homesteads. On "light breeze" days (5mph) when most wind generators are becalmed, this light-and-nimble unit reliably generates power, at charging levels, fully taking advantage of the erratic, gusting winds that are so common in near-ground conditions. A 48VDC, 1,600 rpm brushed permanent magnet motor (#370-350-00 / PE24113G -from a medical centrifuge), with a standard keyed 5/16 inch diameter steel shaft, was used to serve as the generator. A shaft arbor, 3/8-24 right hand (Grainger Item# 3ZN05 / Dayton Item# 3ZN05) was fitted on the shaft, to use as a 12 Volt generator, @ 550 rpm, when turned clockwise. The motor, weighing in at just under 3 pounds, has permanently lubricated bearings, but is not weatherproof. Note: If you plan to use a counter-clockwise set of blades, the timing of the "generator" brushes (2 carbon brushes) and internal commutator is such that the same amount of power (Amps and Volts) is also generated when turned counter-clockwise, but be aware that the shaft arbor manufacturer's suggestion as to "right-hand" and left-hand" thread pertains to motors only, and not wind generators, where the just the opposite thread is required. Note that the Grainger Shaft Arbor requires a thin, soft metal shim inserted against the flat face of the standard keyed generator shaft, for the allen set screw (which has a knurled cup point) to bite into and firmly hold the arbor in place. I used 2 layers, fashioned from an aluminum beer can. Or, use a replacement allen set screw with a soft brass core. Also, two, 1-1/4" thin neoprene washers are needed to pad (and grip) the 1-1/4" steel washers that come with the shaft arbor. The original shaft arbor nut was also replaced, with a nut with a thicker profile, with a nylon locking core. This portable wind generator is ideally suited for one 12 Volt, 21 Amp Hour sealed lead acid battery. Granted, that's not much power, when compared to typical permanent, stationary wind generators. But this lean-and-mean device was designed to fill in the void, to reliably provide 12VDC power to remote, inaccessible locations.

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

step 1: Stock High-Speed Blades for the Wind Generator:
After running the "generator" through a series of bench tests, it became obvious that my simple homemade PVC blades (300 max. rpm) would require a gear-up to properly turn the generator, an inefficient scheme that I was not wild about. And I was also reluctant to commit myself to a number of weekends designing, developing and refineing a set of small, lightweight blades that would achieve the necessary direct-drive speeds (550+ rpm), so I purchased a matched set of three Air-X Airfoil blades. 22-3/16 inches long, and designed for a clockwise rotation, when viewed from the front (shaft end), each with two .25" holes spaced at 23mm (25/32") on center. Having only about 1/4 the torque of the much larger Air-X generator, the 17 watt generator spins very easily, in the slightest of breezes. The blades were mounted on a 5-3/4" diameter, 3/16" thick, ABS faceplate (blade hub), and carefully drilled out to handle either a 3-blade arrangement, as well as a 2blade arrangement option. The blades were mounted to the backside of the faceplate (hub), to position the mass of the blades as close as possible to the shaft bearings. 2 blades are more portable, being easier to stow, protect from damage, and transport, but tend to teeter on the generator shaft, in actual practice. But, after a series of tests, I decided on the 3-blade arrangement, as it provided better performance in low wind conditions (actually typical for many locations). I fashioned a discarded (actually I'm a hopeless pack rat) thick-walled plastic easter egg ornament into an aerodynamic parabolic plastic nose for the hub, and outline-cut the hub to 4-7/8" diameter, flush with the parabolic nose. The arrangement allows for a smooth flow of air through the blades and greatly enhances the performance of the generator, in low wind speeds. The Air-X blades, in a portable environment, are much more exposed to rough handling and damage, than they would experience in a permanent installation. A triangle shaped box will soon be built, to carry the blades, hub, shaft arbor and nose, together as one unit, in order to protect the sharp, thin blades from dings and damage, and ease installation onto the generator shaft, in the field.

step 2: Simple Furling Device for the Wind Generator:
After a series of tests with the Air-X Airfoil blades, I then mounted the generator to a National brand spring hinge (Model# N190-736 V122), to serve as a furling device. With the weight of the generator too heavy to act as a vertical-furling device, the lightweight spring hinge worked quite well as a side-furling device. The generator was mounted on a block of varnished wood, with the axis of the generator offset 1-5/8" from the axis (or pivot-point) of the hinge. The 1-5/8" offset provides the necessary leverage for the furling to properly engage when the wind speed reaches 9-10 mph. A wind speed of 9-10 mph creates a pressure of about 2 pounds on the spinning blades, initiating the furling process, and keeping the DC voltage output, from the generator, at a manageable level. A 1-1/2" diameter hard nylon wheel was also mounted (with a large, long woodscrew, as the axle) to support the 5" swing of the furling generator. A rubber bumper was also added to the rear end of the generator to provide a soft-stop @ 90 degrees to the wind. Some sort of furling device is required, when using Air-X blades, as they are quite capable of speeds of over 2,000 rpm, and, at that rate, require a generator with a much more thicker shaft, and also require a OEM diecast Air-X hub. My simple ABS hub (and tiny 5/16 inch diameter generator shaft) is only suitable for speeds up to about 750 rpm. Also, automatic furling eliminates the higher generator rpm's that cause premature wear on the relative small generator bearings, not to mention the possibility of burning out the electronic charge controller, which is usually rated with an upper voltage limit, as well as the strain on the lightweight portable mast and rigging. Here are the results of the generator, with three Air-X blades, and furling device (but before the parabolic nose was added) under actual wind conditions (before the automatic furling kicks in): Wind Speed (MPH): VDC: Amps: RPM: Watts: 3 5 0.15 186 0.8 3.8 8 0.31 269 2.5 4.4 10 0.42 325 4.2 5.7 15 0.83 533 12.5 6 16 0.87 553 13.9 6.8 17 0.90 573 15.3 9 20 1.02 634 20.4 (sorry about the crude chart, but this site has a very basic word processor -see pdf chart below) The wind generator maxes out at 24VDC, with the furling kicking in -no matter how fast the wind blows, although sudden gusts will sometimes generate short bursts of up to 34VDC, before the tail properly orients the wind generator and enables the automatic furling to take effect. The electronic charge controller is rated up to 25VDC (but takes the occasional 34VDC bursts in stride) and process it into a safe 14VDC - 16VDC for the sealed lead acid battery pack.

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

File Downloads
Windspeed vs Power Chart.pdf ((612x792) 9 KB) [NOTE: When saving, if you see .tmp as the file ext, rename it to 'Windspeed vs Power Chart.pdf']

step 3: Shortening the Length of the Blades for a Safer, More Portable Device:
Even in mild wind conditions, the Air-X blades spin quite fast -so fast the wicked "hiss" they generate actually makes my skin crawl. The thin, sharp, dense blades could easily kill anyone who gets in their way. You would NOT want to use these blades on a yard ornament. I painted the blade tips fluorescent orange and used fluorescent orange guy-lines to brace and support the mast. The generator blades are now well out of harm's way, with adequate, visible rigging in between. In an effort to make the wind generator safer, more manageable -and portable, I carefully examined, and then sawed 4 inches off the ends of the blades (to a new over-all length of 18-3/16 inches long) and, after adding the parabolic nose, have yet to detect a change in the performance characteristics of the highly engineerd blades, except in the furling. The generator actually needs to be re-mounted on a thicker block of varnished wood, with the axis of the generator offset to a new position of about 2-5/8" from the axis/pivot of the hinge (but this has not been tested yet). A wind speed of 9-10 mph will now put a pressure of about 1.37 pounds on the spinning blades, initiating the furling process, and keeping the DC voltage at a manageable level. Later... in an effort to make the wind generator even more safer, even more manageable -and even more portable, I sawed off another 5-1/16 inches off the ends of the blades (to a new over-all length of 12-1/2 inches long). And the generator still flywheels in 5 mph winds, generates a charging current at 7 mph. But, now, the unit doesn't furl until 12 mph winds, producing up to 40 Volts. As the spring in the spring hinge is not designed to be tampered with, to a weaker tension, the generator actually needs to be re-mounted on a thicker block of varnished wood, with the axis of the generator offset to a new position of about 3-3/4" from the axis/pivot of the hinge (but this has not been tested yet). A wind speed of 9-10 mph will now put a pressure of about .67 pounds on the spinning blades, initiating the furling process. But instead of fashioning new wooden generator mounting blocks, a quicker (if not elegant) way to initiate furling, to a lower wind speed, is simply to attach and stretch a simple rubber band, from the right-rear of the generator, to add .5 - 1.5 pounds of tension, coax the blades off their 90 degree (perpendicular) to the wind orientation, to advance the furling process, keeping the DC voltage to a manageable level. After all, once the blades tilt past 90 degrees, all it only takes about 1 pound of wind pressure to force (and hold) the blades into a 0 degree (edge-on) position, fully furled, which is the same regardless of the blade lengths. I enjoy designing and building aesthetic

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

things, but there is no denying that the world is really held together with scotch tape and bailing wire. The spinning blades of a wind generator produce about as much pressure as a solid disk, of the same diameter. That explains why reducing the length of the blades will always require some sort of loosening of the spring tension (or leveraging) of the side-furling device: To change that simplified frontal "circle" into a more controllable ellipse, as viewed from the front, whenever the wind threshold is reached. Some quick math indicates that the improvised generator, with full-length blades, without furling, could possibly generate 70VDC, 100 watts, @ 32mph (2,150rpm, which the Air-X blades, on a special Air-X hub, are fully capable of). But such voltage is beyond the ability to harness into any practical, portable capacity -not to mention designing a truly portable tower that could stand up to such a wind, with a generator that does not furl. To complicate matters, many wind generators are marketed, posting their maximum watt rating -in almost gale-force winds, and novice owners mistakenly purchase highcurrent 12 Volt appliances, with the expectation their wind generator will always be able to power them. A good rule of thumb is 15% of advertised wattage equals the average wattage you'll probably get, in actual field conditions. Reputable dealers may advertise the maximum wattage in their headlines, to, understandably, catch your attention, but will also post a chart of actual watts, for given wind conditions.

step 4: Tower and Rigging for the Portable Wind Generator:
Designed to fully take advantage of gusting wind conditions, the wind generator has an unusually large tail fin, as well as a ball bearing fitting on top of the mast. This enables the unorthodox device to quickly seek out and turn into the next wind gust, with the flywheeling blades always ready to harvest the often erratic and meager winds. The large tail fin also stabilizes the device during furling, holding the wooden body straight-and-true, into the wind. A lightweight, but strong, 24" long stainless steel mast-pivot tube was cannibalized from an extendable shower curtin rod, from a local hardware store. The tube is a sturdy thin-wall construction, internally butted with plastic sleeves on the ends, providing a low-friction pivot that slips perfectly over the 1" diameter fiberglass mast. The generator, Aix-X blades, wooden mount, tail fin, stainless steel mast-pivot tube, and power cord all weigh in at 9-1/2 pounds, total, and mounts lightly on top of an extendable 10 foot tall fiberglass mast pole (actually a modified tree pruning pole), in perfect balance. There's also a 15 foot tall extendable fiberglass tree pruner on the market, providing better wind exposure, that should work quite well, with the same rigging. 4 guy-lines and hardware mount complete the rig. The generator, from shaft arbor tip to tail, measures 45 inches. The power cord is routed through the ring-shaped ball bearing fitting, and inside the hollow, 10 foot tall fiberglass mast. A standard RCA audio jack, used as an electrical connector, slips easily through the 5/8" diameter hole in the ball bearing fitting of the mast and down through the hollow mast. A slip ring (rotating electrical connection) is not needed, as a portable wind generator only pans a total of about 270 degrees, on a typical day. The rigging attaches to a square piece 5" x 5" plywood, 11/16" thick, and glue mounted (PVC glue bonds well on both surfaces) to a PVC pipe which slips over the 1" diameter fiberglass mast. A thumbscrew tightened ring was fitted over the radial-cut end. 4 angled, thin plywood braces will later be added to the underside of the 5" x 5" plywood, for reinforcement. The 4 guy-lines are firmly anchored into the ground with 17" long, heavy, steel "cork-screw" stakes. The entire rig is easily set up and taken down by one person.

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

step 5: Physical Limits of the Portable Wind Generator:
I've test run this generator in winds up to 35mph (a "moderate gale"), but don't recommend it. After all, the simple device is made of wood, and held together with glue and wood screws. After about 5 hours of use in high winds, in an isolated area, I noticed a slight drop in voltage, and cautiously took down the dangerously spinning device, to inspect it, and noticed that the allen set screw, as well as washers and nut on the generator shaft arbor, had begun to work themselves loose! To correct the problem, I added aluminum shims to the generator shaft, neoprene washers, and a lock nut (detailed above). The spring hinge, fitted with special oversized wood screws, remained tight and required no adjustment. This wind generator was designed for, and is best suited, for "light breezes" to "strong breezes" (5 mph - 25 mph), although a 21 Amp, 12 Volt battery was quickly charged in the 35mph windstorm test. And it was satisfying to observe the blades and generator desperately furling back-and-forth, while the entire unit, and the fiberglass mast, strained against the guy-lines, but held, in the insanely violent 35 mph winds. Also, violent, gusting winds will put a strain on the telescoping lock-nut of the 10 foot mast, causing the upper section to slowly work its way down an inch or two, giving the illusion that the guy-lines are becoming slack. The same applies to the lock-nut to the guy-line mount, on the mast. Being portable, this wind generator will, more than likely, be used in close proximity to people, so safety is paramount. Keep the device under a watchful eye: If the winds really pick up, take it down. And never leave any portable wind generator unattended. Use the same care and precautions as one would use with a portable gas generator. The 3-blade (and 2-blade) arrangement self-starts @ 11 mph constant wind, and @ 13 mph gusting wind, with the flywheel action of the thin, but dense, 3-blade arrangement sustains spinning of the blades down to 5 mph wind speeds. I have found that, on days of 5-10mph winds ("light breeze" to "gentle breeze"), an extendable hiking staff, with a rubber foot, is quite useful to push-start the blades, intitate the battery charging process. Two or three of these "jump-starts" is all that is usually needed, over the period of a "light-to-gentle breeze" day, to keep those blades spinning and charge a 21-42 Amp battery pack. Another way to "jump-start" the blades, if mounted on an unusually tall mast, is to simply run the battery pack power through the "generator" for a second or two, to get things moving. A 24 inch long string has been attached to the lower-rear of the tail fin, to serve as a simple telltale: 90 degrees = no wind; 45 degrees = sustainable blade speeds; 30 degrees to 0 degrees (parallel to the ground) = battery charging speeds. As mentioned earlier, the generator is not yet weatherproof, even though all wood surfaces have already been given a good marine varnish. Future plans call for a simple, aerodynamic cowling, over the generator only, made from aluminum sheet metal and aluminum pop rivets. Stay posted for more information and updates.

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

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Comments
50 comments Add Comment view all 55 comments

icelander27 says:

May 30, 2009. 10:22 PM REPLY Another idea is to use blades that would fit inside a fan's protective casing and figure out how to mount that to the generator.

shastalore says:
You should Google the Rutland 504 Wind Turbine. I really like their approach to a simple, durable, portable, and low power wind generator.

Jun 1, 2009. 12:56 PM REPLY

They have solved the design problem of efficient, yet safe, blades. Of particular interest is their outer ring, which not only makes setting up and taking down the generator infinitely safer, it also provides a useful flywheel action, to keep the blades spinning between low-to-the-ground gusting and turbulent winds. In a couple of years I'll be on the lookout for a used version, so I can re-work it with a longer tail vane. Stay posted.

purplemonkeydishwasher says:
would model airplane blades work?

May 14, 2009. 6:02 PM REPLY

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

shastalore says:

May 29, 2009. 11:40 AM REPLY You could try 1/4 scale props. Also, the electric model helicopter props seem to have even greater potential. To turn a small generator it would probably take a 18" or 24" propeller. But, remember that they were really designed as propellers, for a motor. Try and Google the portable "Orange" wind generator. It's still a prototype, but their design is sound, and is a good idea of where to start. But once you get into the realm of 12 Volts / 12 Watts / 1 Amp, or less, there is a dismal return on investment, with wind generators, unless they're used for science fair projects and such. You may be better off with a lightweight mono-crystalline solar panel. I have several of these panels, each with this capacity, and each measures 13.5" x 13.75" and each weighs in at 1.75 pounds. You'll never get a wind generator to generate this much power, with this little weight.

akinich says:
does yours spin clock wise or anti clock wise

May 24, 2009. 11:30 PM REPLY

shastalore says:
My wind generator spins with a clockwise rotation, when viewed from the front (shaft end). But the motor I used is designed to also function just as well with a counter-clockwise rotation. But the Air-X blades were designed for a clockwise rotation, when viewed from the front (shaft end).

May 25, 2009. 9:09 PM REPLY

luvit says:
counter clockwise and anti clockwise are two different things... if you add whistles.

May 26, 2009. 6:13 PM REPLY

luvit says:
ah.. the moderm convenience of being rustic with nature. i'd add whistles to the blades so people would notice it.

May 8, 2009. 5:56 PM REPLY

shastalore says:

May 25, 2009. 9:30 PM REPLY The Air-X blades make a god-awful "hiss" that is clearly heard by anyone in close proximity to the generator. The blades are even made of black plastic, to appear serious, and dangerous. The spinning blades naturally appear and feel threatening to anyone who observes them up close. But from a distance, the wind generator is silent and is completely obscured by normal background sounds. Mounting a whistle on the blade tips would certainly affect the high-speed performance of the blades, as well as creating unacceptable noise in the vicinity.

luvit says:
you make me like it more. so i need whistles.

May 26, 2009. 6:11 PM REPLY

drbill says:
Maybe 3 different sounding whistles would really whip things up !

May 18, 2009. 12:41 AM REPLY

drbill says:
And keep the monsters away !

May 18, 2009. 1:01 AM REPLY

JAK101 says:
How much would you charge for one of these, and can you hook them up to dc, like a store bought fan? Please email me if you feel like selling me one, jared.kindred@gmail.com Thank YOu

May 24, 2009. 12:41 PM REPLY

shastalore says:

May 25, 2009. 9:21 PM REPLY If I made this wind generator for a living I would probably starve <smile>. Any appliance this wind generator powers would have to be a special low-drain device. For example, I purchased a small 3.5" diameter 12vdc fan, from a local drug store, that is very efficient. But I don't plan to use it to keep myself cool. But a typical plug-in, store bought fan would probably require a 12vdc-to-120vac converter, with an unacceptable loss in the power conversion. I will soon post another page to this instructable titled "How Much Power Do You Really Need?" and feature a number of small and efficient 12vdc and 6vdc portable appliances, some of which I have scratch built. This should give everyone a good idea of what this small wind generator is truly capable of doing.

stephenniall says:
Looks great aestethic wise and it is a Great product im thinking of making a miniture version !

May 7, 2009. 7:17 AM REPLY

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

shastalore says:

May 7, 2009. 2:06 PM REPLY Go ahead and build it. Looking back, I designed on the side of caution, and made it a little too heavy and sturdy. You could actually build this wind generator much lighter -and use the same generator. I may also do just that, and mount a new generator, with 50% more power, on my existing wooden rig. As for the over-all design, I tried to give the wind generator a pleasing profile, with classic lines. A habit I developed early in life, with balsa model airplanes, with a zero-tolerance for weight.

DieCastoms says:

May 14, 2009. 3:18 PM REPLY Would it be practical at all to construct most of the fins and possibly some of the blades of this style generator out of Lexan or some other acrylic sheet? Nascar uses Lexan for their windshields so it should hold up in this use well enough. UV may be an issue, but there is also UV protected Lexan. Using the Lexan would fairly-well make the blades and fins disappear or at least blend into the background better and possibly be less obtrusive. Just my $.02 DC

grunthos says:

May 20, 2009. 5:06 PM REPLY Lexan/polycarbonate, yes. Acrylic, no. While acrylic looks like polycarbonate (Lexan), they are very different. Acrylic will break and shatter very easily; it doesn't have the strength. Polycarbonate does. I would be wary of invisible blades being dangerous.

shastalore says:

May 15, 2009. 3:32 PM REPLY Sure, it could be designed, with Lexan, to function well. Just don't design the blades to be invisible, for safety reasons -at least for a portable wind generator. I've noticed that hobbyists and tinkerers tend to plan and build their projects with the most expedient means and materials at their disposal. For example, I was quite intrigued by a post about a wind generator that a hobbyist had put together: It was fairly easy for him to sand-cast an aluminum mount for his generator and quickly machine it down, to snugly fit and bolt into place! What someone on Instructables.com REALLY needs to do is re-design my generator, with graphite composite frame for the vane/fin, with a nylon fabric tightly stretched over it. The weight of the generator and blades are pretty much set. But the over-all weight of the portable, furling generator could then be cut 30%.

ANDY! says:
SWEET. Is there any way of building the blades for real cheap cause I don't want to buy one. 5 out of 5!

May 7, 2009. 6:17 PM REPLY

drbill says:
some of the other wind generator instructables have plans for PVC blades

May 18, 2009. 12:43 AM REPLY

shastalore says:

May 17, 2009. 12:18 PM REPLY There may be a way to quickly and cheaply scratch build a set of high performance blades, matched to the generator, but this subject, in itself, would be an involved and time consuming research project, but an excellent post for Instructables.com, for someone to attempt. But I simply determined that I just don't have the time to go in that direction. I simply bought a set of 3 Air-X matched blades, for $ 100.00. They appealed to me because they were off-the-shelf, and, luckily, had the tried-andproven performance characteristics I really needed. Another advantage is that I could quickly buy some more of the same blades, if one of mine became damaged. And after I received them, I seriously doubt that I could easily build a set of blades, this well designed. Really, some of these manufactured blades are amazing. The Air-X blades, for example, have a slight swept-forward cant, from hub-to-tip (my sketchy plans called for more). And they're extremely stiff and rigid, with an airfoil cross-section (my rough plans had a thicker cross-section). And they would have easily out-performed my scratch built blades. To build these from a PVC pipe, or wood, or fiberglass, could be false economy, as the blades are just as important as the generator. And many of the homemade blade designs on the internet are poorly thought out, and there's rarely any information provided as to how much power is generated for given wind speeds, or how many rpm's are generated by those winds. "5 out of 5"? Thanks! (somebody tell my wife that)

ANDY! says:
How should I cut PVC?

May 18, 2009. 6:04 PM REPLY

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

shastalore says:

May 30, 2009. 3:21 PM REPLY There are numerous plans and cutting methods on the internet as to how to do this, but they tend to be be sketchy and incomplete. But if I were to build a blade from PVC pipes, I would only do a 2-blade design. 3-blade and 4-blade designs tend to falter when they attach to a simple flat disk hub, where the curve of the blades is distorted by the mounting bolts, creating unacceptable drag and a critical loss of performance and rigidity. A 2-blade design, made from one length of PVC pipe, eliminates the need for a separate disk hub and runs much cleaner, from an aerodynamic standpoint, as the blades angles are, simply, correct. First, draw a straight line down the length of a 4 foot length of PVC pipe, 6" inside diameter, 3/32" wall thickness. At the middle of the PVC pipe, carefully mark the point, which you will later drill out for the generator shaft arbor. This line will be the the trailing edge, of both ends of the finished blades. At each end of the PVC pipe, mark a 1 inch width. This will be the width of the tips of the finished blades, as well as the leading edge of the finished blades. 2 inches from the center point (arbor shaft) of your original straight line, and at a right angle to your original straight line, draw a 5.3125 inch arc along the outside of the PVC pipe. This will be the leading edge width of your finished blade. Repeat the process for the other side of the center point, but reversed. Using a flexible ruler as a "straight" edge, draw a straight line from the 5.3125" leading edge point to the 1" leading edge piont at the end of the PVC pipe. Repeat the process for the other end of the pipe, but reversed. This will be the leading edge of the finished blade. Using the same flexible ruler, connect the unmarked areas at the hub with a diagonal line, spanning the 4" area covering both sides of the center point, running from the 5.3125" width mark to 2" mark on your original straight line. Repeat the process for the other side of the center point, but reversed. This layout should produce a blade that will spin faster than most PVC blade designs, will provide more low-end torque, and will produce less high rpm drag. To cut out PVC blades, I use a Dremel, fitted with a small cutting wheel, and simply and quickly do a freehand outline cut. The edges are then quickly, and accurately, dressed out with a rough file or rasp. The back (leeward) side of the blades then need to be beveled, to improve the aerodynamics. But leave the outline of the concave (front) side of the blades absolutely sharp, holding to your orignally drawn dimension lines. To mount the 2-blade piece on the shaft arbor, you'll need to reinforce both sides of the blade "hub" with a front piece, and back piece, from the same PVC pipe, cut with an outline to match the hub of the blade. Glue and clamp. When dry, carefully file down both sides (concave front & convex back) of the "hub" until they're absolutely flat. If you have a drill press, this is easier, in that it can be, slowly and carefully, done with a wood boring bit, the same diameter as the shaft arbor washers, as a light "touch-bore". Next, drill out the hole for the shaft arbor. The glued "hub" must cure for at least 24 hours before testing the blade in the wind. Be advised that PVC blades should only be used on a generator (not the one I used) that turns at no more than about 350 rpm. Also, strong winds can bend the blades back enough to actually strike the mast. Also, cold weather can make the blades brittle and crack.

grandtippler says:
This is a great project.

May 17, 2009. 10:44 PM REPLY

frollard says:

May 10, 2009. 5:01 AM REPLY surely its an official product ...thing...is it possible to have an anemometer on a microcontroller watching the wind speed, and use some of the battery juice to spin the motor up in the 'minimum 5mph wind' to save the need for the hiking stick? Great build :D

shastalore says:

May 10, 2009. 6:00 PM REPLY You're right, if someone manufactures this wind generator, a miniature anemometer should be bundled with the device, and somehow coupled with a custom electronic charge controller, to make everything more productive and efficient. Erratic, low-to-the-ground winds have largely been an unexamined, untapped resource. Until then, my 'ol hiking stick will have to do, as I've already moved on to other things. But it's always fun to see how these things develop and progress.

t.rohner says:

May 17, 2009. 12:52 PM REPLY The easiest way would be a thermal anemometer. No moving parts and omnidirectional. I would suggest a externally heated NTC bridge. If you only need a switching signal, configure the OP-Amp as a comparator and add a trimmer to calibrate the setpoint. http://www.fonema.se/anemom/anemom.html Another idea, why not take a trolling motor used in boating. I have seen them for 50-100$ on ebay. It would be weather-proof by design and the bearings should be able to take the load. A nice instructable and useful for many occasions (mountain day for ham operators...)

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

der_fisherman says:

May 14, 2009. 7:28 AM REPLY I cannot see any prevention of the axial loads damaging (eventually) the motor bearings. Please be aware that most electric motors are NOT designed for such loads....in the long term at least. Especially if not ball bearing in the first place..... It could be possible to change one or both of the ball bearings for a bearing that is good for both axial and radial loads. though actually one is enough usually.... Or one could add an external axial bearing at the end where the prop is mounted (assuming a windmill design where the prop faces into wind). I use a similar arrangement on my homebuilt CNC bearings, at each end is a single (normal) radial bearing and at one end 2 axial bearings either side of the radial bearing, but putting the load on the frame.... as that is cheaper than a single ball bearing for both load types..... If you happen to find/use a DC motor that has a brush system that can be adjusted/moved radially, you will find that the best position for the brushes as a generator is quite different to that needed by a motor, maybe as much as 30° different (if I remember correctly), so by such an adjustment (if possible) you can seriously "up the output" quite dramatically for the same revs....though most motors do not allow such playing around.....the brushes are fixed in position.... I have read that stepper motors can make useful generators, but have not tried it personally you understand.....but as they have no brushes, a point of serious long term wearing is reduced, as is the need to find the optimum position for the brushes! So higher output will be easier to achieve..... But do remember that the output is multiphase AC, so a few diodes are also required.....No big deal...... Please do not see my post as critic, its meant into be helpful to both yourself and anyone else planning to do the same or similar......Otherwise I liked your post, easy to build and very useful.(me being a camper for some weeks each year....!) Regards and thanks for your trouble and ideas.

shastalore says:

May 15, 2009. 10:50 PM REPLY You're right, there are axial load stresses on the generator shaft. But with the well-designed and efficient Air-X blades, my main concern was the centrifugal forces of the fast-spinning blades, on the ABS hub. But the axial load is moderate, and will never exceed 2 pounds anyway. But only time will tell. The generator is quite small, for the size of the blades, and stresses, both axial and radial, are present. But the motor was designed for use with a belt and pulley, so it can be expected to handle the radial forces in stride. The small, sealed ball bearings are replaceable ($ 8.00 each), but periodic rotation of the outside of the bearings, should give a lifetime of service, since the generator is for portable, intermittent use. The only bearing that would be subjected to the axial stresses would be the one in the tail-end of the generator. And that's assuming the it was not designed to handle axial stresses, and something that might have to be dealt with later. In this motor, the flat end of the tail-end shaft is inside the housing, so it could be drilled out and some sort of axial ball bearing could be retro-fitted, in addition to the existing radial sealed ball bearings. As for the timing of the generator, one could certainly file off the die-cast timing notches on the casing of the tail-end of the generator, and, in a 600rpm bench test, rotate that end, back-and-forth, until the optimum current is produced, then drill out new holes, for the full-length housing bolts, on the generator housing. I also understand that this can be done in a static test, by measuring resistance only, while simply advancing/retarding the brushes, but I have been unable to duplicate this. Maybe someone here can provide more definitive information as to how to do it. I advocate DC, carbon brushed, permanent magnet motors, for simplicity. This particular motor has carbon brushes mounted on external holders, making them quick and easy to replace. Diodes, etc., tend to overwhelm the novice experimenter. Although, if someone manufactures these wind generators for the mass market, I wouldn't be surprised at all if if they are produced with brushless motors.

JoeCools says:

May 14, 2009. 6:47 AM REPLY Speaking of Boy Scouts, I have 1 still in Scouts and the other is an Eagle Scout, when ever we set up any kind of lines, we use highly visible fluorescent ribbons 3 to each guide rope so the young ens can see that a rope is there and not to trip over it. Great Instructable! Thanks /Joe

shastalore says:
thank you

May 15, 2009. 2:18 PM REPLY

GEEK1 says:
great instructable

May 14, 2009. 7:09 PM REPLY

shastalore says:
thank you

May 15, 2009. 1:39 PM REPLY

ipaq69 says:

May 12, 2009. 1:19 PM REPLY great job .I am looking at making one for camping and have been researching for a while. My understanding is the slower rated rpm the motor is the higher the output will be. I have taken a perminate magnet motor from an automatic garage door opener and am going to try this wired with diode to change from ac to dc and regulator so as not to overcharge the battery

shastalore says:

May 13, 2009. 5:44 PM REPLY Using a motor, as a generator, is something the manufacturer did not intend, and is careful not to endorse. But, on instructables.com, we do it anyway. Right? But there some general, helpful guidelines: 1 - Use a DC motor, brushed (carbon brushes), permanent magnet. 2 - To generate 12 Volts, DC (= about 17VDC, with no load), you'll need a motor that normally runs on 24-90VDC. For example, my wind generator was

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

built from a 48VDC motor that ran at 1,600rpm. It now generates 17VDC at 600rpm. These are good ratios to be on the lookout for. 3 - Take a heavyduty hand drill, stop watch, and a volt/ohm meter (that also reads up to 10Amps DC) with you while shopping the flea markets, yard sales, and salvage yards for a motor. 4 - Tighten the motor shaft into the chuck of the hand drill, hook up the volt/ohm meter, and give it a good crank to see if it produces the necessary 1417VDC. If the shaft is too large to fit into drill chuck, then the motor is probably too heavy to consider for a portable wind generator anyway. 5 - If the Volts are right, do the same, but test now for DC Amps, being careful not to exceed the limits of your volt/ohm meter, as the Amps mode is usually not fuse protected. If the Amps generated exceeds the capacity of the volt/ohm meter, then the motor is probably too heavy to use as a portable wind generator. 6 - If the Volts and Amps are right, then test for Volts, again, while using the stop watch, to determine what rpm you will need to spin the motor shaft to generate the required power. Now do the same, but turn in the opposite direction, to see if the internal timing, of the commutator and brushes, has any effect on the power. Carbon brushes, 90 degrees to the shaft, are most desirable. Note that some DC motors turn one direction only, and turning the opposite direction will soon destroy the brushes. 7 - If you need 200-300 rpm, then you can easily fashion your blades out of PVC pipe. If you need 400-800 rpm, then you will probably have to purchase a carefully matched set of high performance Air-X blades, or equivalent. 8 - Another, easier way to find a suitable generator is simply buy a complete, el-cheapo wind generator on ebay (but be wary of the advertised wattage), and, after a few test runs, throw most of the components away, except for the generator. Do steps 1-7, above, and then fashion yourself a REAL wind generator. 9 - You'll need, in all cases, an electronic charge controller. A simple diode will not prevent the wind generator from overcharging and burning out your lead acid battery. I purchased a "Chanyn" Model#CQ1210, for $ 55.00, on ebay. It has separate contacts for: Battery, Wind Generator (or Solar Panel), and Load (aka 12 Volt appliances). The charge controller will also prevent the battery from discharging too low, greatly extending the life of the battery.

ReCreate says:

May 12, 2009. 8:05 PM REPLY Probably the easiest way to stop it is to short out the cables,this causes it to try to turn in reverse,Quickly stopping it,Another way,Probably less loud,Is to put a Big battery(30 AMp or so) And hook it up in reverse polarity,At first it will make a big spark,then it will start spinning in reverse,After It stops spinning,Short out the 2 wires to prevent it from spinning again(it may spin,but very slowly)

shastalore says:

May 13, 2009. 10:44 AM REPLY I've tried shorting out the generator, and it does work. But I've also read that there may some problems to that method, so I was reluctant to preach it. Most generators normally heat up, internally, to some degree, while charging. But most of the energy is safely channeled into the electronic charge controller and battery pack. A strong wind, without furling, could possibly overheat a shorted out generator, and if above 160 degrees Fahrenheit, the lacquer coating on the internal copper wiring could burn off, requiring a complete re-wire of the motor/generator. Switching the battery polarity, into the generator, for a quick-stop, could also have the same effect. But someone could design an electronic circuit, specific to the generator, to carefully monitor and control the processes that you described, and it should work quite well, without damage to the generator.

ReCreate says:
It depends on the Scale,Mostly,If you have A huge turbine,Its better not to do that,But small scale,its OK

May 13, 2009. 12:43 PM REPLY

yokozuna says:
Fantastic job sir... 5 stars and subscribed (my first). You'll also have one of my votes at the appropriate time.

May 10, 2009. 9:49 AM REPLY

brokengun says:

May 7, 2009. 8:35 PM REPLY Well put together instructable sir. It's nice to see some smaller wind generators that have a furling setup, pretty neat! I'll definitely keep up with your updates and hopefully you can check out my project soon too. Keep up the good work.

kerns says:

May 7, 2009. 3:06 PM REPLY Great explanatory photo showing your 'warning' guylines. I might suggest adding "crossbar lines" for added safety. Place loop knots on each existing line at knee height; create 4 additional orange lines with a carabiner or similar wind-proof clip at each end, and clip on those lines to create a knee-high visual barrier to "box in" the danger zone near the possible zone of blade passage. Maybe tie mylar strings to those crossbar lines for added visual presence could also be great places to hang informational signs if the generator is being used as a learning piece. Great work, fantastic Instructable - thanks! -Kern

shastalore says:

May 7, 2009. 3:47 PM REPLY For an EarthDay exhibit in the park, your suggestion would work quite well, as some parents might try, to hold their little children up, to playfully paw... at those sharp, hideous spinning blades. And I would definitely put my old Boy Scout knots back into use to prevent that. Your detailed description serves well for this. But for a high-mountain camp, say, in Tibet, my basic rigging should do just fine, as a fully grown adult would have to leap in the air and take a good swipe at the blades to get injured.

http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/

tjsnfrd says:

May 7, 2009. 3:02 PM REPLY AWESOME, AWESOME, AWESOME!!!!! I have been looking to build something like this myself and now I have fantastic instructions to go buy. One thing though....could you send me a message with the name of the company you bought the generator from? Id like to purchase one and build one of these. Thanks again for such a great addition to the site!

shastalore says:

May 7, 2009. 3:36 PM REPLY The exact motor I used is: 370-350-00 PE24113G 48VDC They sell for about $ 300.00, through the medical parts suppliers, but I bought mine from USA WindGen turbines, Athens, Texas, as a surplus item, for about $ 50.00. He also sells on ebay, as "otter5555", and he just may have some of these on hand. I think he received some flack selling these motors, since some of his customers complained that they rusted out. But the quality of this motor/generator is excellent. Since it's portable, just treat it as a fair weather friend. Stay posted, as I will soon build an aerodynamic, weatherproof sheet aluminum jacket, to fit over the generator, with aluminum pop rivets.

nolte919 says:
So once it furls, does it stay furled until you manually reset it? Or does your furling mechanism have a way of resetting itself?

May 7, 2009. 12:22 PM REPLY

shastalore says:
The furling device never has to be reset.

May 7, 2009. 2:02 PM REPLY

In all wind conditions above 9mph, the wind generator is always in some degree of furling, with the generator and blades at ever-changing angles to the wind. The entire wind generator, being fully articulated, is very quick and animated, in appearance, to efficiently conform to gusting, low-to-the-ground winds.

rimar2000 says:
Very nice work. And aesthetic, too

May 6, 2009. 11:18 AM REPLY

shastalore says:
Thank you. I noticed that you're also enjoy tinkering with many projects. How are things down in Argentina?

May 7, 2009. 11:27 AM REPLY

wheatabx says:

May 7, 2009. 5:19 AM REPLY Hello, there great design. I was just wondering if the geny u used is easy to find and what price. If you could point me in the right direction it would be greatly appreciated.

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http://www.instructables.com/id/Portable-12-Volt-17-Watt-Wind-Generator-with-Autom/


								
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