Turn a car alternator into alternative energy by building this cheap and easy homemade wind generator.
If you can turn a wrench and operate an electric drill, you can build this simple generator in two days.
Photo by Robert D. Copeland
Maybe you reside on a boat, vacation in a remote cabin, or live off-grid like me. Or perhaps you’re just interested in lowering your energy bill. Either way, with a handful of inexpensive and easy-to-source materials, you can build a homemade wind generator, making electricity yours for the taking for as long as the wind is blowing. You’ll be able to light up that storeroom, power your barn, or use a generator to keep all your vehicle batteries charged.
Electricity for my off-grid cabin comes from solar and wind power stored in a bank of four 6-volt golf cart batteries wired for a 12-volt system. A charge controller and battery minder keep my system from under- or overcharging. The whole shebang cost me less than $1,000, and I have lights, fans, a television and stereo, refrigeration, and a disco ball that goes up for special occasions.
If you can turn a wrench and operate an electric drill, you can build this simple generator in two days: one day for chasing down parts, and one day for assembling the components. The four major components include a vehicle alternator with a built-in voltage regulator, a General Motors (GM) fan and clutch assembly (I used one from a 1988 GM 350 motor), a tower or pole on which to mount the generator (15 feet of used 2-inch tubing cost me $20), and the metal to build a bracket for mounting the generator on the tower or pole. If you’re a Ford guy or a Mopar gal, that’s fine — just make sure your alternator has a built-in voltage regulator. You’ll also need some electrical cable or wires to hook the alternator up to your storage batteries. I used 8-gauge, 3-conductor cable pilfered from the oil patch. (And they said the transition from fossil fuels to renewables would take years. Pfft!)
The blades for the wind generator are repurposed from a vehicle fan clutch. To attach the blades to the alternator, you can weld the fan clutch hub directly to the alternator hub — just make certain the fan is perfectly in line with the alternator shaft. Also, make sure the alternator’s built-in wire plug-ins are located on what will be the bottom of the generator. If you don’t have access to a welder, you can connect the fan clutch to the alternator using the following materials:
• 5/8-inch-by-3-inch washer, 3/16 inch thick
• Electric drill
• 1/4-inch thread tap
• Drill bit that corresponds to specific thread tap
• (4) 1/4-inch-by-1-1/2-inch to 2-1/2-inch bolts with corresponding nuts and lock washers
Create a union using the 3-inch washer and the four bolts, which will fasten the fan clutch and alternator together. Drill four holes into the washer to match the holes in the fan clutch, and then cut threads in the holes using the 1/4-inch tap. Screw the bolts into the holes. To determine the length of the bolts you’ll need, stack the fan on top of the alternator with the fan pulley resting on the alternator pulley and both shafts in line. Measure the length along the two shafts from the back of the alternator fan to the back of the fan clutch hub. Use this length for the bolts. Unscrew the alternator pulley nut, and remove the pulley and small fan. Slide the union that you made from the washer and four bolts over the alternator shaft, with the bolts pointing away from the alternator. Then, reattach the alternator fan and nut onto the shaft, leaving the pulley off. The large nut will hold the union in place. Attach the fan clutch assembly to the bolts now protruding from the alternator, and tighten the nuts with lock washers in place.
If you have a welder, making a bracket is simple. I used 1-inch square tubing for all the bracket pieces and a 2-foot-long piece of 1-inch pipe for the rotating stem that fits inside the pole. If you don’t have a welder, fear not. The bracket assembly can be put together with 1/2-inch galvanized pipe and fittings. Here’s a list of the pipe fittings you’ll most likely need:
•(5) 1/2-inch tees
•(2) 1/2-inch elbows
•(2) 1/2-inch-by-12-inch nipples
•(2) 1/2-inch-by-6-inch nipples
•(2) 1/2-inch-by-1 1/2-inch nipples
•(2) 1/2-inch-by-2-inch nipples
•(3) 1/2-inch-by-close nipples
A tail fin must be attached to the 12-inch nipple at the back of the bracket to spin the generator around and line it up with the wind’s direction. You can cut a fin that’s about 1 foot high and 2 feet long out of old tin siding or roofing with tin snips or a cutting torch — a right-angle-triangle shape works best. If you’re using corrugated metal, be sure to cut the fin so the corrugations run horizontally. After the fin is cut out, lay it on top of one of the 12-inch nipples and drill three pilot holes through the bottom of the tail fin and into the side of the nipple. Use three screws (steel roofing screws work well) to affix the tail to the nipple.
I used an old 20-foot-tall television antenna tower along with a 2-1/2-inch-diameter pipe for the top piece. You’ll also need to weld or bolt a stop at the top of the tower that will make contact with a stop on your bracket assembly. The stops will only allow the generator to turn 360 degrees clockwise or counterclockwise so your cable doesn’t get twisted around the pole and tower.
A joint of 2-3/8-inch heavy-gauge metal tubing anywhere from 10 feet to 20 feet in length (or height, once erected) makes for a good tower after it’s attached to a building or other sturdy, stationary structure. Make sure it’s secure, and consider using guy-wires if necessary.
After you have all the generator components fastened together and attached to your bracket assembly, mount it to your unerected pole or tower. Insert the pipe on the generator bracket assembly into the pole or the top of your tower. Use two steel washers stacked together to create a smooth surface to act as a bearing between the generator and tower. Attach the positive and negative wires to the alternator and secure them to the bracket and along the tower with zip ties, baling wire, or duct tape. (It isn’t really homemade unless it has a little baling wire and duct tape on it somewhere, now is it?) Make sure to leave enough slack in the wires for the wind generator to rotate 360 degrees.
You’ll likely need assistance standing the tower and generator upright as it will be pretty heavy. Ropes and a come-along will help if you’re going up fairly high. If it’s always windy in your location, you’ll only need to be high enough off the ground to keep the moving parts safely overhead. Securely fasten your tower in place. The wind can be deceptively strong, so don’t cut corners on this final assembly stage. After you’ve erected your wind generator, connect the wires to your battery bank with a charge controller in between to prevent under- or overcharging.
Now, you’ll be ready to hit the lights, crank up the jams, and bust out those old disco moves I know you’ve been saving up for an electric slide with family and friends.
A quick disclaimer: build and use at your own risk. My generator works fine, but you’re responsible for your work. Good luck and power up!
Robert D. Copeland raises and sells grass-fed beef cattle and is the proprietor of a Texas-based off-grid bed-and-breakfast retreat called The Sunflower, complete with straw bale and earth plaster cabins, fresh organic meals, permaculture instruction, workshops, and more! You can find more info at www.RDCopeland.com.
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