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Basic information on what to get and how to put it together
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A motor is a generator ;
spinning wrapped metal coils around magnets, creating Direct Current (DC) power : Positive and Negative lead wires.
From the generator, a charger regulator is necessary to level the electrical voltage - often a 12 volt system is used. The regulator also restricts the electrical flow so that it doesn't flow backward and turn/power the generator/motor itself.
A 12 volt deep cycle/Marine battery or a capacitor is needed to equalize the electricity so that you can steadily power your devices. Fans, flashlights, and radios are devices that can be powered directly from the generator.
Most larger appliances, computers, and sewing machines use Alternating Current (AC). An invertor changes DC power to AC power : there is no Positive and Negative, each lead wire is equally powered.
An ideal generator is a 12 volt permanent fixed magnetic motor. You basically start turning the motor and it produces current. You just need to spin it fast enough to make more than 12 volts to charge a 12 volt battery.
Another method uses an alternator from a car. They can be easier to find and perhaps less expensive. But alternators need to be excited / initially spun very quickly to begin producing energy and if the speed drops too low, it cuts-off and you'll have to spin it quickly again.
Brad Whaley, a teacher in Gilbert, Arizona and a very helpful individual, has detailed at great lengths how to make a bike generator that directly powers a television and a video game using an alternator and capacitor.
-> here's the link to his instructions.
To give you an idea of how much electricity can be produced :
My sewing machine (without the light on) is rated at 50 watts and consumes 1 amp every hour. My bicycle electric generator can make 1 amp every 10 minutes. That means for every 10 minutes of peddling, I can sew for 1 hour.
I also hook my sewing machine up to a 50 watt solar panel. On a good day in Tucson, Arizona- I'll be lucky to get 4 1/2 amps from the sun for the entire day. That's 4 1/2 hours of sewing per day with just the solar panel.
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Use FUSES !!!!! their small price and will save you hundreds of $$$
(always attach fuses to the +positive wire)
S u p p l i e s :
~~ you will need a bicycle and a way of securely lifting its back wheel off the ground -> recommended to use an excercise stand, or you can use a full-excercise-bike that stands on it's own.
~~ a 12 volt permanent fixed magnetic motor, 13-15amps. The more RPM's it's rated the better. here's a link to buy one new, but try searching ebay or craigslist.
~~ 4-8 meters of 10 gauge wire (easily found at hardware and automotive stores)
~~ electrical tape
~~ a digital volt/amp meter
~~ a mountable volt meter ( I opted for a non-digital dial type )
~~ a mountable amp meter ( again, I opted for a non-digital dial type )
~~ up to four in-line automotive type fuses and fuse holders ( most likely 15 amp fuses)
~~ a charger regulator ( a minimum rating of 20 amps)
~~ a deep cycle / marine battery
( the Optima blue-top battery is a reasonably priced choice for performance ) note: batteries are an ever developing science - see below for more details ***
~~ potentially a DC/AC power invertor, depending on what you want to use the electricity for
~~ a rubber fan belt commonly found at hardware and automotive stores. (the length to be determined by your specific generator to bicycle set-up)
~~ by diameter, a slightly smaller aluminum rim than the rim on your bike ***
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***Explanation for a slightly smaller aluminum rim - on how to make the motor/generator turn, other inventors of bike generators have:
1. attached the motor/generator with a rubber bushing of sorts that touches the edge of the wheel to make the generator turn. (mostly seen on bike light generators)
2. probably the highest energy output design incorporates a wheel with high mass and wide diameter to belt or chain drive the turn of the motor/generator.
3. another similiar method (and probably the most popular) puts the bike on a stand and uses the existing back wheel of the bike without a tire. The tireless inner rim provides a perfect groove for a belt to spin a motor/generator.
4. my bike is my daily rider and I want to be able to ride it normally and change the bike quickly to start producing electricity. (taking the tire and tube off the wheel everytime is too much) I saw a way of attatching and centering a smaller aluminum rim through the spokes of the rear wheel ****. This smaller rim provides a perfect groove for a belt drive. I put the bike on an excercise stand; which looks like a small upside-down V. The motor/generator is firmly bolted to the stand, at a very specific angle, and with a specific belt length. These two factors are important for the belt not to jump-off the track or rub the back wheel tire (i use a skinny 1.5 tire). Vice grips and a pre-mock-set-up of the device is essential for finding the exact angle and belt length.
It works very well. Yes, the smaller rim produces fewer revolutions and thusly you'll have to pedal a little faster than with a bigger wheel. And there is some resistance with the angle of the motor/generator to the aluminum rim. The repeated process of mounting the bike to the stand while simultaneously lining-up the belt is slightly tedious. I am content, but there is always room for improvement.
**** How to attach and center a smaller rim to another wheel: I weave the smaller rim through the spokes of the larger wheel. To do this you will need to drill holes in the smaller rim at the specific points where the spokes line-up. first, place the smaller rim against the larger rim in the approximate center. (opposite the cog and chain drive) As a stabilizing tool, use string to tightly hold the smaller rim to the side of the spokes to the existing rear wheel. Measure the distance at the edge of the smaller rim to the edge of the larger rim carefully pushing the rim around until it is evenly spread. with a fine sharpee-type-pen, make a mark on the smaller rim next to each touching spoke. After marking, remove the string, and score each mark with a hammer and scoring tool. Drill the holes with a drill bit ever slightly larger than the diameter of the spokes (these drill bits break easily, so bring extras). After drilling, use an electric grinder to bring down the area where the holes are - this provides a straight(er) line to weave in the spokes of the main wheel (see above pictures). The lower you grind the rim, the easier it will be to true the wheel, but also potentially weaken the structure of the rim- I took off about 6 to 9 millimeters. Don't forget to also grind a place for the air valve! Using a swivel screwdiver truing tool that turns the spoke nipple from the top was most helpful.
*** Batteries:
The common lead acid batteries contain sulfuric acid and are heavy. They cost about $85.
These liquid filled batteries can only be discharged to 50% of their capacity
in other words -> only use half of their available power or you will destroy the battery!
Sealed or Gel batteries are made as well, these types are more flexible and can often be used below 50%. They cost $150.
Lithium batteries are currently the lightest and have no such "50% problem" when being discharged. Currently they cost about $900-$1600 for a 12volt system.
Links to people who have figured out how to make Bicycle electric generators:
http://www.los-gatos.ca.us/davidbu/pedgen.html
http://www.stewardwood.org/resources/DIYcyclepower.htm
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