Doing exercise to stay in shape is good for your health, but what if you could harness the power of all the energy you expend during those workouts? Make some simple additions to an old stationary exercise bike and create a pedal-powered generator. A pedal-powered generator can store energy in a battery to be used later for various applications, including small lighting, small appliances and mobile phone charging.
- Skill level:
Things you need
- Stationary exercise bike
- 1.2 m (4 foot) fan belt
- 12-volt DC motor (or generator with magnets)
- Power inverter
- DC voltmeter
- 12-volt car battery
- 14-gauge wire
- Wing nut wire connectors
- 30 by 50 cm (12 by 20 inch) board
- 2 5 cm by 10 cm (2 inch by 4 inch) "two-by-fours," 90 cm (3 feet) long
- Square shank cutting tool
- Power drill and bits for metal
- 6 mm (1/4 inch) bolts and nuts
- Wire cutter/stripper
Strip the exercise bike of components except the frame, base, seat, handlebars, flywheel, pedals and bicycle chain.
Cut a groove into the flywheel by wedging a square shank cutting tool between the frame or base of the exercise bike and the flywheel, while somebody else slowly pedals. This will create a groove in the middle of the flywheel for the fan belt to fit into.
Drill holes in the metal base of the exercise bike through which to mount the wooden platform to the bike with screws.
Build the wooden platform to mount the motor, the voltmeter, the car battery and the inverter by screwing the two-by-four boards along the undersides of the 30 by 50 cm (12 by 20 inch) board.
Attach the ends of the "two-by-fours" of the wooden platform to the base of the bike with screws through the holes you drilled earlier. Be sure to attach the wooden platform at the proper distance from the flywheel to ensure the 1.2 m (4 foot) fan belt will fit securely around the motor's pulley.
Mount the motor to the platform by drilling 6 mm (1/4 inch) holes in the board and threading the 6 mm (1/4 inch) bolts through the mounting holes on the motor's frame and into the platform, securing the bolts with nuts on the underside of the platform. Be sure to test the tension in the fan belt from the flywheel to the motor pulley before you drill the holes and mount the motor.
Slide the fan belt over the flywheel and the pulley on the side of the motor. The distance between the flywheel and the mounting platform should allow a proper fit for the fan belt so that it doesn't slip.
Mount the voltmeter to the platform behind the motor with screws. There should be mounting holes in the base of the voltmeter, but if there are no holes you can surround the voltmeter with protruding screw heads that hold it down.
Connect the negative and positive output wires of the motor to the negative and positive contacts of the volt meter with 14-gauge wire using the wire cutter/stripper. First, cut two 15 cm (6 inch) long pieces of wire, then strip both ends and connect them to the wires of the motor with twist on wing nut wire connectors. Connect the other ends of the two wires to the voltmeter by sliding them under the permanent screw connectors on the back of the meter and tightening the screws down on the wire ends.
Mount the car battery to the platform by surrounding them with protruding screw heads that hold the battery securely down.
Connect the battery to the voltmeter by using the 14-gauge wire and the wire cutter/stripper to cut two 15 cm (6 inch) pieces of wire and strip the ends. First slide two ends of the wires under the permanent screw connectors on the back of the volt meter and tighten the screws. Then unscrew the car battery's negative and positive contact bolts and wrap the other ends of the wires under the bolts before screwing them back down tightly.
Mount the power inverter onto the wooden platform next to the car battery. Either use screws through the mounting holes or use protruding screw heads surrounding and securing the inverter.
Connect the car battery to the inverter by using the wire cutter/stripper to cut two 15 cm (6 inch) pieces of wire and strip the ends. Then slide two ends of the wires under the contact bolts of the battery before tightening them back down. Slide the other ends of the wires under the permanent screw contacts of the power inverter. The power inverter has power outlet plugs to use while the bike is generating power.
Tips and warnings
- Adding oil to the right spots on the exercise bicycle can make pedalling the generator a lot easier.
- Be sure an adult is present when the generator is being operated because some components may get hot, and any mistakes in wiring can cause a fire hazard.
- If the pedal generator doesn't work at first, check on all the wires and be sure the negative and positive wires are not crossed anywhere.
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