Bike Powered Generator Using an Alternator




Introduction: Bike Powered Generator Using an Alternator

This is an Instructable on how to create a bicycle powered generator using a bike, an alternator, a car battery, a belt, and a wooden frame to connect all of the components together.

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Gather Materials


- Drill

- Drill bits of many sizes

- Lug nuts

- Ratchet and socket set

- Large amount of 1-2 inch nails

- Circular saw

- Smaller washers


- 2x4 wood (at least 20-30 feet of length)

- At least a 10 speed bike (set the speed to the lowest shift)

- Car alternator

- Car battery

- Drive belt (big enough to fit your back wheel and has enough space for the alternator). Depending on how many ribs are on the pulley of the car alternator, acquire a drive belt that can fit it (3 ribs on the alternator = 4 ribs on the drive belt).

- Wiring

- Car battery

- Inverter

Step 2: Preparing the Back Wheel

Remove the Tire from the Rim

1) Remove the bolts from both sides of the wheel, and completely remove the wheel from the bike

2) To remove the tire from the rim, create a slot between the tire and the rim with a flat object and go around the wheel. Carefully pry the wheel from the rim.

Insert the Drive Belt onto the Rim

1) Since the wheel is already out, wrap the drive belt onto the rim and make sure the drive belt has a much larger circumference than the circumference of the wheel. This allows for the alternator to also be inserted to the drive belt.

Attach the Back Wheel back to the Bike

1) Put the wheel back into the bike and use the ratchet to put the bolts back in more efficiently

Step 3: Creating the Wooden Framework

1) Measure the length of the bike. One 2x4 piece of wood should be that length plus an additional 1 foot. This will make a more secure framework.

2) The width of the framework should about 2 feet. Cut 4 pieces of 2 feet of 2x4. These will create a better structural integrity of the framework.

Step 4: Attaching the Bike to the Wooden Framework

1) Depending on the bike, either find, or create a spot on the belly of the bike that can be attached to the wooden framework.

2) A middle cross-section of the framework can provide for a 2x4 beam that can be vertically screwed into the cross-section and a part of the bike

3) To secure it in place, it is recommended to use multiple screws to secure the bike in place.

4) If there are extra wood, use it to your advantage by making the bike more secure and balanced.

Step 5: Attach the Car Alternator to a Piece of 2x4 Wood

1) First, with the drive belt on the wheel, connect the remaining length of the drive belt to the alternator pulley.

2) Pull the alternator away from the bike until the drive belt is fully stretched and feels tightened.

3) Measure how far the alternator is to a cross section of the wooden framework.

4) That length should be the length of a piece of 2x4 wood.

5) Once that piece is cut, attach the alternator to the piece by fitting the alternator snuggly onto it.

6) Use the bolts and bolt the alternator to the very end of the wood. The alternator should be facing the right way if the pulley side of it is on the right side (if viewing from the bike).

Step 6: Connect the Alternator Component to the Wooden Framework

1) Align the alternator so that it is perfectly parallel and lined up to the bike wheel

2) The 2x4 connected to the alternator should be touching the wooden framework so it can be ready to be screwed in place.

3) Finally, screw the alternator and wood piece to the framework.

Step 7: Adding Car Battery and an Inverter to the Alternator

1) Once the alternator is attached to the framework, wire the alternator to the car battery, and then attach that to the inverter. This will invert the AC from the alternator to DC in the inverter.

2) The inverter may have power outlets to plug necessary electronics to test out the set up.

Step 8: End Product of the Bike Set-Up

Be the First to Share


    • Wearables Contest

      Wearables Contest
    • Fix It Contest

      Fix It Contest
    • Fix It Contest

      Fix It Contest

    8 Discussions


    1 year ago

    Sweet, Henry! Back about 1970 (Yeah, I am an Analog Old Fart in a Digital world) I helped a friend cobble up basically the same rig for a science project. Details are fuzzy, but I recall a smallish alternator with a built-in regulator which directly charged a 12V auto battery. He rigged an ammeter and voltmeter and experimented with various pulley diameters as well as gear ratios on the old 10-speed bike. His father owned an auto repair shop, access to a lot more tools and spare parts than a home workshop. I do remember that pedalling was WORK no matter what gears we used on the bike! Very nice post, thank you!


    Reply 1 year ago


    All CAR alternators have a DC output, however there are alternators for other applications that output AC (110 or 240vac- some even look like car alternators)- these are were used on coaches etc to provide AC for things like tv's, players, microwaves etc in the old days), there are also various voltages available (12vdc,24vdc, I have even repaired a 48v bosche)

    He did mention that it was a car alternator in the instructible


    1 year ago

    "wire the alternator to the car battery" - WHAT?!

    The output of an alternator is AC. A battery is DC.

    I am sure the output of the alternator is not 12-13.5V DC.

    You will need to strap a second get away bike to the frame to escape if the battery catches flame=).

    Connect the alternator to a 12V rectifier/regulator and then connect the rectifier/regulator to the battery.

    The rectifier/regulator will accept the AC input rectifier that to DC, and then regulate the voltage to about 13.5V.

    I guess some alternators does have internal reg/rec. But this is not clear in this intractable.

    Also people would like to know how many watts the system deliver. And from that to calculate how long it would take to charge a battery in Amps Hour.

    I would like to know if this is viable? Does it take one to peddle 2hours to charge a 12V 7AH battery or does it take only 10min. - Now this also depends on the battery charging capabilities, but what does your system allow? How long does it take to recharge your battery with this system?


    Reply 1 year ago

    He did specify a car alternator, which does output 12VDC....(well approximately 13.8v if you want to get pedantic)

    Depending on the alternator, you would probably require a bit of extra wiring, one with an inbuilt regulator would need a 12V (switched) connection to the field connection (usually marked F+), however a lot of car alternators have an external regulator, that would need a lot more wiring done to get working, however I can safely say I have never seen a car alternator with external rectifier in 30 years as an auto electrician.....


    Reply 1 year ago

    I know of know vehicle alternators that have an output of ac.
    As all are equipped with an internal rectifier..

    You will find diodes behind the lead wires that connect to the wiring system on any alternator .


    1 year ago

    But... How much output can you generate. How many watts?

    Uncle Kudzu
    Uncle Kudzu

    1 year ago

    I have an old Delco/GM alternator that supposedly needs no external field current to get going, which would be perfect for a project like this. Thanks for sharing!

    So the output of the alternator to the battery is AC? Would it take a lot of effort to charge a small deep cycle 12 volt battery?

    Cool. I always wanted to make a bike generator to make good use of my indoor cycling in winter.