About: I enjoy building things more than actually using them.

BikeGen is a small power generator, mounted to a bike, that recharges two AA batteries while you ride. The batteries can then be used to power the lights on you bike or you can take them out and use them in your other electronic devices. BikeGen also has a standard car 12v power outlet that could be used to recharge your Ipod or cell phone.

This is an updated version of my original Bike Generator. The first version served its purpose but was fairly limited. BikeGen, is better in almost every way and here are some of the reasons why:

1. The generator motor is now mounted with more rigidity to the rack instead of the frame.

2. The friction drive wheel is mounted to the motor with a clamping coupler and now runs on the braking surface of the wheel and not directly on the tire.

3. BikeGen recharges two AA batteries instead of powering the headlight directly, so the lights stay on even while your stopped.

4. Two AA batteries are used to power both the head light and the tail light, which means I don't have to bother buying AAA batteries for the tail light.

NOTE:Please read my Bike Generator Instructable and follow the steps about building the the circuit board before attempting to build BikeGen.

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Step 1: Get the Tools

Step 2: Get the Materials

Here is all the materials I used to build BikeGen.

Raw Materials
Aluminum Angle 3/4"x3/4"-1/16"thick
Aluminum Angle 1-1/4"x1-1/4"-1/16"thick
#6-32 All-thread

4 - #6-32 nylon-lock Nuts
2 - #6-32 x 1-1/2" long Machine Srews
2 - Springs
2 - 1/2" #4-40 Stand-offs
4- #4-40 x 1/4"long Machine Screws
2- #4-40 Nuts

Electrical Parts
18 gauge wire - roughly 25ft
2 - DPDT switches
12volt car outlet
2200 ohm resistor
Battery Holder for 2 AA batteries
D-Sub connectors
Everything used to make the Bike Generator

Other Needed Items
Small Plastic Organizer Box

Step 3: Make the Generator Motor Mount

The motor mount is spring loaded and the friction wheel rides on the braking surface of the rim. This works much better than my original Bike Generator which tended to bounce around on the tire while riding. I also got different tires which wouldn't work well that set up because the have tread vs. the smooth tires I had.

The 3/4" aluminum angle was made to mount to the motor The 1-1/4" aluminum was made to mount to the rack. These two parts are connected together by the two #6-32 machine screws and the two spring. The screws thread into the tapped holes on the motor mount with the springs around them. This allows for the motor to move with the rim as you ride. This ensures that the generator wheel is always in contact with rim. The #6-32 all-thread was used to make two U-bolts. They fit the size of the bars on the rack.

I have included two drawings in the pdf for the two brackets I made to mount the motor. I also created an assembly drawing of the motor, wheel, and brackets. You will need to download the freeeDrawings Viewer to view the drawing.

Step 4: Wire the Electronics

All of the electronics of my Bike Generator were reused and I added the AA battery car charger. The circuit from Bike Generator needs to be changed slightly though. For instructions on how I put together the circuit refer to Bike Generator. For BikeGen I wanted to be able to recharge batteries while I rode and then use those batteries to power both the headlight and tail light. I wanted a good charge controller as well so that the batteries would not be over charged. I looked at a few charge controller kits that you solder together be decided to hack something instead. So I found thisAA Car Charger on ebay and was able to get it shipped for less than $7. This charger has a 1amp charge rate and can charge two AA's in two hours in a car. It also has a trickle charge feature that maintains full battery charge. This is perfect for what I wanted. Also because I was going to output 12volts I got a car power outlet so that I could recharge my cell phone as well.

The variable voltage regulator needs to be set up to output roughly 12 volts. Here is all the information you'll need on the voltage regulator LM317 Voltage Calculator I chose to shoot for 13.75volts, because I have measured the power outlet in my car and its usually over 12 volts. Also I could reuse the 220ohm resistor for 13.75volts. The original 220ohm resistor needs to be desoldered and then placed in the same location as the 150ohm resistor. The 2200ohm resistor can then be soldered in the place of the 220ohm resistor. I then used a dremel to spin the motor to make sure the regulator was working right. It output 13.88volts which was right on the money.

So the original Bike Generator circuit will rectify the AC power from the motor and regulate the voltage to 13.75volts. That power will then be fed to the charger circuit. The charger is then connected to a DPDT switch which is used to switch the batteries form the charger to the lights.

Step 5: Mount Everything to Your Bike

The motor mount should be easy to mount, but I haven't figured out the best way to mount the electronics yet so for right now their just duct taped to the handle bars. The lights will also have to be modified so that you can connect them to the batteries in the electronics box. For the tail light I soldered wires to the PC board and drilled two small holes to run the wires through. In the head light I just wedged the wires onto the connectors for the bulb and put a drop of hot glue there to hold them in place. For both lights I used a D-sub connector on a short section of wire, this is so that I can disconnect the lights easily. I ran wire from the electrical box to each light with pins soldered to the ends. I twisted two wires together with a drill for each light.

Once everything is connected mount it all to your bike and your ready to go.

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    26 Discussions


    4 years ago on Step 4

    Awesome tutorial, I'm going to start a project like this soon!

    One quick question because I'm confused, does the circuit charge the batteries and power the lights at once. Could you elaborate on the functioning of the DPDT switch.



    5 years ago on Introduction

    Does anyone know of any patents that may be similar to this, and why didn't the maker mass produce and sell this idea? It seems like a simplistic idea, and explainable to the average person, and it would be something I would buy for my own bike.

    2 replies
    Doug CostlowElliottl

    Reply 5 years ago on Introduction

    search for bike dynamo or hub generator, devices like this have been a round for a long time and are well developed. In places where bikes are used by many more people these are much more common. In the US the mass market doesn't ride a bike so its not as important.


    5 years ago on Introduction

    Good One. Thanks for sharing with world.

    Any rough idea on what is the RPM at which the generator dynamo is rotating? And what might be rough Nm force acting on dynamo? I might sound too technical, reason is I have been thinking of similar idea but on higher gererator capacity. Like using such spindle DC motor(can be used as generator as well)

    I read that this generator has less clogging and should start up with little force. But the rated RPM is high. So am checking with you to get rough idea.

    My other option include using below motor to generate high power. (ony thing need to find a good bracket)

    You can ask me what am I going to do with such hugh power generated.

    Well, the plan is to feed it to the hub motor. Trying to see how to increase mileage of my 36v 10AH battery. So once I initiate the drive of hub motor from battery and get bike momentum, a relay will cut off power from battery and start using power from generator.

    This whole idea fireoff in me after I saw this freewheel based free energy video

    Please do share what you think on the bicycle rpm and force.


    6 years ago on Introduction

    why not mount the controls between the goose neck and the forks


    8 years ago on Introduction

    I flagged the idea of a generator and have gone solar, connected to batteries that inturn power my lights a night, the usb for charging my mp3 player is currently being sorted, photo's on the way :-) cool as idea(any sort of charging system), especially if you are on your bike a lot


    9 years ago on Introduction

     so clueless about electronics...wish i wasn't, but it's one of those things that i just don't get. ugh!!! was just checking out yr previous 'ible, and together these are great!!!

    it does everything i want it to do- especially for touring by bike, but i just feel lost. maybe it has something to do with being left handed, although i doubt it. i probably just got dropped on my head as a baby too much :)

    thanks for making this though!!! hopefully i can find a friend that understands this better than i do...

    Kid Ninja

    9 years ago on Introduction

    Would it be possible to charge one of those batteries that they use for the little tyke cars?  You know like those battery powered trucks kids ride in.


    9 years ago on Step 4

     hey just quick question, would it work if I just took the circuit and switch directly to a car output? 


    9 years ago on Introduction

    does your generator produce pure dc? if not use a super cap in parralel to your inputs on the generator (+ and -), pedal for a bit and then turn on. result = saw tooth sine wave.

    Doug Costlow

    10 years ago on Introduction

    I recently rode about 15 miles with this and never noticed any extra load on the bike. It makes a humming noise but I couldn't really hear it over the wind. I plan on measuring the current, I'll let you know.


    10 years ago on Introduction

    Why not just power the lights directly from the generator, and skip the batteries?

    1 reply
    Doug Costlowvolto

    Reply 10 years ago on Introduction

    Thats how my first bike generator worked but then when you stop the lights go off. Plus I'd like to be able to take the headlight off and use it as a flash light.


    10 years ago on Step 5

    why not mount the electronics on the rack? or elongate the whole setup to fit on the seat tube or under the saddle?

    1 reply

    right now I'm using two switches to control the charging and the lights so I needed to mount it up front. I would like to build a single circuit that would keep the batteries charged and keep them in the lights themselves and have no switches so all you would do is hook up the lights and go, but I'm working on a few other projects and this has to go to the backburner.