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This version was saved 12 years, 8 months ago View current version     Page history
Saved by Amos Blanton
on November 13, 2011 at 10:14:32 am

Pedal Power to the People!  and other alternative energy sources!


This site has been created for us to share information and designs on Pedal Power, based on experiences during the 2011 Occupy movements.

Please join and help us document the electrical design.


Showing off the pedal power setup at Occupy Boston





FAQ (Frequently Asked Questions)


Q1. What design did you use and where can I get the schematics?



Q2. How did you go about getting the materials?


Q3. What problems did you have in building them and how did you overcome them?



I. Raw Power Generator   


Turns human pedaling into raw, unrefined energy.

     A. Bicycle            
        "typical" mountain bike or street bike.  Strong rear skewer preferred
    B. Mounting stand        
    C. Motor    


II. Power Refinery

    A. Chargers

        1. Storebought - e.g. NC25A -charge controller pricey and efficient but don't require attention. Big Bertha uses this at Occupy Boston.






        2. Simplest-Possible Generators - require few parts, but must be watched carefully

        3. Occupy Generator Schematic - open source, responds to needs of the Occupy communities

    B. Battery

        1. How to Select: Sizes, Prices and Useful life
        2. How to Use

III. Using Power 


Once you have refined power, it can drive the following:


    A. AC inverter -> AC Appliances

    B. DC peripherals at 12 Volts  

        1. Lamps
        2. Radios
        3. Amplifiers

    C. Common DC peripherals below 12 Volts

        1. Cell phone chargers
        2. Appliances < 1 Amp, Internet routers, "Wall wart" devices, a.k.a. "Black Box", "Power Brick," "Power Block"


Real-Life Problems Encountered


1. 12VDC cigarette light plugs popping out from vibration
-marine grade

2. Scumbag lights give false state of charge

3. People charging too fast

4. Skewers get bent b/c load is not on

5. Inefficiencies in coupling

   a. human error

   b. friction creating heat loss, wears tire out faster

6. wear and tree on front wheel

7. batteries draining too low

8. temperature problems
9. People "fixing" the wiring that don't understand how it works.

10. People replacing components that aren't broken, and or walking off with parts.

11. Corrosion

     After only about 1 month of service in the Pedal Power tent, we've already experienced a failure due to corrosion on Bertha. Below is a picture of what was our rectifier board. It was on the crate with the charge controller, thoroughly wrapped in electrical tape. There was no mechanical stress of any kind (that I know of) - just environmental.


The dark patches show where the copper has basically flaked off of the board as a result of corrosion. 

Bertha's tent has a couple inches of standing water on the downhill side. Thankfully, Dana put Bertha up on a palette so she's not actually in the water. But the air must be fairly moist more or less all the time. And, being outside in the elements, there must be plenty of opportunity for condensation as the temperature changes each day.

We recently re-wired everything to make it easier to swap different batteries in and out for charging, and I noticed that many of the bare wires in the charge controller seemed unusually corroded as well. It might be best to "tin" wires with solder the next time we do a rebuild, as I suspect that might keep the electrons flowing smoothly for a little longer.



Good Ideas

1. Lock bikes to generator
2. "Bike docking station"
3. Fitness center
4. Bike tires as V-belts
5. Mudshield
6. Treadmill form

7. Pennyfarthing as generator!!!




A Proposal for Standardizing Electrical Power






This diagram breaks things down into two categories: supplies and loads,.


Supplies - things you can plug stuff into to get power.  Examples include generators (pedal, wind, solar), and battery packs.


Loads - things that consume power.




Voltage 12 Volts


It would be useful to declare some standards - 12 volt being the first one. One could imagine a scenario where all the occupies agree on a standard and an interface for things that create power and things that use it. If OWS needs more power for an event, Boston can send them a few of their generators for a couple days, and / or vice versa. You get all kinds of emergence and unexpected benefits when you standardize the interface as a constraint and then let people innovate what's behind it.




Power Connector: Auto appliance adapter, a.k.a. cigarette lighter.


It has ends that look like this:



If we're using 12 volts, then we might as well use the cigarette lighter plug as the interface because there are lots of things that work with them out of the box. Aside from the many cell phone chargers, usb octopai, etc, you can get for your car, there are also a lot of cool electrical things made for RVs and boats, like coffee pots, slow cookers, refrigerators, and what have you. And marine grade 12 V cigarette sockets / plugs will actually lock in place.

This approach suggests we should focus our efforts in two places.

1. Make universal power regulators that can be used with (almost) any pedal generator

It doesn't take a deep understanding of electrical engineering to make a pedal generator: you just have to figure out how to turn a motor backwards. The difficult part is what to do with the unregulated, dirty, DC electricity that comes out of the generator wires in order to make it consistent, safe, and usable, so it can interoperate with all the things we might want to connect it to. Once a cheap power regulator is designed and made available, lots of people can then make pedal generators. They can order the assembled power regulator from sparkfun, or DIY it from plans made available, and then they're golden: hook up the two wires from the generator to the in, and then hook up the two wires for the out to a cigarette lighter socket. It doesn't matter that their generator looks or works differently than all the rest, as long as the output conforms to the standards.

A thumbnail first draft of a spec for the power regulator:
Contains a bridge rectifier so you can't pedal backwards and generate negative voltage
Takes in power ranging from - 30V to +30V and consistently outputs clean 14.5 volts ( which most 12 volt things can accept, and the extra couple volts are useful if you are charging a battery pack)
Consider using a largish capacitor so one can slow down pedaling or even switch riders for a second and still put out consistent power.

2.  Build Power packs with charge controllers

12 volts won't travel far on a wire without losing its oomph, and we can't put generators everywhere. So that means we need portable power packs to distribute power to where its needed on site. Batteries need charge controllers with simple interfaces to be usable by the masses. They should prevent over charge or undercharge, and they should tell the user when they are being charged or discharged, and approx. how much juice they have left. And it should make difficult to lick the terminals or short the leads, or otherwise do something dangerous.

User Stories

Here are some user stories of how I could imagine this working as we scale up:

The cook notices the light is getting dim, so the next morning someone takes the power pack to the pedal tent, where they charge it for an hour or so. They bring it back, plug it in, and the lights are good for another few days.
One of the people in the media tent needs to work on their laptop all night, so they go the pedal tent and "sign out" a power pack and and AC 120 volt inverter (and possibly leave some kind of collateral). The next morning they return both to the pedal tent coordinator, who places the power pack in the "dead" queue. Legions of healthy young pedalers stop by throughout the day and charge it and the rest of packs back up, under the watchful eye of the coordinator / pedal power team.




Trucker Blanket:

Cost: $27.88

Size:  58" x 27"

Electrical:  Current: 4.2 Amps  Volts (DC): 12    Watts: 50.4 





A Simple Metal Generator Frame



This simple frame was designed and designed and built by Noah Vawter at MIT as part of the MADMEC competition around 2005.

It lifts the rear tire up to where it can rub against the generator motor.  With simple steel materials available

at some hardware stores it's easy to weld together. 


To make a make frame for an adult bike like this, plan to lift the rear axle off the ground 2 inches.  For 26-inch wheel, the highest part of the rear-wheel frame should 15 inches off the ground.  For a perfect 45 degree angle, the length of the base should be twice the height.  The four arms are all sqrt(2)*15 long, e.g. 21 +3/16 inches.  The two halves of the A frame should be at least 8 inches apart. 





It is crucial that the rotor the of Generator makes good contact with the wheel.  For this reason, it's good to be adjustable.



In this photo, you can see the simple adjustment mechanism to raise and lower the motor.

Note that heavy carriage bolts have wrench sockets welded to the ends to cup the rear skewer.




This was an experiment.  You can bolt this material together and chop it up with a hacksaw or angle grinder.

cost of angle grinder ~$100.  It's kind of wobbly though.  It's maybe useful for lightweight parts of the design.



Other sites we have been finding useful









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