David Butcher: Pedal Power Generator

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A Day of Pedaling

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You have to see it to believe it.

Curious about Human Power? Need some exercise? Trying to lose weight? Looking for a zero-carbon workout? Need inspiration? Researching technical information? Expensive electricity and gasoline making you nuts? You have come to the right place.

Every morning, I ride my Pedal Generator to generate electricity.
The Pedal Generator I built and ride charges batteries, that run
an inverter to produce 110v AC, that powers LED lights, the monitor
on my computer, my cell phones, and charges my Roomba, my eGo Electric
Moped, as well as many other battery-powered things.
All Powered by Me.
It is the most inspiring workout you can imagine, and it
saves me money!

Jump To:
Do It Yourself Plans
Latest News
Movies and Specs
Potential Uses
Appliance Power Stats

My Pedal Power History: 35 Years Researching the Power of Human Energy

The 12 Volt DC Pedal Generator you see on this site is a completely original
invention. I built the first version of the 12v Pedal Generator in 1976.
As an improvement over rudimentary bicycle generator and bicycle dynamo
designs, I focused on efficiency and versatility.
While a 12v bike generator is an alternative to my design, pedaling will
be less efficient,
and powering non-electric equipment may be difficult.
A unique feature in my design was a 36″ particle board disk with a groove
routed in the edge that served as the
flywheel and crankshaft
for the permanent magnet 36 volt DC motor
seen at the upper right edge of the device. A small-pitch chain provided the power
transfer system. The groove around the outer edge was lined with
“rim strips” – thin rubber straps that prevented the chain from
slipping and digging into the particle board. They are standard
bicycle parts. The motor was obtained around 1980 from Northern Hydraulic,
now known as
Northern Tool and Equipment Company.
It is a General Electric Permanent Magnet Motor, model 5BPA34NAA44, a very nice
heavy-duty, ball bearing unit. I paid USD $29 for it if I remember
correctly, and I still have it.

The bottom frame of the Pedal Generator was welded steel plate and
channel, the crankset was an American Schwinn ball bearing set,
a cotterless crank conversion spindle, alloy cranks and inexpensive pedals
with toe clips.

The crankset had a steel chainwheel on it. I drilled some larger
holes in the chainwheel and bolted the particle board disk to it. It was
strong enough (fine Schwinn steel!) to hold the weight of the particle
board disk and run true. I routed an oblong hole through the particle
board disk for the “arm” of the crankset.

The seatpost and handlebar tube were standard galvanized water pipe. The
generator/motor was mounted on a piece of 3/4 plywood visible in the motor
pictures seen above, which was then bolted to the water-pipe frame.

The particle board disk was a key feature of this unit. The weight of the
disk served as an excellent flywheel. Human legs and pedals create an
extremely “peaky” torque curve, resulting in jerky motion and lots of
stress on parts. The flywheel smoothes this all out by absorbing part of
the energy on the power stroke, lowering peak torque, and releasing it on
the “dead” part of the stroke, creating torque where Human legs/pedals
cannot generate any. Another thing to remember is that Human legs do not
like extreme stress. The flywheel allows the Human to avoid having to
generate extreme pressure during the power stroke just to make it past the
“dead” spots. Many “bicycle converters” lack the flywheel characteristic
because tires/rims are designed to be so light.

Noisy but extremely efficient, I have powered 12v
CHAIN SAWS directly (yes, while someone else cut wood
with them) with this unit.(1) Pedaling position was similar to a bicycle.
The seat is barely visible at the upper left of the photo, and the
handlebars (dropped, as on a ten speed road bike) are at the upper right.

Burst pedal power output: 25 amps at 17 volts (425 Watts) at 25 years old, and
265 Watts at 52 years old,
and 301 Watts at 55 years old! Yes, I am in better
shape than I was three years ago!

30 minute average output (back when I was in shape) 150 Watts


A drill chuck threaded into the end of the motor shaft provided power for a
flexible shaft drive. Drilling 1/2″ holes through 2×4 fir with this
arrangement was easy. The flex-shaft was rated at 1/2 HP (a commercial unit,
about 3/4 in. thick – not a “dremel” type!!) and I was still worried that
the torque would be too much for it.

For immediate electrical use, cigarette lighter outlets provided direct
access to the generator output. I even had a small 12v toaster oven,
and pedaled bread to toast more than once. For electricity storage
I would charge a 12v 100Ah fork-lift battery. I could approximate
the output of a small 10 amp battery charger.

Instrumentation consisted of a voltmeter and an ammeter, which together
provided me with state of battery charge, output watts and somewhat of a
“speedometer.” The math needed to determine power output was easy:
A 50 amp silicon stud diode mounted to a four inch square piece of aluminum
sheet metal prevented reverse current flows (which would cause the motor
to turn the flywheel, instead of the other way around!), and became
satisfyingly warm after long sprints. It was mounted in the center of
the aluminum plate visible in the first motor picture. For top
efficiency (and safety), a switch was also installed to completely
isolate the diode and motor/generator from the battery.

I had to be careful – I burned out several expensive 12v halogen bulbs powering
them directly. If there was no voltage control, exuberant pedaling would
fry the bulbs in short order. When the storage battery was connected,
this was less of a problem because the battery tended to even out the
voltage, but sprinting would still raise the voltage to the danger level.

I experimented with various non-electrical devices, connected
directly to the chain with their own sprockets. I substituted a
ball-bearing 3600 GPH Labawco type P pump for the generator,
resulting in amazing water pumping capacity. The suction from
the pump was strong enough to collapse the heavy wall
1 inch vinyl tubing used for the intake (radiator hose would have
been better, with the wire reinforcement) and the output shot a
stream of water about 25 feet across the street. A 5 gallon bucket
was emptied using this pump in less than half the time it took a
garden hose to fill it. I believe the pump was driven
to capacity (1 gallon per second, emptying the bucket in five seconds) in

I also tried smaller pumps, including a MATEX rotary vane pump,
with great success. I have had difficulty locating that brand recently
(30 years later!), but Northern Tool & Equipment carries a pump that
appears to be identical.
And what a great price!

I never had a chance to determine how efficient the Pedal Generator was in converting
mechanical energy to electrical energy, but I believe it was probably quite
good. When it was running, only 4 ball bearings were turning, the only
high-speed part was the armature of the motor, and I know from research
chains can be as high as 98+% efficient
in power transfer. The permanent magnet
motor was probably better then average at power generation, because it was
designed to be efficient as a motor. In “reverse” tests, with the motor
driving the unit with no load, the power consumed was less than an amp at
12 volts.
This is negligible, and much of it was resistance loss in the motor
windings, since the motor drew half an amp with no load connected to it.

Status: The Original Pedal Generator never broke down, and never wore out.
I still have the motor and flex-shaft, but several job-related moves
finally forced me to dismantle the unit, even though it was still in
perfect working condition.

(1) Three things about the MINIBRUTE 12 Volt DC chain saw. One, I was in great shape and probably
was generating over one horsepower in the sprint. Two, the branch/log was
about three inches in diameter – not anything near the 10 inch bar length.
And three, the saw was a 12 volt saw, so it was designed to be efficient.
The literature from the saw said that the motor was a permanent magnet
Bosch electric winch motor, which was a good match for the maximum output
of the Pedal Generator. It was great to see the chips fly!

Human Pedal Power Potential: What is possible?

There are many other possibilities that I can think of for this
device. It is much more powerful than a hand crank generator.
The efficiency and variable speed of the output are two features
that can be exploited. Since it requires no fuel, and is not
affected by time-of-day or weather, it would make an excellent
Human-powered emergency generator,
ready for any blackout.
Here are some other devices that could
be powered by the basic unit:

  • Pedal powered charging system for portable “Jump Start” systems.
    These devices feature lights, air compressors, battery chargers,
    power meters, 12 Volt DC outlets, and of course jumper cables.

    Portable Power station
    in the photograph was purchased
    at Costco for $49.95. It can be plugged directly into the
    12 Volt DC output of the PPPM for charging, and then
    moved to wherever the power is needed. Add a small 110 Volt
    AC inverter (100-150 Watt) and you have everything you need for
    portable power. Run a laptop, TV, PA System, or any other small
    electrical device for hours from your stored energy.
    Real Goods
    sells an equivalent device that seems to be the next level up
    in quality and features (and cost, of course!).
  • Pedal powered backup generator for solar electric systems or other off-grid power
    systems. With the newly available
    white LED as a light source, a few minutes
    of pedaling would be enough to create hours of light.
  • Pedal powered biodiesel circulation pump or biodiesel transfer pump –
    direct drive, with no electricity and no battery. If you make biodiesel,
    and you wish to eliminate electric pumps from your biodiesel equipment,
    the Pedal Generator design is perfectly suited to circulate, agitate and
    then transfer a batch of biodiesel, and the power source is YOU!
  • Pedal powered washing
    (this is a tremendous workout,
    especially with the spin/sprint at the end!)
  • Pedal powered clothes dryer (when combined with a simple solar hot-air
    collector – such as your attic! – pedaling would tumble the clothes and circulate
    the heated air)
  • Pedal powered whole-house ventilation fan (15 minutes in the evening to
    cool off an entire house)
  • Pedal powered pump and watering system when combined with a cistern to store rainwater
  • Pedal powered emergency
    sump pump
    – keep your basement dry during a power outage
  • Pedal powered energy source to power astronomy equipment during stargazing.
    (A Human powered star party!) A PPPM in a pickup truck could provide a steady
    60-100 Watt 12 Volt DC power supply, quietly, and keep the riders warm at the
    same time. Switch riders frequently and you’ll keep the all of the
    PPPM Human star party generators warm. Don’t even think of starting vehicles
    during the event!
  • Pedal powered whole-house (central) vacuum cleaner – requires two
    people, of course
  • Pedal powered backup circulation pump and backup air pump for
    tropical fish, expensive pond Koi or other animals requiring
    small but constant energy flows.
  • Pedal powered generator, emergency bilge pump, crew-warmer and
    exerciser for marine use.
  • Pedal powered air compressor (compressing air takes a LOT of power,
    and is not very efficient. This would work for small jobs only, like
    filling tires, staple guns, nail guns, caulking guns, small hand tools
    – no jackhammers!!)
  • Pedal powered offset printing press, sewing machine (an ancient idea),
    hand tools (grinder, disk sander, buffer,
    drill, reciprocating saw, lathe),
    mulch grinder
  • Pedal powered public address systems, projectors, or amplifiers for music –
    Radio Shack has a perfect unit for this!
    A single rider could power two of these with 12 Volts DC direct from the PPPM. Musicians, your green, portable PA system is finally here!
  • Pedal powered Science Fair Project – anything from the efficiency
    of the unit, to the physiology of the rider can be studied. Human power
    generation is a vast subject with many possible areas of scientific
  • Pedal powered replacement for hand cranked generator – your legs
    are almost ten times stronger than your arms. Free your arms and hands
    for other tasks, like reading, knitting, or mousing!
  • Every safe room, bug-out bunker, fallout shelter and hidey-hole should
    have a PPPM pedal powered backup generator. In addition to keeping you
    warm, fed, illuminated, circulated, ventilated and connected with the
    outside world, it can give you something to do besides staring at the walls.
    And it is totally safe with no fuel, fumes, or dangerous voltages!
    (unless you need more than 12 Volt DC appliances) Don’t leave your
    generator or solar panels out as an advertisement for mischief. The PPPM is
    the only power source you can have in the bunker with you.

Basically, any device that was hand cranked, foot-powered, or powered by a
fractional horsepower electric motor could potentially be converted to
pedal power.

Also note, if the base unit is being used to power an auxiliary device
in addition to producing electricity, adding a solar panel will result in
additional power from the motor/generator! That means whatever device you are
powering would receive the combined power of the Human
pedaler and the solar panel. This combination makes the best of both power
sources, as efficiency would be very high, because the solar output would
not suffer the losses of being stored and then extracted from a battery.
Charging a battery and then extracting the same power is less than 80%
efficient, and can be much worse. Direct utilization captures that wasted

Finally, keep in mind that a tandem setup for the pedals,
with the pedals out-of-phase, doubles the power and smoothes out the power
flow. Only one “flywheel” is needed, so this enhancement needs only a
simple pedal/seat addition to the basic unit. With out-of-phase pedals,
peak torque is not increased, so other parts of the system are not
stressed. The torque curve for a complete revolution of the flywheel
simply smoothes out, while RPMs stay constant, resulting in twice the

Latest News: Pedal Powered Prime Mover – Reborn

News: Sun Sep 14 12:44:02 PDT 2014

Last weekend at TechShop San Jose
I completely rebuilt the PPPM, after 10 years of hard riding. It has taken
on the look of a Steampunk Project, except I am the power source instead of
steam. The PPPM is a very interesting machine to see, and now that I have painted
it and replaced worn parts it’s ready for another 10 years of power-generating rides!

News: Sun Nov 16 13:00:00 PDT 2008

The PPPM shared the stage with Tamara Dean,
author of The Human-Powered Home.
After the presentation, the PPPM was moved to the publisher’s booth,
where it became the only
Green Energy powered display
in the San Francisco Green Festival.

News: Thu Nov 18 12:21:13 PDT 2008

The Christian Science Monitor interviewed me
during one of my pedal-powered webcasts, and included
the interview in an

article about Human Power

News: Thu Sep 18 20:19:22 PDT 2008

The Mother Earth News printed an article on generating
power with bicycle generators, and the PPPM was
mentioned: Make
Electricity While You Exercise
. The author describes several
different approaches to Human Power Generation, including
a state-of-the-art design he invented and assembled for a friend.

News: Sat Aug 23 21:21:18 PDT 2008

The San Francisco Chronicle printed a detailed article
on the PPPM: Power From
the Pedals
. It’s a fun article with a detailed diagram of
the PPPM and its power systems, and a firsthand account by the author of
how it feels to generate power.

News: Sat May 10 12:23:17 PST 2008

After a long bike ride, I arrived at UCSC where I worked with
a visionary Professor and an incredible group of students
to construct FOUR PPPMs in ONE DAY! Here is a link to
a photo album showing this unbelievable event:

PPPM Mass Production

The day ended with pizza, and a test of power output, of course!

News: Sun Feb 24 01:23:17 PST 2008

Use this new interactive Circuit Builder Tool
to see what kinds of equipment are needed to power various devices, from
Television sets to Breadmakers.

News: Wed Aug 15 23:06:41 PDT 2007

PPPM technology lit 15 lanterns in an enormous Oak tree at the
Big Chill Festival at Eastnor Castle, UK.

News: Sat May 19 23:06:41 PDT 2007

The PPPM is displayed at the Maker Faire
powering a complete home office. I pedaled all day Saturday, generating 335

News: Tue May 8 23:09:04 PDT 2007

So far in 2007, the PPPM has been on display at the
Burning Man Green House event, Earth Day,
and Springtime in Guadalupe Gardens. Record power
was produced at Guadalupe Gardens: 147 Watt-hours!
See the PPPM Live!

News: Sun Dec 10 14:29:39 PST 2006

PPPM designs and technology powered
Boycott Coca Cola Experience
in London.

The PPPM is powering power the
installation at the Bates Museum by Artist Virginia Valdes.

News: Sun Oct 8 10:30:00 PDT 2006

The PPPM was the power source for a Demonstration of Incandescent
vs. Compact Florescent light bulb energy use at an Energy Fair

News: Sun Sep 24 16:55:16 PDT 2006

Today I tested a 1.5 Farad Xpress Digital Power Capacitor, also
known as an Audio Stiffening Capacitor, as both the power
“smoother” and the voltmeter for the PPPM. The test was
a complete success. I ran two different devices directly
from the PPPM. One was an IBM ThinkPad T40 Laptop, and the other
was a 12 volt air compressor.

The capacitor provided a real-time voltage display, and it
stabilized the voltage and amperage being produced by the PPPM.
When passed through a Targus 12 Volt DC converter to the laptop,
pedaling was smooth and easy. With a comfortable seat the laptop
could be pedaled indefinitely. The air compressor required more
effort, especially when it was used to pump the tires on my
eGO Electric Vehicle to 100 PSI.

The capacitor was on sale at Frys Electronics for $19.95 – a great
deal considering it is both a capacitor AND a voltmeter. While it
does not provide as much information as the Watt’s Up I describe
below, it does address two critical needs: voltage measurement and
power stabilization. It’s not in the same league as my Maxwell 58 Farad
capacitor, but it costs 7 times less! It’s perfect for a basic PPPM.

News: Wed Aug 16 20:30:33 PDT 2006

The Pedal Powered Prime Mover
is a hit
in Australia!
– Main BioSUB Site

News: July 31, 2006, It has been one full
year since I brought the Pedal Generator back to life.
I have been riding that generator
every day, and storing the power it produces in a battery bank.
Motivated people from all over the world have bought plans
to fulfill their own visions for Human Power.
It’s a success!

Previous News: On July 31, 2005,
I rebuilt the Pedal Generator,
and I call the improved model the Pedal Powered Prime Mover,
because it can do much more than generate electricity.

I built the Pedal Powered Prime Mover (base, frame and flywheel) in one day!

The design is similar to the early version in
the picture at the top of this page, but I made a point of reproducing it
in a way that would be friendly to a “do it yourselfer.” The only
tools I have used are: screwdriver, hacksaw, wrench, hand drill,
and wood chisel. I finished it with only those
tools, and all “off the shelf” parts. It’s great to have
the Pedal Generator back online, as the new and improved PPPM I.

I recently installed a power measuring device
called the “Watt’s Up” from BatterySpace.com.
(search for “battery analyzer”)
I think it is the best such device I have seen for this use.
Disclaimer: I was so impressed with this device, I joined their
affiliate program, and the link above goes to it. If you prefer
to go directly to a different site, PowerWerx.com, visit
This device provides a real-time display of volts, amps, watts,
and other valuable and interesting information, such as peak output!
It has become the “speedometer” and “odometer” for the Pedal Generator.
Here it is in action! It’s small, powered
by the electricity it is measuring, and it measures in real time.
In this display I am pedaling with no hands to take the picture,
and the display shows an instantaneous output of 2.68 Amps, 15.83 Volts DC,
42.4 Watts, and also shows that the peak output for that session was
51 Watts. The display cycles through other useful information, like
total Watt-Hours and Amp-Hours produced in that session.
It sure beats the old panel meters I had on the original Pedal Generator!

Pedal Power Movies and Specifications: The Pedal Powered Prime Mover in Action

Here are some movies of the PPPM I in action. One of the last issues I
solved was a slight alignment problem with the flywheel. If
you listen to the movies, that is the loudest sound. The final version
of the PPPM I – which is used in the Ultimate Pedal Powered TV Movie – is
MUCH quieter.

Some of the devices shown in the movies are powered by 110v AC through an
inverter, some are powered from 12 volts DC directly from the PPPM I,
and some are powered mechanically. No batteries are used in ANY
of the movies!

Ultimate Pedal Powered Television:
PPPM I, 400 Watt Victor 12v DC to 110v AC inverter

  • 14 Inch Television: Short Movie,
    Long Movie,
    12v DC 1 Farad capacitor

    (Note: the black bar on the TV screen is caused by unsynchronized camera
    and TV frame rates. The picture is actually perfect.)
  • 32 Inch Television
    12v DC 58 Farad capacitor

Pedaling Effort: Light to Extreme, depending on the screen size 😉

Pedal Powered Laptop Computer: PPPM I, AD-SDR-70W – Universal DC-DC Regulated Adapter, 12v DC 58 Farad capacitor

Pedaling Effort: Light to Medium

Pedal Powered Blender: PPPM I, 12v DC 58 Farad capacitor, 1,000 Watt 12v DC to 110v AC inverter

Pedaling Effort: Light to Medium

Pedal Powered Water Pump: PPPM I, direct drive to 3600 GPH Labawco type P ball-bearing pump, 6 gallons pumped during the movie

Pedaling Effort: Medium

Pedal Powered Trip Hammer: PPPM I, directly driving a 16 ounce (.4Kg) hammer through a 3 foot (1 Meter) swing.

Pedaling Effort: Effortless

Pedal Powered Fan: PPPM I, 400 Watt Victor 12v DC to 110v AC inverter, 12v DC 100,000 MFD capacitor, Box Fan

Pedaling Effort: Moderate (Low Speed), Medium (Medium Speed), High (High Speed)

Pedal Powered Air Compressor: PPPM I, directly powering 12v DC air compressor, 15 PSI added during the movie (50->65 PSI)

Pedaling Effort: A good workout. 100 revolutions generated 30 PSI. Easier than a tire pump!

Pedal Powered Die Grinder: PPPM I, 400 Watt Victor 12v DC to 110v AC inverter, 12v DC 1 Farad capacitor, 10,000-20,000 RPM Die Grinder

Pedaling Effort: Light to Medium

Pedal Powered Vacuum Cleaner: PPPM I, directly powering 12v DC vacuum cleaner.

Pedaling Effort: Medium to Heavy

Pedal Powered LGB
Garden Train: PPPM I, 1.5 Farad Audio Stiffening Capacitor, directly
powering an LGB G-Scale Train.

Pedaling Effort: Very Light – Moderate, Depending on Speed and Grade

The fun part of this is you can “feel” the effort the locomotive is making
when it hits the grade. Controlling the speed of the train is easy – just
speed up or slow down the pedaling. The Capacitor creates “momentum”
electronically which adds to the overall effect. Is your consist
a little too heavy? Don’t just see the action, BE the action.

Pedal Powered Compact Florescent Light: PPPM I, 400 Watt Victor 12v DC to 110v AC inverter, 12v DC 100,000 MFD capacitor, 60 watt equivalent bulb

Pedaling Effort: Very Light (sorry for the pun!)

Pedal Powered Biodiesel Pump (Methoxide Agitation and Transfer): PPPM I, directly powering Hypro 4 roller pump.

Pedaling Effort: Very Light (Agitate) to Medium (Transfer)

You may be wondering if it is possible to do more than
one of these activities at the same time with a single unit.
The answer is YES. The light, for example,
could be combined with any of the other activities. As
long as the rider can handle the extra workload, the
Pedal Powered Prime Mover can deliver multiple outputs simultaneously!

One of the unique features of this design is that the
Pedal Powered Prime Mover is not limited to generating
electricity, unlike other Pedal Generator or Bicycle
Generator systems. The mounting possibilities for pedal
powered machinery are almost infinitely flexible. In the
pedal generator movies above, where the Pedal Powered Prime Mover
is being used directly as a pedal powered water pump for example,
the generator has been removed and the new devices has
taken its place. The flexibility is tremendous. In just a few
minutes, you can change the Pedal Powered Primer Mover to a
pedal generator, or to any of the other configurations you see in
the movies. That means one Pedal Powered Prime Mover can serve
a wide range of pedal power needs, including whatever you are
thinking of right now…

It is more fun than you can imagine to power things by
pedaling, with just you as the “Power Plant.” It’s healthy,
and it’s green, sustainable energy. What would YOU
like to power? Tell me here, and I just might give
it a try and make a movie of the result.

Pedal Generator: Frequently Asked Questions

Over time, a number of questions have asked about the information on the
page. Here are some Frequently Asked Questions and answers/opinions:

Do you have plans available?
YES! Follow the link below to order plans.
Why this design instead of a bicycle generator or a recumbent generator?
This design is simple and efficient. You will generate
up to twice as much power for the same effort
with this design compared to other bicycle generator designs.
Ok, but I see on the web other pedal generator
designs claiming 250 Watts, 300 Watts, even 440 Watts – and people
posting they have “generated 700 Watts” – or way more! Why all the
different numbers?
Some sites quote MAXIMUM power output in an absolute all-out sprint,
and some riders are not quoting actual electrical power generated at all.
They are quoting “calculated output” from their exercise equipment meters
that has nothing to do with real power generation.

I always quote REAL NUMBERS representing measured Amps and Volts coming
OUT OF ME and going INTO A DEVICE or BATTERY. In other words, “real power
output.” Don’t be fooled by the other numbers you see.

Do you have assembled PPPMs available?
NO! It is not cost-effective OR energy-effective to build
the units and ship them. The best way to obtain a PPPM is to assemble
it yourself, or find a local resource to assemble it, such as a Bicycle
Shop. You will also be able to fix it yourself if you built it yourself.
Is there a recumbent version of the PPPM?
It is theoretically possible to convert the PPPM to a recumbent Pedal Generator.
The image at the top of the page shows an early, working prototype of a recumbent version.
In fact, the PPPM could be assembled for both upright AND recumbent use,
and the riders could simply choose the riding position they prefer. The current
plans do NOT contain instructions for this conversion, but a version of the plans
is being written that will provide the details.
If I build the Pedal Generator, how do I power things with it?
Take a look at this
Power Board
I built for an Energy Fair for ideas. It shows how to wire 12
Volts DC through a junction box into an inverter with Ultracapacitors to
smooth out the power, and both cigar lighters for 12 Volt DC appliances,
and a power Strip for 110 Volt AC devices. A 12 Volt DC Laptop Power supply
enabled me to run an IBM Thinkpad directly, drawing only 20 watts. The
Watt’s Up meter shows how much power is flowing out to both the cigar lighter
outlets and the inverter, in real time. You can power anything within reason
with the setup shown. It’s a great visual learning tool for educators
to use in a classroom, too!

Here is a short movie explaining
the inner workings of the Power Board. For mode information, check out the
Interactive Circuit Building Tool!

Do you offer parts in a pedal power kit I could build myself?
No. All of the parts needed to build your own Pedal Powered
Prime Mover are likely to be available locally. All you need are plans.
Would a car alternator work better for generating power?
No. Most automotive alternators have one ball/one sleeve bearing, a
built-in power-robbing cooling fan, and they require external power to
excite them at low-to moderate RPMs. They have never been designed with
efficiency in mind, since they were attached to monstrous motors capable of
producing orders of magnitude more power than the alternator required. They
actually produce AC power, which subsequently must be rectified to DC to
charge batteries. This step causes significant power loss in the diodes
(around 5%). As I noted above, I ran power output around the diode and
directly into the battery to avoid this loss. In addition, alternators are
designed to run at extremely high RPMs (alternator pulleys are smaller
than the driving pulley on the engine, meaning the alternator turns FASTER
than the car engine. Look at your tachometer reading and double it. Whew!),
and do not produce usable power until they are rotating quite rapidly,
requiring high ratios of step-up from your pedals. A well-designed
permanent-magnet ball-bearing motor, preferable one designed to squeeze
every last bit of power out of a set of batteries, will easily beat an
automotive alternator in efficiency, yielding 20-50% more electricity for
the same effort.
Wouldn’t gears help generate more power? And what about belts
instead of chains?
Maybe. Humans can only pedal through a small speed range, about
40-120 RPMs. Below that you can strain your joints, and above that
efficiency falls off. There is a “magic” speed (different for every Human
Being) at which they can generate maximum power. The proper gear ratio
enables the Human to pedal at that speed. You may have noticed, though,
that a Human’s maximum power output can change quickly from fatigue, and
slowly from changes in conditioning and age. The magic speed is always
changing, so having a few closely-spaced “gears” or ratios may enable a
better match of Human to generator. No matter what, though, gears
don’t create energy, they waste energy
, so having fewer of them is
always better. The same goes for bearings, even ball bearings. The
pedal-power generator described on this page has very few of both, so it
is very efficient.

Regarding belts, the transfer efficiency of most belts is less than chains.
This is mostly due to flexing energy loss within the belt material and
friction losses at the engagement points between the belt and the pulleys.
Belts also work best when transferring low torque at high speed (the
opposite of what a pair of legs produce!) which is why you do not see them
on bicycles, for example. There may be some exotic, thin, high strength
belts that could approach the efficiency of chains with the right design.
For example, the “serpentine” belts used in modern automobile engines
are much more efficient than the old “V-belts” from the past. Belts
rely on friction to transfer power. Friction is bad. The best feature of
belts is that they are quiet, so I can’t say to avoid them
completely. If you decide to use a belt to transfer power, use the
thinnest, strongest belt you can find, and place only enough tension on it
to keep it from slipping during use. I do not know whether equivalent
“toothed” and “grooved” belts are equally efficient, but I believe the
toothed belt has slightly lower friction losses. If I can ever find some
real research data on the web I will link it in here.

I would rather use my bicycle in a stand and rig up a
generator connected to the rear wheel, or convert an exercise
machine by attaching a generator to it. Will you help?
I may, but I have all my attention focused on this design. I want
to improve it, and make it even more efficient and easier to build.
Every stand and exercise machine is different, and I can’t invent
a solution for each one separately. It’s also impossible for me
to work with equipment that I can’t see, touch, or measure in any way.

If you are still interested, click on “Convert Your Bicycle” to the left.

Could I generate more power with my bicycle in a stand and
a generator connected to the rear wheel?
No. You certainly can rig up a bicycle stand and hinge the generator
against the back tire using a tension system. I don’t think you will
be able to generate more power than the PPPM does, and here’s why:

To get an idea of how much energy is wasted in a bicycle power train,
pick up the back end of a multi-gear bike, like an 18-speed mountain
bike, and give the wheel a good spin – backwards. See how long that
much energy input can keep the machinery moving. I would be surprised
if you counted more than five complete revolutions, unless you are
testing a perfectly-maintained track bike.

With the same “push” the PPPM flywheel keeps spinning more than a
minute. The difference is not caused by the flywheel – it’s due
to the rapid loss of the energy you put into the bicycle machinery
due to friction. That loss will be a constant drag on YOU as you
ride your bicycle generator.
The PPPM design is simply more efficient.

You will also wear out your bicycle’s tire, gears,
chain, and bearings. If you have an expensive bike,
you will be paying more than you think for your
Human-powered electricity. If you have an inexpensive bike,
it will be even less efficient!

If I pedal now and
store the energy in a battery,
can I watch TV later?
Of course! A Pedal Generator plus a battery is an interesting
combination of technologies. Here are a number of different scenarios:

  1. If you pedal the TV directly, with no battery, almost all of the
    energy you create will go into the TV set. Very efficient.
  2. If you pedal the TV and have a battery attached to the system at
    the same time, the energy used by the TV will be used efficiently. If
    you pedal a bit more energy than the TV needs, the surplus will go
    into the battery. Due to battery inefficiency, you will only be able
    to get some of that surplus energy back. It could be anywhere from 70%
    to 90% depending on the chemistry of the batteries. If you wait a month
    to use the surplus stored in the battery, with some chemistries (like NiMH)
    you may find it has completely dissipated in battery self-discharge.
  3. If you pedal ONLY to the battery, with the idea that you will watch
    TV later, you will loose 10%-30% of ALL the energy you create in the manner
    of #2 above.

So – lets say it takes 60 Watt-hours to watch TV for one hour.

In scenario #1, you pedal at a 60 watt output for one hour, and watch TV
for one hour.

In scenario #2, you pedal at, for example, 70 watt output, and watch TV
for an hour while pedaling. The surplus (10 Wh) gets stored, but you
can only draw 8 Wh back out of the battery, enabling you to watch TV
for an additional 8 minutes, not 10 minutes as you might expect.

In scenario #3, you pedal at 60 watts for an hour with the TV off.
Later you watch TV, and you discover the power is all consumed after
watching 48 minutes of TV (80%).

In other words, if you pedal the TV directly for an hour, you need to
maintain a 60 watt output. If you want to watch TV for an hour later,
after pedaling, you will have to pedal at 70 watts for an hour to
account for the power lost through inefficiency.

No matter what, you will be watching TV!

How much power can one Human Being create?
This is an opinion. I used to be a competitive swimmer, and for a
number of years, I worked out 6 hours a day, swimming approximately 11
miles. Yes, 11 miles a day. If you pedaled that hard for that long you
might be able to run one ordinary refrigerator for 24 hours.
To make any
kind of significant contribution to your energy supply, you must use the
most efficient devices you possibly can. For example, a small refrigerator
designed to be powered by solar power would be much more practical.
For example, if you are prepared to use a slightly
unconventional refrigerator
there is a chance that you could power it with one good workout a day, and
maybe even have some energy left over for other things.
A rule of thumb: if the device was designed to be powered by batteries, even BIG
batteries, you might be able to keep up with it.

If your electric bill shows KWH (kilowatt-hours), take the number, multiply
by 8 (assuming you can crank out 125 watts for an hour, which is very
ambitious) and that is how many hours you will have to be in the saddle
to create the same amount of power. Sorry, it can be depressing.
The moral of the story:
Using less power is as important, if not more important,
than making more.

There are numerous sources of efficient appliances on the web. One place
I like to shop is Real Goods, and
of course I have spent time inventing my own efficient devices. The
white LED
light I built shows how technology can create new
solutions to increase efficiency. Pedaling for an hour at the 200 watt
pace, with 80% efficiency of generation/storage/extraction, would create
enough energy to run that light for 320 hours!!!

You may be interested in the details of the effort and energy
required to run the 12 volt appliances. I have compiled a
Pedal Generator Energy Statistics
page with the details.

Finally, here are some facts. Lots of people write to me and suggest that
a more efficient method of capturing Human energy would result in a better
power output. I am using this page for reference:
Horsepower – Wikipedia.
Here is the figure that matters:

1 horsepower = 33,000 ft/lbf/min = exactly 745.69987158227022 Watts


  • A Human would have to lift 33,000 pounds one foot in a minute
    to generate one horsepower (746 Watts output for one minute) – or, equivalently:
  • A 200 pound human would have to run to the top of a 14 story building
    (12 feet/floor, about 4 seconds per floor, 165 feet straight up)
    in one minute to generate 745 watts of output,
    and would have to continue that pace to keep generating one
    horsepower. Lighter weight people would have to get to the top even faster
    to generate the same amount of power.
  • So – I dare you to generate 746 watts/one horsepower, even for one minute 😉
  • As you can see, even if we could capture Human output with 100% efficiency
    (we can’t) you alone are not going to be able to run a refrigerator or
    air conditioner, or even a plasma screen TV directly by pedaling. No way.
    (Unless it is an unconventional
    !!) However, with the combined output from multiple PPPMs,
    anything is possible!
Can I generate 110v AC? Can I run my electric meter backwards?
I don’t recommend this! (Mostly, because it’s illegal!) If someone were
to replace the permanent magnet DC motor in a Pedal Generator
(such as the one on this page) with a 1/4 to 1/2
horsepower 110v AC induction motor and pedal that it would
result in an amazing thing.
If the motor was hooked to the power lines and it was “pedaled faster
than it wanted to go”, it would start generating 110v alternating current.
Beautiful sine wave AC. If it was creating more energy than your clocks,
refrigerator, all those little square black power supplies you have plugged in
around the house, your lights, and that 300 watt stereo you are listening
to while you pedal all use together, your electric meter would slowly creep
backwards. However, that same motor would generate exactly
0 power if it is not plugged in to 110v AC.

For very light duty “off the grid” use of 110v AC, you can try pedaling
your 12 volt DC generator into a large battery and hooking up an inverter
(12v DC – 110v AC) to get some pretty decent 110v power. In general, plan
on being able to pedal at the rate of about 70-150 watts for half an
hour or so, if you are in good shape. WARNING: You CAN’T use
an ordinary inverter to “run your meter backwards”!!!! (Think smoke
and flames!) If you are lucky enough to have a “grid tied” inverter
that matches the output of the PPPM, you just might be able to send
power back to the grid. However,
read this
before you consider a grid-tied pedal generator.

For efficiency, however, you are much better off producing 12v
DC for a 12v DC TV (for example) than you are producing 12v DC to charge a
battery to run an inverter to power a 110v AC TV
. The UPS
(uninterruptable power supply) for my website computer system can power
the computer for about five minutes. The same battery (12v 1.5 AH)
would power my laptop computer for about 45 minutes. Everything
(efficiency-wise) works FOR you when the device being powered is designed
to be efficient (12v DC) and AGAINST you when it is not (110v AC).

How do I know how much power an appliance requires?
Almost every appliance, motor, light bulb, etc. has a “Watts”
rating. You need to know how many Watts the appliance uses while
it’s running. Keep in mind, some appliances, like air compressors
and refrigerators, require a MUCH higher amount of power to start than
they do once they are running. Others, like washing machines, use
variable amounts of power depending on what they are doing at any
given moment (pumping vs. agitating vs. spinning, for example).

The BEST way to know how many Watts an appliance require is to measure it!
Here are several ways to measure power (Watts) used by devices:

How big should my batteries be?
If you are considering building a similar system, plan on using
two batteries, and a simple switch which allows you to use one while
charging the other. Flip this switch right before you begin charging to
ensure that you are charging the battery with the lowest charge (the one
most recently used). Also be sure to use a battery that is roughly equal
to ten or twenty times your power output for a charging session. For
example, if you crank out ten amps for an hour each time you charge, choose
a 100-200 amp hour battery. Larger batteries will simply loose charge
through self-discharge faster, resulting is less efficiency for your
system and more useless work for you.
What are “rim strips” and what did they do in the original
Pedal Generator?
On the original Pedal Generator, I used rim strips on the outer
edge of the particle board disk to keep the chain from slipping.
They were exactly what you would use on bicycle rims to
keep the spokes from poking through. The rim strips I used were for narrow
27 inch wheels. They were approximately one half inch wide. I had tried
leaving the particle board groove bare, and there was no way to prevent
the chain from slipping.

The particle board disk I used was too large for a single rim strip, so
I used two strips end-to-end and glued together with silicone rubber.
I overlapped the seam several inches. They are quite thin, so there
was no noticeable “bump” going over the seams. I was also pleasantly
surprised to find they prevented slipping completely, and there was
no evidence of any wear on them for the life of the machine. Be
careful when lubricating the chain, however. Keep the lubrication on
(and inside if possible) the rollers, not on the outside of the side
plates. I was very careful to not let the lubricants reach the
parts of the chain contacting the rubber strips.

Where can I learn more about Electricity?
Learn about basic DC electricity here,
and all kinds of electricity here.


  1. The most efficient way to use the power you
    create is not to create electricity at all, but to pedal power your (pump,
    fan, hoist, winch, drill press, grinder, sewing machine, etc.) directly
    through a mechanical connection.
  2. The second most efficient way to use the power is to
    pedal a generator to electrically power your (television, radio,
    floodlight, chain saw, laptop computer)
    directly, with no
    Be careful about controlling voltage, or use a good
  3. The least efficient way to use your power is to
    generate electricity and store it in a battery, then extract it
    from the battery to power some device. Avoid this method in favor
    of methods 1 and 2!!

Movie of David pedaling furiously on the rebuilt PPPM I

That’s me above, on the rebuilt PPPM I. The DIY plans for constructing
your own Pedal Powered Prime Mover
available for purchase ($USD50) below.

Online Magazine/Site Mentions:

Make: Television – I give the Pedal Powered Blender a whirl.

Planet Green – 5 Ways Going Green Can Help You Lose Weight (PPPM is #3).

Bicycling Magazine – High-Voltage Workouts.

The Christian Science Monitor – An electric workout through pedal power.

The Mother Earth News – Make Electricity While You Exercise

The San Francisco Chronicle – Power From the Pedals

Earthtoys Emagazine June 2006 – A PPPM Workout

Treehugger’s Article on the PPPM

WorldChanging: Another World Is Here: BikePower! (Pedal Powered Electricity)

Make: Features the PPPM

Interesting References:

The Human-Powered Home – If you
are looking for more information on all forms of Human Power – get this book!

Visit The BioSUB Project to read how the PPPM
was used to generate power in a unique underwater habitat.

An excellent writeup giving details on a different design based on a bicycle and rollers.

A handcrafted masterpiece demonstrating unique construction.

Yahoo 12 Volt DC Power Group

Yahoo Human Powered Devices Group

Pedal Powered Grid Tied Inverter (PPPM-sized) Note: not tested by me!

Nifty Digital Voltage Meter and Socket Multiplier

12 Volt Appliances and Devices – Including LCD DVD/TV Combo!

P2 – Awesome!

AltE Kill-A-Watt database – how much power do devices use?

Modern Outpost, lots of interesting Personal Power Gadgets

Alternative Energy News

Cyclean, The pedal powered washing machine

The Easyseat – the only seat I used on my PPPM

Solar Panels, Inverters, RV Chargers

Many different kinds of Inverters

Tons of 12 volt battery and charging information

Every imaginable kind of 12 Volt Appliance

The 12 Volt Shop (UK)

Battery and power supply technical information

Joan Baez ‘Rejoice in the Sun’ – Silent Running

Home Power magazine
is the Hands-on Journal of Home-Made Power. If you are
interested in making your own electricity from renewable energy,
alternative vehicles, or finding out the latest in related technologies and
life-styles, then this publication can keep you up to date.

Waistlines Continue to Grow in U.S.

Free Energy from Magnets! (I don’t believe in this, but if YOU do, off you go!)

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