Bicycle Powered Charger

Kento Yamaguchi

ECE 498 Senior Capstone Design

Advisor: Professor Hedrick

November 20, 2015

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Report Summary

Most people growing up learn how to use a bicycle when they are little, but they are not used

often after growing up. Bicycles are a method of transportation and exercise that most people overlook

because there are many alternatives. Most people would prefer to use a car for transportation, or use

the gym for exercise.

Using these alternatives to bicycles are not environmentally friendly. A car burns fuel which

pollutes the earth. The gym uses a lot of energy in order to light up the facility, turn on the televisions,

or power up their electronic equipment.

The goal of this project is to add an addition benefit to the bicycle: energy harvesting. By adding

to the set of useful properties a bicycle has, it will motivate people to use their bicycles. Mechanical

energy is required to turn the pedals of the bicycle. This energy can be put into good use in order to

produce electrical energy using the Bicycle Powered Charger.

The design requirements help shaped what this project would look like and how it would

function on a bicycle. It needs to provide enough voltage and current to any USB electronic device

attached to it. It also has to be light and easy to attach or detach. Safety is also a concern, since

electricity can be dangerous at higher voltages.

The design requirements helped determine what the design alternatives are. In order to get the

most amount of voltage out of this device is to maximize the efficiency of the device. This is mostly

dependent on which components are chosen.

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Table of Contents

Report Summary Page 1

Table of Contents Page 2

Table of Figures and Tables Page 2

1. Introduction Page 3

2. Background Page 4

3. Design Requirements Page 7

4. Design Alternatives Page 10

5. Preliminary Proposed Design Page 12

6. Final Design and Implementation Page 14

7. Performance estimates and results Page 15

8. Production schedule Page 15

9. Cost analysis Page 16

10. User’s Manual Page 16

11. Conclusion Page 17

12. References Page 18

Table of Figures and Tables

Figure 1 – The block diagram of the charger. Page 9

Table 1 – Project schedule Page 15

Table 2 – Cost of the project Page 16

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1. Introduction

Cycling is also a low cost method of transportation. It does not require expensive recurring

maintenance and does not require a fare for travelling on. The only cost required to use a bicycle is the

initial costs when buying a bicycle.

Cycling is a different method of exercise. When people think of exercise, they think of running,

weight lifting, and getting tired. Getting out a bicycle and riding is not something people usually think

about when they want to exercise.

Transportation and exercise should be good enough reasons to use a bicycle over its

alternatives. However, it doesn’t. The bicycle remains unpopular due to the presence of cars and gyms.

The alternatives of the bicycle are much preferred over the bicycle, even if the bicycle combines two

essential daily functions. If there was another benefit to using a bicycle, then it might motivate people to

use their bicycles more often.

The Bicycle Powered Charger will add another benefit to the bicycle. This project will harvest the

energy that a person uses when pedaling on a bicycle. The mechanical energy from turning the pedals

can be converted to electrical energy using a small generator. Users of this device would see that they

can create their own electrical energy and they will want to challenge themselves in creating their own

energy. Furthermore, this device will help the environment by using human produced electrical energy

instead of the power grid’s energy, which may receive its sources for polluting resources.

This paper will be organized in the following manner. The paper will first present the problems

that this project will solve, and provide project goals as solutions to the problems. The background of

the bicycle concerning the various aspects of issues that the bicycle has the potential to solve will be

given next. The design requirements includes detailed specifications that the project will be based on.

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Then, a preliminary proposed design will be given, which will be presented based on design

requirements and alternatives.

2. Background

The bicycle has many aspects surrounding it. Bicycles issues surrounding it includes economic,

environmental, and health. Bicycles usage is influenced by the economy. It can also help the

environment. Using a bicycle is good for a person’s health.

The first issue that the bicycle can solve is the economy. Many people use their cars to run short

distances that can easily be reached by walking or using a bicycle. However, not many people have this

kind of time, so they prefer to use their cars.

Cars go through depreciation as soon as it is bought. Depreciation is defined as the decrease in

an asset’s value throughout its useful lifetime. This is calculated because cars will not be reliable as they

age, which must be taken into account when selling cars. By the end of five years, an average car worth

$30,000 when bought will only be worth $12,000 after five years. This is a depreciation of $18,000.

Averaging this number over five years gives $3,600 per year of depreciation. $3,600 could buy at least

three high end bicycles, which will last longer and is cheaper, at the cost of travel time. [1] [2]

Furthermore, cars need the recurring costs of gasoline to run. A car needs to stop by a gasoline

stop at least once a week to refuel so it can run. If a car is not supplied with gasoline, then it cannot run.

When added to the cost of depreciation, the costs of depreciating and maintaining a car is a lot more

than the cost of a bicycle.

People are concerned about the future of the environment. Most views of the current state of

the environment are pessimistic. Everyday there are headlines stating how bad the state of the

environment is, and how the government plans on solving these issues. They are concerned about the

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water they drink and the air they breathe and how the pollution of their vital necessities will affect their

health.

The biggest cause of pollution comes from one’s own home. Many appliances require electrical

energy. Everything – lights, computers, refrigerators – require the use of electrical energy in order to

operate. This electric energy comes from the power grid. The energy from the power grid may come

from polluting resources, such as coal or gas, which emit toxic materials into the atmosphere. This is

bad. However, the consumer may not be aware where the power grid gets its energy from. Therefore,

they may not be able to control where they get their energy from. [3]

Another main cause of pollution is the emission of fossil fuels from transportation. Everyday

people have to get from one place to another. The most popular choice of transportation is a car. Since

many people use cars every day, the emission from every car combined creates a global problem. This is

polluting the earth’s natural atmosphere. Cars aren’t the only problem – other sources of transportation

also create pollution, such as a bus or subway. They create more pollution than cars, unless enough

people are using mass transportation. [3]

Gymnasiums can be used for healthy exercise at the cost of energy consumption. It has all the

machines to train various aspects of exercise, such as cardio or weight lifting. However, they have an

environmental problem. Gyms are big, and require a lot of lighting, temperature control, and electricity

to power up treadmills. Furthermore, they are usually empty when compared to the maximum

occupancy. They consume a lot of energy with very little effort. Therefore, it is not environmentally

friendly to work out at a gym, however, people need to stay healthy.

Health is another issue people face. Exercise is important for one’s health, but many people are

too busy or lazy to exercise daily. Part of this is due to longer life expectancies. Since people predict that

they will have a longer life due to better technology, they aren’t watching their health. However, living

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longer does not necessarily indicate a healthier life. A person could live very long but would have to

suffer from their poor life decisions that will affect them for as long as they live, which could end up to

be very long.

Food consumption remains the same but with decreasing exercise, people are not burning the

calories they need to in order to maintain a healthy body. In order to maintain a healthy body, one must

try to exercise regularly. Sometimes it can be hard to fit exercise when someone’s schedule is very busy,

especially if it is a low priority.

These problems presented so far may be mitigated by a bicycle. Bicycling is a method of

transportation that does not emit pollutants into the air like cars do. It is healthier to ride a bicycle than

to use a bus to reach a destination because riding a bicycle burns more calories than standing in a bus

and waiting for the destination.

Some work has already been done with the Bicycle Powered Charger. The generator stand,

dynamo, and the Copenhagen Wheel are all devices which take in a user’s input mechanical energy and

outputs an electrical energy response.

A bicycle generator stand is a stationary stand which connects to the back wheel. Since the

pedals of the bicycle drives the back wheel, the back wheel turns. The back wheel superficially touches a

spinning metal rod. This metal rod is connected to a generator, which will generate electricity. This

generator uses a spinning magnet in order to generate a current. [4]

A dynamo is a DC generator. It uses electromagnetism in order to work. The rotating magnets in

the dynamo creates a current through a wire. This has two applications. The first is a hub dynamo. This

is preinstalled on a bicycle’s wheel. When the wheel turns, the hub generates electricity. The second is a

USB charger energy. This device attaches to the rim of the wheel. As the wheel turns, there is a wheel on

the dynamo which spins, generating electricity. [5]

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The Copenhagen wheel works differently than the previous two devices, but has the same

concept: it takes in mechanical energy to produce electrical energy. Instead of using electrical energy to

power up an input, the Copenhagen wheel takes in the mechanical energy from pedaling. This energy

can be stored or released in the form rotational energy. The wheel turns by itself without pedalling,

helping a cyclist ride on uphill terrains if desired. The Copenhagen wheel can be adjusted using a

smartphone app which controls how much help a user can get from the wheel. [6]

This project will add on to the existing work by having energy storage. The current methods

available require the use of energy right away or else it is lost or never used. In the case of the

Copenhagen wheel, it stores energy, but is not used to power up an electronic device. With storage, the

energy produced can be used in other applications at a later time when the bicycle is not available.

3. Design Requirements

The design requirements have been chosen to fit the needs of the user while satisfying the

designer. In the beginning, the designer wanted to create a versatile device that could replace the use of

the existing wall outlet when powered up, and it would include a voltage display and solar panel to go

along with it. Over time, the idea of the device’s features have faced reality and smaller expectations of

the device’s use were made in order to fit the time and cost allotted for the project.

Potential users of this project will be people who already use bicycles as part of their daily

routine. These people will be the first to know because they are already aware of the benefits of using

the bicycle. They already know what to expect out of a bicycle. They will also be the first people to know

about the Bicycle Powered Charger when it is released to the markets. One of the main problems this

design will have is that it will add resistance to the bicycle. Since the device will be attached to the

pedals, there is rotational resistance from turning the gears. The device will have an extra weight on the

bicycle. This will make the bicycle heavier, making it harder to move.

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Since this device will add some extra difficulties moving the bicycle, some requirements have to

be made. First, the overall resistance must not slow the user down by more than 10 minutes on a 1 hour

bicycle commute. There are some cyclists who commute one hour to and from work, and it would only

make sense to do this if the workplace was one hour away. It is easy to plan 10 minutes ahead, however,

it might not be as easy if any more than 10 minutes was required to prepare earlier to get to work on

time.

Also, the weight of the project should not be more than 5 pounds. Five pounds is not a lot of

weight added to a bicycle. Anyone using a bicycle will most likely not be affected by another 5 pounds to

ride the bicycle.

Another interference the Bicycle Powered Charger may have is that it might introduce more

wires that may get in the way. While riding the bicycle, something will be attached to the device in order

for it to be charged. The cable for this device might distract the rider from riding their bicycle. One way

to solve this problem is to have a basket to put the device on the front of the bicycle. However, not

many people are comfortable with having baskets on their bicycles.

Another requirement for this device is that it must be easy to attach and remove. Attaching the

device shouldn’t be too difficult, or a potential user will eventually give up in attaching their device.

Detaching the device should also be easy, because a user might want to take the battery off and use it

on an appliance indoors. Also, it may be raining outside and the user might now want to damage the

device by getting it wet. Another reason for removing this device is that if a person parks their bicycle in

a public place, they do not want to have it stolen, so they will take it off. Once the device is detached for

whatever reasons, the user will want to attach it again because he or she will want to generate

electricity again. Therefore, this process of attaching and detaching the device must be easy and should

only take a few minutes.

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Next, the upper and lower limits for voltage supplied to the input must be taken into

consideration. These values will be based on safety and usefulness. For safety, no more than 15 volts will

be stored on the device at any given point in time. This amount of voltage is harmless to a human being.

This voltage should not be a problem since a 9 volt rechargeable battery will be used. For usefulness, the

output voltage must be 5V, since USB outputs usually contain this voltage and most phones chargers

state that they need 5 volts.

The lower limit should also be considered. The generator must deliver 5 volts. The rod must be

turned fast enough to produce the 5 volts.

The main components of this device are the generator, battery, and output. Their relationship is

shown on Figure 1.

Figure 1: The block diagram of the charger

The generator is needed to turn mechanical energy into electrical energy. The mechanical

energy will come from turning the pedals. The generator will convert this mechanical energy to electrical

energy.

The electrical energy will be stored in the battery. The purpose of this is to use the energy later.

Since the device will be easy to attach and detach, the battery can be moved and used in an indoor

appliance. If there is a device such as a phone attached to the bicycle outlet, then the battery will charge

the phone directly while getting energy from the generator.

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The last portion of the project is the outlet. This will be a USB port that will supply 5 volts to a

device attached to it. This is where all the power that goes into turning the pedals of the bicycle will be

released as electrical energy.

The goal of this project is to supply 5 volts to a device attached to the Bicycle Powered Charger.

This is determined based on what a USB port is expected to output.

This device should also produce enough energy to charge the battery by 50% of its maximum

storage in 10 miles. This was chosen because 10 miles is reasonable for a person who wants to bike to

work. The battery should be charged by 50% in 10 miles because 50% is sufficient to get a device

working if used in an electronic application.

Lastly, the efficiency of this device should be at least 30%. The device is expected to go through

a lot of energy loss due to friction and slippage between components.

4. Design Alternatives

It has been determined that there will be three parts to this project. The three parts are the

generator, battery, and outlet. These components will be tested separately and the best performing

components will be used in the final design of the project.

The first part of the project is the generator. There is a choice between an AC or DC generator.

The choice of generator will depend on the amount of energy and efficiency it can produce. This is an

example of where both quantity and quality need to be maximized. AC power generates a lot of energy.

However, the energy losses are huge compared to DC power. AC power has the advantage over

quantity, while DC power has the advantage over quality.

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Motors used backwards may also generate electricity. Motors use electrical energy and convert

it to mechanical energy. This is similar to how model cars work. When used backwards, it can generate

electricity.

Good generators were hard to find online, so a motor run backwards will be sufficient. Even

though the motor will have to run fast in order to provide 5 volts, a buck boost converter will be

attached in order to amplify the voltage. This now raises the question: should an AC or DC motor be

used?

The AC generator uses an armature. The armature and a static magnetic field to work. The

armature is a spinning electromagnet which rotates around the field winding. This creates a current.

Since magnets have both a positive and negative field, the output current also varies between positive

and negative current. Positive and negative current implies the direct in which current is flowing, which

is where alternating current gets its name from. [7]

The DC generator uses brushes in order to create a current. This current is similar to the

alternating current. A commutator is added to the generator which contains two slip rings. When the

alternating current goes through the one slip ring, it will change to the other, remaining in the same

polarity. That way, current always flows in one direction. [7]

The next portion of this project is the battery. This battery must be able to store energy and

release it anytime energy is being brought in by the pedal or exerted by the energy output. The main

types of batteries viable for this project are the Nickel-Metal Hydride battery, Lithium-Ion battery, and

lead-acid battery.

The energy output is the last main component of the project. This will be either a USB port or a

power outlet. USB ports are easier to work with, and easier to get the required amount of voltage with.

However, a portable power outlet is more versatile. If a person is carrying a laptop in their backpack

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while riding their bicycle, they can charge their laptop using the portable power outlet. Most laptops

come with a charger that plugs into a wall instead of a USB port, so having a power outlet would

increase the versatility of the project.

An addition to the project that could be useful is an LCD display system that can measure how

much electricity is inside the battery. Then it will display the amount of voltage in the battery. This is

important for testing purposes. More importantly, a user of this project can look at this display to check

how much energy they have produced in the battery.

5. Preliminary Proposed Design

Now that the requirements and alternatives have been presented, the preliminary proposed

design will be determined. The generator, battery, and output will be chosen, along with the coupling

system used to connect the components together.

The AC motor was chosen because it can generate more voltage at a lesser input power by being

attached to a rectifier. The rectifier keeps an AC signal at a constant value by using a capacitor, which

stores charge. The capacitor will discharge as the input power goes down, keeping the amount of output

voltage as constant as possible. As the input voltage go towards its trough, the capacitor will discharge

and keep the output voltage positive until the input voltage is greater than the discharged voltage.

A lithium ion battery will be used in the design because it is useful in similar applications. Most

rechargeable batteries are lithium ion batteries. They are easy to find and there is a lot of online

information about them, which would make them easy to implement. Also, they are used for small scale

applications such as USB devices. Lithium ion batteries can be used for a project similar to the Bicycle

Powered Charger, which is why the lithium ion battery will be chosen for this project.

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The USB port was chosen because it is easier to generate 5 volts than 120 volts for a portable

outlet. Achieving 5 volts is hard enough. It requires a lot of input power in order to produce 5 volts from

a motor. Time and money limitations are other factors that lead to this decision. It would take a longer

time to implement an outlet, and would cost a lot more if using a lot of voltage amplifiers. The utility of

choosing a USB port over an outlet diminishes, however it will still be useful. Many devices use USB port,

such as phone chargers and flash lights, so this project is not completely useless.

This USB port and battery will be attached to the back of the bicycle. The idea is that the USB

port will be near the user’s pocket, which is most likely the place where the user will put their phone

while it is charging. This will reduce interference with the user. If a user wanted to attach a flashlight,

then the flashlight would most likely go on the back of the bicycle as well, so that incoming cars will be

able to detect the rider during the night. Also, the system will be closer to the generator, making the

coupling system as minimal as possible.

The generator will be attached to a sprocket, which will touch the chain of the bicycle. The

sprocket will be attached to a base that can slide according to where the chain is. As the user shifts his

or her gears, the sprocket will move along with the chain. This will make it easy to attach and remove

while also having minimal interference with the normal function of the bicycle. While it is preferable to

always have the generator attached to the highest gear at all times, this method would interfere with

the chain if the user decides to switch from low to high gear.

A buck boost converter will be necessary to control the charge of the battery. The voltage

generated by the motor only generates 5 volts when an angular velocity of around 300 revolutions per

minute is used. A rider could not turn their pedals 300 revolutions per minute, so the voltage will have

to be amplified in order to reduce the number of revolutions per minute to something more reasonable.

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Efficiency will be calculated for the Bicycle Powered Charger. To calculate efficiency, the ratio of

the output power to the input power will be used. The output power is electrical energy. It is defined as

voltage times current. The input power is mechanical energy. In this application, it is defined as torque

times angular velocity.

𝑒𝑓𝑓𝑖𝑒𝑛𝑐𝑦 =𝑃𝑜𝑢𝑡𝑃𝑖𝑛

=𝑉 ∗ 𝐼

𝜏 ∗ ѡ

The voltage and current can be calculated using a multimeter and is the easiest to calculate. The

angular velocity depends on the radius and linear velocity.

To test the Bicycle Powered Charger, a test of distance and time will be conducted. To ensure

that test results are as accurate as possible, each test will be done five times. It is important to note that

the tests will be done during the winter months, so it is only feasible to do the tests indoors. The tests

will have to be small enough to accommodate the indoors environment.

The bicycle will to riddle for one mile. The time it takes to complete one mile will be recorded

for a bicycle without the device. Then, the Bicycle Powered Charger will be attached and the time and

voltage gained will be recorded. The results should show that the bicycle runs no slower than 10% of the

bicycle without the device. One of the design requirements state that the battery should be charged by

at least 50% of its maximum storage in 10 miles. Therefore, the test should show that the battery has

increased by at least 5% in one mile.

Once the test has been conducted, the user will want to know the test results for 10 miles.

While the data is not linear and the time can’t be multiplied by 10 to get the time in ten miles, it would

provide a close approximation, which is what the user would want.

6. Final Design and Implementation

To be completed for ECE 499.

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7. Performance estimates and results

First, a test was done on a motor run backwards. The setup consisted of a multimeter connected

in series with the motor to calculate current. The oscilloscope was connected in parallel to calculate

voltage. The tachometer is used to calculate angular velocity. A drill was used to spin the motor, which

the tachometer read. The drill was spun until the oscilloscope read a maximum of 5 volts coming out of

the motor. For both motors tested, the AC and DC motor, the required speed was 300 revolutions per

minute.

8. Production schedule

This section will provide a summary of what has already been done as of November 2015, and

what will be done over the next few months. This plan is made so that it will accommodate the

scheduling of the coursework and the designer’s personal life. Table 3 provides this summary.

Time Thing to complete

Spring 2015 Project was chosen 2 presentations done Project requirement paper Project requirement paper complete.

Summer 2015 Research on topic Ride a bicycle for 10 miles Work on website to the fullest extent as of now

September 2015 Apply for grants Get parts ordered

October 2015 Project presentation Second grant period

November 2015 ECE 498 essay due

December 2015 No work

January 2016 Finish prototype

February 2016 Capstone presentation

March 2016 ECE 499 essay Website due

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April 2016 No work

May 2016 Steinmetz Day

June 2016 Graduation from Union College

Future Make the project something people would want to buy

Table 1: Tentative project schedule. Changes may be made while doing this project.

9. Cost analysis

The purpose of this project is to do tests in order to determine the best possible method of

coupling the system together. Testing the components for the project requires expensive tools. The cost

of the project is outlined in Table 4.

Item Reason needed Cost

AC Generator Generate energy from bicycle and compare test results with a DC generator.

$7.32

DC Generator Generate energy from bicycle and compare test results with an AC generator.

$16.99

AC Motor Convert it to a generator to see if online theories work.

$30.95

DC Motor Convert it to a generator to see if online theories work.

$3.49

Nickel-Metal Hydride battery 9.6V, 1600mAh

Store energy and compare results with other batteries.

$20.50

Nickel-Zinc battery 9.6V, 2000mAh

Store energy and compare results with other batteries.

$19.99

Lithium Ion battery 9.6V

Store energy and compare results with other batteries.

$16

Sealed lead acid 12V, 22Ah

Store energy and compare results with other batteries.

$51.98

USB port 5V maximum output

Plug in an electronic device as a way to start testing the system.

$35.00

Outlet port Plug in an electronic device after the USB port is successful.

$44.99

Used bicycle The device used to test the project.

$60

Bicycle Chain Connect two sprockets together.

$10.17

3 bicycle sprockets Spare parts in case the bicycle gears break

$90

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Torque Meter Measure the amount of torque my bicycle is exerting.

$1632

LCD Display for voltage Show the user how much voltage is inside the battery.

$15.95

Total $2,055.33

Table 2: The total cost of designing the project.

The cost of the Bicycle Powered Charger for a customer should be worth five years of energy

saved added to the cost of production. This should total the total cost of the project itself excluding the

bicycle and the amount of money saved in five years of use. Assuming that the average cyclist produces

100 Watts per hour and has a one hour commute every day, they would be producing 1,000 Watts per

week. Next, assume that the user will only ride in the non-winter months. This means that there are 40

weeks when the user would use their bicycle. The user would be saving or generating 40 kWatts of

power a year. Multiplying this number gives 200 kWatts in five years. Assuming that 1 kWatt is $0.15,

the total cost of saving would be $30. At the end, this project should cost around $430, which is

expensive. [8]

10. User’s Manual

To be completed for ECE 499.

11. Conclusion

The goal of this project is to create a use for bicycles and help the environment by providing an

alternative to charging portable electronics. Doing so will allow the user to have an alternative to

charging their device on an outlet, where the energy comes from a power grid, which usually comes as a

cost. The prototype for this system will provide one method for achieving this goal. With this device,

cyclists may charge up their portable electronics while enjoying bicycling.

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12. References

[1] http://www.edmunds.com/car-buying/how-fast-does-my-new-car-lose-value-infographic.html

[2] http://fitness.costhelper.com/bike.html

[3] http://www3.epa.gov/climatechange/ghgemissions/gases/co2.html

[4] http://www.econvergence.net/The-Pedal-A-Watt-Bicycle-Generator-Stand-s/1820.htmz

[5] http://www.edisontechcenter.org/generators.html

[6] http://www.bloomberg.com/bw/articles/2014-01-30/innovation-copenhagen-wheel-for-

electric-hybrid-bikes

[7] http://www.differencebetween.com/difference-between-ac-and-vs-dc-generator

[8] "Power Consumption of Household Appliances." Power Consumption of Household Appliances. N.p.,

n.d. Web. 05 June 2015.