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Table of Contents

Introduction..............................................................................................3Background/Existing Products.................................................................3-4Concept Development..............................................................................5-10

Concept A................................................................................................5-6Concept B.................................................................................................6-7Concept C.................................................................................................7-8Concept D................................................................................................9-10Decision Matrix.......................................................................................10-11Cost Analysis...........................................................................................11-12Conclusion...............................................................................................12Works Cited..............................................................................................13Appendix A: Mechanical Drawings.........................................................14-22Appendix B: Calculations........................................................................23-24

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Introduction

In the United States alone, nearly twenty tons of carbon dioxide from motor vehicles is

emitted per capita every year. These numbers are only growing; sweeping changes must

be made to curb harmful greenhouse gas emission and man’s dependence on fossil fuels.

Though in existence for over a century, lately electric vehicles have risen in popularity

due to the rising cost of gasoline. They offer a drastic reduction in overall energy

consumption as opposed to traditional internal combustion engine propulsion. This

project deals with the design and construction of one such EV; an electric motorcycle.

Electric motorcycles are a viable alternative to ICE motorcycles. They offer comparable

overall weight, and with a sufficient power supply, performance as well. The following

will present several concept ideas and evaluate each.

Background/Existing Products

In recent years, the reduction of human induced environmental impact has been at the

forefront of new innovation. Carbon emissions have come under great scrutiny as a major

contributing factor of climate change. Internal combustion vehicles account for roughly

28% of green house gasses emitting twenty tons of carbon dioxide per capita each year in

the United States alone.1 A new approach to transportation is needed to offset these

troubling numbers and foster a new attitude for the advancement of our culture within the

restraints of our environment and level of comfort.

One proposed solution comes with the development of fully electric vehicles. EV’s are

propelled by an electric motor that draws its power from chemical energy storage via a

battery pack. The utilization of electric vehicles yields both advantages and

disadvantages. Advantages include: increased energy efficiency, and decreased pollution

in the form of both emissions and noise. Whereas the advantages of an electric vehicle

can be categorized by attributes pertaining to clean energy, its disadvantages can be

attributed to performance and cost. The main hurdle that EV's face is the task of

efficiently storing the energy required to meet the average driver’s performance needs,

i.e. battery size/storage capacity. There exists a delicate balance between an efficient EV

and one that is not. Vehicle weight is that dominant limiting factor. An efficient

aerodynamic vehicle profile and a low coefficient of rolling resistance can be achieved

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with relative ease. A battery pack that marries a long vehicle range and relative light

weight is much more difficult to achieve. Though advances have been made in the

production of smaller, light weight batteries (lithium-ion, lithium polymer), their high

cost limits their use in many applications. Often, cheaper lead-acid batteries are

implemented, but their greater weight will drastically reduce driving range.

The effects of heavy a battery stack can be countered by a reduction in vehicle size. By

reducing the size of the vehicle, energy requirements drop dramatically. A low

aerodynamic profile, lightweight chassis and low rolling resistance from thin tires will

result in improved performance. These trade-offs render a motorcycle a prime candidate

for an EV application. There are few examples of electric motorcycles currently in

production. Figure 1-1 illustrates the performance specifications of three of these e-bikes

currently on the market.

Brand Claimed

HP (hp)

Battery

Capacity

(Kwh, V)

Battery

Type

Range

(miles)

Top

Speed

(mph)

Charge

Time

(hours)

Quantya

EVO1

16 1.9, 52 Li-ionPoly

25 40 3

Brammo

Enertia

17 3.1, 76.8 LiFePO4 42 60 4

ElectricMotorsport

GPR-S

19 3.3, 81 LiFePO4 60 70 4/1.5Stock/

optionalcharger

Senior

Design

Team

15 1.68, 48 SLA * * <6

Table 1: Various Electric Vehicle Performance Specifications

*Discussed below

Concept Development

Concept A

Ideally, the motorcycle frame would be large enough to easily accommodate the

peripherals and components necessary to have a functioning electric motorcycle. Concept

A reflects one possible configuration where the motor is affixed to a motor-mount on the

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center brace of the cage. Four 48 volt, 36 amp-hour lead acid batteries are secured to the

front beam, open to the air to allow for ventilation. In order to maintain a low center of

gravity, the batteries are positioned close to the motor without causing interference. The

motor controller and the charger are bolted to the center divide on either side of the frame

Figure 1: Concept A, Lead-acid Battery Configuration 1

Analysis

Cost

A larger, replacement frame and chassis will cost approximately two hundred dollars and

will add 20-40 pounds of weight to the motorcycle. Though heavier and more expensive,

a larger frame will allow for a more comfortable ride and better storage of the power and

drive systems.

Performance

The added weight would cause the performance of the bike to suffer. In addition to

weight the bigger frame would mean a greater frontal area, increasing air resistance.These added variables would decrease the range of the motorcycle.

Comfort

Fabrication becomes easier with a bigger frame and rider comfort would arguably be

better. This is because a bigger frame affords more flexibility in positioning and

rearranging certain components to suit the rider, thus improving the comfort of the ride.

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Concept B

The following concept utilizes the existing frame and chassis. Four: 12 V, 35 A-hr sealed

lead acid batteries will be connected in series to make a 48 V, 1.68 kW battery stack. An

Etek-R, brushed permanent magnet electric motor from electric motorsport will be used.

It is capable of producing 15 peak horsepower and will easily aid the team in reaching the

design specifications. An Alltrax, 48 V, 300 Amp motor controller is ideally suited for the

Etek-r. A Soneil, 6 Amp, continuous amperage charger will charge the battery stack from

a fully drained state in under six hours.

Figure 2: Lead-acid Battery Configuration 1

Cost

This design is the least expensive of the four. The existing frame is utilized as well as the

least expensive battery option.

Performance

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Performance varies only slightly between each lead acid battery pack. Concepts B and C

are lighter than concept A. The largest gains come from the lighter lithium polymer

battery pack. It’s drastically reduced weight, and higher power delivery make it the most

desirable option.

Comfort

The battery charger and motor controller are placed beneath the rider’s seat; this will

raise the rider by approximately 4 inches and as a result will decrease the rider’s comfort.

The small frame is also not very comfortable for a full grown adult to ride for an

extended period of time.

Concept C

Like Concept B, concept C features four: 48 volt, 36 amp-hour lead acid batteries. Placed

in battery trays on the frame, two will be placed over the rear tire similar to saddle bags

on a cruiser type motorcycle and two will be placed behind the fork in front of the riders

knees. Motor and motor mount placement is the same for both lead-acid configurations B

and C. Charger and motor controller are to be mounted in a box inside of the

motorcycle’s seat. The charger is to be placed furthest back facing the rear so as to

maximize accessibility.

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Figure 3: Lead-acid Battery Configuration 2

Analysis

Cost This configuration is to be used as an option if supplementary funding is not received for

the purchase of a bigger frame and a more efficient battery stack. Expenses will be

similar if not equal to those in Concept A because all components are the same with

different mounting locations.

PerformanceThis configuration will exceed the customer’s needs. The power supply and motor will

reach the desired top speed and range. Weight is equal to Concept B. Due to the front

batteries being mounted higher on the frame, the bike’s center of gravity will be raised

and consequently its handling will suffer.

Comfort

Due to the increased seat height from the charger and controller box, a hard seat should be used as to not further raise the height of the rider. Depending on how long the rider’s

legs are, the two front batteries may impede leg room.

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Concept D

This design concept design is similar to the pervious concepts with the exception of a few

minor modifications to the components of the bike. The larger motorcycle frame will be

used to house the components. The battery charger’s location will change from under the

operator’s seat to the underside of the frame of the bike. Also the lead acid batteries

previously selected to power the bike will be removed and lithium polymer batteries will

take their place.

Figure 4: Lithium Polymer battery configuration, larger frame

Cost

Due to a few modifications to the pervious concepts the total cost of the bike will

increase. The lithium polymer batteries used for this concepts are 3.2 volts each and cost

$3.50 per Amp. Under ideal conditions a 35Amp/hr battery set up would make a very powerful electric vehicle. The price per battery will be roughly $122.50. Also the bike

requires 48 volts to the power the motor, therefore 15 batteries will be required to attain

48 volts. The total price of the battery pack will be approximately $1837.50. Another

design suggestion for the batteries to reduce the price is to lower the amperage from

35Amp/hr to 20Amp/hr. This will decrease the price from $122.50 to $70.00 per battery

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and the total cost of the battery pack will decrease from $1837.50 to 1050.50. The frame

used in this concept will cost more since it is larger than prior frame. The price of the

other components such as the motor, motor controller and battery charger will remain the

same since the same products will be installed on the larger frame.

Performance

It is impossible to determine the overall weight of this concept due to the unknown

weight of the larger frame, but the team estimates a 20-40 lb increase over the smaller

frame. The lithium polymer batteries are much larger than the SLA pack. The total weight

of the battery pack will decrease from 104 lbs to 49.5 lbs. The lighter and lower placed

lithium polymer batteries will lower the center of gravity which will aid in handling.

Comfort

The addition of a larger frame and given that all the major components of the bike will be

tucked away between the riders legs-inside the frame, the rider will be quite comfortable.

Decision Matrix

Concepts

A B C D

SpecificationsSpecification Weight

Rating (1-5)

Weighted score

Rating

Weighted score

Rating

Weighted score

Rating

Weighted score

Configurability 22% 4.0 0.9 1.0 0.2 1.0 0.2 4.0 0.9

Weight 33% 1.0 0.3 2.0 0.7 2.0 0.7 4.0 1.3

Cost 11% 2.0 0.2 4.0 0.4 4.0 0.4 1.0 0.1

Comfort 22% 4.0 0.9 3.0 0.7 2.0 0.4 4.0 0.9

Availability 11% 1.0 0.1 5.0 0.6 5.0 0.6 1.0 0.1

Score 2.44 2.56 2.33 3.33

selection No Yes No Yes*

The decision matrix above supports the group’s intuition that Concept D is the

more desirable design. It will exceed all the customer’s needs and performance

requirements. Unfortunately, this design is only possible at a high cost premium. The cost

of the custom battery pack alone exceeds the group’s current budget. With this in mind

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the second best option, Concept B will achieve the projects goals. It will meet the 25mph

minimum top speed, and the 5 miles minimum range and still be under budget.

Cost Analysis

Table two represents the total cost for each concept. Because their components are thesame, concepts B and C have the same cost and are therefore represented on the same

row. Concept A utilizes the larger frame and is slightly more expensive. The fourth

concept will only become an option if funding for a lithium-polymer battery pack is

found.

Concept Motor Controller Batteries Charger Frame Total

A 450.00 325.00 295.80 159.00 200.00 $1,429.80

B&C 450.00 325.00 295.80 159.00 Free $1,229.80D 450.00 325.00 1,837.50 159.00 200.00 $2,971.50

Table 2: Cost Analysis

Figure 5: Etek-R Brushed Permanent Magnet Motor

Power: 8 cont-- 15 pk hp

Voltage: 48 Volt rated

Speed: 3700 rpm @ 48V

Unloaded (72 rpm per volt)

Figure 6: Alltrax motor Controller

24-48 Volts/300 amp

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Figure 7: Lithium Polymer Batteries, 48 V, 35 A-hr

Figure 8: Soneil Continuous Amperage Battery Charger 6A, 48 V

Figure 9: Marathon Deep Cycle Sealed Lead Acid Battery 48 V, 35 A-hr

Conclusion

The United States is swiftly moving towards an all electric economy. Over 15,000 MW of

wind energy has been installed in the last two years. Almost 9,000 MW of solar energy

was installed in 2008 alone. These numbers show no tendency to level out. Though oil is

a necessary component of the world economy, it is man’s responsibility to curb his

dependency on it. Moving to an all electric transportation system would do just that.

Small electric vehicle’s like the one described in this report are an excellent means to aid

in the transition to a more environmentally friendly transportation system. The team is

actively seeking funding for higher efficiency batteries. Until that goal is achieved,

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Concept B will be the main objective. Under budget and on time, the team is confident in

their abilities to produce a first rate motorcycle.

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Works Cited

1. Ehsani, Mehrdad, Yimin Gao, Sebastien E. Gay, Ali Emadi. Modern Electric, HybridElectric, and Fuel Cell Vehicles. Boca Raton: CRC Press, 2005

2. BatteryMart.com. 8 February 2010 <http://www.batterymart.com/>.

3. Advanced Battery Systems, LLC. 8 February 2010<http://www.advancedbattery.com/>

4. Emotors Online.8 February 2010<http://www.e-motorsonline.com>

5. Electric motor superstore 8 February 2010<www.emotorstore.com/>

6. Neatorama.com 21 February 2010 <http://www.neatorama.com/2007/01/27/photo-of-manhattan-after-ice-caps-melt/>

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Appendix A: Mechanical Drawings

Figure 10: Etek-R Motor

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Figure 11: Small Frame

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Figure 12: Larger frame

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Figure 13: Motor mount

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Figure 14: Alltrax motor controller

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Figure 15: Soneil Battery Charger

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Figure 16: Lithium polymer battery pack

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Figure 17: SLA battery

Figure 18: Electrical system schematic

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The above schematic illustrates the necessary connections between components to power

the motorcycle. To charge, AC power will enter the battery charger and through a pre-

installed battery management system – charge the batteries. Battery power will travel

through a DC contactor, which acts as a cutoff switch between the batteries and motor

controller. The motor controller receives a PWM signal from the throttle and controls the

speed of the motor. A 12 V DC converter will also be installed to run accessories like the

headlights, taillights speedometer etc.

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Appendix B: Calculations

The following illustrates the necessary the necessary power from the motor to propel the

heavier motorcycle (Concept D) to 25 mph. Weight has increased from 155 kg to 185 kg.

The team also decided to decrease the time necessary to reach top speed, ten seconds was

deemed too slow (new time is four seconds).

From Product Specification report:

The equation takes into account the vehicle mass factor δ, which is estimated at 1.0425 [1].

Mass of the motorcycle alone is approximately 105 kg, and rider weight is 80 kg.

Combined, these make up total motorcycle weight Mv. An acceptable acceleration time

(ta) of 4 seconds was chosen to reach the top speed. Final velocity (V f ) is 25 mph (11.17

m/s), while initial velocity (V b) is 0 mph. For motorcycles with properly inflated tires, the

coefficient of rolling resistance (f r ) is approximately 0.0055. Air density (r a) is 1.2 kg/m3

for standard atmospheric conditions. The drag coefficient (Cd) for the motorcycle wasestimated at 0.95 [1]. Frontal area of the motorcycle (A f ) was measured. A 6’1” tall rider,

seated upright on the motorcycle displaces a frontal area of 0.46 m^2.

Tractive power was calculated to be 3.228 kW or 4.32 hp. After estimating for a 25% loss

of efficiency from the battery stack, motor, driveline and control electronics; the final

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necessary tractive power was found to be 4.035 kW or 5.41hp. The team chose a 4.5 kW

motor which is ideally suited for this application.

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