Fabrication of Electric Bicycle

“Fabrication of Electric Bicycle”
Major Project Report
Submitted in Partial Fulfillment of the Requirements for the
Degree of
BACHELOR OF TECHNOLOGY
IN
ELECTRICAL ENGINEERING
By
Vaibhavi Parvatikar-14BEE082
Parth D. Patel-14BEE090
Department of Electrical Engineering
Institute of Technology
NIRMA UNIVERSITY
Ahmedabad 382 481
May 2018

CERTIFICATE
This is to certify that the Major Project Report entitled “Fabrication of Electric
Bicycle” submitted by Ms. Vaibhavi A. P. (14BEE082) & Mr. Parth D. Patel
(14BEE090) towards the partial fulfillment of the requirements for the award of degree
in Bachelor of Technology in the field of Electrical Engineering of Nirma University is
the record of work carried out by him/her under our supervision and guidance. The
work submitted has in our opinion reached a level required for being accepted for
examination. The results embodied in this major project work to the best of our
knowledge have not been submitted to any other University or Institution for award of
any degree or diploma.
Date:
Guide
Dr. Akhilesh Nimje
Associate Professor
Nirma University
Head of Department
Department of Electrical Engineering
Nirma University
Ahmedabad
Director
Nirma University
Ahmedabad

TO WHOMSOEVER IT MAY CONCERN
This is to certify that Ms. Vaibhavi A. Parvatikar (14BEE082) and Mr. Parth D. Patel (14BEE090) and
students of B.Tech. in Electrical from Institute of Technology, Nirma University worked in Nirma
University for their project in Semester VIII, 2017- '18. During this period, he/she was found regular and
had done his/her project on “Fabrication of Electric Bicycle”, under my supervision.
He/she has worked with utmost dedication and high level of engineering and analytical competence.
We wish him all the best for their future endeavors.
Date:
(Signature)
Dr. Akhilesh Nimje

Undertaking for Originality of the Work
We, Vaibhavi Anand Parvatikar and Parth Dashratbhai Patel, Roll No.
14BEE082 and 14BEE090 , give undertaking that the Major Project entitled
“Fabrication of Electric Bicycle ” submitted by us, towards the partial fulfillment
of the requirements for the degree of Bachelor of Technology in Electrical
Engineering Department of Nirma University, Ahmedabad, is the original work
carried out by me and I give assurance that no attempt of plagiarism has been
made. I understand that in the event of any similarity found subsequently with any
other published work or any project report elsewhere; it will result in severe
disciplinary action.
__________________
Signature of Student
Date: _______________
Place: _______________
Endorsed by:
(Signature of External Guide)
(Signature of Internal Guide)

ACKNOWLEDGEMENT
I must acknowledge the strength, energy and patience that almighty GOD bestowed upon me to
start & accomplish this work with the support of all concerned, A few of them I am trying to
name hereunder.
I would like to express my sincere respect and profound gratitude to authorities and staff of
electrical engineering department for providing the department facilities for my project work. I
would also like to thank all my friends who have helped me indirectly for the completion of my
dissertation work. I would also like to thank all the teaching and non-teaching staff for
cooperating with me and providing valuable advice, which helped me in the completion of this
project.
No words are adequate to express my indebtedness to my parents and for their blessing and good
wishes. To them I bow the deepest reverence.
- Vaibhavi A. Parvatikar (14BEE082)
- Parth D. Patel (14BEE090)

ABSTRACT
Building Projects plays a vital role in improving skills as well as in boosting career opportunities
for an engineer. Designing and building any machine comes with its share of success and
failures. This is a way of brainstorming, creating new ideas which help in betterment of our
future and also opens to other new ideas.
The Electric Bicycle has been popular for the last two decades and now its market is also
booming in India. Bicycle being the greenest mode of transportation comes with a drawback that
cannot be ignored in this fast paced world. Transportation is now greeted as time saving process.
So, this is where electric bicycle mainly came into picture. People need a green, health
preserving, fast mode of transportation and E-bicycle gave it all. More than just being these
things electric bicycles are also able to generate back electric power by the use of pedal power
through regenerative mode of the motor used.
There are many uses of an Electric bicycle, like it is now also being used in Heart rehabilitation
centers for patients having heart, lung problems.
Our Aim is to Fabricate an Electric Bicycle, which can be used for commercial and medical
purposes.

OBJECTIVE
Electric Bicycle is the upcoming trend which will drive the world to greener yet keep it going on
the current pace it is running on. It will also reduce the carbon footprint , giving some relief to
already melting earth by being powered by renewable and also by regenerative mode of power
storage. Not just this, this project is also been made for medical purposes, like heart
rehabilitation centers which want their patients to exercise a normal breathing pattern by mild
exercise which can easily be provided by the help of Electric bicycle. This project is a step
forward to the fast-pedaling world.

LIST OF FIGURES
Figure No: Name of the Figure Page No:
Fig 1.1 A Commercially sold electric bicycle 01
Fig 2.1 Mid- Drive Motor 04
Fig 2.2 Front Wheel Hub Motor 05
Fig 2.3 Rear Wheel Hub Motor 06
Fig 3.1 Simulation Graph at 25% throttle power 11
Fig 4.1 Schematic of controller 14
Fig 4.2 Controller 15
Fig 4.3 Speed Throttle 16
Fig 4.4 Electric brake 16
Fig 4.5 Battery level indicator 17
Fig 4.6 Frame Design 18
Fig 4.7 Actual Fabricated Frame 19
Fig 4.8 Wheel with Hub motor 19
Fig 5.1 Cylindrical Cell Internal Structure 21
Fig 5.2 Prismatic Cell Internal Structure 21
Fig 5.3 Li-ion single battery 22
Fig 5.4 Soldered Battery Pack 22
Fig 5.5 Battery Design in Fusion360 23
Fig 5.6 36 V, 13.2 Ah Battery Pack 23
Fig 5.7 Block Diagram of working of Safety circuit 24
Fig 5.8 BMS (Battery Management System) 25
Fig 6.1 Actual Fabricated Electric bicycle 26

CONTENTS
ACKNOWLEDGEMENT IV
ABSTRACT V
OBJECTIVE VI
LIST OF FIGURES VII
TABLE OF CONTENTS VIII
CHAPTER 1: INTRODUCTION TO HYBRID BICYCLES 1
CHAPTER 2: TYPES OF MOTOR AND DIFFERENT MOUNTING POSITIONS 3
2.1 TYPES OF MOTOR 3
2.2 DIFFERENT MOUNTING POSITIONS 4
CHAPTER 3: THE POWER CALCULATION OF BLDC MOTOR 7
3.1 PARAMETERS AFFECTING POWER CALCULATIONS 7
3.2 TOTAL POWER REQUIREMENT 7
3.3 SYMBOL AND PARAMETER DEFINITION 8
3.4 FORCE REQUIREMENT AND PARAMETERS 9
3.5 MOTOR TORQUE BEHAVIOR 10
3.6 SIMULATION GRAPHS 11
CHAPTER 4: COMPONENTS IN ELECTRIC BICYCLE 13
4.1 CONTROLLER OF BLDC MOTOR AND SENSORS 13
4.2 SPEED THROTTLE 15
4.3 ELECTRIC BRAKE 16
4.4 BATTERY LEVEL INDICATOR 17
4.4 FRAME DESIGN 18
4.5 WHEEL DIMENSION 19
CHAPTER 5: BASIC OF STORAGE DEVICES AND DESIGN OF A BATTERY 20
5.1 BATTERY SELECTION 20
5.2 BATTERY CELLS FOR E-BICYCLE BATTERY 21
5.3 MAKING OF BATTERY FROM SMALL CELL 22
5.4 SAFETY CIRCUITS OF BATTERY 23
CHAPTER 6: ELECTRIC BICYCLE 26
CONCLUSION 27
REFERENCES 28

1 | I N S T I T U T E O F T E C H N O L O G Y N I R M A U N I V E R S I T Y
CHAPTER 1: INTRODUCTION TO ELECTRIC BICYCLES
Electric / Hybrid bicycle uses electrical energy to drive a motor .These types of bicycles are
capable of being driven on all types of terrain with greater ease and speed. All components are
same as per a normal bicycle except the design changes are made according to the additional
components present like motor , controller and the type of batteries installed. There are many
types of motors which can be used in hybrid bicycle and also there are many possibilities to
mount them on different places in bicycle. The motor mainly helps the rider by providing
assistance in pedaling with less pedal power required. An E-bicycle also contains rechargeable
batteries.
Fig 1.1: A Commercially sold Electric Bicycle
There are many types of Electric Bicycles, some are mentioned below
Class 1: Pedal Assist / Pedelec
It is the most common type of electric bicycle. The rider pedals the bike normally while a motor
provides assistance, increasing the power transmitted to the rear wheel and also eases out
physical work required. The pedalling takes far less effort than it normally would, which allows
for higher speeds and effortless climbing over steep hills. Controller and the settings set up can

control the amount of assistance the rider desires, but not above 25 kilometres per hour (kph) or
approximately 15 miles per hour which is the maximum speed for this class.
Class 2: Throttle
Much like a motorcycle or scooter, a throttle operated electric-bicycle propels the bike forward
without any pedalling required from the rider. Most can provide a variable amount of power
depending how on throttle push. These are much less common than their pedal assist
counterparts as many countries have laws that prohibit them entirely.
Class 3: Speed Pedelec
The design of this vehicle is similar to a standard pedelec but, they allow for a higher maximum
speed of 45 kph or approximately 28 mph . In many areas this class of e-bicycle is considered a
motor vehicle requires its riders to be licensed.

CHAPTER 2: TYPES OF MOTOR AND DIFFERENT MOUNTING POSITIONS
In this chapter we are going to discuss about types of motors which can be used and their
mounting in hybrid bicycle
2.1 Types of motors
1. Induction motor:
An induction motor is an AC electric motor in which the electric current in the rotor needed to
produce torque is obtained by electromagnetic induction from the magnetic field of
the stator winding.
2.DC motor
In the below table different types of motor and their advantages and disadvantages have been
listed:
 Permanent Magnet Brushless DC Motor:
PMBL DC motor has permanent magnets on rotor which generates constant field flux.
Where the stator consists armature windings.
 Permanent Magnet Brushed DC Motor:
PM DC motor has same construction like normal DC motor but it has permanent magnet
to generate field flux instead of field winding.
TYPE ADVANTAGES DISADVANTAGES DRIVE USED
Stepper DC High holding torque
and higher positioning
precision
Slow speed and
requires controller
Multiphase DC
Brushless DC High efficiency, low
maintenance, and
longer life span
High initial cost and
requires controller
Multiphase DC
Brushed DC Low initial cost and
easy speed control
High maintenance and
short life span than
other two
Direct (PWM)

2.2Mounting of motors
1.Mid-Drive Motor:
Mid-Drive Motor is present where the gear is positioned in the bicycle. This type of motor
mounting is used for better performance and higher efficiency. The Mid-drive type of mounting
drives the wheel indirectly by the help of gears and connecting chain which also helps as a
multiplier of speed.
But a major disadvantage is due to high torque output the single chain ring can break often so it
leads to recurring maintenance and other drawback is its high cost.
• Mid drive systems are known for being able to climb long steep hills because they can
leverage the lower gears of the bike and keep their rpm’s in an efficient range without
getting stuck up like a hub motor.
• Removing the front or rear wheel is easy because there are no motor wires or hardware to
remove (compared to hub motors).
• But, the disadvantage here is more wear and tear of chains and auxiliaries.
Fig 2.1:Mid Drive Motor

2. Hub Motor:
A Hub motor is incorporated inside the centre of the wheel itself and drives it directly.
I. Front Hub Motor:
 It creates an all-wheel drive bike because the motor drives the front wheel and you can
power the rear wheel with your pedal power.
 Front hub motor systems are easy to install and remove too, because there is no gear
system to deal with.
 Front hub motors can provide for a more balanced bike weight distribution only if the
battery is mounted in the middle or back part of the bike, which is the case in normal
scenarios.
 The front hub motors generally are focused on the lower power range around 250 to
500W range.
 The higher torque hub motors need larger spokes and sturdy rims, and also due to this
design of frame changes.
Fig 2.2: Front Wheel Hub Motor

II. Rear Hub Motor:
 There is a wide range of power options (250 watts to 750 watts and beyond) because the
bike’s frame provides a good structural platform to handle high torque from the motor.
 Rear hub motors can provide assist with a throttle or pedal assist.
Fig 2.3: Rear Wheel Hub Motor
 For this project a BLDC motor has been used. The main purpose behind using this type
of motor is the use of electronic controller makes it easier to change and control speed
with less time gradient present. Moreover, though the initial cost seems high the longer
life span and low maintenance gives higher return on the initial investment.
 Front hub motor is used here as the advantages are perfectly matched with a city terrain.
Also front mounting gives more load balancing and also simplifies design parameters.

CHAPTER 3:THE POWER CALCULATION OF BLDC MOTOR
3.1 Parameters affecting Power calculations:
Depending upon how much the rider is pedaling and taking into account the right combination
of pedaling and motor movement, it can be about 80% of efficiency can be harnessed by the type
of motor used . For example ,a 500 Watts motor produces (Watt = 500 *[80%]/100) about
400Watts of output power.
There are mainly three factors that influence the efficiency declination, are rolling resistance,
wind resistance and gravity.
1. First approximation about power drag Pdrag is determined by the frontal area (A) of the
bicycle and riders shape and sizes. Drag coefficient (Cd ) that characterized the shape of
the electric-bicycle and rider, and the cube of the speed ( v3
) and air density.
2. The second approximation, power rolling resistance PRc is determined by the gravity (g)
and mass of e-bicycle and rider (m), rolling coefficient that defines the rolling resistance
of the wheel ( Rc ) and the speed of electric-bicycle (v)
3. The last one is power hill or climbing Pslope, in turn determined by the gradient or slope
of the hill (gradient %). The gravity (g) and mass of the electric-bicycle and rider (m) and
the speed of the electric-bicycle and rider (v) which is shown in equation.
3.2 Total power requirement:
The required total electric-bicycle power Ptotal for the electric-bicycle that can be given by the
sum of power resulting from drag Pdrag, slope ratio Pslope or Pslope and the rolling resistance
PRc.

3.3 Symbol and Parameter Definition:
This table explains all the symbols used in above power approximation calculation.
Symbol Parameter Unit Comments
M Mass Kg The mass of rider and electric-bicycle
Velocity Km/h The motor stops working when the vehicle amounts
to a speed of 30 km/h or higher.
g Gravity m/s2
Gravity acceleration is 9.81 2 m/s2
 Angular
velocity
Rad/ s The rate of change of angular displacement of the
particle in a given time is known as angular velocity,
symbolized by = θ /t , where θ is the angular
displacement, and t is time taken
T Torque of
motor
Nm Torque is defined by something that produces
torsion or rotation; in other words, torque is the
moment of a force or system of forces tending to
cause rotation
 Density of
air
kg/m3
The typical value of density of air for most human
like  is 0.4 kg /m3
A Frontal
Area
m2
The frontal area is the area of the mass encountered
by the air. Typical values are A= 0.4 m2
for
crouched cyclist , A=0.6 m2
for upright cyclist.
Rc Rolling
coefficient
- The rolling coefficient depends on friction effect.
Cd Drag
coefficient
- The drag coefficient is small for aerodynamic bodies
D Diameter of
wheel
- The wheel diameter depends mainly the size and
power output of motor used.

3.4 Force requirement and calculations:
Basic force equation:
Vehicle is considered as a rigid body so that it can be modelled as a lumped mass at the vehicle’s
centre of gravity.
( ) ( ) ( )
= Sum of all forces acting to increase vehicle speed
= Sum of all forces opposing vehicle’s movement
Rolling Resistance:
One major effect of rolling resistance is tyre deflection which causes hysteresis in tyre material.
Rolling resistance is:
Cr= rolling resistance coefficient
Cr depends on tyre material, its radius, working condition (i.e. inflation pressure, tyre
temperature, road surface and speed but as our speed consideration is 30 – 40km/hr, Cr value is
steady and low as 0.008
Grading force (Fg):
Incase of a road grade (or inclination), only component of force will be affected
Alpha is angle between the level road and reference horizontal plane.
( ) ( )

Where rise is vertical rise and run is horizontal distance covered
The total wheel force is:
( ) ( ) ( ) ( ) ( )
Where Fa, Fr, is coasting forces and is accelerating force.
Wheel power and energy:
( ) ( ) ( )
∫ ( )
3.5 Motor Torque Behavior
Torque is the force that is required for turning of the motor. Motors can have high torque and
low speed, or low torque and high speed, having two different levels of outputs. For both gear
driven motor or directly driven motor the torque behavior or output remains similar
Here it is tried to present the characteristics of motor by doing calculations on the main units of
torque (T) and speed of motor’s angular velocity (ω).
Power (P) = Torque (T) * Rotation speed(ω)
T = P/ ω
ω = / (1.8 * Diameter of wheel)

3.6 Simulator graphs
These graphs show the Torque , Power, Efficiency and Load curve as per the throttle power
applied and changes in the speed too.
Fig 3.1: Graph at 25% Throttle power

Fig 3.2: Graph at 75% throttle power
Fig 3.3:Graph at 100% throttle power
So, here on observation the outcome is clear, the more throttle power applied considering all
other variable as constants more will be the output speed. Here all other parameters like Terrain
grading, Human power or pedal power, Mass of the system and other coefficients are considered
as constant.

CHAPTER 4: COMPONENTS PRESENT IN ELECTRIC-BICYCLE
4.1 Controller of BLDC Motor and Sensors
4.1.1Controller and Motor Specification
Rated Voltage 36V
Rated Power 350 Watts
Wheel Size 26"
Rated Speed 28km/hr
Rated Efficiency >=83%
Reduction Ratio 1:4.4
Weight 2.5kg
Open Size 100mm
Drive and Free Wheel N/6-95
Cable Location Shaft Centre Right
Spoke Specification 13g
Surface Colour Silver
Salt Fog Test 24/96
Noise < 55 db
Waterproof Grade IP54
4.1.2 Controller
There are mainly two types of controllers which are designed to be effective on two types of
motor, brushed and another brushless. According to the motor in use the controller function
varies. Brushless motors are popular because of high efficiency, ease of controlling and
durability, and it is also supported by the reduced cost factors.
There are various sensors present in addition with the controller for keeping a check on speed
movements. To do this the main sensor, Hall sensor is used. The reason is also that e-bike
requires strong initial torque to complement the low powered motor, this mechanism to control
with safe the speed, the sensor has special functions to monitor the speed accurately. These

electronic sensors provide real time data input to the. Usually the measuring values by the sensor
are the force applied to the throttle, and the instantaneous speed of the vehicle. The controllers
work with closed-loop speed control mechanism for precise speed control. This closed loop
mechanism provides precise control over the e-bike by adjusting the speed , over-voltage surge,
over-current input, other levels of protections. Controller uses PWM (pulse width modulation)
to adjust the power input to motor. In some e-bikes regenerative braking system brings additional
role of power generation and management from the controller. In short, its main function is to
maintain safety.
Fig 4.1: Schematic of Controller

Fig 4.2: Controller
4.2 Speed Throttle
The maximum speed of this bicycle is 30kmph. Depending on the external parameters like type
of terrain, traffic and others , it is required to provide the rider a way to vary speed. This is where
a throttle or accelerator is necessary.
In the previous chapter the simulation graphs also projected the importance of a throttle. If the
pedal power changes then it helps the throttle power, but the speed is always restricted to
maximum as described.
A throttle allows to drive a vehicle from zero to rated or full speed. It is fitted on the right handle
bar and is connected to the controller.

The throttle converts DC voltage received from the battery to alternating voltage as per the shift
in the position. This alternating voltage with variable frequency and amplitude drives the Front
hub motor at different speeds. It is also technically referred to as a Hall Effect type.
Fig 4.3: Speed Throttle
4.3 Electric brake
It will actuate the controller to apply resistive force in terms of electric energy to motor at the
time of braking. This is most important part when the controller is supporting a regenerative
mode of working. On application it triggers the controller to cut-off the power to the motor and
start the regenerative mode.
While placing this brake is easy but balancing of overall load of the e-bike is also necessary. Any
type of uneven loading will make the effect of braking more either on the front or rear side.
Due to moisture shorting of internal wires can take place which as a result can cause the throttle
to be stuck in a wide open throttle position. The electric brake safeguards the speed and also
releases the throttle position.
Fig 4.4: Electric Brake

4.4 Battery Level Indicator
Battery Level Indicator as its name suggest displays the charge level of the rechargeable Li-Ion
battery. Here there are many other functions too that are included in this indicator, which are
mentioned below.
Fig 4.5: Battery Level Indicator
(1) ON/OFF Switch for power assistance
(2) ON/OFF Switch for front light
(3) MODE Switch for choosing power level assistance
(4) LED indicator for power level assistor
(5) LED battery capacity indicator
 Battery Capacity Indicator
1. LED Level indicates that battery is fully charged.
2. LED Level indicates that battery is 75% charged.
3. LED Level indicates that battery is 50% charged.
1
2
3 5
4

4. LED Level indicates that battery is almost empty and needs to be recharged (
About 25% charge left)
4.5 Frame Design
The frame is designed considering the loading of the motor and the rider's weight. Usually the
battery design is also a parameter affecting the design of the frame as the battery pack and the
controller are to be placed inside the frame.
Depending on the total weight of the system considered the material is decided for the frame.
The different measurements taken into consideration while designing frame are mentioned
below:
Fig 4.6:Frame Design Parameters
The above numbered distances are known as
1. Reach 5.Wheel Base
2. Top tube 6. Head Angle
3. Stack
4. Chain Stay

4.5.1 Actual Frame Fabrication
Fig 4.7: Actual Fabricated Frame
4.6 Wheel Dimension
Fig 4.8: Wheel frame
The wheel diameter is 26 inches and accordingly
the front handle and chain stay distance has been
calculated.
The spindle is of stainless steel alloy and this
diameter has been calculated as the motor power
output.

CHAPTER 5:BASIC OF STORAGE DEVICES AND DESIGN OF A BATTERY
5.1 Battery Selection
A container consisting of one or more cells, in which chemical energy is converted into
electricity and used as a source of power is known as battery.
5.1.1Types of batteries:
Rechargeable Disposable
Nickel-
Metal
Hydride
(NiMH)
LSD
NiMH
(Low self-
discharge)
Nickel-
Zinc
(NiZn)
Rechargeable
Alkaline
Alkaline High-Drain
Alkaline
Lithium
(not
lithium
ion)
Carbon
Zinc
Good
for most
uses,
except
where
you
need
long
shelf
life
Good for
most,
including
long shelf
life
Good
for
devices
which
benefit
from
extra
voltage.
Longest shelf
life of any of
the
chargeable
batteries.
So no need to
replace them
again
Cheap,
widely
available,
but can't
be
recharged
and can
leak
Not
recommended
for most of the
uses. If you
have got a
high drain
device, a
rechargeable
is probably
better.
Powerful
but one
time use
and small
risk of
explosion
Cheaper
and least
powerful.
Good
only for
low drain
devices.
5.1.2 Calculation for the battery:
See the following equations to calculate the range from amperage and voltage:
Ah (Amp hours) × V (volts) = Wh (Watt hours)
 Select a 36-V, 10-AH battery with 360 Wh.
1. P (power) = Work / t (time)
2. P × t = Work = Force × distance
3. Force = mass × acceleration
4. Distance = Wh / Force
Electric bicycles are often restricted to a speed of 30 km/h across level ground. A larger wattage
increases the range and can increase the uphill torque. However, a larger wattage does not
typically increase the maximum speed.

5.2 Battery Cells for E-bicycle Battery
Following types of battery cells can be used in electrical bicycles to make compact fast charging
battery pack.
1. Cylindrical cell
Fig 5.1: Cylindrical Cell Internal Structure
2. Prismatic cell
Fig 5.2: Prismatic Cell Internal Structure

5.3 Making of battery pack
Battery cells come in fixed voltage and capacities. Capacities may vary, but voltages don’t vary.
In order to meet your power requirement a battery pack may need to be used. The type of battery,
the number of cells, the shape of the components of the pack will be determined by the voltage
and load current of the device being powered.
Other consideration will be available space, operating temperature, usage condition,
transportation requirements, and charge/discharge specifications. For this project the battery
specifications are mentioned below.
Type of battery used 18650 Lithium Ion rechargeable
Number of Units 60 units
Nominal Capacity (each) 2200 mAh
Nominal Voltage Average 3.7V
Charge Current 1000 - 2000 mA
Discharge current 440 - 4400 mA
Charge time 4-8 hours
Charge cut-off voltage 4.2 V
Discharge cut-off voltage 3.0 V
Fig 5.3:Li-ion single battery

Fig 5.4: Soldered Battery Pack
Fig 5.5: 36 V, 13.2 Ah Battery Pack

Fig 5.6: Battery design in Fusion360 of 36v and 13.2Ah
5.4 Safety circuits of Battery
Safety circuits are need because of following reasons.
1. Overcharging
2. Over discharging
3. Over current
Safety circuit will work accordingly following block diagram. If charging current will exceed the
limit of safety circuit it will block the charging current to flow through battery and if discharging
current will reduce below limit then safety circuit will disconnect the battery supply from the
circuit.
If during operation of battery output current will increase then rated value of battery
suddenly safety circuit will disconnect the battery supply.
Fig 5.7: Block Diagram of working of Safety circuit
Specifications of BMS(Battery management system):
Battery Management System (BMS), is an electronic device which controls charging and
discharging of the rechargeable battery. It controls the maximum and minimum level of voltage
and keeps the current discharging rate in check. The necessity of this device is to protect our
batteries and it is also required for its longer working.
 Single over-charge protection voltage 4.25V ± 0.05V (4.20-4.35V/0.05V per upgrade)

 Single over-charge recovery voltage: 4.10-4.00V
 Single over-discharge protection voltage: 2.50V ± 0.1V (2.50-3.0V/0.05V per upgrade)
 Single over-discharge recovery voltage: 2.80V ± 0.1V
 Protection Current consumption: ≤300UA
 Short circuit protection current: 40A ± 3A
 Short circuit protection time: 500MS
 Temperature protection: 55/65/75 degrees
 Discharge current: 18A
 The maximum instantaneous current: 40A
 Single balanced voltage: 4.19V ± 0.02V
 Single balanced current: ≤ 55MA
 Charge current: ≤10A
Fig 5.8: BMS (Battery Management System)

CHAPTER 6: ELECTRIC BICYCLE
Fig 6.1: Assembled Electric bicycle
MOTOR 500W Front Direct Drive
BATTERY 36V, 11.6Ah
DISTANCE(IN SINGLE CHARGE) 25-35 miles
TOP SPEED 20mph
RIMS Triple Wall Deep 25mm
CHARGING TIME 6 - 8 Hours
WHEEL DIAMETER 26 Inches
BATTERY 36V, Li-Ion battery pack

CONCLUSION
In this major project, we have covered all the essential components that go into making of hybrid
bicycle and fabricated the same. We saw the parameters affecting the designs, the ideal
component designs and calculation of speed, torque and other motion related parameters.
Covered here is the detailed topic of battery design required for the same purpose. There is also a
discussion for regenerative braking and types of drives that can be used. Thus, all the aspects
from designing the physical exterior model to the mechanical and electrical driving designing
calculations were covered in this project. All these elements calculated have been put into
practical form. We have designed and fabricated the Electric Bicycle for the calculated
parameters.

REFERENCES
1. Research and Development Work on Lithium-ion Batteries for Environmental Vehicles,
by Takaaki Abe, Kazuki Miyatake, Yoshio Shimoida and Hideaki Horie
2. http://www.navigantresearch.com/wp-content/uploads/2013/03/EBIKE-13-Executive-
Summary.pdf
3. https://www.researchgate.net/publication/224299571_Electric_bicycle_using_batteries_a
nd_supercapacitors
4. https://www.sciencedirect.com/science/article/pii/S0966692316301934
5. https://www.citylab.com/transportation/2016/08/e-bike-safety-speed/494936/
6. http://www.electricbikesimulator.com/calculator.php?language=en
7. http://www.avdweb.nl/solar-bike/formulas-for-power-calculations-on-ebikes-and-hub-
motors.html
8. https://www.electricbike.com/watt-hours
9. http://www.ebikeschool.com/much-power-electric-bicycle-need
10. http://www.phantomX2.com/prodecotech/electricbike
11. http://community.silabs.com/t5/Contests/DC12-S1-50-Brushless-DC-motor-controller/td-
p/99379
12. https://www.electricbike.com/watt-hours/
13. https://www.umweltbundesamt.de/sites/default/files/medien/378/publikationen/hgp_elect
ric_bikes_get_things_rolling.pdf

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