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BATTERY MANAGEMENT SYSTEM FOR SOLAR APPLICATION

Mohd Fazlan bin Ali

Bachelor in Electrical Engineering

(Control, Instrumentation and Automation)

JUNE 2013

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BATTERY MANAGEMENT SYSTEM WITH SOLAR APPLICATION

MOHD FAZLAN BIN ALI

A report is submitted in partial fulfillment of the requirement for the degree

of Bachelor in Electrical Engineering

(Control, Instrumentation and Automation)

Faculty of Electrical Engineering

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

JUNE 2013

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I declare that this report entitle “Battery Management System for Solar Application” is the result of my

own research except as cited in the references. The report has not been accepted for any degree and is

not concurrently submitted in candidature of any other degree.

Signature : ………………………………

Name : ……………………………....

Date :…………………………….....

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“ I hereby declare that I have read through this report entitle “Battery Management System for Solar

Application ” and found that it has comply the partial fulfillment for awarding the degree of Bachelor

of Electrical Engineering (Control, Instrumentation and Automation)”

Signature : ………………………………

Supervisor's Name : En Norhafiz Bin Salim

Date : ………………………………

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ACKNOWLEDGEMENT

First and foremost, I would like to take this golden opportunity to express my

appreciation to my final year project supervisor, Mr Norhafiz bin Salim for being a dedicated

lecturer guiding me through this project to run smoothly. This project cannot be completed and

perfected if without the valuable suggestion and useful information from my supervisor. His

patience and enthusiastic in guided me through this final year project have gave me a great

courage in completing this project.

Apart from that, I also would like to thanks to my lecturer Dr. Abdul Rahim bin

Abdullah and all my friends for the helped especially, Mohd Hazwan bin Abdullah and Mohd

Shahmir bin Mohmad Selami in giving me their morals support during this project

development and also shared some information with regards to the photovoltaic system and

the software guide.

Last but not least, I would like to express my deepest love and gratitude to my beloved

parents for giving me unlimited encouragement during my studies in University Technical

Malaysia Malacca (UTeM).

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ABSTRACT

Battery Management System for solar application system consists of lead asid battery

serving as its energy storage elements. The most commonly used storage technology for solar

application is the lead acid battery. This system is constructed for the purpose of gathering

data on different charge and discharge current flow through the storage and load. The aim of

this project is to analyze a charging process with battery utilization in a way to optimize load

variation and making the overall system more reliable. The solar charge controller with Pulse

Width Modulation (PWM) technique making the solar panels able to optimize under varying

illumination level. The battery charging from different power of solar panel is the key point

to found the suitable sources to power up these prototype. The new system configuration with

parallel is to create a optimal storage. According to the size of battery characteristic, the

battery management is optimized for longer life time and batter performance. Charge and

discharge of SLA battery at 50% of battery capacity conducted on the static load resistor

through 90 watt laptop adaptor. Voltage and current were recorded during an increment of out

power from 10W to 70W. The experimental result analyzed through this project carry out via

actual measurement and hardware that has been developed. This prototype of portable dc

power supply has been developed and tested under lab experimental . All results were verified

through experiment with the load variation that has been done.

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ABSTRAK

Sistem Pengurusan Bateri untuk aplikasi sistem solar terdiri daripada bateri asid

plumbum berfungsi sebagai elemen storan. Teknologi storan yang biasa digunakan untuk

aplikasi solar ini adalah bateri asid plumbum. Sistem ini dibina untuk tujuan pengumpulan

data ke atas cas dan nyah cas yang berbeza-beza melalui sistem storan dan beban. Tujuan

projek ini adalah untuk menganalisis proses mengecas dengan menggunakan bateri dengan

cara untuk mengoptimumkan kepada perubahan beban dan menjadikan keseluruhan sistem ini

lebih dipercayai. Pengawal cas solar dengan teknik Pulse Width Modulation (PWM) adalah

teknik yang menjadikan panel solar dapat mengoptimumkan di bawah tahap pencahayaan

yang berubah - ubah . Bateri cas daripada sumber kuasa yang berubah - ubah dari panel solar

adalah kunci kepada penemuan sumber yang bersesuaian untuk sistem prototaip ini berfungsi.

Konfigurasi sistem dengan penyambungan selari untuk menghasilkan storan yang optimum.

Menurut saiz serta ciri bateri, pengurusan bateri dapat dioptimumkan untuk masa jangka hayat

lebih panjang dan serta dengan prestasi lebih baik. Cas dan nyahcas bateri SLA pada 50%

kapasiti nya dijalankan pada perintang beban melalui 90 watt adaptor komputer riba. Voltan

dan arus telah direkodkan semasa kenaikan kuasa dari 10W sehingga 70W. Hasil experiment

di analisa dalam projek ini dijalankan melalui ukuran sebenar serta perkakasan yang telah

dibangunkan. Prototaip bekalan kuasa dc mudah alih ini dibangunkan dan diuji dalam makmal

eksperimen .Semua keputusan telah disahkan melalui eksperimen dengan perubahan beban

yang telah dilakukan.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

ACKNOWLEDGEMENT ii

ABSTRACT iii-iv

TABLE OF CONTENTS v-vii

LIST OF TABLES viii

LIST OF FIGURES ix-x

LIST OF APPENDICES xi

1 INTRODUCTION

1.1 Background 1

1.2 Problem statement 2

1.3 Objective 2

1.4 Project Scope 3

2 LITERATURE REVIEW

2.1 Introduction 4

2.2 Solar Panel 5-8

2.3 Solar Charge Controller Operation 8

2.3.1 Stage 1 (Bulk Charge) 9

2.3.2 Stage 2 (Boost Charge / absorption charge) 9

2.3.3 Stage 3 (Float Charge) 9-10

2.4 Storage system 10-11

2.4.1 Lead - Acid Batteries 11

2.4.2 Liquid Vented 11

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2.4.3 Sealed Lead - Acid Batteries (VRLA) 12

CHAPTER TITLE PAGE

2.4.4 Alkaline Batteries 12

2.4.5 Battery Capacity 12-13

2.5 Battery Management System (BMS) 13-14

3 METHODOLOGY

3.1 Project development process steps 15-18

3.2 System Overview 19

3.2.1 Overall layout of circuit development 19-20

3.3 Mechanical Construction 21

3.3.1 Mechanical Development 21-26

3.4 Hardware Development 27

3.4.1 Battery configuration 27

3.4.1.1 Series connection 28

3.4.1.2 Parallel connection 29

3.4.1.3 Combined in parallel and serial 30

3.5 Experiment steps 30

3.5.1 Experiment 1 30-32

3.5.2 Experiment 2 33-34

3.5.3 Experiment 3 35-36

4 RESULT

4.1 Definition Process 37

4.2 Experiment 1 37-39

4.3 Experiment 2 40-41

4.4 Experiment 3 42

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CHAPTER TITLE PAGE

5 ANALYSIS AND DISCUSSION OF RESULT

5.1 Definition Process 43

5.2 Experiment 1 43

5.2.1 Analysis and discussion on result 43-46

5.3 Experiment 2 46

5.3.1 Analysis and Discussion on Result 46-48

5.4 Experiment 3 49

5.4.1 Analysis and Discussion on Result 49-50

5.5 Discussion 51-52

6 CONCLUSION AND RECOMMENDATION

6.1 Conclusion 53-54

6.2 Recommendation 54

REFERENCE 55

APPENDICES 56-57

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LIST OF TABLES

TABLE TITLE PAGE

2.1 Different type of Solar Panel 6

2.2 Advantages of Crystalline PV Cells 8

2.3 Disadvantages of Crystalline PV Cells 8

3.1 Hardware development flow 25-26

3.2 Specification of Seal Lead Acid Battery (SLA) 28

3.3 General specification of the 30 watt of solar panel 31

3.4 General specification of the 75 watt of solar panel 33

3.5 The approximate battery and cell voltages for various

states of charge 34

4.1 Average analysis data of solar panel in 5 days from

7 March 2013 - 12 March 2013 38

4.2 Calculation power efficiencies of solar panel 39

4.3 Data during charging battery of

Solar Charge Controller 40

4.4 The data 90 W laptop adapter 42

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LIST OF FIGURES

LIST TITLE PAGE

2.1 a Monocrystalline cells 6

2.2 b Polycrystalline cells 6

2.2 c Amorphous cells 7

2.2 Solar Charge Controller (Battery Charging) 8

3.1 a Top view of battery layout 17

3.1 b Isometric view of frame with battery layout 17

3.2 Flowchart of Project Flow 18

3.3 Overall system of Battery Management System

with Solar Application 19

3.4 Design mechanical frame by using Solid Work software

3.4 a Shaded With Edge View 21

3.4 b Hidden Line Visible View 21

3.5 Material used (L Angle steel bar) 22

3.6 Frame of portable dc power supply 22

3.7 Frame with acrylic casing front view 23

3.8 Frame with acrylic casing rear view 23

3.9 Parallel connection of SLA battery 27

3.10 90 Watt Universal Laptop Adaptor 28

3.11 Series connection 28

3.12 Parallel connection 29

3.13 Combined series and parallel connection 30

3.14 Diagram of solar connection 31

3.15 30 Watt of Solar 31

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3.16 Meter measurement 32

LIST TITLE PAGE

3.17 100 ohm (10watt) ceramic resistor 32

3.18 Experiment layout 33

3.19 The 90 watt laptop adaptor 35

3.20 TERCO current meter 35

3.21 TERCO Watt meter 36

3.22 TERCO Load Resistor MV110 36

5.1 The voltage of solar panel 43

5.2 The current of solar panel 44

5.3 The power (watt) of solar panel 45

5.4 The radiation from sun 45

5.5 The average battery voltage and solar voltage 46

5.6 The PV current and battery current 47

5.7 The battery capacity - State of charge (SOC) 48

5.8 Input and output power of laptop adaptor 49

5.9 Input and output current of laptop adapter 50

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LIST OF APPENDICES

APPENDIX TITLE PAGE

A Sealed Lead Acid Battery Specification Chart

(AGM and GEL) 56

B Gantt Chart 57

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CHAPTER 1

INTRODUCTION

1.1 Background

The electrical energy has become of the most important aspect for human, because the

equipment and the future of many portable electrical devices such as cellular telephones,

notebook computer, personal digital assistant, and etcetera need electricity to get it operated.

Continuous use of electronic devices will lead to reduction of the power source. Additional

electrical energy are required to continue the without disrupting the work operations.

Limitation of power sources are an issue if the laptop or hand phone when there is shortage of

battery. So, the portable dc power supply base on Battery Management system (BMS) to be

supplied to some of load (laptop or cell phone ) at a time is an alternative way. With the

availability of solar power as a source of renewable energy, it is easy to handle and easy to

recharge solar energy plays an important role in the generate of electric power. Solar

photovoltaic modules produce electrical energy in the solar arrays. The nonlinear output power

of Photovoltaic (PV) source mainly depends upon the environmental condition such as level of

light intensity. For stand-alone solar systems, storage device are required to store energy that

are not connected to the grid supply. The selection of the suitable battery type is important to

emphasis on deep of discharged to ensure an optimization charge/discharge cycle also to

prolong the battery life. The (BMS) with solar charge controller in solar system to improve

the efficiency of the array and charge safely to the storage system. The BMS overcome the

charge/discharge by implanting system with more reliable and efficiently.

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1.2 Problem statement

The usage of outlet socket are very important for us to get electric supply for electronic

devices. Usually, user must be close with the outlet socket when using the electronic device

due to battery weakness. Limitation of power sources is an issue when the electronic device is

having a lack of battery supply. With the availability portable dc supply base on Battery

Management System (BMS), the user is able to use the electronic devices at anywhere.

BMS is a process to ensure that a battery cell string receives an optimum charge without

conducting damage to the battery string. Battery is regular depth of discharged (DOD)

because of no ideal dc source from solar energy and this may not to ensure charge/discharge

cycle optimally. The poor charge/discharge cycle may results in sulfation, stratification or

gassing resulting in the end of battery life. In addition, erratic temperature range during

operation interfere optimal storage level. The battery management system is required to

overcome these problems by making the system more reliable and efficient. Thus, a proper

charging/discharging will prevent the battery becoming repeatedly overcharged or

undercharged [3][4].

1.3 Objective

i. To investigate Battery Management and Solar system.

ii. To develop a BMS and Solar network for load variation.

iii. To verify between theoretical and experimental result.

iv. To analyze the entire battery management and solar system.

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1.4 Project Scope

In order to achieve this objective, several scopes had been outlined which to

implemented of the portable dc power supply base on Battery Management System (BMS).

The solar panel will be used to harvest solar energy and the ratings is 30Watt at 18Volt and

75Watt at 17Volt. In this (BMS) , solar charge controller is use in order to optimize the entire

system . The Seal Lead Acid Battery (SLA) si selected as a storage elements energy system.

The load test will be conducted on laptop and mobile phone as a load. The charge/discharge

process and output power of the (BMS) will be analyzed throughout the experimental result

that will be taken.

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CHAPTER 2

LITERATURE REVIEW AND PROJECT BACKGROUND

2.1 Introduction.

Literature review in terms of definition is a review of the research that has been made

about a particular problem that has been identified and needs to be answered. It is done in

order to enquire an understanding of the project and to identify what the key issues are. This

review should describe, summarize, evaluate and clarify the project. It also goes beyond the

search for information and includes the identification and articulation of relationships between

the literature and the field of research.

The research can be done through books, journals, web pages, reports and others. From

these sources, a literature review has to be organized around and related to the thesis and the

result has to be synthesized into a summary so that the areas that are important can be

identified. Other than that, questions that need further research are also formulated here. The

term ‘green system’ that has been getting more attention lately making the solar-powered

device to be more popular. Thus, come an idea of having a portable solar charger in order to

charge up small devices. A solar charger comes with an internal battery where the sun’s

energy gets stored in the device itself so that devices can be charge even without the presents

of lights. The downside of having a charger without battery is that if there is no sun equals no

phone or music. Therefore, this paper works out on what is really needed in a solar charger.

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2.2 Solar Panel

Solar power is one of the first things that come to people’s minds when the topic of

renewable energy is discussed. Implementation of solar panels for multipurpose has bring a lot

of benefits in many industries such as transportations, agricultural and residential. There are a

few advantages of having solar as the renewable source of electricity such as it can provide

needed source of electrical to all the household or office consumptions. Other than that, any

other additional solar modules that have to be added according to the demand can be done

easily as solar modules are only in the form of panels, without moving parts and can be

installed in windows, walls or roof tiles form. The electricity is also provided without emitting

any greenhouse gases.

There are quite a number of journals that were published regarding to solar and one of

it is title “Modeling and Simulation of Maximum Power Point Tracker for Photovoltaic

System”. It is mentioned in this paper where the utilization of the solar energy can be divided

into two ways which are the solar heating and cooling and these energies needed, can be

converted into electrical energy through photovoltaic cells. Unfortunately, the disadvantage of

the PV system is due to its nonlinear, insolation level and temperature dependent current and

voltage. However, in these fast evolving world, the solutions are already found such as the

manufacturing process of solar arrays need to be improved, and also by controlling the

insulation input to PV array which is shown in this project too [1] .

A paper that was published which is entitle “Effect of Dc to Dc Converters on Organic

Solar Cell Arrays for Powering Dc Loads”, that discuss about solar cells that are divided into

two main classes which are organic and inorganic. Inorganic solar cells are made from

crystalline silicon and the organic solar cells that differ from inorganic by their carbon-based

semiconducting materials such as Buckminsterfulleine. Organic cells have more advantages

than inorganic solar whereby they are lighter in their weight, more flexible and also less

costly. The only bad side that organic cell has is that the poor power-conversion efficiency [2].

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Table 2.1 : Different type of Solar Panel

TYPE OS SOLAR PANEL EXPLAINATION

Figure 2.1 a : Monocrystalline cells

Monocrystalline cells are cut from a single

crystal of silicon, which means that they are

basically a slice from a crystal.

In appearance, these cells have a smooth texture

and the thickness of the slice will be able to be

seen clearly.

These cells have to be mounted in a rigid frame

are the most efficient and the most expensive to

produce.

Figure 2.2 b : Polycrystalline cells

Polycrystalline cells are a slice cut from a whole

block of silicon, which means that these cells

consist of a large number of crystals.

They have a speckled reflective appearance and

the thickness of the slice can be seen.

These cells are slightly less efficient and slightly

less expensive than Monocrystalline cells but

they also need to be mounted in a rigid frame.

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Figure 2.2 c : Amorphous cells

Amorphous cells are manufactured by

placing a thin film of amorphous (non

crystalline) silicon onto a wide choice of

surfaces.

These are the least efficient and least

expensive to produce of the three types.

Due to the amorphous nature of the thin

layer, it is flexible, and if manufactured on a

flexible surface, the whole solar panel can be

flexible.

One characteristic of amorphous solar cells

is that their power output reduces over time,

particularly during the first few months, after

which time they are basically stable.

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Table 2.2 : Advantages of Crystalline PV Cells

Crystalline PV Cells Amorphous PV Cells

High efficiency level Cheap and affordable

A single element production Si It comes in a wide variety

It has a great accuracy in terms of production Flexible, can adapt different positions

Easy to recycle all environmental impacts Produced more quickly and efficiently.

Table 2.3 : Disadvantages of Crystalline PV Cells

Crystalline PV Cells Amorphous PV Cells

Very Expensive Low efficiency level

Hard to produce in different models Restricted by many constraints

Rigid and hard to adapt visible light beams A wide array is needed

Large arrays required to achieve sufficient

energy

Different elements many undermine the

quality

2.3 Solar Charge Controller Operation

Figure 2.2 : Solar Charge Controller (Battery Charging)

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2.3.1 Stage 1 (Bulk Charge)

Current is sent to the batteries of the maximum safe rate they will accept until their

voltage rises to about 80 to 90% of their fully charged value. The bulk charging voltage is

typically about 14.8V but may be as high as 15.5V for a 12V system, this may vary so that the

maximum possible current in maintained. Gel batteries often have lower recommended

voltages in the region of 13.8 to 14.1V.

2.3.2 Stage 2 (Boost Charge / absorption charge)

When the battery has recharged to the Boost voltage set point, constant-current

regulation is used to prevent heating and excessive battery gassing. The boost stage remains

120minute and then goes to Float Charge. The voltage remains constant, typically about 14.2V

for a 12V system(depending on temperature) and the current tapers off as the battery reaches

100% charge.

2.3.3 Stage 3 (Float Charge)

For a 12V battery bank a voltage of about of about 12.8 to 13.2V is maintained across

the batteries to keep them in good condition. After the battery is fully charged in Boost voltage

stage, the controller reduces the battery voltage to Float voltage set point. When the battery is

fully recharged, there will be no more chemical reactions and all the charge current transmits

into heat and gas at this time. Then the controller reduces the voltage to the floating stage,

charging with a smaller voltage and current. It will reduce the temperature of battery and

prevent the gassing, also charging the battery slightly at the same time. The purpose of Float

stage is to offset the power consumption caused by self consumption and small loads in the

whole system, while maintaining full battery storage capacity. In the Float stage, loads can

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continue to draw power from the battery. In the event that the system loads exceed the solar

charge current, the controller will no longer be able to maintain the battery at the Float set

point. Should the battery voltage remains below boost reconnect charging voltage, the

controller will exit Float stage and return to Bulk charge.

2.4 Storage system

In photovoltaic system , the energy is stored in batteries during the day so as to be used

at night. Also ,as photovoltaic system's power output varies throughout any day, a battery

storage system can provide a relatively constant source of power. Batteries are not hundred

percent efficient. Some energy is lost as heat and in chemical reactions. Therefore, additional

photovoltaic modules are needed to compensate for the loss. Utility grid -connected

photovoltaic system do not require batteries, though they can be used as an emergency backup

power source. The following types of batteries are commonly used in PV system : Lead Acid

Batteries which are either liquid vented or sealed VRLA - ( Valve Regulated Lead Acid) and

Alkaline batteries which are also of two types, Nickel Cadmium and Nickel -Iron.

Batteries are electrochemical device and can be classified as a storage in battery

management system. Solar batteries wider used in renewable energy system is flooded lead

acid battery and low maintenance types such as gel and Absorbed Glass Matte (AGM) lead

acid batteries. For both of low maintenance are considerably more expensive and not as

currently available [3]. It can be operate at high temperature range compared with flooded

lead acid battery. Not only using battery method as a storage device, combining with ultra

capacitor can yield the higher density of capacity storage and also improve on

charge/discharge cycle. So, at the mean time it can achieve better cycle life of storage system

[4]. Otherwise from [5] state that the Li-lon battery is the most higher density capacity storage,

and compactable for all situation for Electric Vehicle (EV) system. Various paper discuss of

different type of battery. The AGM lead acid battery been identify following suitable

characteristic with the propose Battery Management System (BMS). The AGM lead acid

battery are found to be attractive for BMS with solar application. This battery is low