Battery Charger Circuit With Over Current And Over-Voltage Protection

Battery charger puts energy into a secondary cell or rechargeable battery by forcing an electric current through it. The purpose of cell protection is to provide the necessary monitoring and control to protect the cells from out of tolerance ambient or operating conditions and to protect the user from the consequences of battery failures. Cell protection can be external to the battery and this is one of the prime functions of the Battery Management System. This device prevents charging battery from over-voltage and over-current so that the charger can be left unattended.

TABLE OF CONTENTS

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

TABLE OF CONTENT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• PROBLEM STATEMENT
• AIM/OBJECTIVE OF THE PROJECT
• PURPOSE OF THE PROJECT
• SIGNIFICANCE OF THE PROJECT
• APPLICATION OF THE PROJECT
• LIMITATION OF THE PROJECT
• ADVANTAGES OF THE PROJECT
• METHODOLOGY
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

2.1      REVIEW OF BATTERY CHARGER

2.2      HISTORICAL BACKGROUND OF BATTERY CHARGER

2.3      REVIEW OF RECHARGEABLE BATTERY

2.4      REVIEW OF CHARGER UNITS

2.4.1 SUPPLY UNIT

2.4.2 THE RECTIFYING UNIT

2.4.3 THE SMOOTHING UNIT

2.4.4 THE REGULATOR AND REGULATED

2.4.5 D.C CHARGING UNIT

CHAPTER THREE

3.0      CONSTRUCTION METHODOLOGY

3.1      BLOCK DIAGRAM OF THE SYSTEM

3.2      CIRCUIT DIAGRAM

3.3      CIRCUIT DESCRIPTION

3.4      SYSTEM OPERATION

3.5      DESCRIPTION OF MAJOR COMPONENTS USED

CHAPTER FOUR

4.1            RESULT ANALYSIS

4.1      CONSTRUCTION PROCEDURE AND TESTING

4.2      CASING AND PACKAGING

4.3      ASSEMBLING OF SECTIONS

4.4      TESTING OF SYSTEM OPERATIONOBSERVATIONS

4.6     DIFFICULTIES ENCOUNTERED ON THE SYSTEM

4.7     COST OF PRODUCTION

CHAPTER FIVE

• SUMAMRY
• CONCLUSIONS/SUGGESTIONS

5.3     REFERENCES

CHAPTER ONE

1.0                                                     INTRODUCTION

1.1                                     BACKGROUND OF THE PROJECT

A battery charger is an electrical device employed in charging batteries. A Battery charger comes in various designs and voltage. The choice of a particular and type of charger depends largely on the size of battery or batteries.

The battery charge is built in such a way that it delivers a constant value of d.c current into the battery it is charging in the opposite direction from which current flows on the batteries during discharge one cannot successfully design a battery charge without a fundamental understanding of the accumulator because it also makes up the operation according to [Xie, Z.; Liu, Q.; Chang, Z.; Zhang, X. 2013].

Every charging Battery requires monitoring, that is, keeping a check on the key operational parameters during charging and discharging such as voltages and currents and the battery internal and ambient temperature. The monitoring circuits would normally provide inputs to protection devices which would generate alarms or disconnect the battery from the load or charger should any of the parameters become out of limits.

There are three main objectives common to all Battery Management Systems

• Protect the cells or the battery from damage
• Prolong the life of the battery
• Maintain the battery in a state in which it can fulfil the functional requirements of the application for which it was specified.

To achieve these objectives the battery managing system the device will incorporate one or more protecting device.

The aim of this work is to build a charger that will automatically shut off the charging process when battery attains full charge thereby protecting the device from overcharge. This main aim of this work is protect this device from over-current and overvoltage.

1.2                                             PROBLEM STATEMENT

In the last decade, battery chargers used to be the most devices that exposes batteries to explosion and cell deterioration due to over-current or overvoltage experience because of lack of inbuilt regulating device. This automatic battery charger came to overcome this problem in that in that it has an inbuilt protecting device which protects the charger from being overcharged due to over-current or overvoltage.

1.3                                        OBJECTIVES OF THE PROJECT

The objective of the project is to design a device that will recharge 12v lead acid battery when discharged and at the same time protect the battery from overcharge.

1.4                                           PURPOSE OF THE PROJECT

The purpose of this work is to ensure the safety of charging battery, that is, to protect battery from over-current and over-voltage.

1.5                                      SIGNIFICANCE OF THE PROJECT

This device charges 12v acid battery mainly, however, if the output voltages are adjusted can be used to charge battery of lower or higher voltages. Apart from charging batteries, this device can also be used as a battery level monitor due to the battery level feature it contains. This device has protecting device which protects battery from overcharging. [Xie, Z.; Liu, Q.; Chang, Z.; Zhang, X. 2013]

1.6                                       APPLICATION OF THE PROJECT

Battery charger is used in the following devices for the purpose of recharging devices’ batteries according to (Sequeira, C.A.C, 2011), Such batteries are:

1. It is used in inverter
2. It is used in cellphone
3. It is used in Solar energy system
4. It is used in vehicles
5. It is used in an uninterruptible power supply (UPS), etc.

1.7                                        LIMITATION OF THE PROJECT

The only problem with this device is that it takes longer time to recharge car battery because of the low current output, and it is design only for a 12 battery.

1.8                            ADVANTAGES OF AUTOMATIC CHARGER

Features of this automatic battery charger made it more advantageous than other types and they are as below (Sequeira, 2011):

• Automatic battery charger has an indicator to indicate when the battery is charging and fully charged
• It has a manually operated switch that is used to ON and OFF the entire system.
• It composes of in-built active components which stop charging process when the battery is fully charged.
• It consumed less current but generate high current to the load.

1.9                                     PROJECT WORK ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.