Design And Construction Of An SMPS Based 12V Automatic Battery Charger With Battery Full Cut-Off And Digital Display

ABSTRACT

This project is on a SMPS based 12v automatic battery charger with battery full cut-off and digital display. The Automatic Battery Charger circuit presented in this work can automatically charge a 12V battery. Special features of the charger are as follows. It automatically controls the charging current as per the status of the battery. Battery voltage level as well as charging status are indicated on the LCD display. At end of this work a switching power supplies was built which have high efficiency and durable which is fit to be used in a variety of electronic equipment, including computers and other sensitive equipment requiring stable and efficient power supply.

TABLE OF CONTENTS

Title page

Approval page

Dedication

Acknowledgement

Abstract

Table of content

CHAPTER ONE

• Introduction
• Background of the study
• Problem statement
• Aim/objectives of the project
• Significance of the project
• Application of the project
• Scope of the project
• Project work organisation

CHAPTER TWO

LITERATURE REVIEW

2.1      Review of Related works

2.2      Switch mode power supply

2.3      Types of switch mode power supply

2.4      Application of switch mode power supply

2.5      Advantages and disadvantages of switch mode power supply

2.6      Contribution to Knowledge

2.7      Proposed system’s Theories

CHAPTER THREE

3.0      METHODOLOGY

3.1      Block diagram of the system

3.2      Circuit Diagram

3.3      Circuit description and operation

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 operation

4.6     Precaution

CHAPTER FIVE

• Conclusions
• Recommendation

5.3     REFERENCES

CHAPTER ONE

1.0                                                     INTRODUCTION

• Background of the Study

A battery charger is described as is a device that provides electricity to convert into stored chemical energy for storage in an electrochemical cell by running an electric current through it (Zhang et al, 2013).

A battery charger that is based on switched-mode power supply (SMPS) is an electronic circuit that converts power using switching devices that are turned on and off at high frequencies, and storage components such as inductors or capacitors to supply power when the switching device is in its non-conduction state. The circuit was built around TNY267 switching regulator which performs the functions of the PWM generator, MOSFET chopper switch, error amp, and control circuit.

A Battery charger comes in various designs and voltage.  The choice of a particular charger depends largely on the size of battery. Mini battery charger could be used to charge batteries whose voltage is 12 volts.

It converts an AC power line voltage to a steady state DC output voltage as required by all electronic circuits. The SMPS circuit of the charger converts the available unregulated AC or DC input to a regulated DC output. The input is taken from the AC mains and then rectified, filtered and fed to a high frequency DC-DC converter. SMPS circuit of the charger can be operated within the kHz to MHz frequency range. The increased switching frequencies cause a decrease in the size of the energy storage elements, such as the capacitors, inductors and transformers, in an almost linear manner [3]. 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 [Zhang et al, 2013].

This work is aimed at building a SMPS based digital battery charger with battery full cut off feature and LCD.

• PROBLEM STATEMENT

Using switch Mode power supply in a battery charger was invented to solve problems observed in conventional battery charger such as low frequency and efficiency. Linear DC regulated power supplies (“linear supplies”) used in switch Mode power supply alters the output voltage to the required value through the power frequency (50/60 Hz alternating current) voltage transformer [8]. After being lowered (or raised) to the appropriate AC voltage value, the waveform is rectified, filtered, and stabilized by a voltage regulation circuit, and is then output as a regulated direct current (DC) which can be used to charge a 12v battery charger.

1.3                               AIM AND OBJECTIVES OF THE PROJECT

The main aim of the project is to build an SMPS based 12v automatic battery charger with battery full cut-off and digital display. The objectives of the work are:

1. To build the prototype of the device
2. To automatically controls the charging current as per the status of the battery.

• To display the charging status of the charging battery on the LCD

1. To increase frequency and efficiency of a battery charger.

1.4                                      SIGNIFICANCE OF THE PROJECT

Using this digital display charger will serve as a means of keeping a battery in good condition in that the charger maintains float voltage, if battery is fully charged.

Apart from charging batteries, this device can also be used as a battery level monitor due to the battery level and digital display features.

Carrying this work will go a long way teaching students how SMPS based battery charger is been made and the operation of battery charger. This study will also be of great benefit to all users of charger and rechargeable devices in that it will help them to understand how their battery is been charged and how chargers are operated.

In a switching power supply, the regulating device operates in the saturation or cut-off area as opposed to the linear power supply regulator which operates in the less efficient linear range.

Switching power supply has Small size, lighter weight, and higher efficiency (can reach nearly 99%). It also have larger output ripple, RFI/EMI interference from pulsed power, higher output voltage if failure occurs [14].

1.5                                       APPLICATION OF THE PROJECT

Battery charger is used in the following devices for the purpose of recharging device batteries:

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                                              SCOPE OF THE PROJECT

The scope of this work covers building an SMPS based digital battery charger which incorporates a switching regulator to convert electrical power efficiently. It is mainly used for obtaining a controlled dc power supply as output. It is used to convert power (voltage) using switching devices that are turned on and off alternatively at high frequencies. It uses storage components like inductors or capacitors to supply power when the switching device is in its non-conduction state (off-state). SMPS circuit possesses high efficiency and is widely used in various electronic equipment such as computers, battery chargers, and other sensitive equipment requiring a stable and efficient power supply.

The system automatically controls the charging current as per the status of the battery. Battery voltage level as well as charging status is indicated on the LCD.

1.8                                        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.