Design And Construction Of An Automatic Battery Charger Using Thyristor (SCR)

This project is titled design and construction of a battery charger using SCR. Automatic battery charger presented here is an acid battery charger that is designed to charge any acid battery using thyristor to supply the required current.

This charger will charge any 12V lead acid battery including flooded, gel and AGM. It is fully automatic and will charge at a rate up to about 4A until the battery voltage reaches a preset point at which it will switch to a very low current float charge. If the battery voltage drops again the charger will begin charging until the voltage once again reaches the cutoff point. In this way it can be left connected to a battery indefinitely to maintain full charge without causing damage. An LED indicates when the battery is fully charged

The objective of this project is to design and construct an electrical /electronic equipment, a thyristor controlled battery charger, that will supply electrical energy (charges) to a charge storage device; a battery, in a process to restore the battery’s used up energy.

CHAPTER ONE

1.1                                                     INTRODUCTION

A battery charger is an electrical device employed in charging batteries that are usually charged by battery charges are the storage batteries also known as “accumulators”.

The charger is made up of various electrical and electronics component which for the purpose of clanty are group into your basic unit they are:

The power supply units

The smoothing circuits

The regulating unit and

Regulated D.C charging units

A Battery charger comes in various designs and voltage. The choice of a particular and of charger that depends largely int eh size of battery or battery or batteries which on mterds to charge the mini battery changer could be used to charge batteries of 12 volts. The bigger battery changes are for batteries with voltage ranging from 12 – 48 volts. These are the heavy duty 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 with out a fundamental understanding of the accumulator because it also makes up the operation.

1.2                                        OBJECTIVES OF THE PROJECT

The objective of the project is to design a device that will recharge 12v lead acid battery when discharged using scr.

1.3                                      SIGNIFICANCE OF THE PROJECT

The main objective of the study is to be able to actualize another efficient way of recharging a mobile phone through intelligible research and experiments.

1. This study shall benefit many people who consider mobile or portable devices as important aspects of their lives. Furthermore, this Interface device is expected to be a user-friendly device that everyone can make use of.
2. This study shall benefit the Electric companies for the users can save more electricity when using Interface device. The little amount of power can be used at its maximum level.
3. This study shall benefit the environment. There is no waste generated with this product and energy is conserved.
4. This study shall benefit the future researchers for this can help them to have a better idea.
5. 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.
6. Apart from charging batteries, this device can also be used as a battery level monitor due to the battery level feature it contains.

1.4                        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, just with little circuit adjustment
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.

1.5                         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.

1.6               ADVANTAGES OF AUTOMATIC CHARGER

Features of this automatic battery charger made it more advantageous than other types and they are as below:

• Automatic battery charger has an indicator to indicate when the battery is 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.

1.7                         STATEMENT OF THE PROBLEM

This device came to bring solution for battery charging which helped in achieving the aim and objective of this study. Such as:

1. To design and construct an interface device that could amplify an extremely small value of current to a value suitable for recharging battery
2. To determine the functionality of the interface device in terms of: Current, Voltage, Voltage gain, Power, Power efficiency, Impedance
3. Automatic start charging and stop charging when the battery is fully charge and vice versa.

1.8                                 DEFINITION OF TERMS

Battery Charger – is a device used to put energy into a secondary cell or rechargeable battery by forcing an electric current through it. (www.wikipedia.com, 2014)

Charge – there are two kinds of charge, positive and negative

– like charges repel, unlike charges attract.

– positive charge comes from having more protons than electrons; negative charge comes from having more electrons than protons.

Charge Rate – is often denoted as C or C-rate and signifies a charge or discharge rate equal to the capacity of a battery in one hour. (www.wikipedia.com, 2014)

Mobile Phone – any wireless telephone capable of operating while moving at any speed, battery powered and small enough to be easily carried by a person.

Interface device – circuit that is between the mobile phones that do the process of transferring stored energy.

Rectification – a process of converting alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.

Rectifier – a circuit capable of rectifying an alternating current to a direct current.

Step Up DC – DC Converter – also known as boost converter. A DC to DC power supply with an output voltage greater than its input voltage. It is used to sustain the amount of voltage needed for the charging circuit to function.

1.9                                         METHODOLOGY

To achieve the aim and objectives of this work, the following are the steps involved:

1. Study of the previous work on the project so as to improve it efficiency.
2. Draw a block diagram.

• Test for continuity of components and devices,

1. Design and calculation for the battery charger was carried out.
2. Studying of various component used in circuit.
3. Construct a battery charger circuit.

• Finally, the whole device was cased and final test was carried out.

1.10                                           PROJECT 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.