Design And Construction Of A 5V Cell Phone Battery Charger

ABSTRACT

This project is titled design and construction of a 5V cell phone battery charger. A 5V cell phone battery charger is an electronics device used in charging 5v cell phone batteries when used up by the instrument connected to it. This electronics device has the ability to stop charging when the battery is fully charged and starts charging when the battery voltage drops below the set point.

A 5V cell phone battery charger is basically a DC power supply source. Here a transformer is used to step down the AC mains input voltage to the required level as per the rating of the transformer. The transformer output is rectified by BR1 and the positive DC supply is directly connected to the charger’s output contact, while the negative terminal is connected through current limiting resistor R2. D2 works as a power indicator with R1 serving as the current limiter and D3 indicates the charging status.

A bridge rectifier configuration is used to rectify the low voltage AC into DC and is further smoothed by a high value electrolytic capacitor. This DC is fed to an electronic circuit which regulates the voltage into a constant level and is applied to the battery under charge, where the energy is stored through an internal process of chemical reaction.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

INTRODUCTION

1.1      BACKGROUND OF THE PROJECT

• OBJECTIVE OF THE PROJECT
• SIGNIFICANCE OF THE PROJECT
• SCOPE OF THE PROJECT
• APPLICATION OF THE PROJECT
• LIMITATION OF THE PROJECT
• TYPES OF CELL PHONE BATTERIES
• PROJECT ORGANIZATION

CHAPTER TWO

LITERATURE REVIEW

• HISTORICAL BACKGROUND OF CELL PHONE BATTERY
• REVIEW OF CELL PHONE BATTERY CONSTRUCTION
• REVIEW OF BATTERY CHARGE AND DISCHARGE

CHAPTER THREE

3.0      METHODOLOGY

• SYSTEM BLOCK DIAGRAM
• USB PHONE CHARGER OPERATION
• USB MOBILE CHARGER CIRCUIT DIAGRAM
• COMPONENTS USED IN THIS CIRCUIT
• COMPONENTS DESCRIPTION
• USB MOBILE CHARGER CIRCUIT DESCRIPTION
• USB CONNECTION AND CONFIGURATION

CHAPTER FOUR

• CONSTRUCTION PROCEDURE AND TESTING
• CASING AND PACKAGING
• TESTING OF SYSTEM OPERATION
• MAINTENANCE OF THE SYSTEM
• BILL OF ENGINEERING MEASUREMENTS AND EVALUATION

CHAPTER FIVE

• CONCLUSION
• RECOMMENDATION
• REFERENCES

 CHAPTER ONE

• INTRODUCTION

1.1                                           BACKGROUND OF THE STUDY

Cell phone Battery charger is an electronics device used in charging and recharging batteries when used up by the cell phone. This electronics device has the ability to stop charging when the battery is fully charged and starts charging when the battery voltage drops below the set point

The Cell phone Battery charger uses household current to put an electric charge into a discharged battery. The charger’s circuits convert 240-volt household alternating current (AC) to the 9-volt direct current (DC), then regulate to 5v that the cell phone battery needs.

This charger will charge any cell phone battery that is rated 5v. It is fully automatic and will charge at a rate up to about 800mA 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 maximum level and then stop charging. 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.

1.1                               OBJECTIVE OF THE STUDY

The objective of this project is to design a charger that will charge any cell phone battery that is rated 5v that will automatic charge any cell phone at a rate up to about 800mA until the battery voltage reaches a preset point at which it will switch to a very low current float charge

1.2                          SIGNIFICANCE OF THE PROJECT

The main advantages of this cell phone battery charger over other chargers is the ability of the charger to indicate battery charging levels and also the ability to stop charging when the battery is fully charged and resume charging when the battery level drops below  the set level.

1.3                                                 SCOPE OF THE PROJECT

The charger is made up of various basic units they are:

• The power supply units
• The smoothing circuits
• The regulating unit and
• Regulated D.C charging units

Features of this charger are as below:

• It 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 consumed less current but generate high current to the load.

1.4                                APPLICATION OF CELL PHONE BATTERIES

This charger provides lightweight, high energy density power sources for a variety of devices. To power larger devices, such as electric cars, connecting many small batteries in a parallel circuit is more effective and more efficient than connecting a single large battery such devices include:

• Portable devices: these include mobile phones and smartphones, laptops and tablets, digital cameras and camcorders, electronic cigarettes, handheld game consoles and torches (flashlights).
• Power tools: Li-ion batteries are used in tools such as cordless drills, sanders, saws and a variety of garden equipment including whipper-snippers and hedge trimmers can be charged with this device.
• Electric vehicles: Because of their light weight Li-ion batteries are used for energy storage for many electric vehicles for everything from electric cars to Pedelecs, from hybrid vehicles to advanced electric wheelchairs, from radio-controlled models.

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 5v cell phone batteries.

1.6                                       TYPES OF CELL PHONE BATTERIES

The battery is the lifeblood of your mobile phone. The designers of mobile phones try hard to minimize and use more efficiently the power that the batteries use, which in turn gives longer service from smaller, lighter cell phone batteries.

There are four basic types of rechargeable battery used in mobile phones. Let us examine the advantages and disadvantages of each of them.

Lithium Polymer (Li-Poly) Batteries

Li-Poly are the newest and most advanced technology for cell phone batteries. Ultra-lightweight, they do not suffer from memory effect and will deliver up to 40% more battery capacity than a Nickel Metal Hybrid (NiMH) of the same size.

“Memory effect” happens when rechargeable batteries are not fully discharged between charge cycles; as a result the battery “remembers” the shortened cycle and is thus reduced in capacity.

Not needing a cell casing makes Lithium Polymer cell phone batteries thinner and lighter batteries. However, they are still quite rare.

Lithium Ion (Li-Ion) Batteries

This is the current and most popular technology for cell phone batteries. The only real drawback of Lithium Ion cell phone batteries is that they are expensive. As such, they tend to be supplied with only top-of-the-line phones. Lithium Ion batteries are slightly lighter than NiMH batteries, but they also have a longer lifetime.

A Lithium Ion battery may be damaged by extensive overcharging (continuously on a cell phone charger for more than 24 hours).

Nickel Cadmium (NiCd) Batteries

Nickel Cadmium cell phone batteries are old technology. This is the rechargeable battery that most people are familiar with. NiCd batteries suffer from memory effect, and they must be completely discharged before recharging or else damage can occur. The chemicals used in NiCd batteries are not environmentally friendly, and the disposal of cadmium-rich waste is an increasing problem.

They are the cheapest variety of phone batteries. Their affordability helps to bring down the overall cost of mobile phones.

Nickel Metal Hydrid (NiMH) Batteries

Nickel Metal Hydride (NiMH) batteries claim to be superior to NiCd because they don’t contain cadmium. The cell phone batteries are made from non-toxic materials and are environmentally friendly. They also deliver a higher capacity in relation to their size and weight.

NiMH cell phone batteries are relatively new technology and are prone to the “memory effect”, but only to a very small extent. To maximize performance, it is advised to completely discharge the battery after every 20th recharge.