Design And Construction Of A Variable Battery Charger

 ABSTRACT

This project work is on design of a variable Battery charger. This work makes it possible for someone that run, say a 3v to 12 rechargeable batteries to recharge their battery when they are discharged

A variable 12V battery chargers is an electronic device that supplies different level of electric energy to different battery of different voltage rating.

CHAPTER ONE

1.1                                                        INTRODUCTION

Battery charger is an electronics device used in charging and recharging batteries when used up by the instrument connected to it. This electronics device has the ability to charger battery of 3v to 12 limit when they are used up.

The 12-volt 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 12-volt direct current (DC) that the battery needs.

A 12-volt battery charger is roughly the size of a car battery. It has a thick cable ending in two heavy-duty copper alligator clips, a black clip for the battery’s negative terminal and a red one for positive. The charger has an on-off switch and a meter to indicate charging power.

All battery chargers have a power input, which receives energy from the energy source, and a power output that delivers energy to the load. In most battery charger, the power input and output consist of electrical connectors or hardwired circuit connections, though some power supplies employ wireless energy transfer in lieu of galvanic connections for the power input or output.

To obtain a complete circuit for this work, the circuit is mainly composed of the:

• Input transformer:   The input transformer is used to transform the incoming line voltage down to the required level for the power supply. Typically the input transformer provides a step down function. It also isolates the output circuit from the line supply.
• Rectifier:   The power supply rectifier converts the incoming signal from an AC format into raw DC. Either half wave or more commonly full wave rectifiers may be used as they make use of both halves of the incoming AC signal.
• Smoothing:   The raw DC from the rectifier is far from constant falling to zero when the AC waveform crossed the zero axis, and then rising to its peak. The addition of a reservoir capacitor here fills in the troughs in the waveform, enabling the next stage of the power supply to operate. Large value capacitors are normally used within this stage.
• Voltage adjuster:   This stage of the power supply takes the smoothed voltage and uses a variable ic to provide a variable output virtually regardless of the output current and any minor fluctuations in the input level.

1.2                                                   AIM OF THE PROJECT

The aim of this 12v variable battery charger is to provide the required voltage and current  to the battery using an AC supply at the input. 12v variable battery charger is to design a power supply with one output terminal with variable output voltage, and the output is gotten by turning the voltage adjuster known as the potentiometer.

1.3                                           LIMITATION OF THE PROJECT

This device is limited at producing from 3v – 12 v output using a 24 volts center tap transformer.

1.4                                         SIGNIFICANCE OF THE PROJECT

This work makes it possible for someone to use one battery charger to charge different battery of higher or lower voltage rating without considering buying a new or different battery charger.

 1.5                                          APPLICATION OF THE PROJECT

A 12v variable battery charger is a charger that electricians and electrical project hobbyists use to charge batteries used for power supply. The power supply is used as a gauge to make sure the piece of work the person has completed is able to withstand certain amounts of voltage and current load. Tests are generally conducted by applying different amounts of voltage to the piece of completed work a little at a time to ensure the stability of the circuit the individual has created. These types of power supplies also are used by hobbyists to power small electronics requiring variable voltage and by tattoo artists to power tattooing guns.

By using such a 12v variable battery charger, the individual is able to spot any temperaments or inconsistencies in the circuit he’s created in a manner that allows for adjustment to be made without having to scrap the entire project. A 12v variable battery charger is a useful tool for anyone who has a background with electrical circuitry and components. It also has many uses other than just testing.

In addition to being used to test circuits, this type of power supply may be used by miniature hobbyists as well. For example, such tools are commonly used by those who work with miniature electronic train sets. The battery charger can be adjusted to either speed up or slow down the train as it is pushed around the track by the power of the completed circuit.