COMPLETE SCHOOL PROJECT TOPICS & MATERIALS :
CHAPTERS: Chapter 1-5
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ABSTRACT
This project comprises many chapters that deal extensively with designs and construction of battery charger with auto-cut off which is capable of charging a 12 volts battery. In this construction research, designs were carried out which historic research was used to break down and evaluate to a low level understating of what an auto-cut of charger system is all and how it can be constructed and the main purpose of the project. The charging current, as well as the power to the circuit, is obtained from 1 0 – 18 volts 2 Ampere step down transformer. The law voltage AC can be rectified by the bridge rectifier comprising D1 through D4 and made ripple-free by the smoothing capacitor C1 for charging purposes, 18V DC is used while to power the circuit, 9 volts regulated DC form IC1 is used. IC2 (CA 3140) is used as a simple voltage comparator to drive the relay. After the series steps of inversion pure DC is achieved that can charge a specified DC battery. The relay saves as the Tripping command to the pin i.e to operate automatically when the battery is fully charged and when is weak.
CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
In the context of a renewable energy source, a device that consists of electrodes and electrolytes for the storage of chemical energy, but brings about a reaction between its electrodes and the electrolyte in a way to cause the flow of electrons through an external circuit is known as a battery the circuitry to recharge the batteries in a portable product is an important part of any power supply design. The complexity and cost of the charging system primarily depends on the type of battery and the recharge time.
The life span of a battery mostly used by automobile drivers can be maximized by avoiding over loading, overcharging, and inputting charge current higher than battery manufacture’s rated value (Bangaru, at al, 2013). It was observed over time that most commercial battery charging service centers in town (Enugu, Nigeria) that are patronized by automobile drivers uses the conventional battery charger type that is built without an automatic charging cut-off circuit to provide charging services to their customers. The unavailability of this automatic charging cut-off circuit causes the operator to constantly be on manual check to determine when the connected battery is charged (Baker, 2014).
Irrespective of the discharge level of the battery received from customers, the service center operator often connects the battery and allows it to charge over night without monitoring. This frequent practice often leads to overcharging of the connected battery. Secondly, in an attempt to deliver quick service and satisfy the customer’s expected time of need, they sometimes, adjust the charging setting of the charger to increase the charging current so as to reduce the charging time in order to get the battery charged within a short time. This kind of practice shortens the life span of the battery. However, these common problems had suggested the development and construction of a 12V portable battery charger with built-in automatic charging cut-off circuit in order to encourage domestic usage. This would help automobile drivers to avoid charging problems associated with commercial services centers (Bangaru, at al, 2013).
Some components like a protection fuse and current reverse prevention diode were considered during development of this product to prevent problems that may result from short circuit current and reverse current.
Considering, the compact shape of the battery charger, with very low ventilation an extractor fan was incorporated to drive away hot air and moisture that would be generated inside the charger compartment during operation (Bangaru, at al, 2013).
1.2 Statement of the problem
A simple 12volts charger works by supplying a constant DC or pulsed DC power source to a battery being charged. The simple charger does not alter its output based on time or the charge on the battery. This simplicity means that a simple charger is inexpensive. The circuit of a battery charger has the ability to convert voltages from one form to another (usually AC to DC voltages). This process is carried out through the use of some important components like: rectifiers, capacitor to filter and remove ripples from the AC source and a voltage regulator (IC). However, this project is based on the construction of a 24V/12volts simple battery charger with local materials to reduce cost. The proposed project design works on 24V/12V batteries. There is resistance connected in the battery charger to limit the short circuit current.
1.3 Aim and Objectives of the study
The aim of this project work is to carry out a design and construction of auto cut-off car battery charger.
The specifics objectives are as follows:
- To design a device that will recharge 24V/12v lead acid battery when discharged.
- To design a device that has the ability to indicate charging process, low battery and fully charge levels through LED indicators.
- To design and construct a battery charger that can be use to charge any kind of 24V/12V rechargeable batteries including alkaline, NiCad or lead acid batteries.
1.4 Significance of the study
A simple 24V/12volt battery charger is a simple circuit that comprises of different component that are soldered together on a circuit board to give or produce a require function. Therefore, the importance of this project work is to aid both technicians and students on how to construct a simple battery charger circuit and how it works. It is hoped that after the construction of this charger circuit, it will be kept on the laboratory to be used for battery charging and for practicals and other academic functions.
1.5 Scope of the Study
This project work is limited to the Design and Construction of Auto Cut-off Car Battery Charger. The circuit input voltage is 240volts from the A.C supply mains which will be stepped down by a step-down transformer to 12volts. The 12volts A.C is rectified through a bridge rectifier and filtered through capacitor connected in parallel from the positive terminal of the bridge rectifier. The output voltage is used to charge a battery. The project is limited to 24V/12V batteries. It is not advisable to use on rechargeable batteries outside 24V/12V.