Design And Construction Of A 9V Battery Level Indicator

Electrical Electronics Engineering

The design and construction of a 9V battery level indicator involve creating a circuit that detects the voltage of the battery and displays it in a user-friendly format. This project typically utilizes basic electronic components such as resistors, LEDs, and a voltage comparator integrated circuit (IC). By employing a voltage divider circuit, the battery’s voltage is scaled down to a range suitable for the comparator IC. This IC then compares the scaled voltage with preset thresholds, triggering corresponding LEDs to indicate the battery’s level. Proper calibration ensures accurate indication across the battery’s discharge curve, enhancing reliability. The construction process involves soldering the components onto a prototyping board or PCB, followed by integrating a power switch and enclosure for user convenience and safety. Testing and calibration procedures are crucial to validate the indicator’s functionality and accuracy, ensuring its effectiveness in providing real-time battery level feedback for various applications, including portable electronics and hobbyist projects.

ABSTRACT

Battery level indicator indicates the status of the battery just by glowing LED’s. For example six LED’s are glowing means battery capacity 60% remains. This article explains you how design battery level indicator. You can use this circuit to check car battery or inverter. So by using this circuit, we can increase the lifetime of battery.

The heart of this battery level indicator circuit is LM3914 IC. This IC takes input analog voltage and drives 10 LED’s linearly according to the input analog voltage. In this circuit there is no need of resistors in series with led’s because current is regulated by the IC.

This device is designed to monitor 1.5V to 9V DC.

CHAPTER ONE

1.0 INTRODUCTION

Knowing the amount of energy left in a battery compared with the energy it had when it was full gives the user an indication of how much longer a battery will continue to perform before it needs recharging.

This would be easy if the battery could be discharged at a constant rate. The charge in a battery is equal to the current multiplied by the time for which it flowed. Unfortunately there are two problems with this. In all practical batteries, the discharge current is not constant but diminishes as the battery becomes discharged, usually in a non-linear way. Any measurement device must therefore be able to integrate current over time. Secondly, this method depends on discharging the battery to know how much charge it contained. In most applications except perhaps in qualification testing, the user (or the system) needs to know how much charge is in the cell without discharging it.

It is not possible either to measure directly the effective charge in a battery by monitoring the actual charge put into it during charging. This is because of the Coulombic efficiency of the battery. Losses in the battery during the charge – discharge cycle mean that the battery will deliver less charge during discharge than was put into it during charging.

The Coulombic efficiency or charge acceptance is a measure of how much usable energy is available during discharging compared with the energy used to charge the cell.

Nowadays, electronic indicators are used which provide or give a continuous reading of the battery condition. This method of course needs indicators to provide the measurement data of the current battery status, memory to store the battery.

1.1 OBJECTIVE OF THE PROJECT

Low voltage or Over-charging in batteries can make the plates swell and can cause internal shorts. It shortens the life in batteries, even if you don’t get shorts. It also causes the plates to deteriorate faster than just regular charging. A float charge to balance is not the bad overcharging that causes a lot of water to boil out.

The objective of this work is to construct a device that will indicate and let the user know the status of battery of a device just by glowing the number of LED’s.

1.2 SIGNIFICANCE OF THE PROJECT

Battery level indicator will let you know the status of battery of a device just by glowing the number of LED’s. For example four LED’s are glowing means battery capacity is 40 percent.

1.3 APPLICATION OF THE PROJECT

You can use this battery level indicator circuit with your inverter or with your car battery; it will give you indication about your battery status.

In Automobiles

Some automobiles are fitted with a battery condition meter to monitor the starter battery. This meter is, essentially, a voltmeter but it may also be marked with coloured zones for easy visualization.

In Electronic devices

A battery indicator is a feature of many electronic devices. In mobile phones, the battery indicator usually takes the form of a bar graph – the more bars that are showing, the better the battery’s state of charge.

In Computers

Computers may give a signal to users that an internal standby battery needs replacement. Portable computers using rechargeable batteries generally give the user some indication of the remaining operating time left on the battery. A Smart Battery System uses a controller integrated with an interchangeable battery pack to provide a more accurate indication of the state of battery charge.

This device can also be used in the following places:

Telecommunications
CATV / Broadband
Mission Critical Facilities
UPS Systems
Financial Institutions
Mining
Transportation Operations
Hospitals
Emergency Lighting
Call Centers
Battery Suppliers and Manufacturers.
Battery Service Groups
Medical/Biotechnology. All for the purpose of knowing the voltages of their devices.

1.4 BASIC ADVANTAGES OF LED LIGHT IN THE PROJECT

Energy efficient – LED’s are now capable of outputting 135 lumens/watt
Long Lifetime – 50,000 hours or more if properly engineered
Rugged – LED’s are also called “Solid State Lighting (SSL) as they are made of solid material with no filament or tube or bulb to break
No warm-up period – LED’s light instantly – in nanoseconds
Not affected by cold temperatures – LED’s “like” low temperatures and will startup even in subzero weather
Directional – With LED’s you can direct the light where you want it, thus no light is wasted
Excellent Color Rendering – LED’s do not wash out colors like other light sources such as fluorescents, making them perfect for displays and retail applications
Environmentally friendly – LED’s contain no mercury or other hazardous substances
Controllable – LED’s can be controlled for brightness and color

1.5 LIMITATION OF THE PROJECT

This device can only indicate voltage from 1.5v to 9v.
It indicate voltage level via LEDs
The operating voltage of this IC is 3v to 25v DC

1.6 SCOPE OF THE PROJECT

Voltage Monitor is a simplistic and inexpensive battery monitoring system designed to monitor battery string voltage for over and under voltage conditions. This Battery Voltage Monitor is used in 1.5V – 9V applications – and reads battery bus status, detects different dc voltages using contacts probes. Monitoring for battery string voltage will provide critical battery cell protection and ensure the longevity of the battery system. Over voltage can lead to overcharging and overheating of the batteries, which can cause irreversible cell destruction. Under voltage will also cause irreversible battery damage if left uncorrected. Measuring battery voltage with this device will allow the user to determine how charged their batteries are, and allow for immediate corrective action if needed.

1.7 ADVANTAGES OF THE PROJECT

It is portable
It has measuring probe which is labeled black ( –ve) and red (+ve)
High reliability and durability
Simple installation
Monitors Voltage in 1.5 – 9V batteries.

1.8 PROJECT WORK ORGANISATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to a battery level indicator. In this chapter, the background, significance, objective limitation and problem of a battery level indicator were discussed.

Chapter two is on literature review of a battery level indicator. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.