Design And Construction Of A 9V Battery Level Indicator

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

1. Energy efficient – LED’s are now capable of outputting 135 lumens/watt
2. Long Lifetime – 50,000 hours or more if properly engineered
3. 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
4. No warm-up period – LED’s light instantly – in nanoseconds
5. Not affected by cold temperatures – LED’s “like” low temperatures and will startup even in subzero weather
6. Directional – With LED’s you can direct the light where you want it, thus no light is wasted
7. 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
8. Environmentally friendly – LED’s contain no mercury or other hazardous substances
9. Controllable – LED’s can be controlled for brightness and color

1.5                                           LIMITATION OF THE PROJECT

1. This device can only indicate voltage from 1.5v to 9v.
2. It indicate voltage level via LEDs
3. 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.