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Lead acid battery charger with voltage analyzerr Mini project 2011
ABSTRACT
Now-a-days maintenance free lead acid batteries are common in vehicles, inverters, and UPS systems. If the battery is left in a poor state of charge, its useful life is shortened. It also reduces the capacity and recharge ability of the battery. For older types of batteries, a hygrometer can be used to check the specific gravity of the acid, which, in turn, indicates the charge condition of the battery. However, you cannot use a hygrometer for sealed type maintenance-free batteries. The only way to know their charge level is by checking their terminal voltage.
Dept. of EEE 1AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
Chapter 1
INTRODUCTION
With the lack of centralized power grids, car batteries have taken the place of oneOf the
main energy sources available in developing countries. With this in mind, ourObjective will
be to design a cheap, versatile and efficient lead acid car battery charger which will interest
and appeal to the “cost-minded” customer. Today maintenance-free lead-acidbatteries are
common in vehicles,inverters, and UPS systems. If thebattery is left in a poor state of charge,
itsuseful life is shortened. It also reduces thecapacity and rechargebility of the battery.For
older types of batteries, a hygrometercan be used to check the specific gravityof the acid,
which, in turn, indicates thecharge condition of the battery. However,you cannot use a
hygrometer for sealed-type maintenance-free batteries. The onlyway to know their charge
level is by checking their terminal voltage.
To their specific users:
Universal 12 Volt battery charger
Ability to charge a typical 12 Volt lead-acid battery
Overcharge protection
State of charge indicator
Affordable
We used these requirements as guidelines to implement our product as well asInclude
additional features that we thought are important to the functionality.
Dept. of EEE 2AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
Chapter 2
BLOCK DAIGRAM
Each individual module was designed and constructed separately. After successful
simulation and testing, they were put together to create the finalized version.
Dept. of EEE 3AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
3. CIRCUIT DIAGRAM
3.1 CIRCUIT MODEL
Battery Voltage level to detect are
<9.8V
>9.8V
11.5V
12.0V
12.5V
Select reference voltage in 5 V
Choose a zener diode with 5V
Dept. of EEE 4AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
Resistor,Re = 5V/1.25mA
= 4k
= 3.9k(std)
Total current through the voltage level indicator circuit is limited to 0.3mA
Total resistance in the divider network = 12.5/0.3mA
= 41k
= 38k(std)
For 12.5 voltage
V=(Vcc * R5)/(total resistance)
5V=(12.5 * R5)/(38k)
R5=15.2k
= 15k(std)
For 12 voltage
V=(Vcc * (R5+R4))/(Total Resistance)
5V=(12*(15.2+R4))/(38k)
R4=15.83-15.2
=0.63k
=680ohm(std)
For 11.5 voltage
V=(Vcc*(R5+R4+R3))/(Total Resistance)
5=(11.5*(15.83+R3))/(total Resistance)
R3=16.52-15.83
=0.691ohm
= 680ohm(std)
Dept. of EEE 5AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
For 9.8 voltage
V=(Vcc*(R5+R4+R3+R2))/(Total Resistance)
5=(9.8*(16.52+R2))/(38)
R2=19.38-16.52
=2.86k
=2.7k(std)
Resistor, R1 = Total Resistance – (R2+R3+R4+R5)
= 38 – 19.38 k
= 18.62k
= 18k
Resistor R7 to R10
= 5V/(10mA)
= 500ohm
= 470ohm(std)
Trasnsformer 12V,2A
So diode used for rectifier is IN 5408 ( 4 No’s)
Dept. of EEE 6AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
4. COMPONENTS USED
1. 230V AC Primary to 0-12V 2AMP Secondary Transformer
2. Diode IN5402
3. IC LM324
4. PZ1 Piezo Buzzer
5. LED
6. Capacitor
7. Zener Diode
8. Resistor
9. Fuse
10. Crocodile Clips
11. PCB
Dept. of EEE 7AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
Chapter 5.
COMPONENT DESCRIPTION
5.1. 230V AC Primary to 0-12V 2AMP Secondary Transformer
A transformer is an electrical device that transfers energy from one circuit to another by
magnetic coupling with no moving parts. A transformer comprises of two or more coupled
windings, or a single tapped winding and, in most cases, a magnetic core to concentrate the
flux. An alternating current in one winding creates a time-varying magnetic flux in the core,
which induces a voltage in the other windings. Transformers are used to convert between
high and low voltages, to change impedance, and to provide electrical isolation between
circuits.
If a load is connected to the secondary, an electric current will flow in the secondary
winding and electrical energy will be transferred from the primary circuit through the
transformer to the load. In an ideal transformer, the induced voltage in the secondary winding
(VS) is in proportion to the primary voltage (VP), and is given by the ratio of the number of
turns in the secondary (NS) to the number of turns in the primary (NP) as follows:
By appropriate selection of the ratio of turns, a transformer thus allows an alternating current
(AC) voltage to be "stepped up" by making NS greater than NP, or "stepped down" by making
NS less than NP. In the vast majority of transformers, the windings are coils wound around a
ferromagnetic core, air-core transformers being a notable exception.
Transformers range in size from a thumbnail-sized coupling transformer hidden inside
a stage microphone to huge units weighing hundreds of tons used to interconnect portions of
power grids. All operate with the same basic principles, although the range of designs is
wide. While new technologies have eliminated the need for transformers in some electronic
circuits, transformers are still found in nearly all electronic devices designed for household
("mains") voltage. Transformers are essential for high voltage power transmission, which
makes long distance transmission economically practical.
Dept. of EEE 8AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
5.2.Diode IN5402
A signal diode is one of many types of diodes, which are small components of electrical
circuits, manufactured from semiconductors that force electricity to flow in only one
direction. Signal diodes which are also sometimes known by their older name of the Point
Contact or Glass Diode are physically very small in size compared to their larger Power
Diode cousins and control small currents up to about 100mA. Generally, the PN-junction of a
signal diode is encapsulated in glass to protect it and they generally have a red or black band
at one end of their body to help identify which end is its Cathode terminal.
Silicon diodes are designed to pass very small currents, and have several applications
in the signal processing field. The arrow in the symbol of diode points in the direction of
conventional current flow through the diode meaning that the diode will only conduct if a
positive supply is connected to the Anode (A) terminal and a negative supply is connected to
the Cathode (K) terminal thus only allowing current to flow through it in one direction only,
acting more like a one way electrical valve, (Forward Biased Condition). However, we know
that if we connect the external energy source in the other direction the diode will block any
current flowing through it and instead will act like an open switch, in reverse biased mode.
Dept. of EEE 9AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
The characteristics of a signal point contact diode are different for both germanium and
silicon types and are given as: Germanium Signal Diodes - These have a low reverse
resistance value giving a lower forward volt drop across the junction, typically only about
0.2-0.3v, but have a higher forward resistance value because of their small junction area.
Silicon Signal Diodes - These have a very high value of reverse resistance and give a forward
volt drop of about 0.6-0.7v across the junction. They have fairly low values of forward
resistance giving them high peak values of forward current and reverse voltage. Signal
Diodes are manufactured in a wide range of voltage and current ratings. There are
bewildering arrays of static characteristics associated with the humble signal diode but the
important ones are as follows; maximum forward current, peak inverse voltage and maximum
operating temperature. The diode characteristics are shown in Figure.
Dept. of EEE 10AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
5.3.IC LM324
An operational amplifier ("op-amp") is a DC-coupled high-gain electronic voltage amplifier
with a differential input and, usually, a single-ended output. An op-amp produces an output
voltage that is typically hundreds of thousands times larger than the voltage difference
between its input terminals.
5.4.Piezo Buzzer
A buzzer or beeper is an audio signaling device, which may be mechanical,
electromechanical, or Piezoelectric. Typical uses of buzzers and beepers include alarms,
timers and confirmation of user input such as a mouse click or keystroke
5.5.LED
A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in
many devices and are increasingly used for other lighting. Introduced as a practical electronic
component in 1962, early LEDs emitted low-intensity red light, but modern versions are
available across the visible, ultraviolet and infrared wavelengths, with very high brightness.
When a light-emitting diode is forward biased (switched on), electrons are able to
recombine with electron holes within the device, releasing energy in the form of photons.
This effect is called electroluminescence and the color of the light (corresponding to the
energy of the photon) is determined by the energy gap of the semiconductor. An LED is often Dept. of EEE 11
AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
small in area (less than 1 mm2), and integrated optical components may be used to shape its
radiation pattern.LEDs present many advantages over incandescent light sources including
lower energy consumption, longer lifetime, improved robustness, smaller size, faster
switching, and greater durability and reliability. LEDs powerful enough for room lighting are
relatively expensive and require more precise current and heat management than compact
fluorescent lamp sources of comparable output.
5.6.Capacitor
A capacitor (formerly known as condenser) is a device for storing electric charge. The forms
of practical capacitors vary widely, but all contain at least two conductors separated by a non-
conductor. Capacitors used as parts of electrical systems, for example, consist of metal foils
separated by a layer of insulating film.
A capacitor is a passive electronic component consisting of a pair of conductors
separated by a dielectric (insulator). When there is a potential difference (voltage) across the
conductors, a static electric field develops across the dielectric, causing positive charge to
collect on one plate and negative charge on the other plate. Energy is stored in the
electrostatic field. An ideal capacitor is characterized by a single constant value, capacitance,
measured in farads. This is the ratio of the electric charge on each conductor to the potential
difference between them.
Dept. of EEE 12AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
5.7.Zener Diode
A Zener diode is a type of diode that permits current not only in the forward direction
like a normal diode, but also in the reverse direction if the voltage is larger than the
breakdown voltage known as "Zener knee voltage" or "Zener voltage". The device was
named after Clarence Zener, who discovered this electrical property.
A conventional solid-state diode will not allow significant current if it is reverse-
biased below its reverse breakdown voltage. When the reverse bias breakdown voltage is
exceeded, a conventional diode is subject to high current due to avalanche breakdown. Unless
this current is limited by circuitry, the diode will be permanently damaged due to
overheating. In case of large forward bias (current in the direction of the arrow), the diode
exhibits a voltage drop due to its junction built-in voltage and internal resistance. The amount
of the voltage drop depends on the semiconductor material and the doping concentrations.
5.8.Resistor
A resistor is a two-terminal passive electronic component which implements electrical
resistance as a circuit element. When a voltage V is applied across the terminals of a resistor,
a current I will flow through the resistor in direct proportion to that voltage. This constant of
proportionality is called conductance, G. The reciprocal of the conductance is known as the
resistance R, since, with a given voltage V, a larger value of R further "resists" the flow of
current I as given by Ohm's law:
5.9.Fuse (2.5 AMP)
A fuse is a type of sacrificial overcurrent protection device. Its essential component is a
metal wire or strip that melts when too much current flows, which interrupts the circuit in
which it is connected. Short circuit, overload or device failure is often the reason for
excessive current.
Dept. of EEE 13AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
A fuse interrupts excessive current (blows) so that further damage by overheating or fire
is prevented. Wiring regulations often define a maximum fuse current rating for particular
circuits. Overcurrent protection devices are essential in electrical systems to limit threats to
human life and property damage. Fuses are selected to allow passage of normal current and of
excessive current only for short periods
5.10 Crocodile Clips
A crocodile clip (or spring clip) is a temporary electrical connector, named for its
resemblance to a crocodile's jaws. Functioning much like a spring-loaded clothespin, the
clip's two tapered, serrated jaws are forced together by a spring to make them grip a metal
object. One of the jaws usually has either a wire permanently attached or a 4 mm banana plug
inserted into it, for connection to an electrical circuit. The clip may be partly covered by a
plastic shroud or "boot" to prevent accidental short-circuits.
5.11. PCB
Printed circuit board, or PCB, is used to mechanically support and electrically connect
electronic components using conductive pathways, tracks or signal traces etched from copper
sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring
board (PWB) or etched wiring board. A PCB populated with electronic components is a
printed circuit assembly (PCA), also known as a printed circuit board assembly (PCBA).
Printed circuit boards are used in virtually all but the simplest commercially-produced
electronic devices.
PCBs are inexpensive, and can be highly reliable. They require much more layout
effort and higher initial cost than either wire wrap or point-to-point construction, but are
much cheaper and faster for high-volume production; the production and soldering of PCBs
can be done by totally automated equipment
Dept. of EEE 14AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
Chapter 6
WORKING
When the circuit is connected to the battery and push switch S2 is pressed (withS1
open), the battery voltage is sampled by the analyzer circuit. If the supply voltage sample
applied to the non-inverting input of an op-amp exceeds the reference voltage applied to the
inverting inputs, the output of the op-amp goes high and the LED connected at its output
Dept. of EEE 15AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
Lights up.
The different levels of battery voltages are indicated by LED1 through LED4. All the LEDs
remain lit when the battery is fully charged (above 12.5V). The buzzer connected to the
output of IC1 also sounds (when S2 is pressed with S1 kept open) as long as the voltage of
battery is above9.8V. If the voltage level goes below 9.8V, the buzzer goes off;this indicates
that it’s time to replace the battery. The status of LEDs for different battery voltages is shown
in the table.
The circuit can be assembled on a general- purpose PCB or a bred board. Use
4mmwire and crocodileclips to connect the charger to the battery. A 2.5-amp fuse connected
to the output of the charger protects the analyzer circuit against accidental polarity reversal.
Chapter 7
RESULT
The circuit presented here can replenish the charge in a battery within 6-8 hours. It
also has a voltage analyzing circuit for quick checking of voltage before start of charging,
since overcharging may damage the battery. The voltage analyzer gives an audio-visual
Dept. of EEE 16AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
indication of the battery voltage level and also warns about the critical voltage level at which
the battery requires immediate charging.
The status of LEDs for different battery voltages is shown in the table.
Chapter 8
CONCLUSION
We were able to accomplish our main goal, and that is design a working prototype for a 12V
lead-acid battery.
Dept. of EEE 17AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
In this project we have learned more than just how to make a simple universal battery
charger and drawing upon our EE knowledge from our previous classes. We experienced our
first taste of design and major project management. Along with these specific skills, we also
improved our time management and team work skills. Throughour design project we
experience many success and failures in the process, and have had to make a lot of important
design decisions. With more time we could have taken our rough design and brought it to
usable standalone charger.
BIBILOGRAPHY
1. RV owners’ forum:
Dept. of EEE 18AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
http://www.trailerlife.com/cforum/index.cfm/fuseaction/thread/tid/683429/gotomsg/683780. cfm
2. Boaters World: www.boatersworld.com
3. Battery Stuff.com: http://www.4unique.com/battery/soneil/soneil-12v2-5a.htm
4. PCB Pro.com: http://www.pcbpro.com
5. Powerstream.com: www.powerstream.com/PV-Control.htm
6. Datasheetwww.datasheet.in
Dept. of EEE 19AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
ANNEXURE
CONTENTS
Dept. of EEE 20AWH Engg. College
Lead acid battery charger with voltage analyzerr Mini project 2011
Introduction 1
Block Diagram 2
Circuit Diagram 3
Components used 6
Component Description 7
Working 13
Result 14
Conclusion 15
Bibliography 16
Annexure ` 17
Dept. of EEE 21AWH Engg. College