ANNA UNIVERSITY

COIMBATORE
PIEZOELECTRIC CHARGER
A PROJECT REPORT

SUBMITTED BY

MAHIN K.S Reg No. 070106502016

NIDHIN MOHAN Reg No. 070106502021
PARVON P.R Reg No. 070106502022
SREENIVASAN.G Reg No. 070106502029
In Partial fulfillment for the award of the degree
Of
BATCHELOR OF ENGINEERING
IN

ELECTRICAL AND ELECTRONICS ENGINEERING

Er.PERUMAL MANIMEKALAI COLLEGE OF ENGINEERING

HOSUR-635117

ANNA UNIVERSITY COIMBATORE-641047

OCTOBER 2010
 ANNA UNIVERSITY: COIMBATORE-641047
OCTOBER 2010
Er.PERUMAL MANIMEKALAI COLLEGE OF ENGINEERING
HOSUR

BONAFIDE CERTIFICATE
Certified that this project report PIEZOELECTRIC CHARGER
is the bonafide work done by
MAHIN K.S Reg No. 070106502016

NIDHIN MOHAN Reg No. 070106502021

PARVON P.R Reg No. 070106502022

SREENIVASAN.G Reg No. 070106502029

of the final year ELECTRICAL AND ELECTRONICS ENGINEERING 2010-

2011. This is submitted in the partial fulfillment for the award of the degree of
BACHELOR OF ENGINEERING, ANNA UNIVERSITY, COIMBATORE.
Who carried out the project work under my supervision.

HEAD OF DEPARTMENT PROJECT GUIDE

Mr. K. UMESHA M.E, (PhD), Mr. T MANJUNATH. M.E,

DEPARTMENT OF EEE, DEPARTMENT OF EEE,

PMC TECH, PMC TECH,

HOSUR HOSUR

Submitted for the viva-voice held on at Er.Perumal

Manimekalai college of Engineering, Hosur.

INTERNAL EXAMINER EXTERNAL EXAMINER

 ACKNOWLEDGEMENT

We are grateful to the ALMIGHTY who helped us in all

the ways throughout the project and who has molded us into what we are today.

We are extremely grateful to the Honorable chairman,

honorable secretary and honorable trustee and beloved principal

Dr.C.GAJENDRAN M.E.,Ph.D of Er.Perumal Manimekalai College Of

Engineering, Hosur for providing all the necessary facilities in the college for

the successful completion of this project.

We express our sincere gratitude to our project guide HOD

Mr.K.UMESHA M.E.,Ph.D, Er. Perumal Manimekalai College Of

Engineering.

We are thankful to Mrs.R.CHANDRALEKHA M.E, co-

ordinator, Department of EEE, Er. Perumal Manimekalai College Of

Engineering, Hosur for his constructive suggestion and guidance in this

endeavor.

We are thankful to Mr.T.MANJUNATH M.E, Department

of EEE, Er. Perumal Manimekalai College Of Engineering, Hosur for his

constructive suggestion and guidance in this endeavor. We extend our thanks

also to the teaching staff, which helped us in completing our project.

 ABSTRACT

Piezoelectric effect is one of the reversible process

and charge which accumulates in certain solid materials in response to applied

mechanical strain. Piezoelectricity is the direct result of the piezoelectric effect.

When the mechanical force applied to the

piezoelectric ceramic crystal vertically an electric charge will be produced in

horizontal sides

We fix the piezoelectric ceramic crystal in between foot and footwear. When we

walk, mechanical force applied to the crystal, hence piezoelectricity produced.

The produced electricity is direct current. So, we can store it and can use

whenever.
 INDEX

1. INTRODUCTION

2. BLOCK DIAGRAM

3. CIRCUIT DIAGRAM

4. PIEZOELECTRICITY

5. MECHANISM

6. CRYSTAL CLASSES

7. MATERIALS

8. ACTUCTORS

9. SENSOR DESIGN

10. PIEZOELECTRIC CRYSTAL

11. CHARGABLE BATTERY UNIT

i. APPLICATION

ii. VOLTAGE

iii. BATTERY CHARACTERISTICS

iv. ADVANTAGES

v. DISADVANTAGES

vi. AVAILABITY

vii. CHARACTERISTICS

viii. CHARGING

ix. CHARGE CONDITION

x. CHARGING METHOD

xi. PROBLEM WITH NI-Cd

12. TESTING AND RESULT

13. ADVANTAGES

14. APPLICATION

15. FURURE EXPANSION

16. CONCLUSION

17. BIBLIOGRAPHY
 INTRODUCTION

Now a days Energy saving is one of the most important thing.

Since conventional energy sources will not be available for a long time. So we

have to find and develop new energy sources. The energy sources, which are

going to find should be very cheap.

The aim of this project is to find an energy source, which should be

available in an easy way.

By using piezoelectric effect, we can develop an energy source.

And by using this energy piezoelectric charger can be done.

Piezoelectricity is the charge which accumulates in certain solid

materials in response to applied mechanical strain.

 BLOCK DIAGRAM

MECHANICAL
FORCE

PIEZO ELECTRIC CHARGABLE

CRYSTAL BATTERY UNIT
LOAD

MECHANICAL
FORCE
CIRCUIT DIAGRAM
 PIEZOELECTRICITY

Piezoelectricity is the charge which accumulates in certain

solid materials (notably crystals, certain ceramics, and biological matter such

as bone, DNA and various proteins) in response to applied mechanical strain.

The word piezoelectricity means electricity resulting from pressure. It is derived

from the Greek piezo or piezein , which means to squeeze or press, and electric

or electron , which stands for amber an ancient source of electric charge.

Piezoelectricity is the direct result of the piezoelectric effect.

The piezoelectric effect is understood as the linear

electromechanical interaction between the mechanical and the electrical state in

crystalline materials with no inversion symmetry. The piezoelectric effect is a

reversible process in that materials exhibiting the direct piezoelectric effect (the

internal generation of electrical charge resulting from an applied mechanical

force) also exhibit the reverse piezoelectric effect (the internal generation of a

mechanical force resulting from an applied electrical field). For example,lead

zirconate titanate crystals will generate measurable piezoelectricity when their

static structure is deformed by about 0.1% of the original dimension.

Conversely, lead zirconate titanate crystals will change about 0.1% of their

static dimension when an external electric field is applied to the material.

Piezoelectricity is found in useful applications such as the

production and detection of sound, generation of high voltages, electronic

frequency generation, microbalances, and ultra fine focusing of optical

assemblies. It is also the basis of a number of scientific instrumental techniques

with atomic resolution, the scanning probe microscopes such as STM, AFM,

MTA, SNOM, etc., and everyday uses such as acting as the ignition source for

cigarette lighters and push-start propane barbecues.

 MECHANISM

The nature of the piezoelectric effect is closely related

to the occurrence of electric dipole moments in solids. The latter may either be

induced for ions on crystal lattice sites with asymmetric charge surroundings (as

in BaTiO3 and PZTs) or may directly be carried by molecular groups (as in cane

sugar).

The dipole density or polarization (dimensionality

[Cm/m3]) may easily be calculated for crystals by

summing up the dipole moments per volume of the crystallographic unit cell.

As every dipole is a vector, the dipole density P is also a vector or a directed

quantity. Dipoles near each other tend to be aligned in regions called Weiss

domains.

The domains are usually randomly oriented, but can

be aligned during poling (not the same as magnetic poling), a process by which

a strong electric field is applied across the material, usually at elevated

temperatures of decisive importance for the piezoelectric effect is the change of

polarization P when applying a mechanical stress.

This might either be caused by a re-configuration of

the dipole-inducing surrounding or by re-orientation of molecular dipole

moments under the influence of the external stress. Piezoelectricity may then

manifest in a variation of the polarization strength, its direction or both,

with the details depending on ,

v The orientation of P within the crystal ,

v crystal symmetry

v The applied mechanical stress.

The change in P appears as a variation of surface charge

density upon the crystal faces, i.e. as a variation of the electrical field extending

between the faces, since the units of surface charge density and polarization are

the same, C/m2] = [Cm/m3]. However, piezoelectricity is not caused by a change

in charge density on the surface, but by dipole density in the bulk. For example,
a 1 cm3 cube of quartz with 2 kN (500 lbf) of correctly applied force can

produce a voltage of 12500 V.

Piezoelectric materials also show the opposite effect, called

converse piezoelectric effect, where the application of an electrical field

creates mechanical deformation in the crystal.

 CRYSTAL CLASSES

Any spatially separated charge will result in an electric field,

and therefore an electric potential. Shown here is a standard dielectric in a

capacitor. In a piezoelectric device, mechanical stress, instead of an externally

applied voltage, causes the charge separation in the individual atoms of the

material, .

Of the thirty-two crystal classes, twenty-one are non-centre

symmetric (not having a centre of symmetry), and of these, twenty exhibit direct

piezoelectricity (the 21st is the cubic class

432). Ten of these represent the polar crystal classes, which show a spontaneous

polarization without mechanical stress due to a non-vanishing electric dipole

moment associated with their unit cell, and which exhibit piezoelectricity. If the
dipole moment can be reversed by the application of an electric field, the

material is said to be ferroelectric.

v Polar crystal classes: 1, 2, m, mm2, 4, 4 mm, 3, 3m, 6, 6 mm.

v Piezoelectric crystal classes: 1, 2, m, 222, mm2, 4, 4, 422, 4 mm,

42m, 3, 32, 3m, 6, 6, 622, 6 mm, 62m, 23, 43m.

For polar crystals, for which P 0 holds without applying a

mechanical load, the piezoelectric effect manifests itself by changing the

magnitude or the direction of P or both.

For the non-polar, but piezoelectric crystals, on the other hand, a

polarization P different from zero is only elicited by applying a mechanical

load. For them the stress can be imagined to transform the material from a non-

polar crystal class (P =0) to a polar one, having P 0.

 MATERIALS

Many materials, both natural and man-made, exhibit piezoelectricity:

Naturally-occurring crystals:

Berlinite (AlPO4), a rare phosphate mineral that is structurally identical to

quartz

Cane sugar

Quartz

Rochelle salt

Topaz

Tourmaline-group minerals

Other natural materials:

Bone

Tendon

Silk

Wood due to piezoelectric texture

Enamel

Man-made crystals:

Gallium orthophosphate (GaPO4), a quartz analogic crystal

Langasite (La3Ga5SiO14), a quartz analogic crystal

Man-made ceramics:

Tetragonal unit cell of lead titanate

The family of ceramics with perovskite or tungsten-bronze structures exhibits

piezoelectricity:

Barium titanate (BaTiO3)Barium titanate was the first piezoelectric

ceramic discovered.

Lead titanate (PbTiO3)

Lead zirconate titanate (Pb[ZrxTi1x]O3 0<x<1)more commonly known

as PZT, lead zirconate titanate is the most common piezoelectric ceramic

in use today.

Potassium niobate (KNbO3)

Lithium niobate (LiNbO3)

Lithium tantalate (LiTaO3)

Sodium tungstate (Na2WO3)

Ba2NaNb5O5

Pb2KNb5O15
Lead-free piezoceramics:

More recently, there is growing concern regarding the

toxicity in lead-containing devices driven by the result of restriction of

hazardous substances directive regulations.

To address this concern, there has been a resurgence in the

compositional development of lead-free piezoelectric materials.

Sodium potassium niobate (NaKNb). In 2004, a group of Japanese

researchers led by Yasuyoshi Saito discovered a sodium potassium

niobate composition with properties close to those of PZT, including a

high TC.

Bismuth ferrite (BiFeO3) is also a promising candidate for the

replacement of lead-based ceramics.

Sodium niobate NaNbO3

So far, neither the environmental impact nor the stability of supplying these

substances has been confirmed.

 ACTUATORS

Metal disk with piezoelectric disk attached, used in a buzzer

Amplified piezoelectric actuator with multilayer ceramic

As very high electric fields correspond to only tiny changes

in the width of the crystal, this width can be changed with better-than-

micrometer precision, making piezo crystals the most important tool for

positioning objects with extreme accuracy thus their use in actuators.

Multilayer
ceramics, using layers thinner than 100 microns, allow reaching high electric

fields with voltage lower than 150 V.

These ceramics are used within two kinds of actuators:

direct piezo actuators and Amplified Piezoelectric Actuators. While direct

actuator's stroke is generally lower than 100 microns, amplified piezo actuators

can reach millimeter strokes.

SENSOR DESIGN
 PIEZOELECTRIC CRYSTALS

Piezoelectric crystals are one of many small scale

energy sources. Whenever piezoelectric crystals are mechanically deformed or

subject to vibration they generate a small voltage, commonly know as

piezoelectricity. This form of renewable energy is not ideally suited to an

industrial situation.

The ability of certain crystals to generate Piezoelectricity

in response to applied mechanical stress is reversible in that piezoelectric

crystals, when subjected to an externally applied voltage, can change shape by a

small amount. This deformation, though only nanometres, has useful

applications such as the production and detection of sound.

Probably the best-known use of piezoelectric crystals is

in the electric cigarette lighter. Here, pressing the button causes a spring-loaded

hammer to hit a piezoelectric crystal, the high voltage produced by this ignites

the gas as the current jumps over a small spark gap. This technique also applies

to some gas lighters used on gas grills or stoves.

Another common usage of a piezoelectric crystal energy

source is that of creating a small motor; such as that used in a reflex camera to

operate the auto focus system. These motors operate by vibration. The two

surfaces
are forced to vibrate at a phase shift of 90 degrees by a sine wave that has been

generated at the motors resonant frequency. This forces a frictional force where

the two surfaces meet and as one of the surfaces is fixed the other is forced to

move.

It has been found that piezoelectric crystals that have

been embedded in the sole of a shoe can yield a small amount of energy with

each step.
 CHARGABLE BATTERY UNIT

Nickel-cadmium :

From top to bottom "Gumstick", AA, and

AAA NiCd batteries.

specific energy 4060 Wh/kg

energy density 50150 Wh/L

specific power 150W/kg

Charge/discharge efficiency 70%90%

Energy/consumer-price ? US$ per Wh

Self-discharge rate 10%/month

Cycle durability 2,000 cycles

Nominal cell voltage 1.2 V

Disassembled Ni-Cd battery from cordless drill.

1: Outer metal casing (also negative terminal)

2: Separator (between electrodes)

3: Positive electrode

4: Negative electrode with current collector Everything is rolled. .

Applications:

Sealed NiCd cells may be used individually, or assembled

into battery packs containing two or more cells. Small NiCd dry cells are used

for portable electronics and toys, often using cells manufactured in the same

sizes as primary cells. When NiCds are substituted for primary cells, the lower

terminal voltage and smaller ampere-hour capacity may reduce performance as

compared to primary cells.

 Miniature button cells are sometimes used in photographic

equipment, hand-held lamps (flashlight or torch), computer-memory standby,

toys, and novelties.

Specialty NiCd batteries are used in cordless and wireless

telephones, emergency lighting, and other applications. With a relatively low

internal resistance, a NiCd battery can supply high surge currents. This makes

them a favorable choice for remote-controlled electric model airplanes, boats,

and cars, as well as cordless power tools and camera flash units. Larger flooded

cells are used for aircraft starting batteries, electric vehicles, and standby power.

Voltage:

Nickel-cadmium cells have a nominal cell potential of 1.2 V. This

is lower than the 1.5 V of alkaline and zinc-carbon primary cells, and

consequently they are not appropriate as a replacement in all applications.

However, the 1.5V of a primary alkaline cell refers to its initial, rather than

average, voltage. Unlike alkaline and zinc-carbon primary cells, a NiCd cell's

terminal voltage only changes a little as it discharges. Because many electronic

devices are designed to work with primary cells that may discharge to as low as

0.90 to 1.0 V per cell, the relatively steady 1.2 V of a NiCd is enough to allow

operation. Some would consider the near-constant voltage a drawback as it

makes it difficult to detect when the battery charge is low.

NiCd batteries used to replace 9 V batteries usually only have

six cells, for a terminal voltage of 7.2 volts. While most pocket radios will
operate satisfactorily at this voltage, some manufacturers such as Varta made

8.4 volt batteries with seven cells for more critical applications.

12 V NiCd batteries are made up of 10 cells connected in series.

 BATTERY CHARACTERISTICS

Comparison to other batteries:

Recently, nickel-metal hydride (Ni-MH) and lithium-ion

batteries (Li-ion) have become commercially available and cheaper, the former

type now rivaling NiCd in cost. Where energy density is important, Ni-Cd

batteries are now at a disadvantage compared to Ni-MH and Li-ion batteries.

However, the Ni-Cd battery is still very useful in applications requiring very

high discharge rates because the Ni-Cd can endure such discharge with no

damage or loss of capacity, though recharging it without complete drain can

have somewhat of the opposite effect.

Advantages:

When compared to other forms of rechargeable battery, the NiCd

battery has a number of distinct advantages.

The batteries are more difficult to damage than other batteries, tolerating

deep discharge for long periods. In fact, NiCd batteries

in long-term storage are typically stored fully discharged. This is in

contrast, for example, to lithium ion batteries, which are less stable and

will be permanently damaged if discharged below a minimum voltage.

 NiCd batteries typically last longer, in terms of number of

charge/discharge cycles, than other rechargeable batteries such as

lead/acid batteries.

Compared to lead-acid batteries, NiCd batteries have a much higher

energy density. A NiCd battery is smaller and lighter than a comparable

lead-acid battery. In cases where size and weight are important

considerations (for example, aircraft), NiCd batteries are preferred over

the cheaper lead-acid batteries.

In consumer applications, NiCd batteries compete directly with alkaline

batteries. A NiCd cell has a lower capacity than that of an equivalent

alkaline cell, and costs more. However, since the alkaline battery's

chemical reaction is not reversible, a reusable NiCd battery has a

significantly longer total lifetime. There have been attempts to create

rechargeable alkaline batteries, such as the rechargeable alkaline, or

specialized battery chargers for charging single-use alkaline batteries, but

none that has seen wide usage.

The terminal voltage of a NiCd battery declines more slowly as it is

discharged, compared with carbon-zinc batteries. Since an alkaline

battery's

voltage drops significantly as the charge drops, most consumer

applications are well equipped to deal with the slightly lower NiCd

voltage with no noticeable loss of performance.

 Nickel-metal hydride (NiMH) batteries are the newest, and most similar,

competitor to NiCd batteries. Compared to NiCd, NiMH batteries have a

higher capacity and are less toxic, and are now more cost effective.

However, a NiCd battery has a lower self-discharge rate (for example,

20% per month for a NiCd, versus 30% per month for a traditional NiMH

under identical conditions), although low self-discharge NiMH batteries

are now available, which have substantially lower self-discharge than

either NiCd or traditional NiMH.

This results in a preference for NiCd over NiMH in applications where

the current draw on the battery is lower than the battery's own self-

discharge rate (for example, television remote controls). In both types of

cell, the self-discharge rate is highest for a full charge state and drops off

somewhat for lower charge states. Finally, a similarly sized NiCd battery

has a slightly lower internal resistance, and thus can achieve a higher

maximum discharge rate (which can be important for applications such as

power tools).

Disadvantages:

The primary trade-off with NiCd batteries is their higher cost and the

use of cadmium. They are more costly than lead-acid batteries because nickel

and cadmium are more costly materials.

 One of the NiCd's biggest disadvantages is that the battery exhibits a

very marked negative temperature coefficient. This means that as the cell

temperature rises, the internal resistance falls. This can pose considerable

charging problems, particularly with the relatively simple charging systems

employed for lead-acid type batteries.

Whilst lead-acid batteries can be charged by simply connecting a

dynamo to them, with a simple electromagnetic cut-out system for when the

dynamo is stationary or an over-current occurs, the NiCd under a similar

charging scheme would exhibit thermal runaway, where the charging current

would continue to rise until the over-current cut-out operated or the battery

destroyed itself.

This is the principal factor that prevents its use as engine-starting

batteries. Today with alternator-based charging systems with solid-state

regulators, the construction of a suitable charging system would be relatively

simple, but the car manufacturers are reluctant to abandon tried-and-tested

technology.

Availability:

NiCd cells are available in the same sizes as alkaline batteries, from

AAA through D, as well as several multi-cell sizes, including the equivalent of

a 9 volt battery. A fully charged single NiCd cell, under no load, carries a
potential difference of between 1.25 and 1.35 volts, which stays relatively

constant as the battery is discharged. Since an alkaline battery near fully

discharged may see its voltage drop to as low as 0.9 volts, NiCd cells and

alkaline cells are typically interchangeable for most applications.

In addition to single cells, batteries exist that contain up to 300 cells

(nominally 360 volts, actual voltage under no load between 380 and 420 volts).

This many cells are mostly used in automotive and heavy-duty

industrial applications. For portable applications, the number of cells is

normally below 18 cells (24V). Industrial-sized flooded batteries are available

with capacities ranging from 12.5Ah up to several hundred Ah.

Characteristics:

The maximum discharge rate for a NiCd battery varies by size.

For a common AA-size cell, the maximum discharge rate is approximately 18

amps; for a D size battery the discharge rate can be as high as 35 amps.

Model-aircraft or -boat builders often take much larger

currents of up to a hundred amps or so from specially constructed small

batteries, which are used to drive main motors. 56 minutes of model operation

is easily achievable from quite small batteries, so a reasonably high power-to-

weight figure is achieved, comparable to internal combustion motors, though of

lesser duration.

Charging:
 NiCd batteries can be charged at several different rates,

depending on how the cell was manufactured. The charge rate is measured

based on the percentage of the amp-hour capacity the battery is fed as a steady

current over the duration of the charge. Regardless of the charge speed, more

energy must be supplied to the battery than its actual capacity, to account for

energy loss during charging, with faster charges being more efficient.

For example, the typical overnight charge, called a C/10 (or

0.1C) charge, is accomplished by applying 10% of the battery's total capacity

for a period of 1416 hours; that is, a 100 mAh battery takes 140 mAh of

energy to charge at this rate. At the rapid-charge rate, done at 100% of the rated

capacity of the battery in 1 hour (1C), the battery holds roughly 80% of the

charge, so a 100 mAh battery takes 120 mAh of energy to charge (that is,

approximately 1 hour and fifteen minutes).

Some specialized NiCd cells are capable of being charged

in as little as 1015 minutes at a 4C or 6C charge rate, but this is very

uncommon. It also exponentially increases the risk of the cells overheating and

venting due to an internal overpressure condition: the cell's rate of temperature

rise is governed by its internal resistance and the square of the charging rate.

Thus, at a 4C rate, the amount of power entering the cell is

sixteen times higher than the power at the 1C rate. The downside to faster

charging is the higher risk of overcharging, which can damage the battery.[3] and
the increased temperatures the cell has to endure (which potentially shortens its

life).

The safe temperature range for a NiCd battery in use is

between 20C and 45C. During charging, the battery temperature typically

stays low, around 0C (the charging reaction absorbs heat), but as the battery

nears full charge the temperature will rise to 4550C. Some battery chargers

detect this temperature increase to cut off charging and prevent over-charging.

When not under load or charge, a NiCd battery will self-

discharge approximately 10% per month at 20C, ranging up to 20% per month

at higher temperatures. It is possible to perform a trickle charge at current levels

just high enough to offset this discharge rate; to keep a battery fully charged.

However, if the battery is going to be stored unused for a long period of time, it

should be discharged down to at most 40% of capacity (some manufacturers

recommend fully discharging and even short-circuiting once fully discharged),

and stored in a cool, dry environment.

Charge condition:

High quality NiCds has a thermal cut-off so if the battery gets

too hot the charger stops. If a NiCd is still warm from discharging and been put

on charge, it will not get the full charge possible. In that case, let the battery

cool to room temperature, then charge. Watch for the correct polarity. Leave

charger in a cool place when charging to get best results.

Charging method:
A NiCd battery requires a charger with a slightly different

voltage than for a lead-acid battery, especially if the NiCd has 11 or 12 cells.

Also a charge termination method is needed if a fast charger is used. Often

NiCd battery packs have a thermal cut-off inside that feeds back to the charger

telling it to stop the charging once the battery has heated up and/or a voltage

peaking sensing circuit. At room temperature during normal charge conditions

the cell voltage increases from an initial 1.2 V to an end-point of about 1.45
 PROBLEMS WITH Ni-Cd

Over charging:

Over charging must be considered in the design of most

rechargeable batteries. In the case of NiCds, there are two possible results of

overcharging:

If the negative electrode is overcharged, hydrogen gas is produced.

If the positive electrode is overcharged, oxygen gas is produced.

For this reason, the anode (negative) is always designed for a

higher capacity than the cathode, to avoid releasing hydrogen gas. There is still

the problem of eliminating oxygen gas, to avoid rupture of the cell casing.

NiCd cells are vented, with seals that fail at high internal

gas pressures. The sealing mechanism must allow gas to escape from inside the

cell, and seal again properly when the gas is expelled. This complex

mechanism, unnecessary in alkaline batteries, contributes to their higher cost.

NiCd cells dealt with in this article are of the sealed type

(see also vented type). Cells of this type consist of a pressure vessel that is

supposed to contain any generation of oxygen and hydrogen gasses until they

can recombine back to water. Such generation typically occurs during rapid

charge and discharge and exceedingly at overcharge condition. If the pressure

exceeds the limit of the safety valve, water in the form of gas is lost. Since the
vessel is designed to contain an exact amount of electrolyte this loss will rapidly

affect the capacity of the cell and its ability to receive and deliver current.

To detect all conditions of overcharge demands great

sophistication from the charging circuit and a cheap charger will eventually

damage even the best quality cells.

Environmental consequences of cadmium:

NiCd batteries contain between 6% (for industrial

batteries) and 18% (for consumer batteries) cadmium, which is a toxic heavy

metal and therefore requires special care during battery disposal. In the United

States, part of the price of a NiCd battery is a fee for its proper disposal at the

end of its service lifetime. Under the so-called "batteries directive"

(2006/66/EC), the sale of consumer nickel-cadmium batteries has now been

banned within the European Union except for medical use; alarm systems;

emergency lighting; and portable power tools.

This last category is to be reviewed after 4 years. Under the

same EU directive, used industrial nickel-cadmium batteries must be collected

by they producers in order to be recycled in dedicated facilities.

 TESTING AND RESULTS

v Output voltage per crystal : 1-2 volts

v Output current per crystal : 0.1-0.5 mA

Case 1:

When we connect in series manner, voltage will be added.current will be

constant

Case 2:

When we connect in parallel manner, current will be added.voltage will be

constant

Case 3:

In both case power should be added.

 ADVANTAGES

1. Easy to develop

2. Less circuit complexities

3. Less cost

4. Portable

5. Less weight

6. Small size
 APPLICATIONS

1. Street light charger

2. Mobile phone charger.

3. Torch charger

4. Military applications (wire fewer chargers)

5. Used in trickle charging

 FUTURE EXPANSION

POWER WALKIG

Build a device that lets you charge batteries for

your +Input , -Input

Nooooo!!!! Youre out walking, and your mp3 player dies! Peter Pachoumis

You're halfway through listening to "Layla" when it happens:

Your MP3 player's battery dies. Normally you'd

have to wait until you were at your computer to finish rocking out, but there is

an easy and eco-friendly way to do it on the go. First, slip a piezoelectric

transducer -- a device that generates a tiny charge when touched -- into your

shoe. A connected module collects the voltage created every time you take a
step and continuously powers up a rechargeable AA battery. (It takes a lot of

walking to get a full charge, but it's perfect for reviving or topping off a gadget.)

Once the battery is charged, put it into a DIY five-volt converter, and plug in

your dead MP3 player. Now you can listen to the guitar solo while you walk

some more juice into another batter.

Walk Your Way to a Charged-Up Gadget

Luckily, you have a fresh AA battery in your shoe charger:

Pop it into the converter box, plug into the MP3 player...: Peter Pachoumis
... and enjoy your tunes as you walk off into the sunset: Peter Pachoumis
 CONCLUSION

Our project PIEZOELECTRIC CHARGER deals with

piezoelectric effect and piezoelectricity. The energy produced due to

piezoelectric effect can be used for charging battery. In other words

piezoelectricity is an energy source.

In future, piezoelectricity and usage of piezoelectric charger

will be introduced for efficient charging purposes.

Our observations are going on this field for a better usage of

piezoelectricity.
 BIBLIOGRAPHY

v Wikipedia.org

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