Cell n Battery

8/8/2019 Cell n Battery

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CellA cell is a device which converts chemical energy into electrical energy and when two or more cells are connected in

,series that cell becomes b a t t e r y . :There are two types of cells Primary and SecondaryPrimary

A primary cell which produces electrical energy and after few hours of working becomes inactive is called

.primary cell These cells , . ,are generally we used in torch radio etc Basic primary cells are Voltaic Cell Daniel, , .Cell Lechlanch Cell Dry Cell etc

SecondaryA secondary cell which is used repeatedly to produce electrical energy after charging it is called.secondary cell These cells are , , .generally we used in mobile ups inverter etc Basic secondary cells are Lead Acid

, . .Cell Edison Cell Nickel Cadmium Cell etc

Primarily a el l ( - , + )is c onstructed b y using m etals Zinc @ ve c harge Copper @ ve c harge and(electrolyte solution H2SO 4 ). Metal is in the form of rod or plate structure and H2SO4 + H2 (O Water is used for)sulphuric acid dilution acts as electrolyte used for .chemical reaction

Bulb

Zinc Rod

( )ZnH2SO4

Vessel

Copper Rod( )Cu

- +

In electrochemical reaction + ve terminal is called a n o d e- ve terminal is called c a t h o d e


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orking

The glass vessel contains H2SO4, as we insert Zinc Rod init due to chemical reaction H y d r o g e ngas bubbles.form around it The :reaction is as

.a The H2SO4 :break into three ions two H+ ( )Hydrogen ions and one SO4-- ( ) .Sulfate ion

a.

H2SO4 2H+ + SO4- -

.b At the same moment Zinc loses 2e-to become Zn++ .ions

Zn Zn++ + 2e

.c Then this Zn++ions combine with the SO4--ion to form ZnSO4 ( )Zinc Sulfate which dissolves in the

.acid

Zn++ + SO4 - - ZnSO4

.d The electrons from the Zinc Rod combine with the hydrogen ions to form H2 (molecules Hydrogen)Gas in the form .of bubbles on the zinc rod

2H+ + 2e H2

, -In this way e flow from Copper Rod to Zinc Rod inside the vessel and Zinc Rod to Copper Rod outside the.vessel The EMF of the . .cell is around 1 08 Volts This is o lt ai c C el linvented in 1800 by l es sa nd ro V ol ta .


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an ie l C el l

The worlds first useful cell developed by .ro f Da n ie l .in 1836 The working and:construction is as followsCopper Rod

Porous Pot

CuSO4CrystalH2SO4

Zinc RodCuSO4

Vessel

.1 Copper vessel contains CuSO4 .solution

.2 Upper part has a chamber filled with CuSO4 ,crystals help for.immunity in the solution

.3 .A porous pot is kept into copper vessel with zinc rod

.4 Copper rod acts as a n o d eand Zinc rod acts as c a t h o d e .

.a The H2SO4 :break into three ions two H+ ( )Hydrogen ions and one SO4-- ( ) .Sulfate ion

a.H2SO4 2H+ + SO4- -


Zn Zn++ + 2e

.c Then this Zn++ ions combine with the SO4-- ion to form ZnSO4 ( )Zinc Sulfate which dissolves in.the acid

Zn++ + SO4 - - ZnSO4

.d :The CuSO4 breaks into two ions one Cu++and one SO4 - -

CuSO4 Cu++ + SO4 - -

.e ++At the same moment Cu combines with liberated 2e

Cu++ + 2e Cu

.This cell can produce up to 1 1 Volts


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echlanch Cell ry Cell

Carbon Rod

PorousVesselMnO2Powder

NH4Cl

Zinc Rod

Glass Vessel

Seal

Carbon Rod

Coarse Cloth

Bag Power MixtureZinc Pot

Paste

Vent

=Power Mix MnO2 + +C NH4 +CLZnCl2

=Paste NH4 +Cl ZnCl2 + Plaster

of ParisA glass vessel filled with NH4 .Cl A zinc rod is immersed.into glass vessel A porcelain pot with carbon rod and

MnO2 .power is placed into glass vessel

.Carbon road acts as anode and zinc road acts as cathode

.It is modification of Lechlanch cell It has paste in.place of electrolyte solution Due to this type of

, .construction we can place it in any position

It has zinc pot filled with paste of NH4 ,Cl ZnCl2 and.Plaster of Paris The Plaster of Paris provide toughness

.to the paste Then a carbon rod with brass cap is

immersed into coarse cloth bag filled with power mixtureof MnO2, ,Carbon NH4 Cl and ZnCl2 : :in the ratio of 10 10: . .2 1 This mixture acts as electrolyte Coarse bas is

.placed into zinc pot

This cell is then sealed and a small hole is made in the.top cover for gas escape

/ . .The O P voltage is of 1 5 Volts


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:Chemical reaction of Lechlanch Cell and Dry Cell is as follows

.a :NH4Cl brake into two ions One NH4+and One Cl-

NH4Cl NH4+ + Cl-


Zn Zn++ + 2e

.c ++Then Zn combines with two Cl-inos

Zn++ + 2Cl- ZnCl2

.d 2NH4 + 2e 2NH3 + H2

H2 + 2MnO2 Mn2O3 + H2O

2Mn2O3 + O2 4MnO2


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ead Acid Cell- .Generally there are two types of lead acid batteries on the basis of their construction method These are either

. - ,Flooded or Sealed All lead acid batteries produce hydrogen and oxygen gas during charging that is called.electrolysis These gases are allowed to escape through vent however in the sealed cell gases are recombined but if

.gas pressure is high internal valve regulates its pressure

lo od ed l ea d a ci d ba tt e ri e s .are those where the electrodes called plates are immersed in electrolyteDuring the charging , ,process gas form which is vented to the atmosphere distilled water must be added to manage

.the electrolyte level

. .e g - .12 V automobile battery

ea le d l ea d a ci d b at te r ie s ,confine the electrolyte but have a vent or valve to allow gases escape ifpressure exceeds a certain . , -level During charging a lead acid battery generates oxygen gas at the positive.electrode These batteries are designed in such .way that generated gas is captured and recombined in the battery The

-valve regulated battery is the most common type of sealed .battery These batteries are developed for less.maintenance practice So it is called a in te na nc e f re e .batteries

. .e g UPS battery

Construction. . +It consists of hard rubber container There are two types of plates in the group One is ve plate group

and another is ve plate . + . +group ve plates are one more plate than ve plate Due to this each ve plate from.both the side remain active These plates are in the form of m e s h .and that mesh is of lead In the mesh e ad l ea d

.is deposited To support these plates hard rubber . + ,blocks are used For ve and ve plate separation hard rubber.or wood is used Diluted H2SO4 . +is used as electrolyte These ve and ve plate groups are connected to terminals

+ +outside the battery marked as P and N or ve and ve or red color for ve and .black color for ve There is a.vent on the top of the cover


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-Vent Plug

Hard RubberContainer

- Ve Plate

Diluted H2SO4

Separator

Rest

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- +


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Chemistry

- ,Generally in the lead acid cell the negative electrode is made by ( )e ad P b and the positive electrode is made by( )ea d pe r ox id e Pb 0 2 . These electrodes or say plates are deposited into i lu te d H 2SO 4 ( H 2S O 4 + H 2 ) . There.are two processes to be occurred discharge and charge

( )Discharging is the process of providing energy current to the load and charging is the process of providing.current to the battery for to come back to original state

ur in g t he di sc har ge p roc es s +At ve electrode PbO2 + H2SO4 PbSO4 + H2O-At ve electrode +Pb H2SO4 PbSO 4 + 2H+

,After all the sulfuric acid exhausted only electrodes and water is present which has no more. ,capacity to provide the charge for load In this state the cell is said to be fully

. -discharged In a lead , (acid cell the charge is determined by acid strength H2SO4 ). This strength iseasily checked by a device called a y d r o m e t e r ( )which measures the specific gravity density of the

.electrolyte

uring the charging process +At ve electrode PbSO4 + H2 +O O- - PbO 2 +H2SO4

-At ve electrode PbSO4 + 2H+ +Pb H2SO4

. ,If the EMF of the cell has reduced upto 1 8 Volts due to the regular use it is required to.recharge it . .For this process DC power supply is connected to battery according to the polarity i e

+ +ve to ve . ,and ve to ve of DC power supply to battery respectively During the charging the cellrevert back .to original position


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Electrolyte : Medium that conducts chargeIons : Positively charged or negatively charged atomsOxidation

: .Any reaction in which electrons are lost

Reduction : .Any reaction in which electrons are gainedAnode : - ve Terminal

- ve Electrons are released from this electrode to the electrolyte internal to the battery

Cathode : + ve Terminal+ ve Electrons in the electrolyte are collected by this electrode

lectrochemical Cell ( )Simple Battery Contains two electrodes Anode and Cathode immersed in a medium that conductscharge

.n e b at te r y ce l l ca n pr o du ce 2 1 v ol ts2 vo l t ba tt er y h a s 6 ce l ls

.2 vo lt b a tt er y c an pr od uc e 1 2 6 v o lt s


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ell Connection, :The group of cell is battery so according to that the symbol of cell and battery is as follows

( ).The rating or capacity of the battery is expressed in Ampere Hours Ah Batteries are of various ratings ranging. , .from 1 Ah to 144 Ah Generally 72 Ah 108 Ah and 144 Ah batteries are used

,If we take a battery of 4 Volt 2 Ah then the battery can provide 4 volts with 2 amp for 1 hour or 4 volts with 1 amp. ,for 2 hours With the same if we have 12 volts battery with the rating of 144 Ah then it can provide 12 volts with

.144 amp for 1 hour or 12 volts with 1 amp for 144 hours But in practice a normal battery can not supply more than 20.to 25 A current

. We can connect batteries in series as well as parallel The connection system is just like resistors what we connect. .In series as well as parallel But in this we take care of polarity

Cell Battery

+ - +-

+ --

+ - + -

+ -

+ -

Series Parallel

I i ll ti bt i lt ll d th i l ll h t i t t Wh


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In series cell connection we can obtain more voltage called . . .m f .than a single cell where current is constant Where,as in parallel cell connection we obtain more current than a single cell where voltage called . . .m f .remains same

. . .To get total e m f in e ri es c ir cu itET = nE ET : . . . ( )Total e m f Volts

:n Number of cells: . . .E e m f of one cell

. . . . . . . .e g If we connect three 1 5 volts cell in series then the total e m f i e ETis

ET = nE =n 3 = .E 1 5 Volts

then ET = . = .3 x 1 5 4 5 Volts

. . .To get total e m f in a ra ll el c ir cu itET = e ET : . . . ( )Total e m f Volts

: . . .e e m f of one cell

. . . . . . . .e g if we connect three 1 5 volts cell in parallel then the total e m f i e ETis

ET = e = .e 1 5 volts

then ET = .1 5 volts

,Remember that if the battery or cell is ideal then the voltage remains same and if the battery or cell is connected.to load then the voltage is dropped by the load The flow of current will produce a voltage drop across each

.resistance in the circuit

, .As we know that each component has some resistance power the same thing applied with cell or battery So theresistance property of cell or battery is called n t er n al r e si s ta n ce .of cell or battery

To calculate the internal resistance =r ES /V I :r Internal resistanceES : Source voltage

: ( = )V Voltage drop V IR:I Current

( )Th lt f ll i 1 5 lt i id l diti i l d d if t thi ll t 5 h


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. .e g . ( . . )The voltage of cell is 1 5 volts in ideal condition i e no load and if we connect this cell to 5 ohmload then the voltage drop is . , .1 25 volts then what is the internal resistance of cell

=r ES /V I r : internal resistanceES : source voltageV : ( = )voltage drop V IRI : current

therefore =r ?

E S = .1 5 volts= .V 1 25 volts=I ?

( ),first we find I current according to ohms law = /I V R

= . /I 1 25 volts 5 ohm

= .I 0 25 amp

So = . . / .r 1 5 volts 1 25 volts 0 25 amp

= . / .r 0 25 0 25

=r 1 ohm

To find o t al i nt er na l r es is ta n ce i n s e ri es c el l c i rc u it rT= nr :n number of cells:r internal resistance of one cell

To find o t al i nt er na l r es is ta n ce i n p a ra ll el c e ll ci r cu it rT = /r nTo find circuit ur re n t in se ri e s ce l l ci r cu it =I ET / rT + R

To find circuit ur re n t in pa ra l le l c el l c ir cu i t = / +I E R rT

g If t 12 ll i ith 2 lt f h ll ith th i t l i t i 0 2 h d


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. .e g If we connect 12 cells in s e r i e s . ,with 2 volt of each cell with the internal resistance is 0 2 ohm and.the load is 10 ohm Then what .is the circuit current

,So to find I in series circuit the formula is =I ET / rT + R

=I currentET = total voltage

=rT total internal resistance=R load resistance

First we find total voltage ET = nE = 12 cells x 2 volts = 24 volts

Second we find total internal resistance rT = nr = .12 cells x 0 2 ohm = .2 4 ohm

Then =I ET / rT + R = / . +24 2 4 10 = / .24 12 4

= .1 93 amp

.The series circuit current is 1 93 Amp

. .e g If we connect 12 cells in p a r a l l e l . ,with 2 volt of each cell with the internal resistance is 0 2 ohm and.the load is 10 ohm Then what .is the circuit current

,So to find I in parallel circuit the formula is = / +I E R rT

First we find E =E 2 volts

Second we find rT rT = /r n = . /0 2 12 = .0 016 ohm

Then = / +I E R rT = / + .2 10 0 016 = / .2 10 016

= .0 199 amp

.The parallel circuit current is 0 199 Amp


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( . . )To calculate the capacity of the battery i e how long it will work with full load the formula is

=Capacity Ampere x Hour. .e g . ,If the battery can supply 7 5 amp current for 8 hours with 6 volts then what is the capacity

=apacity Ah =A ampere=h hours

= .Capacity 7 5 x 8 = 60 Ah

. . .i e This battery can provide 6 volts with 60 amp current for 1 hour or 6 volts with 1 amp for 60 hrs

, ( )If the with the above same configuration the current drop drain is 5 ampere then how long the battery.will work

attery life ( ) =in hours /apacity Current Drain =Capacity 60 Ah=Current Drain 5 Amp

= /Battery life 60 5

=Battery life 12 hrs


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harging Techniques. .Secondary cells are required to charge as they get inactive The charging is done only by DC source Those methods are

:as follows

onstant Voltage Method. . .In this method voltage is kept constant Initially dynamo is used The magnitude is kept constant in this method The

. . . . . .. ,e m f of dynamo is always greater than the battery e m f If we want to charge more than one battery connect all in

. . .parallel Rheostat is used to maintain magnitude of current An ampere meter is used for current indication In this. . . , .process the e m f of the dynamo remains constant so the method is called constant voltage method The connection:diagram is as follows

onstant Current Method/In this method the magnitude of current is at 1 10th . .of the battery Rheostat is used to maintain magnitude of current. .An ampere meter is used for current indication Bulbs are used to regulate the current The connection diagram is as

:follows

DC Fuse A

Rh

eos

ta

t

Battery under charge


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DC Fuse A

Rh

eos

ta

t

Battery under charge

rickle Charging Method.This method is used when battery is not capable for charging due to uncharged or below the discharge level In this

% .method charging is done at a very low charging current nearly about 2 of the discharge current

, , , ,Now a days ready made battery chargers are used which consists of Transformer Rectifier Ammeter Voltmeter Voltage.and Current Controller


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Maintenance . :Regular maintenance of Lead Acid battery is necessary The instructions are as follows

.1 / /Normal charging discharging current rate is 12 A or 1 10th .of Ah

.2 .New battery should be used regularly

.3 .At least once in a week battery must be discharged and recharge

.4 . .Only distilled is used And it must added to battery to fully dip the plates

.5 + .ve as well as ve terminals must be cleaned

.6 . .Relative density of electrolyte is not less than 1 18

.7 .Vent plugs are removed during charging

.Relative density or so called specific gravity is measured by hydrometer

olar Cell

Solar cell is a semiconductor device which,has capacity to convert visible light IRand or UV light directly into electrical

.energy To do this special semiconductors, are used Amorphous Silicon Gallium

.Arsenide and Cadmium Selenium All thesesemiconductor substances are light

.sensitive But apart from those substances-Crystalline Silicon is most commonly

. . . .used The e m f or say voltage is directly:depends on two factors

.1 Atomic Structure of the substance and

.2 Crystalline structure of the same.substance


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+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

Cell Connection Parallel and Series

ilver Oxide Cell, , .This one type of most commonly used cell generally used for Calculator Watch Toys etc and also called asut to n C el l .due to its shape

Advantages of this cell is

.1 .Very small size

.2 .Good working condition at high temperature

.3 .Has very good resistance to shock and vibration

.4 .Very long working capability5.

Cell n Battery

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