Battery (History & Working Principle of Batteries)

In the modern era, electrical energy is normally converted from mechanical energy, solar energy, and chemical energy etc. A battery is a device that converts chemical energy to electrical energy. The first battery was developed by Alessandro Volta in the year of 1800. In the year 1836, John Frederic Daniell, a British chemist developed the Daniell cell as an improved version of the voltaic cell. From that time until today, the battery has been the most popular source of electricity in many daily life applications.

In our daily life, we generally use two types of battery , one of them is which can be used once before it gets totally discharged. Another type of battery is rechargeable which means it can be used multiple times by recharging it externally. The former is called primary battery and the later is called secondary battery . Batteries can be found in different sizes. A battery may be as small as a shirt button or may be so big in size that a whole room will be required to install a battery bank. With this variation of sizes, the battery is used anywhere from small wrist watches to a large ship. We often see this symbol in many diagrams of electrical and electronics network. This is the most popularly used symbol for battery . The bigger lines represent positive terminal of the cells and smaller lines represent negative terminal of the cells connected in the battery .

We are often confused about the terms battery cell and battery . We generally refer a battery as a single electro-chemical cell. But literally, battery does not mean that. Battery means a number of electro-chemical cells connected together to meet a certain voltage and current level. Although there may be a single cell battery , literally, battery and cell are different.

History of Battery

In the year of 1936 during the middle of summer, an ancient tomb was discovered during construction of a new railway line near Bagdad city in Iraq. The relics found in that tomb were about 2000 years old. Among these relics, there were some clay jars or vessels which were sealed at the top with pitch. An iron rod, surrounded by a cylindrical tube made of wrapped copper sheet was projected out from this sealed top.

When these pots were filled with an acidic liquid, they produced a potential difference of around 2 volts between the iron and copper. These clay jars are suspected to be 2000 year old battery cells. In 1786, Luigi Galvani, an Italian anatomist and physiologist was surprised to see that when he touched a dead frog’s leg with two different metals, the muscles of the legs contracted. He could not understand the actual reason why, otherwise he would have been known as the first inventor of the battery cell. He thought the reaction might be due to a property of the tissues. After that, Alessandro Volta realized that same phenomenon could be created by using cardboard soaked in salt water instead of frog's leg. He sandwiched a copper disc and a zinc disc with a piece of cardboard soaked in salt water in between them and found a potential difference between the copper and zinc. After that in 1800, he developed the first Voltaic Pile (battery) constructed of alternating copper and zinc discs with pieces of cardboard soaked in brine between them. This system could produce measurable current. Alessandro Volta's voltaic pile was considered the first "wet battery cell". Thus, the history of battery began. The main problem with the Voltaic pile was that, it could not deliver current for a long time. This problem was solved by a British inventor John F. Daniell in 1836. He invented a more developed version of the battery cell which is known as the Daniell cell. Here in this cell, one zinc rod is immersed in zinc sulfate in one container and one copper rod is immersed in copper (II) sulfate in another container. The solutions of these two containers are bridged by a U shaped salt bridge. A Daniell cell could produce 1.1 volt and this type of battery lasted much longer than the Voltaic pile.

In 1839, the fuel cell was designed by Sir William Robert Grove, a discoverer and man of science. He mixed hydrogen and oxygen within an electrolyte solution, and created electricity and water. The fuel cell did not deliver enough electricity, but it is helpful.

Bunsen (1842) and Grove (1839) created enhancements to battery that used liquid electrodes to supply electricity.

In the year of 1859, Gaston Plante; first developed the lead acid battery cell. This was the first form of rechargeable secondary battery. The lead acid battery is still in use for many industrial purposes. It is still the most popular to be used as car battery .

In 1866, the battery was again developed by a French engineer, Georges Leclanche. It was a carbon-zinc wet cell battery known as the Leclanche cell. Crushed manganese dioxide mixed with a bit of carbon forms the positive electrode and a zinc rod is used as the negative electrode. Ammonium chloride solution is used as a liquid electrolyte. After some years, Georges Leclanche himself improved his own design by replacing liquid ammonium chloride solution with ammonium chloride. This was the invention of the first dry cell.

In 1901, Thomas Alva Edison discovered the alkaline accumulator. Thomas Edison's basic cell had iron as the anode material (-) and nickel oxide as the cathode material(+). This is just one portion of an endless history of battery .

Step by Step Development in History of Batteries

Developer/Inventor	Country	Year	Invention
Luigi Galvani	Italy	1786	Animal Electricity
Alessandro Volta	Italy	1800	Voltaic Pile
John F. Daniell	Britain	1836	Daniell Cell
Sir William Robert Grove	Britain	1839	Fuel Cell
Robert Bunsen	German	1842	used liquid electrodes to supply electricity
Gaston Plante	France	1859	Lead Acid Battery
Georges Leclanche	France	1866	Leclanche Cell
Thomas Alva Edison	United States	1901	Alkaline Accumulator

Working Principle of Battery

To understand the basic principle of battery properly, first, we should have some basic concept of electrolytes and electrons affinity. Actually, when two dissimilar metals or metallic compounds are immersed in an electrolyte, there will be a potential difference produced between these metals or metallic compounds.

It is found that, when some specific compounds are added to water, they get dissolved and produce negative and positive ions. This type of compound is called an electrolyte. The popular examples of electrolytes are almost all kinds of salts, acids, and bases etc.

The energy released during accepting an electron by a neutral atom is known as electron affinity. As the atomic structure for different materials are different, the electron affinity of different materials will differ. If two different kinds of metals or metallic compounds are immersed in the same electrolyte solution, one of them will gain electrons and the other will release electrons. Which metal (or metallic compound) will gain electrons and which will lose them depends upon the electron affinities of these metals or metallic compounds. The metal with low electron affinity will gain electrons from the negative ions of the electrolyte solution. On the other hand, the metal with high electron affinity will release electrons and these electrons come out into the electrolyte solution and are added to the positive ions of the solution. In this way, one of these metals or compounds gains electrons and another one loses electrons. As a result, there will be a difference in electron concentration between these two metals. This difference of electron concentration causes an electrical potential difference to develop between the metals. This electrical potential difference or emf can be utilized as a source of voltage in any electronics or electrical circuit. This is a general and basic principle of battery .

All batteries cells are based only on this basic principle. Let’s discuss one by one. As we said earlier, Alessandro Volta developed the first battery cell, and this cell is popularly known as the simple voltaic cell. This type of simple cell can be created very easily. Take one container and fill it with diluted sulfuric acid as the electrolyte. Now immerse zinc and one copper rod in the solution and connect them externally by an electric load. Now your simple voltaic cell is completed. Current will start flowing through the external load.

Zinc in diluted sulfuric acid gives up electrons as below:

These Zn ^{+ +} ions pass into the electrolyte, and their concentration is very high near the zinc electrode. As a result of the above oxidation reaction, the zinc electrode is left negatively charged and hence acts as cathode. The diluted sulfuric acid and water disassociate into hydronium ions as given below:

Due to the high concentration of Zn ^{+ +} ions near the cathode, the H₃O⁺ ions are repelled towards the copper electrode and get discharged by removing electrons from the copper atoms. The following reaction takes place at the anode:

As a result of the reduction reaction taking place at copper electrode, copper is left positively charged and hence it acts as the anode.

Daniell Battery Cell: The Daniell cell consists of a copper vessel containing copper sulfate solution. The copper vessel itself acts as the positive electrode. A porous pot containing diluted sulfuric acid is placed in the copper vessel. An amalgamated zinc rod dipping inside the sulfuric acid acts as the negative electrode.

When the circuit is completed, diluted sulfuric acid in the porous pot reacts with zinc so as to liberate hydrogen gas. The reaction takes place as below:

The formation of ZnSO₄ in the porous pot does not affect the working of the cell, until crystals of ZnSO₄ are deposited.

The hydrogen gas passes through the porous pot and reacts with the CuSO₄ solution as below:

Copper so formed gets deposited on the copper vessel.

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Classification of Engineering Materials

Basic Classification of Engineering Materials

Basically Engineering Materials Can be classified into two categories-

1. Metals
2. Non-Metals

Metals

Metals are poly crystalline bodies which are having number of deferentially oriented fine crystals. Normally major metals are in solid states at normal temperature. However, some metals such as mercury are also in liquid state at normal temperature. All metals are having high thermal & electrical conductivity. All metals are having positive temperature coefficient of resistance. Means resistance of metals increase with increase of temperature. Examples of metals – Silver, Copper, Gold, Aluminum, Iron, Zinc, Lead, Tin etc.

Metals can be further divided into two groups-

1. Ferrous Metals – All ferrous metals are having iron as common element. All ferrous materials are having very high permeability which makes these materials suitable for construction of core of electrical machines. Examples: Cast Iron, Wrought Iron, Steel, Silicon Steel, High Speed Steel, Spring Steel etc.
2. Non-Ferrous Metals- All non-ferrous metals are having very low permeability. Example: Silver, Copper, Gold, Aluminum etc.

Non-Metals

Non-Metal materials are non-crystalline in nature. These exists in amorphic or mesomorphic forms. These are in both solid & gases forms at normal temperature. Normally all non-metals are bad conductor of heat & electricity. Examples: Plastics, Rubber, Leathers, Asbestos etc.

As these non-metals are having very high resistivity which makes them suitable for insulation purpose in electrical machines.

Difference between Metals and Non Metals

Sl. No.	Property	Metals	Non-Metals
1.	Structure	All metals are having crystalline structure	All Non-metals are having amorphic & mesomorphic structure
2.	State	Generally metals are slid normal temperature	State varies material to material. Some are gas state and some are in solid state at normal temperature.
3.	Valance electrons & conductivity	Valance electrons are free to move with in metals which makes them good conductor of heat & electricity	Valence electrons are tightly bound with nucleus which are not free to move. This makes them bad conductor of heat & electricity
4.	Density	High density	Low density
5.	Strength	High strength	Low strength
6.	Hardness	Generally hard	Hardness is generally varies
7.	Malleability	Malleable	Non malleable
8.	Ductility	Ductile	Non ductile
9.	Brittleness	Generally non brittle in nature	Brittleness varies material to material
10.	Luster	Metals possess metallic luster	Generally do not possess metallic lustre (Except graphite & iodine)

Other classification of engineering materials:

Engineering materials can also be classified as below-

1. Metals & Alloys
2. Ceramic Materials
3. Organic Materials

Metals & Alloys:

Metals are poly crystalline bodies which are have number of deferentially oriented fine crystals. Normally major metals are in solid states at normal temperature. However, some metals such as mercury are also in liquid state at normal temperature. Pure metals are having very low mechanical strength, which sometimes does not match with the mechanical strength required for certain applications. To overcome this draw back alloys are used. Alloys are the composition of two or more metals or metal & non-metals together. Alloys are having good mechanical strength, low temperature coefficient of resistance. Example: Steels, Brass, Bronze, Gunmetal, Invar. Super Alloys etc.

Ceramic Materials:

Ceramic materials are non-metallic solids. These are made of inorganic compounds such as Oxides, Nitrides, Silicides and Carbides. Ceramic materials possess exceptional Structural, Electrical, Magnetic, Chemical & Thermal properties. These ceramic materials are now extensively used in different engineering fields. Examples: Silica, glass, cement, concrete, garnet, Mgo, Cds, Zno, SiC etc.

Organic Materials:

All organic material are having carbon as a common element. In organic materials carbon is chemically combined with oxygen, hydrogen & other non-metallic substances. Generally organic materials are having complex chemical bonding. Example: Plastics, PVC, Synthetic Rubbers etc.

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Biot Savart Law

Biot Savart Law

The mathematical expression for magnetic flux density was derived by Jean Baptiste Biot and Felix Savart. Talking the deflection of a compass needle as a measure of the intensity of a current, varying in magnitude and shape, the two scientists concluded that any current element projects into space a magnetic field, the magnetic flux density of which dB, is directly proportional to the length of the element dl, the current I, the sine of the angle and θ between direction of the current and the vector joining a given point of the field and the current element and is inversely proportional to the square of the distance of the given point from the current element, r. this is Biot Savart law statement.

Where, K is a constant, depends upon the magnetic properties of the medium and system of the units employed. In SI system of unit,
Therefore final Biot Savart law derivation is,
Let us consider a long wire carrying an current I and also consider a point p. The wire is presented in the below picture by red color. Let us also consider an infinitely small length of the wire dl at a distance r from the point P as shown. Here r is a distance vector which makes an angle θ with the direction of current in the infinitesimal portion of the wire. If you try to visualize the condition, you can easily understand the magnetic field density at that point P due to that infinitesimal length dl of wire is directly proportional to current carried by this portion of the wire. That means current through this infinitesimal portion of the wire is increased the magnetic field density due to this infinitesimal length of wire, at point P increases proportionally and if the current through this portion of wire is decreased the magnetic field density at point P due to this infinitesimal length of wire decreases proportionally. As the current through that infinitesimal length of wire is same as the current carried by the wire itself.
It is also very natural to think that the magnetic field density at that point P due to that infinitesimal length dl of wire is inversely proportional to the square of the straight distance from point P to center of dl. That means distance r of this infinitesimal portion of the wire is increased the magnetic field density due to this infinitesimal length of wire, at point P decreases and if the distance of this portion of wire from point P, is decreased, the magnetic field density at point P due to this infinitesimal length of wire increases accordingly.
Lastly, field density at that point P due to that infinitesimal portion of wire is also directly proportional to the actual length of the infinitesimal length dl of wire. As θ be the angle between distance vector r and direction of current through this infinitesimal portion of the wire. The component of dl directly facing perpendicular to the point P is dlsinθ,
Now combining these three statements, we can write,
This is the basic form of Biot Savart's Law Now putting the value of constant k (which we have already introduced at the beginning of this article) in the above expression, we get
Here, μ₀ used in the expression of constant k is absolute permeability of air or vacuum and it's value is 4π10^-7 W_b/ A-m in S.I system of units. μ_r of the expression of constant k is relative permeability of the medium.

Now, flux density(B) at the point P due to total length of the current carrying conductor or wire can be represented as,

If D is the perpendicular distance of the point P form the wire, then
Now, the expression of flux density B at point P can be rewritten as,
As per the figure above,
Finally the expression of B comes as,
This angle θ depends upon the length of the wire and the position of the point P. Say for certain limited length of the wire, angle θ as indicated in the figure above varies from θ₁ to θ₂. Hence, flux density at point P due to total length of the conductor is,

Let's imagine the wire is infinitely long, then θ will vary from 0 to π that is θ₁ = 0 to θ₂ = π. Putting these two values in the above final expression of Biot Savart law, we get,

This is nothing but the expression of Ampere's Law .

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Norton Theorem (Norton Equivalent Current and Resistance)

Norton Theorem

This theorem is just alternative of Thevenin theorem. In Norton theorem, we just replace the circuit connected to a particular branch by equivalent current source . In this theorem, the circuit network is reduced into a single constant current source in which, the equivalent internal resistance is connected in parallel with it. Every voltage source can be converted into equivalent current source .

Suppose, in complex network we have to find out the current through a particular branch. If the network has one of more active sources, then it will supply current through the said branch. As in the said branch current comes from the network, it can be considered that the network itself is a current source . So in Norton theorem the network with different active sources is reduced to single current source that's internal resistance is nothing but the looking back resistance, connected in parallel to the derived source. The looking back resistance of a network is the equivalent electrical resistance of the network when someone looks back into the network from the terminals where said branch is connected. During calculating this equivalent resistance, all sources are removed leaving their internal resistances in the network. Actually in Norton theorem, the branch of the network through which we have to find out the current, is removed from the network. After removing the branch, we short circuit the terminals where the said branch was connected. Then we calculate the short circuit current that flows between the terminals. This current is nothing but Norton equivalent current I_N of the source. The equivalent resistance between the said terminals with all sources removed leaving their internal resistances in the circuit is calculated and said it is R_N. Now we will form a current source that's current is I_N A and internal shunt resistance is R_N Ω.

For getting clearer concept of this theorem, we have explained it by the following example, In the example two resistors R₁ and R₂ are connected in series and this series combination is connected across one voltage source of emf E with internal resistance R_i as shown. Series combination of one resistive branch of R_L and another resistance R₃ is connected across the resistance R₂ as shown. Now we have to find out the current through R_L by applying Norton theorem. First, we have to remove the resistor R_L from terminals A and B and make the terminals A and B short circuited by zero resistance. Second, we have to calculate the short circuit current or Norton equivalent current I_N through the points A and B. The equivalent resistance of the network, To determine internal resistance or Norton equivalent resistance R_N of the network under consideration, remove the branch between A and B and also replace the voltage source by its internal resistance. Now the equivalent resistance as viewed from open terminals A and B is R_N, As per Norton theorem, when resistance R_L is reconnected across terminals A and B, the network behaves as a source of constant current I_N with shunt connected internal resistance R_N and this is Norton equivalent circuit.

Norton Equivalent Circuit

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Electrical Engineering Overview

Under Basic Electrical Engineering

Welcome to this open and free electrical engineering study site. A strong team of well experienced electrical engineers in different fields of electrical technology has prepared this site for helping all people in the electrical community. The site covers entire aspects of the subject, from basic engineering to advanced and modern topics related to Electrical Engineering and Technology.

All articles of this site are totally based on practical experiences as well as a strong base of theoretical knowledge. The materials on this site are mainly concentrated on the field of electrical power systems but also cover all the basic electrical theories and definitions related to this part of engineering. This site is useful for all professionals dealing with electrical power transmission systems and electrical power distribution systems. It is also very very useful for those students who are studying for electrical engineering degrees or diploma courses at different colleges and universities. This site plays a vital role for getting extra knowledge beyond the text books. Materials on this site are written in very simple and understandable English. Information on this site can also be utilized as reference for different fields of electrical engineering and technology. Our study materials cover almost all the field of electrical power system engineering from basic to advanced.

So go through these electrical topics and get required knowledge for professional applications in electrical technology as well as for educational purposes. This is an absolutely free, open and online electrical power transmission and distribution reference cum guide book.

This site covers many important topics related to different parts of power system engineering, like, basic electrical, electrical power transformer, electrical switch gear, power system protection, electrical power transmission system etc. The site provides many video presentations for different electrical theories to make your electrical engineering study more easy and understandable. In few words, it can be said that this site covers almost all topics related to electrical power system engineering and technology.

Electrical Engineering

The most familiar form of energy in our daily lives is electrical energy. The branch of engineering which deals with producing, managing and utilizing this energy, is referred as electrical engineering. This field of engineering was introduced in an organized manner in the mid of 19th century. Electrical technology is not as old as civil and mechanical technologies. Interest in this field of study grew after the invention of electricity. It was June 1752 when Benjamin Franklin first tried to catch electricity from clouds during a heavy storm with the help of a flying kite. This was the beginning and to date still we are trying to manage this energy. Managing electrical energy (producing, transmitting, distributing, utilizing) is nothing but electrical engineering. Commercially this became an occupation only after 1950.

Electrical engineering is core engineering like civil and mechanical but it has a wide range of subfields. After modernization, many fields of engineering grew out of electrical such as electronics, computer, telecommunication engineering and many more. All the fields of study that directly or indirectly deal with electricity come under electrical engineering.

In a power generation plant where electrical energy is produced, the application of this engineering is huge. All the mechanical and as well as electrical equipment involved in producing electrical energy, such as alternators, boilers, turbines etc. are controlled and protected by electrical signals. All the relays and switches involved in operation of the equipment are either electro-mechanical or static electronics devices. In the modern age, these devices are digitally controlled by computer software. So in addition to core electrical engineering, these electrical engineering sub fields (electronic, computer, software engineering and IT) are also involved in power generation.

When the voltage level of generated power is stepped up, electrical transformers are required. For proper control and protection of these transformers, a sophisticated switchgear system is required. Electrical switchgear includes all circuit breakers, electrical isolators, current transformers, potential transformers, control and protection relay system and many more. Modern electrical engineering deals with production, planning, operation, and maintenance of these systems.

After stepping up the electrical power, it is transmitted to a load center. Huge electrical technology is involved in electrical power transmission systems and networks including large national grids. The problems associated with these systems are solved by electrical engineering including all engineering sub fields.

History of Electrical Engineering

Benjamin Franklin in 1752, was the first man who tried to utilize electricity from clouds by flying a kite during a stormy night. In 1780, Luigi Galvani was surprised when he saw that a dead frog’s leg twisted when it was touched by a silver and copper stick. He misunderstood the actual reason, thinking that the electricity came from the leg itself, and referred it as animal electricity. After development in 1800 by Alessandro Volta of the voltaic cell as a simple method of producing electricity from a chemical reaction, an actual revolution occurred in this field and the history of electrical engineering totally changed from this time.

It is needless to say that most of the theories, on which this field of engineering is built, are related to electromagnetism. The law of electromagnetism was invented by Michael Faraday in the year 1831. This law is popularly known as Faraday’s law of electromagnetic induction. The relation between current and voltage in a conductor was already stated by Georg Ohm, in 1827. This is Ohm’s law . Based on these two theories development of electrical technology began. In his experiment with electromagnetic induction, Michael Faraday designed the most basic model of an electrical rotating machine. In 1873, James Clerk Maxwell, published his famous article on magnetism and electricity.

Werner von Siemens the founder of the German multinational engineering and electronic company Siemens, made great contributions in the early days of the history of electrical engineering. He was a great inventor and developer. Another great contributor to the electrical engineering was Sir Thomas Edison. We all know him as inventor of electric light bulb in the year 1879. This invention was a revolution. He was also the builder of the first electrical supply network in the world.

Although there were so many developments and research works going on before 1882, the study of electricity was not recognized as a separate field of engineering. In that year electrical engineering was introduced as a separate branch of engineering by TU Darmstadt University Germany. This was the beginning of studying electrical engineering as a professional degree. In that very year Edison started the world’s first electric supply business at DC 110V. Initially, a total of 59 houses in Manhattan were connected to his network.

Although, alternating current had already been developed in Europe in the year 1850 by Guillaume Duchenne, it was not yet commercially distributed. George Westinghouse, an American entrepreneur and engineer, finally came forward and financially supported the development of the AC power network. By the end of nineteenth century AC power transmission and distribution became popular and started dominating DC distribution systems.

After development of the distribution network, electricity reached consumers. After electricity reaches the consumer, it is utilized for operating different equipment run by electricity. Electrical engineering is also involved in developing such industrial and domestic equipment at the consumer end. Many scientists and engineers involved themselves in inventing and developing such equipment. A new window had been opened in history of electrical engineering.

In 1895, Nikola Tesla transmitted radio frequency signal across a distance of eighty kilometers and developed radio transmitters.

In 1897, the cathode ray tube was invented by Karl Ferdinand Braun and development of television technology began. In 1902, Willis Carrier developed air conditioning machines. In 1941, Konrad Zuse introduced the first form of programmable electromechanical computer. In 1943, Tommy Flowers produced first prototype of programmable digital computer. In 1946 Percy Spencer invented the microwave oven. Every day there are new inventions and developments in electrical engineering and technology. The discussion is far from over. Here, we tried to give an overview only.

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