What is Battery ? Types of Battery

 Battery

         Storage battery is the most important electrical system of a vehicle. It supplies the current for the starting motor and various electrical components and accessories. 

    It is the electro chemical apparatus which supplies regular current due to chemical inside.

Types of Battery

 1) Lead acid battery

 2) Alkaline battery

 3) Zinc air battery

1) Lead acid Battery

  Construction

  The major components of the battery are:

      

       a) Container 

       b)  Plates

       c) Separators

       d)  Cell covers

       e) Electrolyte

a) Container

           Battery containers are single piece construction. It is made of either hard rubber ( moulded ebonite) ( or) of a bituminous rubber.

  Modern car batteries are strong, transparent and light weight plastic,

b) Plates

    There are two types of battery plates, the positive and the negative. The battery plates rest at the bottom of compartments containing bridges.

  For each plate there is supporting frame work or grid. It is made of an alloy of lead and antimony. The function of the grid is to hold the active material and to carry current in the plates.

  The active material in the positive plate grid is red lead and the negative plate in the form of paste.

  After forming process, these are converted into lead peroxided for the positive plate and spongy lead for the negative plate.

The negative plate group contains one plate more than positive plate group.

c) Separators

 Thin sheets are called separators of some non conducting material. To avoid direct contact and thus short circuiting and positive and negative plates, these sheets are inserted between them.

 The most widely used separator is P.V.C ( polyvinyl chloride )

d) Cell covers

  Cell covers provide a sealing for the cells. They are mounted from hard rubber. Each cell cover contains holes for the positive and negative posts, a vent and a filler openings.

 Filler openings are used to check specific gravity of Electolyte. Cell covers are sealed in the container by running pitch.

e) Electrolyte

 The battery is filled with electrolytic solution of sulphuric acid. The ratio is one part of acid added to 3 parts of water.

Working principle 

   The positive plates contain lead peroxide and negative plates have spongy lead. while discharging lead converted to lead sulphate. So the electrolyte is diluted due to water formation.

   During recharging lead sulphate on positive plates is converted into peroxide, While negative plates lead sulphate is converted to spongy lead.

  The water is splited into oxygen and hydrogen during charging. then hydrogen combines with sulphate ions to form sulphuric acid.

  Then hydrogen combines with sulphate ions to form sulphuric acid.

Cell voltage 

  The open circuit voltage of a fully charged battery cell. A six volt battery would be made of 3 cell, and 12volt battery contain 6 cells connected in series.

The cell voltage should not fall below 1.7volts during service.

Battery capacity

  It is defined as the amount of current delivered from a battery. It depends on the electrolyte, number and area of plates in the cell.

 The battery capacity decreases with decrease of temperature.

2) Alkaline Battery

     Alkaline batteries are of two types. The nickel cadmium type is suitable for automobile service. Nickel- iron type is the other one.

  In nickel cadmium type, the active material on positive plate is nickel hydroxide. On negative plate it is cadmium oxide.

  The electrolyte used is potassium hydroxide oxide. The positive and negative plates is in finely perforated steel tubes, which combine together to form a plate.

 Even under severe jolts, no active material is lost from the plates and no sediment is produced. The electrolyte takes part in no chemical reactions on charging or discharging.

Advantages

1) High rate of charging

2) Slow rate of discharging

3) Suitable for rough use

4) Longer life

Disadvantages

1) Cell capacity is 1.2 volt per cell only. so bigger in size

2) More resistance

3) Lesser efficiency

4) High cost

Battery charging

Need for charging

   A generator is provided for charging the battery. If the battery is rundown, the charging rate will be higher. Under certain conditions, it happens.

 If the vehicle is in idle, frequent use of starter and the use of other electrical accessories, the battery gets discharged to extent.

 So, the external recharging may become necessary apart from the generator charging.