Lead Acid Battery
There are two types current namely ac and dc. We know that, DC current can be stored. The electrical energy in dc nature store in the form of chemical energy. The device that stores electrical energy in chemical energy is called “electric cell“. Electric cell has small storage capacity. So cells are connected in series or parallel combination to increase storage capacity. After combination of cells are called batteries. There are many batteries are available but in this topic we will discuss about Construction, working and applications of lead acid battery. Lead acid battery is most commonly used battery as a storage device.
Construction of Lead Acid Battery
This battery has different parts. These parts are explained below.
It is the outer body of the lead acid battery. It is made of hard rubber material so it can bear mechanical stress and strain. The material selected for construction of container should be such that which do not react with chemical. It is sealed at top to avoid spilling of the electrolyte. Some space left at bottom of the battery so that sediments that drops from the plates collected here in order to protect the short circuit between active material.
An antimonial lead alloy covered with active material is used for manufacture of plates of lead acid battery. The positive plate is made from lead peroxide and negative plate is made from spongy lead. To increase the capacity of a battery we use large number of plates. The number of positive and negative plates are sandwiched.
Separators are thin sheets with small holes placed between the positive and negative plates for preventing internal short circuit.
Dilute sulphuric acid is used as an electrolyte in lead acid battery. The plates are completely immerse in an electrolyte. Electrolyte is the medium through which the current produces by chemical changes.
Vent Caps or Filler Caps
The function of these caps to prevent escape electrolyte but allow the free exit of the gas during charging It can easily removed for adding water and to insert the nozzle of hydrometer for checking specific gravity of electrolyte. These are made of rubber.
Inter-cell Connector are used to connect the cells together.
Working Principle of Lead Acid battery
There are two plates immersed in dilute sulphuric acid. The positive plate is of lead peroxide chocolate brown in color and negative plate is of spongy lead. when the load is connected across two terminals of the cell, the current start flowing due to chemical action between plates and electrolytes.
When cell discharge it delivers current to the load, the molecules are dissociated into hydrogen ions and sulphate ions. During discharging action, hydrogen ions moves towards anode and sulphate ions move towards cathode. At discharging time specific gravity of the battery decreases.
For charging, the cell is connected to the dc source. When cell is recharged, the hydrogen ions moves towards cathode and sulphate ions moves toward anode to the lead acid battery.
Applications of Lead Acid Battery
It is used in automobiles for starting and lightning.
It is used with inverter circuit as a storage device.
It is used in telephone exchanges.
It is used in railway system for storing electrical energy.