Category: 4. Batteries

The various advantages of nickel–cadmium cells such as longer life, low maintenance cost, low internal resistance, etc. prompted the scientists to develop these cells in small sizes. Since the emf developed by these cells is 1.2 V, which is very near to the emf developed by dry cells (1.5 V), these cells have been developed…

The two cells can be compared on the basis of the following particulars (Table 4.2): Table 4.2  Comparison of Lead-Acid and Nickel-Iron Cell 4.15  NICKEL–CADMIUM CELL It was developed by a Swedish scientist Waldemar Jungner in 1899. 4.15.1  Construction Cathode  –  Ni(OH)4  Anode  –  Cd (Cadmium) Electrolyte  –  KOH (Potassium hydroxide) of specific gravity 1.2. Its construction is similar to a nickel–iron cell with the…

It is also known as Edison cell as it was developed by an American scientist Thomson A Edison in 1909. 4.13.1  Construction It contains two plates, that is, a positive plate (cathode) and a negative plate (anode). The active material of cathode is Ni(OH)4 and of anode is iron (Fe) when fully charged. The two plates are…

Lead–acid batteries have innumerable commercial applications. Some of the important applications are as follows:

The average life of a lead–acid battery is two to four years depending upon its manufacturing qualities and technique. However, to obtain longer life and efficient service, the following points must be kept in view:

Whenever terminal voltage of a battery falls below 1.8 V per cell, it is put under recharging. The following points must be kept in mind while charging a battery: Note: An over current may produce excessive heat and damage the battery. Generally, the following two methods are employed for charging a battery: Example 4.7 A battery…

The efficiency of a battery (or cell) can be defined in the following two ways: Example 4.4 An alkaline cell is discharged at a steady current of 4 A for 12 hour, the average terminal voltage being 1.2 V to restore it to its original state of voltage, a steady current of 3 A for…

The quantity of electricity that a battery can delivery during single discharge until its terminal voltage falls to 1·8 V/cell is called the capacity of a battery. The capacity of a battery or cell is commercially expressed in ampere-hour and is generally denoted by A-H.   Capacity of a battery or cell = IdTd ampere-hour Where Id =…

When a lead–acid cell is ready for use, its positive plate is made of load peroxide (PbO2) chocolate brown in colour and the negative plate is of spongy lead (Pb) grey in colour. Both the plates are immersed in a dilute sulphuric acid (H2SO4) of specific gravity about 1.28. When a load is connected across…

A single cell can supply a very low current at low voltage. Generally, to operate electrical and electronic circuits, a large current at high voltage is required. Therefore, a number of cells are connected in series, parallel, and series–parallel grouping. 4.5.1  Series Grouping When a number of cells are connected in such a way that the…