Construction of Lead Acid Battery

Construction of Lead Acid Battery Points : Construction of Lead Acid Battery Battery positive and negative plates are immersed in dilute sulphuric acid solution and kept apart by separators in each of its cells. Let us study in detail each part of the lead acid battery. Positive Plate The positive electrode is a plate of lead with square holes or slots in it, lead peroxide PbO₂ (a reddish material) is pressed into these holes or slots and is the active positive material in the charged cells. Negative Plate The negative electrode or plate is of “spongy” lead Pb. Due to possibility of bucking of lead on positive plate in the niultiplate lead acid cell there is always one more negative plate than the number of positive plate. Separators Separators are of porous material generally made from thin sheets of wood and are placed between positive and negative plates, insulating the plate from one another and thus avoiding the short circuiting of the battery. Separators must be sufficient porous to allow circulation of electrolyte between the plastic. Now — a — days, separators are also made up of glass wool mat, micro porous rubber, micro porous plastic and perforated PVC. In addition to good porosity, a separator should have a high electric resistance and good mechanical strength. The curved surface of the separator should always face the positive plate. Containers Are made of vulcanized rubber or hard rubber, moulded plastic, ceramics, glass or celluloid and accommodate the positive and negative plates, separators sediment chamber. During the chemical reaction the active material gets collected in the sediment chamber and thus prevents short-circuiting through the sediments. In battery container, partition walls are also provided between the different cells so that their electrolyte should not mix together. Each cell is provided with a lid know as a cell cover fitted with vent plug. Holes are provided in the vent plug for the gases to escape, which are formed during chemical reaction. The cells covers are seated with a sealing compound. Plate Connector Is made up of pure lead. All positive and negative plates are assembled and welded separately with it forming positive and negative groups. Post Terminal A small pole extended upward from each group of welded plates from helps to connect individual cells in series to form battery. Cell Connectors These are the thick-drilled bars made of pure lead. The cells are connected and welded in series to form battery with help of cell connectors. Electrolyte It is mixture of diluted sulphuric acid having specific gravity of 1.850 diluted with distilled water in the ratio of 1:3 thereby making the specific gravity of electrolyte 1.280.

Specific gravity = Weight of an equal volume of any substance/Weight of an equal volume of water at same temperature Active Material of Lead Acid Cell Are those material which takes active part in chemical reaction. The active materials of the lead cell are:
1. Lead peroxide (PbO₂) for positive plate.
2, Sponge lead (Pb) for negative plate.
3. Dilute sulphuric acid (H₂SO₄),