Construction of Lead Acid BatteryPoints : Construction of Lead Acid BatteryBattery 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 PlateThe 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 PlateThe 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. SeparatorsSeparators 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.ContainersAre 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 ConnectorIs made up of pure lead. All positive and negative plates are assembled and welded separately with it
forming positive and negative groups.Post TerminalA small pole extended upward from each group of welded plates from helps to connect individual cells in
series to form battery.Cell ConnectorsThese 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.
ElectrolyteIt 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
temperatureActive Material of Lead Acid CellAre 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),
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