Lead acid batteries are rechargeable batteries consisting of lead plates with a sulfuric acid/water electrolyte solution. Car batteries and deep cycle batteries use lead acid technology. All batteries have positive and negative terminals, marked (+) and (-) respectively, and two corresponding electrodes.
Construction, Working, Connection Diagram, Charging & Chemical Reaction Figure 1: Lead Acid Battery. The battery cells in which the chemical action taking place is reversible are known as the lead acid battery cells. So it is possible to recharge a lead acid battery cell if it is in the discharged state.
The construction of a lead acid battery cell is as shown in Fig. 1. It consists of the following parts : Anode or positive terminal (or plate). Cathode or negative terminal (or plate). Electrolyte. Separators. Anode or positive terminal (or plate): The positive plates are also called as anode. The material used for it is lead peroxide (PbO 2).
Pure lead is too soft to use as a grid material so in general the lead is hardened by the addition of 4 – 6% antimony. However, during the operation of the battery the antinomy dissolves and migrates to the anode where it alters the cell voltage. This means that the water consumption in the cell increases and frequent maintenance is necessary.
Following are some of the important applications of lead – acid batteries : As standby units in the distribution network. In the Uninterrupted Power Supplies (UPS). In the telephone system. In the railway signaling. In the battery operated vehicles. In the automobiles for starting and lighting.
The electrolyte is mostly water, and the plates are covered with an insulating layer of lead sulfate. Charging is now required. One not-so-nice feature of lead acid batteries is that they discharge all by themselves even if not used. A general rule of thumb is a one percent per day rate of self-discharge.