Lead acid batteries are the most widely common type of rechargeable battery since they were introduced in 1859. Lead acid battery has a low energy to weight ratio and a low energy to volume ratio, yet the ability to supply high surge currents makes the cells have a moderately large power to weight ratio, which makes them attractive for automotive sector for providing the high current required by starter motors.
Concept of the lead-acid batteries
The discharging lead acid batteries produce electrical energy by releasing the strong chemical bonds of H2O (water) molecules which are formed from the acid’s H+ ions and PbO2’s O2− ions. On the other hand, during charge phase the battery functions as a device for splitting water, and when charged the battery’s chemical energy is stored as potential difference between the positive side’s PbO2 on the and the negative side‘s pure lead, in addition to the Sulphuric Acid which is in aqueous condition.
The lead acid battery’s grid structure is composed of a lead alloy, as small quantities of different metals are added to improve electrical properties and get the mechanical strength. The most used additives are calcium, tin, antimony and selenium.
Lead acid batteries market share and applications
The lead acid battery for deep cycle applications can provide 200- 300 charge/ discharge cycles. The main reason for the relatively short life cycle are depletion of active material, grid corrosion on the positive electrode and expansion of the positive plates.
Lead acid is not used in fast charging applications as with most types, a full charge can take up to 16 hours. The battery should always be stored at astate of full charge. Low charge can cause sulfation, a condition which decreases the performance of the battery. Adding carbon to the negative electrode can reduce this problem yet this decreases the specific energy.
In 1990s lead acid battery market share represented nearly 45% of all batteries sold globally, with an estimated manufacturing value of $15 billion. Large format lead acid batteries are widely used for storage in the backup power supplies in cell phone towers, hospitals and other high-availability requirement designs and standalone power systems.
The reasons for its popularity is being dependable and cheap on a cost per watt base. There are few battery type options which deliver bulk power with as low cost as lead acid, and this makes the lead acid battery perfect for different application like vehicles, forklifts, and UPS ( uninterruptible power supplies).