Lead acid battery, also known as lead-acid battery, is a type of battery with electrodes mainly made of lead and electrolyte made of sulfuric acid solution. It is generally divided into two types: open type batteries and valve controlled batteries. The former requires regular acid injection maintenance, while the latter is a maintenance free battery.
Lead acid batteries are the earliest type of rechargeable battery invented by French physicist Gaston Plante in 1859. Although it has a very low energy to weight ratio and a low energy to volume ratio, its ability to provide high surge currents means that the battery has a relatively large power to weight ratio. These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required for starting motors.
Although lead chemistry has matured, it is still widely used today. There are sufficient reasons for its popularity. Lead acid is reliable and inexpensive based on cost per watt. Almost no other battery can provide high power as cheaply as lead-acid, making it cost-effective in cars, golf carts, forklifts, ships, and uninterruptible power supplies (UPS).
The grid structure of lead-acid batteries is made of lead alloy. Pure lead is too soft to support itself, so a small amount of other metals were added to obtain mechanical strength and improve electrical performance. The most common additives are antimony, calcium, tin, and selenium. These batteries are commonly referred to as "lead antimony" and "lead calcium".
Adding antimony and tin can improve deep circulation, but this will increase water consumption and demand for balance. Calcium can reduce self discharge, but lead calcium plates may have growth side effects due to gate oxidation during overcharging. Modern lead-acid batteries also use doping agents such as selenium, cadmium, tin, and arsenic to reduce antimony and calcium content.
During deep cycling, lead-acid is heavier than nickel and lithium based systems and has poorer durability. Complete discharge leads to strain, and each discharge/charging cycle permanently deprives the battery of a small amount of charge. When the battery is in good working condition, the loss is minimal, but once the performance drops to half of the nominal capacity, fading will increase. This wear characteristic is applicable to all batteries to varying degrees.
According to the discharge depth, lead-acid used for deep cycle applications can provide 200 to 300 discharge/charging cycles. The main reasons for its relatively short cycle life are gate corrosion on the positive electrode, depletion of active materials, and expansion of the positive electrode plate. At higher operating temperatures and when drawing high discharge currents, this aging phenomenon will be accelerated.
Charging lead-acid batteries is simple, but correct voltage limits must be followed. Choosing a low voltage limit can cover the battery, but it can lead to performance degradation and accumulation of sulfate on the negative electrode plate. High voltage limitation can improve performance, but it will form gate corrosion on the positive electrode plate. If repaired in a timely manner, sulfation can be reversed, but corrosion is permanent.
Lead acid cannot be charged quickly, and for most types, it takes 14 to 16 hours to fully charge. The battery must always be fully charged. Low battery power can lead to sulfation, which can damage the performance of the battery. Adding carbon to the negative electrode can reduce this issue, but it can also lower the specific energy.
