Lead-acid batteries are a type of rechargeable battery commonly used in vehicles and backup power systems. They consist of lead dioxide and sponge lead plates submerged in a sulfuric acid solution. When the battery discharges, a chemical reaction occurs, producing electricity to power devices like cars and forklifts. These batteries are popular due to their low cost and ability to deliver high surge currents. However, they are relatively heavy and have a shorter lifespan compared to other battery types, such as lithium-ion batteries. Despite this, their reliability makes them a staple in many applications, including uninterruptible power supplies (UPS).