subject: Types of Lead Acid Batteries [print this page] Types of Lead Acid Batteries Types of Lead Acid Batteries
The lead acid battery is an electrical storage device that uses a reversible chemical reaction to store energy. They have a capacity of six or more volts, enough to power a vehicle or boat. Designed to serve multiple purposes, all the lead acid batteries provide either starting or deep cycle power. The only difference is in the amount and duration of power delivered.
Driven by diverse applications, two designations of batteries emerged. They are the sealed lead acid (SLA), which is also known under the brand name of Gel cell, and the valve regulated lead acid (VRLA). Technically, both batteries are the same. No scientific definition exists as to when an SLA becomes a VRLA. (Engineers may argue that the word sealed lead acid' is a misnomer because no lead acid battery can be totally sealed. In essence, all are valve regulated.)
The SLA has a typical capacity range of 0.2Ah to 30Ah and powers portable and wheeled applications. Typical uses are personal UPS units for PC backup, small emergency lighting units, ventilators for health care patients and wheelchairs. Because of low cost, dependable service and minimal maintenance requirements, the SLA battery is the preferred choice for biomedical and health care instruments in hospitals and retirement homes.
The VRLA battery is generally used for stationary applications. Their capacities range from 30Ah to several thousand Ah and are found in larger UPS systems for power backup. Typical uses are mobile phone repeaters, cable distribution centers, Internet hubs and utilities, as well as power backup for banks, hospitals, airports and military installations.
Unlike the flooded lead acid battery, both the SLA and VRLA are designed with a low overvoltage potential to prohibit the battery from reaching its gas-generating potential during charge. Excess charging would cause gassing and water depletion. Consequently, the SLA and VRLA can never be charged to their full potential.
Today, the flooded lead acid battery is used in automobiles, forklifts and large uninterruptible power supply (UPS) systems.
Among modern rechargeable batteries, the lead acid battery family has the lowest energy density. The largest single application of lead acid batteries is for the starting, lighting, and ignition of automobiles, trucks and buses. A lead-acid battery has been widely applied as an inexpensive reliable high safety secondary battery for SLI (starting, lighting and ignition) and other purposes.
