tailieunhanh - Battery Basics Everyone Should Know phần 2

Những bài viết này đã được công bố trên các tạp chí thương mại khác nhau và đã đạt được sự quan tâm của nhiều độc giả. Điều này đi trở lại cuối những năm 1980 và các chủ đề tài liệu được như hiệu ứng nhớ của pin NiCd và làm thế nào để khôi phục lại chúng. | The SLA must always be stored in a charged state. During the mid 1970s researchers developed a maintenance-free lead acid battery which could operate in any position. The liquid electrolyte was transformed into moistened separators and the enclosure was sealed. Safety valves were added to allow venting of gas during charge and discharge. Driven by diverse applications two designations of batteries emerged. They are the sealed lead acid SLA also known under the brand name of Gelcell 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 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. Among modern rechargeable batteries the lead acid battery family has the lowest energy density. For the purpose