APC Smartcell UPS battery - lead acid

Microprocessor-controlled SmartCell battery packs help provide Matrix-UPS' maximum datacenter security. If one battery should fail, the self-diagnosing LED can indicate the failure of an individual SmartCell. Because SmartCells are connected in parallel, the failed battery can then be "hot-swapped" out, while the remaining batteries keep the protected system up and running. Swapping batteries out of your Matrix won't happen very often. In fact, while other brands' UPSs may require two or three replacements, SmartCells might need only one during the service life of the unit. These extraordinary batteries last longer because they operate at room temperature. SmartCells also can be added easily to provide as much runtime as your application requires.