Introduction
Battery system maintenance and monitoring are key elements in the reliability of any DC battery powered system and are IEEE and NERC requirements. Also, most battery manufacturers require regular maintenance and maintenance records of purchased batteries for any warranty claims. The nature of construction of VRLA batteries prevents internal inspection of cell plates and elements that are normally done as part of standard maintenance of flooded lead acid batteries. This limits the ability to identify and record problems with batteries or their cells. However, there are still key elements of a cell’s condition which can be identified and documented to show a battery or cell is operating normally or exhibiting a problem. These include: cell voltage, internal resistance value and temperature. With the right equipment and measurement frequency, potential problematic cells can be identified and addressed before a failure occurs and renders the back up power source unavailable.