Failure detection of stationary lead-acid batteries in service in various regions of Brazil

The valve-regulated lead-acid battery (VRLA) was introduced in Brazilian telecommunications companies in 1992 and its application has been increasing since 1998 when the Telecommunications Brazilian Company-Telebras-was privatized and also with the introduction of the wireless telecom in Brazil. For the TelCos the reliability of the battery is very important since it is the guarantee that the telecommunications systems still work when occurs an AC energy breakdown. Nowadays the technical operators´ main concerns about batteries is how to know the real degradation of the battery in a brief time, without disconnect it from the energy system. Worldwide, one of the techniques that has been intensively studied for battery evaluation is the internal resistance measurement. Since 1996 CPqD has been working with impedance and conductance measurements techniques for battery evaluation and during this time we have been done several works with Brazilian Telcos. The purpose of this paper is to report the field work involving performance evaluation and failure detection of VRLA batteries through conductance, impedance and voltage measurements, sometimes with capacity tests too. The measurements were made at six-month intervals during one or two years periods. We are showing the comparative results of several examples of batteries installed in Central Offices, UPS, Outdoor Cabinets and Radio Base Station, in different regions of Brazil.