Considerations for the configuration and arrangement of valve regulated monobloc batteries in enclosures

In today´s rapidly changing and increasingly competitive world of telecommunications power, there is a continuous requirement for a reduction in costs while achieving increases in overall system power density. Much of this is being driven by the demand that has been created from the Internet/data market explosion. The combination of these conditions has led to the design of increasingly smaller battery enclosures that are utilized in both wireless and outside plant fixed wired applications. Almost exclusively, these enclosures utilize valve regulated lead acid cells and batteries (VRLA), and frequently there are no temperature controls for the battery compartments. The magnitude of the installed base of cabinets and batteries, and the impact of uncontrolled environments, has created concern about the actual life of these batteries and the safety of the systems. As a result there have been a number of studies done reporting on the effect of high temperatures on lead acid batteries, and thermal models developed to characterize how ambient conditions impact the actual temperature performance of the batteries themselves. It is the goal of this paper to present the data and results of a series of tests run to characterize the thermal behavior of typical 10 year front terminal monobloc batteries in a standard cabinet enclosure under recharge conditions. The variables examined include; battery spacing, rack vs. cabinet systems, and the effects of forced air flow. In addition the paper considers industry standards on these issues and explores recommendations for future studies