Backup Battery cooling for Radio Base Stations

Abstract: Telecommunication systems are expanding around the world. From infrastructure networks to macro and pico systems, including RBS (Radio Base Station). To ensure the availability of RBS during a shortage on the electricity grid,EricssonABdeveloped BBS (Battery Base Stations) and BBU (Battery Base Units). The battery temperature is very critical to the battery life and the battery’s electrical performance. Taking energy efficiency and environmental issues in consideration, the need of a battery thermal management system increases. Therefore, sustainability is included to the core of this project. The performance of VRLA (Valve Regulated Lead-Acid) backup batteries for telecommunication RBS can be greatly improved by keeping an adequate control of the battery temperature. A solid relation between temperature and battery lifetime exists, which urges the need to keep batteries around their optimal life and performance temperature; 25°C. Different ways of cooling currently used atEricssonABare presented in this paper, including different ways of improving the cooling system performance. By testing, the variation of battery temperature with different air gaps separating the batteries were monitored. Other cooling methods, such as liquid cooling and PCM (Phase Change Materials) were also studied. Literature studies and test results showed a promising potential for such technologies to be granted green light to be used for future products. Tests were made to study the thermal conduction within battery cells. The efficiency of liquid cooling was tested as well; a cold plate heat exchanger was manufactured and used for the preliminary testing.