A flexible Wireless Sensor Network platform for implementation of diverse applications has been developed and deployed at Instituto Superior Tecnico – Technical University of Lisbon (IST-TUL). Since its initial deployment in 2007, this testbed has grown steadily, supporting new nodes, applications and experiments. However, some initial problems, which were solved on an ad hoc basis, were becoming more serious as the network spanned throughout the campus. Major issues, like global power management, have to be tackled not only with traditional protocol level approaches but also from a system’s viewpoint, providing solutions capable of guaranteeing a consistent testbed. We discuss the main issues related with the development of power management solutions, presenting our architecture, design choices and implementation, and address the lessons learnt from its integration. Experimental evaluation of our solution has shown considerable energy savings, extending network lifetime by up to nine times.