Thermal baffling of batteries in a simulated optical network unit: thermal design and analysis

A local powering method for the optical network unit (ONU) is considered in which commercial AC is used to power the ONU normally and batteries located in the ONU provide back-up power during power outages. Because batteries are such an integral part of this scheme, its success depends critically on the cost, reliability, and life expectancies of the batteries. The authors describe a 'thermal baffling' technique, in which a barrier is used to buffer the batteries from the heat of the ONU electronics. This technique is currently being used in 10 simulated ONUs that are part of a Bellcore field demonstration. A technique for quantifying the benefits of temperature control on battery life is presented and used to develop a temperature design criterion for the simulated ONUs. A thermal model for a generic ONU enclosure with a thermal baffle is presented, and results from the model are compared with experimental data from a simulated ONU. Finally, initial data from the field demonstration are presented and discussed.<>