Nick Williard, Wei He, Michael Osterman, Michael Pecht
The functionality and reliability of portable microelectronics systems is often limited by the ability of the power supply to provide a continuous source of energy. In modern portable applications, lithium ion, and lithium polymer batteries have become the choice energy system. The selection of these batteries is based on their high volumetric and gravimetric energy densities and their ability to be scaled up or down to fit the needs of a dynamic range of applications such as automobiles, unmanned aerial vehicles (UAV), active RFID tags and wireless sensors. Performance of these batteries is heavily dictated by the use conditions such as current rate of charge and discharge. In order to optimize performance of electronic systems, the user must know the state of charge (SOC) of the battery so that periods of recharge can be anticipated and scheduled. The user must also know the state of health (SOH) of the battery in order to plan for the replacement of the battery.
In this paper battery design parameters and how they relate to the inherent battery capacity are discussed. Considerations for predicting capacity under various discharge current rates are given. Also, the hardware and software requirements of determining SOC and SOH of lithium ion batteries in portable applications are discussed. The resulting goal of these considerations is for the implementation of a full battery prognostics and health management (PHM) system capable of providing predictions for remaining useful performance.
Keywords-telecom equipment; data center; free air cooling; reliability; prognostics health management (PHM )
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