Cost/benefit analyses of a new battery pack management technique for telecommunication applications: future directions with fuel cell/battery systems

A new approach to battery pack and fuel cell management, the battery health manager-BHM™ and the fuel cell health manager-FCHM™, both cell-based techniques that manage power supplies without disrupting operations, was described at INTELEC 2002. Using the BHM, each cell (or module) in a battery pack can be cycled to up to a full-load discharge, and then smart charged, in a regenerative cycling process, to optimize cell capacity and life, without removing the cells from the battery string or compromising inter-cell connections. A historical database providing full state-of-health (SOH) information for backup battery packs is now available based on BHM™ technology. In addition to conventional information such as float voltage and current, temperature and internal resistance, the database created by BHM™ technologies is able to provide critical SOH information including voltage, current, and temperature for up to full discharge cycles on all the individual cells of the backup battery pack. A cost/benefit analysis of this powerful cell based technique for telecommunication applications is shown using this database as well as previously published data. A new concept, the fuel cell health management (FCHM™) technique, is applicable to fuel cell stack management. Fuel cells and fuel cell battery/hybrid systems are being considered for telecommunication applications. Because of the difficulty in storing hydrogen, in many fuel cell applications the hydrogen is produced chemically from fuel such as methanol or natural gas using a fuel reformer to strip out the hydrogen. In addition to hydrogen and carbon dioxide, reformates contain significant concentrations of carbon monoxide (CO) and H₂S, catalyst poisons which degrade the fuel cell electrical output. Recent results for a PEM fuel cell operating on 100 ppm CO show however that there is a significant loss of overall efficiency when compared with results for pure hydrogen. As an alternative cheaper approach than current practices to dealing with hydrogen contaminants, we have applied pulsed oxidation for the removal of CO and regeneration of CO poisoned cells using a microprocessor-based fuel cell health manager. We will present results for the regeneration of Pt a- nd Pt-Ru anodes in a PEM fuel cell fed with CO concentrations as high as 10,000 ppm (1% CO). The results of a cost/benefit analysis for the use of a FCHM™ on a 4 kW fuel cell system are also presented.