Operational characteristics of Powersafe batteries in BT power equipment racks

Arising from unexpected operating characteristics of batteries used in British Telecom (BT) power equipment racks from 1989 onwards, a new field investigation policy was developed between BT and its battery suppliers. This paper reflects the findings of the first 18 months of investigation with respect to Powersafe batteries under the “adopt an exchange” scheme. Initially, the main parameters for investigation were battery temperature, and battery float current, the objective being to determine if one parameter was driving the other. In order to do this, a comprehensive list of both battery and equipment characteristics were measured, and as a consequence conclusions have been made not only on the battery temperature and its float current, but on peripheral issues such as battery ventilation and battery differential temperature. A proposal is made to moderate the battery differential temperature through ventilation, and observations reflecting the performance of monitors are reviewed. A new approach is proposed to address the subject of battery monitoring which consists of the parallel operation of diagnostic and predictive techniques