Nickel Cadmium Battery Systems for Aerospace Support Equipment

This paper describes a sintered plate nickel cadmium battery system, including charge and discharge regulating circuitry capable of delivering 8 kilowatts of power within a 27.4 to 31 volt dc limit, and discusses the characteristics of these batteries in these applications. Flexibility for complete or temporary power interruptions are provided. Nickel cadmium batteries have been chosen for these operations because of (1) their capability of delivering high levels of current from small packages and (2) their proven high reliability in extended service. To optimize the performance of the nickel cadmium battery requires controlled charging profiles. Generally, energy must be restored to the battery at 140% of the discharge ampere hour rating. Circuitry for automatically accomplishing this charge are described. The regulation of output voltage between 31 and 27.4 volts was deemed critical in this application. End cell switching techniques and control methods are described for improving the voltage regulation of the system under conditions of high and low load values.