IEEE Std 485-2020 pdf download – IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications.
3. Defi nitions For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary Online 5 , or IEEE Std 1881™, IEEE Standard Glossary of Stationary Battery Terminology, should be consulted for terms not defined in this clause. cell size: The rated capacity of a cell or the number of positive plates in a cell. continuous load: Loads that are energized throughout the duty cycle. coup de fouet: Initial voltage drop and recovery experienced when discharging a lead-acid battery. duty cycle: The sequence of loads a battery is expected to supply for specifi ed time periods. equalizing charge: A charge, at a level higher than the normal fl oat voltage, applied for a limited period of time, to correct inequalities of voltage, specifi c gravity, or state of charge that may have developed between the cells during service. fl oat service: Operation of a dc system in which the battery spends the majority of the time on fl oat charge with infrequent discharge. Syn: standby service. NOTE—The primary source of power is normally the battery charger or rectifi er. 6 momentary load: loads that can occur one or more times during the duty cycle, but are of short duration, not to exceed one minute during any occurrence. non-continuous load: loads energized only during a portion of the duty cycle.
4. Defning loads 4.1 General considerations The duty cycle imposed on the battery by any of the conditions described herein depends on the dc system design and the requirements of the installation. The battery supplies the dc power requirements when one or more of the following conditions occur: a) Load on the dc system exceeds the maximum output of the battery charger b) Output of the battery charger is interrupted c) AC power to the battery charger is lost [may result in a greater dc power demand than item b)] The most severe of these conditions, in terms of battery load and duration, should be used to determine the battery size for the installation. 4.2 Load classifcation The individual dc loads supplied by the battery during the duty cycle are classified as continuous or noncontinuous. Noncontinuous loads lasting 1 min or less are designated “momentary loads” and should be given special consideration (see 4.2.3).