# IEEE Std 485-2020 pdf free

**IEEE Std 485**-2020 pdf free.IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications.

For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary Online , or IEEE Std 1881TM, 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 specified time periods.

equalizing charge: A charge, at a level higher than the normal float voltage, applied for a limited period of time, to correct inequalities of voltage, specific gravity, or state of charge that may have developed between the cells during service.

float service: Operation of a dc system in which the battery spends the majority of the time on foat charge with infrequent discharge. Syn: standby service.

NOTE一The primary source of power is normally the battery charger or rectifier.

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.

period: An interval of time in the battery duty cycle during which the current (or power) is assumed to be constant for purposes of cell sizing calculations.

rated capacity: The capacity assigned to a cell by its manufacturer for a given discharge rate, at a specified electrolyte temperature, to a given end-of discharge voltage.

The loads applied to the battery are normally categorized as constant power, constant resistance, or constant current. However, for sizing purposes, the loads are treated as constant power or constant current. The designer should review each system to be sure all possible loads and their variations are included. If the loads are solely constant power loads, sizing as described in Annex D is appropriate and simplifies the sizing process.A duty cycle diagram showing the total load at any time during the cycle is an aid in the analysis of the duty cycle. To prepare such a diagram, all loads (expressed in either current or power) expected during the cycle are tabulated along with their anticipated inception and shutdown times. The total time span of the duty cycle is determined by the requirements of the installation.

Loads whose inception and shutdown times are known are plotted on the diagram as they would occur. If the inception time is known, but the shutdown time is indefinite, it should be assumed that the load continues through the remainder of the duty cycle. Similarly, if the shutdown time is known, but the inception is not, it should be assumed that the load begins when the duty profile begins.

Loads that occur at random should be shown at the most critical time of the duty cycle in order to simulate the worst-case load on the battery. These are noncontinuous or momentary loads as described in 4.2.2 and 4.2.3.To determine the most critical time, it is necessary to size the battery without the random load(s) and to identify the section of the duty cycle that controls battery size. Then the random load(s) should be superimposed on the end of that controlling section as shown in Figure 1 (see 6.4.4).IEEE Std 485 pdf download.