IEEE 1115A-2007 pdf free.IEEE Recommended Practice for Sizing Nickel-Cadmium Batteries for Stationary Applications Amendment 1: Additional Discussion on Sizing Margins.
It is prudent design practice to provide a capacity margin to allow for unforeseen additions to the dc system, and less-than-optimum operating conditions of the battery due to improper maintenance, recent discharge. ambient temperatures lower than anticipated, or a combination of these factors. A method of providing this design margin is to add a percentage factor to the cell size determined by calculations. If the various loads are expected to grow at different rates, it may be more accurate to apply the expected growth rate to each load for a given time and to develop a duty cycle from the results.
Note that the ‘margins” required described by and 6.3.3 of IEEE Std 323-1983 are to be applied during qualification” and are not related to design margin.”
The cell size calculated for a specific application will seldom match a commercially available cell exactly, and it is normal procedure to select the next higher cell size. The additional capacity obtained can be considered part of the design margin.
Insert the fiJlloH’ing subclause: Effects of cycling
If a nickel-cadmium battery is used in a stationary application with constant-voltage charging. in which charge-discharge cycling occurs, the battery state of charge (SOC) may be affected over time, and the available capacity may be reduced. Although the battery can usually be brought back to a full state of charge, it may require an off-line high-rate charge. Adjustment of the design margin provides a convenient method for compensating for this reduction in available capacity.
The extent to which available battery capacity may be affI2ctcd depends on the frequency and depth of cycling, charging regime. and the specific cell design. The battery manufacturer should be consulted for an estimation of the SOC after a specified number of cycles to a specified depth of discharge and based on the expected temperature, charging voltage(s), and charging time.IEEE 1115A pdf download.