Sizing Batteries for Generating Stations

Wheelchair batteries II: Capacity, sizing, and life

“…The average load for the indoor test in Table 2 is 19.2 watts, or 0.8 ampere, and for the outdoor test it is 129 watts, or 5 .4 amperes . of the battery in terms of energy, watt-hours, which is a scalar function that equals the sum of the individual power demands on the battery during discharge by Pavg t = Pitt + P2t2 + P3t3 + [8] where the P i are variable loads, and ti are the corresponding times for each load . Since t is the total time for discharge of the battery, and for repeating duty cycles, it is convenient to define the time fraction as pi = ti/t Substituting the time fraction in Equation [8] gives The average power can be predicted for any repeating duty cycle .…”

“…In order to apply the results of the measurement of duty cycles to predict the discharge time for a particular battery (the first sizing approach), a method for taking into account the variation in power demand and time must be considered . Hoxie (3) presented an approach in 1954 that is still being used by the battery industry (8) . In order to get good results with the Hoxie method, it is necessary to carefully consider each part of the duty cycle and in some cases a proper interpretation is necessary.…”

“…The second approach to sizing is to determine the size of the battery in terms of positive plates required in each cell for the expected duty cycle and required time of discharge . An approach is given by Hoxie (3) and Migliaro (8), but they use a method which has certain difficulties when considering duty cycles with decreasing rate of discharge and complicated duty cycles . In this paper, the revised Palmgren-Miner Rule approach which is more straightforward will be used.…”