The capacity of batteries is not a fixed value as suggested above but is
affected by discharge rates, operating schedules, temperature, and other factors.
At best, therefore, capacity is an estimate of expected life under certain
conditions. Table 2–1 illustrates approximate service capacities for several
sizes of carbon-zinc batteries at three values of current drain at 21°C. Under
the conditions listed, the AA cell has a capacity of (3 mA)(450 h) 1350
mAh at a drain of 3 mA, but its capacity decreases to (30 mA)(32 h) 960
mAh at a drain of 30 mA. Figure 2–14 shows a typical variation of capacity
of a Ni-Cad battery with changes in temperature.