Civil Engineering Reference
In-Depth Information
FIGURE 10-13
Charge/discharge cycle life of sealed nickel-cadmium battery versus temperature and depth
of discharge.
FIGURE 10-14
Lead-acid battery capacity variations with temperature.
means that the battery at a given temperature can deliver the same number
of equivalent full cycles of energy regardless of the depth of discharge. The
total Wh energy the battery can deliver over its life is approximately constant.
Such observation is useful in comparing the costs of various batteries for a
given application.
The life consideration is the dominant design driver in the battery sizing.
Even when the load may be met with a smaller capacity, the battery is
oversized to meet the life requirement as measured in number of charge/dis-
charge cycles. For example, with the same Wh load, the battery that must
charge/discharge twice as many cycles per period needs approximately
double the capacity to have the same calendar life.
