L2
L5
L4
L3
L1
L6
L7
L7
1
30
60
90
120
150
179
180
320
280
240
200
180
120
80
40
1
Minutes
Min
Lead-Acid Storage Batteries
DOE-HDBK-1084-95
SIZING AND SELECTION
Rev. 0
Page 27
Batteries
SIZING AND SELECTION
Sizing and selection of lead-acid batteries should be performed according to ANSI/IEEE Std
485, IEEE Recommended Practice for Sizing Large Lead Storage Batteries for Generating
Stations and Substations. As described earlier, the duty cycle is the most important criterion
in battery sizing and selection. ANSI/IEEE Std 485 contains directions as well as a sample
exercise for determining the duty cycle. A simple duty cycle diagram is shown in Figure 15.
Each of the loads (designated by L
) requires a certain amperage for a specified time and
1-6
duration. In the example duty cycle, a randomly occurring load (L ) is assumed to occur in
7
the 120th minute. The placement of randomly occurring loads in the duty cycle is also
covered in ANSI/IEEE Std 485.
Figure 15. Diagram of a duty cycle.
