Lucent Technologies Lineage
®
2000 ECS Battery Plant H569-416
3 - 8 Engineering, Planning & Ordering
Issue 2 August 1996
Table 3-C lists reserve time practices which have been used in
some telecommunications applications where maintaining
power to the load is critical. The figures are not intended to be
guidelines except in the absence of any specified customer
practices.
The noise and transient filtering capability of batteries may also
be considered in selecting the minimum battery capacity. Many
using systems specify the maximum allowable input noise.
Applications (such as UPS-supplied ac power) which do not
require batteries for dc reserve purposes may require batteries or
some other means for noise filtering. Compare the input noise
requirements of the using system to the ECS Battery Plant
specifications in Table 2-A.
Fill in the minimum reserve time below.
n. Minimum battery reserve time: ____ hours
Battery capacity is usually specified in terms of AMPERE-
HOURS, a measure of energy. The ampere-hour rating is the
product of a constant discharge current and the time to discharge
a fully charged battery to a specified end voltage. For
comparison purposes, most vendors of telecommunications
batteries specify ampere-hour ratings at the 8-HOUR RATE of
discharge to an end voltage of 1.75 volts per cell. Many battery
vendors also supply ratings at other discharge rates, such as 3, 5
and 24 hour rates.
Although ampere-hour ratings are useful for rough estimates of
battery size, actual battery selection should be based on curves
or tables of discharge current versus time.
Table 3-C: Reserve Capacity
Back-up Source
Typical Reserve Time
Attended Location Unattended Location
Stationary Engine
(automatic start)
3 hours
3 hours + travel time
Stationary Engine
(manual start)
4 hours
4 hours + travel time
Portable Engine
4 hours + travel time
Uninterruptible
Power Supply
0 hours (batteryless)
