Lucent Technologies Lineage
®
2000 ECS/GPS Battery Plant J85500G-2
Issue 6 May 1999
Engineering, Planning and Ordering 3 - 3
Battery voltage
Battery plant operating voltage is directly related to the
recommendations of the battery manufacturer. These
recommendations must include:
•
the steady-state voltage for maximum life or float voltage,
•
the end voltage after complete discharge,
•
the maximum recharging voltage, and
•
the initial charging method.
Equalize or boost charging is recharge capacity greater than the
float voltage.
Rectifier and load equipment voltage ranges are associated with
typical battery voltage ranges.
A battery string consists of a number of battery cells connected
in series to provide the desired plant operating voltage. Although
virtually any plant voltage is possible by varying the number of
cells per string, this manual deals specifically with nominal 48
volt systems.
The nominal cell voltage of lead-acid-type batteries is usually
defined as 2 volts. The actual recommended float voltage of
lead-acid batteries differs slightly among vendors and varies
with chemistry. The most common float voltages are 2.17, 2.27
and 2.35 volts per cell.
Nominal 48 volt systems typically use 23 or 24 cell battery
strings for float voltages that range from 49.91 to 56.40 volts per
string. Standard arrangements are more commonly available for
24-cell strings than for 23-cell strings. The Lucent Technologies
VR-series battery, for example, is designed to float at 2.27 volts
per cell and is available in 24-cell arrangements for float voltage
of 54.48 volts per string, or 23-cell arrangements for loat voltage
of 53.21 volts perstring. Lucent Technologies KS-type flooded
lead-acid batteries float at 2.17 volts per cell (52.08 volts per
string).
Customers should select a battery type and vendor based on their
maintenance and replacement strategies, weighing initial cost,
expected life, service requirements and replacement cost against
each other. Once the battery is chosen, the following information
is needed for the battery plant engineering process.
6. Float voltage per cell: ____ volts
