7
SECTION 8
8.0 Initial Charge
Batteries lose some charge during shipment as well as during
the storage period prior to installation. The battery should be
installed and given its initial charge as soon after receipt as
possible. At the completion of initial charge, record voltage
and specific gravity of each cell while still on charge and
retain records for future reference per Section 14.0.
8.1 Constant Voltage Method
Constant voltage is the principal method to give the initial
charge, as most modern chargers are of the constant volt-
age design. In addition, some systems have equipment
with voltage limitations making the use of constant current
charging undesirable.
Determine the maximum voltage that may be applied to the
system equipment. The voltage divided by the number of
cells connected in series will establish the maximum voltage
per cell that may be used.
For lead-calcium types refer to Table A for initial charge volt-
ages and charge durations. Select the highest voltage the
system will allow, to perform the initial charge in the shortest
period of time.
The recommended time periods are considered minimum.
Raise the voltage to the maximum value permitted by the
system equipment. When charging current has tapered
and stabilized (no further reduction for 3 hours), charge for
the hours shown in the appropriate table and for the battery
temperature, at the time of stabilization, until the lowest cell
voltage ceases to rise. Monitoring of cell voltages should be
started during the latter 10% of the applicable time period to
determine lowest cell in battery.
INITIAL CHARGE
Recommended Voltages and Time Periods
NOTE:
Time Periods listed in tables A and B are for cell
temperatures from 70°F (21°C) to 90°F (32°C). For tem-
peratures 55°F (13°C) to 69°F (20.5°C) double the number
of hours. For temperatures 40°F (4°C) to 54°F (12°C) use
four times the number of hours.
TABLE A
Lead-Calcium Types
Cell Volts
Time-Hrs.
1.215
sp. gr.
Time-Hrs.
1.250
sp. gr.
2.24
444
—
2.27
333
—
2.30
210
—
2.33
148
333
2.36
100
235
2.39
67
160
2.42
48
108
2.45
38
73
2.48
36
55
2.50
32
44
8.2 Initial Charge — Electrolyte
Levels
During the initial charge, there will be an increase in the
electrolyte levels and they may go above the high level
mark. (See Section 3.2). This is due to gases, that were lost
during transportation or standing in storage, being restored
to the cells. Do not remove any electrolyte even though
levels may be above high level. When battery is placed
on floating charge (See Section 9.2). the electrolyte levels
should return close to the high level line.
Removal of electrolyte during the initial charge with sub-
sequent restoration with water of levels which have fallen
following placement on float charge mode could result in
variations or sub-normal specific gravity values.
SECTION 9
9.0 Operation
9.1 Floating Charge Method
In this type of operation, the battery is connected in parallel
with a constant voltage charger and the critical load circuits.
The charger should be capable of maintaining the required
constant voltage at battery terminals and also supply a nor-
mal connected load were applicable. This will then sustain
the battery in a fully charged condition and also make it
available to assume the emergency power requirements,
in the event of an AC power interruption or charger failure.
9.2 Float Charge — Float Voltages
Table B lists recommended float voltage ranges for lead-cal-
cium battery systems. Select a per cell and overall battery
float voltage appropriate for the specific gravity of the bat-
tery.
TABLE B
Recommended Float Voltages
Lead Calcium Types:
Nominal 1.215 sp. gr.
2.17 to 2.25 VPC
Nominal 1.250 sp. gr.
2.23 to 2.33 VPC
Modern constant voltage output charging equipment is
recommended for the float charge method of operation of
GNB
stationary type batteries. This type of charger, properly
adjusted to the recommended float voltages, together with
adherence to recommended maintenance procedures, will
maximize battery reliability and life.
After the battery has been given its initial charge (see
Section 8.0), the charger should be adjusted to provide the
recommended float voltage (see Table B) at the battery ter-
minals. For example, a 60-cell lead-calcium battery should
have 132.6 volts maintained at its terminals. . . 60 cells x
2.21 volts per cell (V.P.C.) = 132.6 volts.
