Exide Technologies Section 93.10 - Manual (Page 11)

8
TABLE C
Recommended Float Voltages
Modern constant voltage output charging equipment is rec-
ommended for the floating charger method of operation of
GNB
stationary type batteries. This type of charger, proper-
ly adjusted to the recommended float voltages, together with
adherence to recommended maintenance procedures, will
assist in obtaining consistent serviceability and optimum 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 C) at the battery ter-
minals. For example, a 60-cell lead antimony battery should
have 130 volts maintained at its terminals. . . 60 cells x 2.17
volts per cell (V.P.C.) = 130 volts.
Do not use voltages for lead-antimony types higher than
shown in table C, as excessive water consumption and
reduced battery life will result.
Lead-calcium types may be floated at any of the voltage val-
ues (Table C) shown for a particular nominal specific gravi-
ty. Use the lower VPC value in the appropriate nominal spe-
cific gravity group, where system equipment voltage limita-
tions will not permit higher values. The use of higher VPC
values may make it unnecessary to give an equalizing
charge. However, the use of higher float voltages where
high ambient temperatures prevail may result in reduced
battery life.
9.3 Voltmeter Calibration
Panel and portable voltmeters used to indicate battery float
voltages should be accurate at the operating voltage value.
The same holds true for portable meters used to read indi-
vidual cell voltages.
These meters should be checked
against a standard every six months and calibrated when
necessary.
9.4 Cycle Method of Operation
This method is recommended for lead antimony type cells
only. Lead-calcium cells should not be cycle operated.
In cycle operation, the degree of discharge will vary for var-
ious applications. Therefore, the frequency of recharging
will also vary. The recharge is conducted by manually start-
ing the charge, generally using the normal finish rate. The
amount of charge necessary depends on the number of
ampere hours discharge. If a shorter recharge period is
desired, higher charge rates equal to the eight-hour rate of
discharge may be used when the battery is more than 25%
discharged and the cell voltage on charge is below 2.33
volts.
When the cell voltage reaches 2.33, the charge rate should
be reduced to the normal finish charge rate. The finish
charge rate is defined as amperes equal in numerical value
to 5% of the cell’s 8-hour capacity in ampere hours. For
example, if the cell has an 8-hour capacity of 1680 AH, its
finish rate is 84 amperes. The charge should be stopped
when the specific gravity is ten (.010) points below the nor-
mal fully charged value.
The battery is now available for the next discharge require-
ment. The battery should be given an equalizing charge
monthly by continuing the regular charge until there is no
increase in specific gravity of the pilot cell for three hours.
when using the finish charge rate.
9.5 Recharge
All batteries should be recharged as soon as possible fol-
lowing a discharge (within 8 hours). With constant voltage
chargers, this will be accomplished automatically. However,
to recharge in the shortest period of time, raise the charger
output voltage to the highest value which the connected sys-
tem will permit. Do not exceed those voltage values listed in
Table D or Table E on page 9.
SECTION 10
10.0 Equalizing Charge
An equalizing charge is a special charge given a battery
when non-uniformity in voltage or specific gravity has devel-
oped between cells. It is given to restore all cells to a fully
charged condition using a charging voltage higher than the
normal float voltage and for a specified number of hours, as
determined by the voltage used.
Non-uniformity of cells may result from low floating voltage
due to improper adjustment of the charger or a panel volt-
meter which reads incorrect (higher) output voltage. Also,
variations in cell temperatures greater than 5°F (2.78°C) in
the series string at a given time, due to environmental con-
ditions or rack arrangement, can cause low cells.
10.1 Equalizing Frequency
The following guidelines cover lead-antimony and lead-
calcium types. Recommendations not applying to all types
will be so designated.
A. An equalizing charge should be given quarterly or as
required by conditions in the following paragraphs (Note:
lead-calcium types at nominal 1.215 sp. gr. floated 2.20
V.P.C., to 2.25 V.P.C., nominal 1.250 sp. gr. floated at 2.27
V.P.C. to 2.33 V.P.C. and nominal 1.300 sp. gr. floated at
2.31 V.P.C. to 2.37 V.P.C. may not require equalizing charges).
B. Equalize when the temperature corrected specific grav-
ity of the pilot cell (or any cell for the quarterly reading)
is more than 10 points below its full charge value. (See
Section 11.2)
C. Equalize when the floating voltage of the pilot cell (or
any cell for the quarterly reading) is below 2.13 volts
(nominal 1.215 sp. gr.), 2.18 volts (nominal 1.250 sp.
gr.) and 2.23 volts (nominal 1.300 sp. gr.) or more than
.04 volts below the average for the battery.
Lead-Antimony Types:
Nominal 1.215 sp. gr.
2.15 to 2.17 VPC
Nominal 1.250 sp. gr. 2.19 to 2.23 VPC
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
Nominal 1.300 sp. gr. 2.28 to 2.37 VPC