Exide Technologies Section 93.10 - Manual (Page 14)

NORMAL VOLTAGE RANGE
Average
Type Float Voltage Variation
Lead-Antimony
Nominal 1.215 sp. gr. 2.15 to 2.17 V.P.C. ± .04 V.P.C.
Nominal 1.250 sp. gr. 2.19 to 2.23 V.P.C. ± .04 V.P.C.
Lead-Calcium
Nominal 1.215 sp. gr. 2.17 to 2.25 V.P.C. ± .05 V.P.C.
Nominal 1.250 sp. gr. 2.23 to 2.33 V.P.C. ± .05 V.P.C.
Nominal 1.300 sp. gr. 2.28 to 2.37 V.P.C. ± .05 V.P.C.
12.1 Cell Voltage Variation
Damp Covers
Cell voltage variation can also be the result of damp cell cover
tops. Spilled electrolyte when taking hydrometer readings can
result in parasitic currents paths across the tops of cell covers.
This reduces the float current through the cell resulting in volt-
age variations. See Section 18.0 - Battery Cleaning —to correct
damp cover condition.
12.2 Cell Voltage -
Temperature Correction
To properly analyze cell uniformity within the string, cell voltages
should be corrected for cell electrolyte temperature. Cell voltage
variation that may have developed since a previous quarterly set
of readings may be due to cell temperature variations within the
string that may have resulted from a change in ambient condi-
tions. Therefore, correcting cell voltage for cell temperature may
make it unnecessary to apply an equalizing charge which oth-
erwise had been believed necessary.
See Section 10.1 -
Equalizing Frequency.
12.3 Correction Factor
The temperature correction factor for cell voltage equals 0.003
volts for each degree fahrenheit (0.0055V/C°) using a base 77°F
(25°C). The correction is added to the measured cell voltage
above 77°F (25°C) and subtracted below 77°F (25°C).
Example: Measured cell voltage = 2.19V @ 87°F(30.5°C) cell
temperature. Correction = 10°F x .003V (3.5°C x .0055V) =
.03V. Therefore, corrected cell voltage = 2.19V + .03V = 2.22
volts.
If the cell temperature in the example had been 67°F (19°C), the
correction would be .03 volts which is subtracted from the mea-
sured voltage of 2.19V. The corrected cell voltage = 2.19V - .03V
= 2.16V.
SECTION 13
13.0 Pilot Cell
A pilot cell is selected in the series string to reflect the gen-
eral condition of all cells in the battery regarding specific
gravities, float voltage and temperature. It serves as an indi-
cator of battery condition between scheduled overall indi-
vidual cell readings.
A slight amount of electrolyte may be lost each time a specific
gravity reading is taken, even though it is recommended that all
electrolyte in the hydrometer be returned to the cell after read-
ing. Therefore it is suggested that the pilot cell be changed to
another cell annually to provide a representative specific gravity
indicator for the battery.
SECTION 14
14.0 Records
A complete recorded history of the battery operation is
required. Good records will also show when corrective
action may be required to eliminate possible charging, main-
tenance or environmental problems.
Data should be recorded on Stationary Battery Maintenance
Report shown on page 15. Report headings should be filled
in completely on the date of installation.
The following data should be read and permanently record-
ed for review by supervisory personnel.
A. Upon completion of the initial charge and with the battery
floating at the desired float voltage for one week, read
and record individual cell voltages, connection resis-
tances, specific gravities [corrected to 77°F (25°C)],
ambient temperature plus cell temperatures and elec-
trolyte levels for 10% of the cells. The cell temperature
readings should be from each step or tier of the rack to
reflect temperature range of the battery.
This first set of readings will be the basis for comparison
with subsequent readings to reflect possible operating
problems and the need for corrective action.
B. Monthly - Observe the general appearance and cleanli-
ness of the battery. Record battery terminal voltage.
Check electrolyte levels and adjust if necessary. Check
for cracks in cells and leakage. Note any evidence of cor-
rosion at terminals and connectors. Record pilot cell volt-
age, specific gravity and temperature.
C. Quarterly - Supplement the monthly inspection and
record keeping with these additional measures. Check
and record the specific gravity and voltage of each cell.
Check and record the electrolyte temperature of one cell
on each level of individual racks.
D. Annual - Supplement quarterly reports with these extra
procedures. Make a detailed visual inspection of each
cell.
Tighten all bolted connections to the specified
torque values. Take and record connection resistances
of each cell to cell, cell to terminal, inter-level and load
connections. Remake any connections that are more
than 20% above installation base value. Check integrity
of the rack.
E. Any time the battery is given an equalizing charge (see
Section 10.1), an additional set of individual cell readings
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