Exide Technologies Section 92.61 - Manual (Page 24)

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C. Individual cell(s) float is more than +/- 0.05 volts from aver-
age.
D. Accurate periodic records (See Section 15) of individual
cell voltages show an increase in spread since the previ-
ous semi-annual readings.
An annual equalize charge is recommended to help ensure
uniform cell performance.
13.2 Equalizing Charge Method
Constant voltage charging is the method for giving an equal-
izing charge. Determine the maximum voltage that may be
applied to the system equipment. This voltage, divided by the
number of cells connected in series, will establish the maxi-
mum volts per cell that may be used to perform the equalizing
charge in the shortest period of time (not to exceed 2.35 VPC
applicable at 77°F, 25°C). Refer to Table C for voltages and
recommended time periods.
NOTE: Charge volts listed in Table C are for 77°F. For other
temperatures a compensation factor of .003 V/°F (.0055
V/°C) per cell is recommended. The minimum voltage is
2.20 VPC. The maximum voltage is 2.35 VPC. Temperature
correction does not apply outside of this range.
V corrected = V25°C - ((T actual-25°C) x (.0055 V/°C))or
V corrected = V77°F - ((T actual-77°F) x (.003 V/°F))
See Appendix A for standard values.
STEP 1
A. Set constant voltage charger to maximum setting without
exceeding 2.35 VPC.
Example: For a target charge of 2.35 VPC on a 24-cell
system, you would set the charger voltage to 56.4 volts.
B. Record time and current at regular intervals – every hour
as a minimum.
C. Continue charging the battery until there is no further drop
in charge current over 3 consecutive hours.
D. When the current has stabilized, proceed to step 2.
STEP 2
A. Continue the charge for the time listed in Table C
depending on the charger voltage setting. The time is IN
ADDITION to the time spent charging in Step 1.
Example, charge for 12 hours if the charger voltage is set to
2.35 VPC.
TABLE C
EQUALIZE CHARGE (77°F)
CELL VOLTS TIME (HOURS)
2.30 24
2.35 12
B. Record cell voltages hourly during the last 3 hours of the
charge time. If, after the charge time has completed, but the
lowest cell voltage has continued to rise, you may extend the
charge, monitoring cell voltages hourly, until the lowest cell
voltage ceases to rise.
C. Proceed to Step 3.
STEP 3
The Equalize charge is now complete. Charger voltage can
now be reduced to float voltage setting per Section 12.2. For
a target float charge of 2.25 VPC on a 24-cell system, you
would set the charger voltage to 54 volts.
SECTION 14
14.0 Pilot Cell
A pilot cell is selected in the series string to reflect the gen-
eral condition of cells in the battery. The cell selected should
be the lowest cell voltage in the series string following the
initial charge. See Section 11.0 - Initial Charge. Reading and
recording pilot cell voltage monthly serves as an indicator of
battery condition between scheduled overall individual cell
readings.
SECTION 15
15.0 Records
The following information must be recorded at installation,
and annually for every year of operation after installation.
These records must be maintained throughout the
life of the battery and made available for review by GNB
representatives for capacity or life related warranty claims.
Failure to collect and store these maintenance data will void
the warranty. Please review the warranty statement specific
to the battery application for any additional requirements.
• Individual cell voltages
• Overall string voltage
• Ambient temperature immediately surrounding battery
• Battery temperature at several places throughout the string.
Recommend 1 reading per battery stack. More data points
are recommended for larger batteries and to check for
temperature gradients. Readings on the tray, cell cover
or negative terminal are good places to measure battery
temperature. Take readings away from HVAC sources.
• Float current measured at stack to stack connections
(optional)
• Ohmic measurements (optional). Baseline ohmic readings
of individual cells should be taken 6 months from the date of
initial charge.
• Retorque connectors as part of annual maintenance.
ONCE PER YEAR READINGS ARE THE ABSOLUTE
MINIMUM REQUIRED TO PROTECT WARRANTY. More
frequent readings are recommended, especially for critical
sites. Good record-keeping will prevent minor issues from
escalating into more serious problems over time. See Figure
25 for sample record-keeping form.