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www.enersys.com Publication No. US-FL-IOM-002 January 2007
9.0 OPERATION
9.1
Float Operation
In this type of operation, the battery and the critical load circuits are continuously connected in
parallel with a constant voltage charger. The charger must be capable of:
• charging the battery from the discharged condition while supplying the DC power to the
connected DC load,
• providing the required constant float voltage, and
• providing voltage for equalizing the battery.
Float voltage sustains the battery in a fully charged condition and makes it available to provide
the emergency power required in the event of an AC power interruption or charger failure.
The table below lists the recommended average float volts per cell for nominal specific gravities
used in stationary service.
TABLE 9.1
RECOMMENDED AVERAGE FLOAT VOLTS PER CELL
FOR NOMINAL SPECIFIC GRAVITIES
Average Float Volts per Cell
Nominal Specific Gravity
Suffix
Antimony Calcium
1.250
1.215
B
None
2.17 - 2.21
2.15 – 2.20
2.21 – 2.30
2.17 – 2.26
An equalizing charge should be given when:
• the temperature corrected specific gravity has fallen more than 10 points (.010).
• one or more cells fall below the following critical voltages on float, corrected for
temperature. (Refer to Section 9.4 for equalizing charge.)
TABLE 9.2
MINIMUM TEMPERATURE – CORRECTED FLOAT VOLTAGES
Nominal Specific Gravity
Cell Voltage
1.215
1.250
2.13
2.14
Summary of Contents for PowerSafe Data Safe
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