Float Volts per Cell
Nominal
Specific
Lead
Lead
Gravity
Antimony
Calcium
1.170
2.13 to 2.20
----
1.215 (std.)
2.15 to 2.22
2.17 to 2.26
1.250
----
2.21 to 2.30
1.300
----
2.25 to 2.34
Equalizing Volts per Cell
Nominal
Specific
Lead
Lead
Gravity
Antimony
Calcium
1.170
2.33
----
1.215 (std.)
2.33
2.33 to 2.38
1.250
----
2.38 to 2.43
1.300
----
2.45 to 2.50
Increasing the specific gravity for a given cell
size will increase its output, but may reduce its
life. In some applications where battery physical
size must be kept as small as possible, the higher
specific gravities are specified.
d.
End Voltage (per cell).
The end voltage (per cell) is the voltage at which
the battery is set to disconnect from the UPS to
prevent overdischarging the battery. End voltages
used in the industry are 1.60, 1.63, 1.65, 1.67
(standard), 1.70, and 1.75 volts per cell. Any
discharge below 1.50 volts per cell can damage the
battery. Raising the end voltage will increase the
battery size for a given load if other parameters
are not changed.
e.
Ventilation.
Ventilation of storage battery areas is required by
NFPA 70. A safe environment for such areas exists
where the concentration of gaseous hydrogen does not
exceed 2 percent accumulation per unit volume.
Factors used to determine this condition are the
size and type of battery to be charged; room volume;
maximum volume of hydrogen gas emitted during
charging; and ventilation rate. Approximately 0.016
cubic foot per hour of hydrogen gas is produced from
each fully charged wet cell per charging ampere.
Valve-regulated cells typically produce considerably
less. Once sufficient ventilation is produced, no
need exists for explosion-proof wiring, vapor-proof
fixtures, or other special provisions. Mechanical
ventilation (an exhaust fan) should be provided in
accordance with the battery manufacturer's
SECTION 16265A
Page 35
Previous Page
