C&D Technologies RS-990 Liberty Series 1000 - Manual (Page 25)

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If continuous adjustment of the battery plant charger voltage relative
to ambient temperature is impractical, it is recommended the
appropriate fixed float voltage setting of Table 4 is used.
At temperatures below 77°F (25°C), battery capacity will be reduced
by approximately 0.5 percent per degree Fahrenheit.
Caution must be exercised when operating or storing batteries at low
temperature because of the possibility of electrolyte freezing.
Although the specific gravity of your fully charged battery may present
no freezing problem, the discharged specific gravity may. Refer to Part
1, Section 2, Table 1.
3.5 High ambient temperature
At higher than normal ambient temperature 77°F (25°C), gas that may
exceed the rate of recombination will be evolved internally. This gas
will vent to the atmosphere when internal pressure causes the relief
valve to open. This is the equivalent of water loss that cannot be
replenished and therefore accelerates the rate of dry-out, resulting in
loss of capacity. The Liberty Series 1000 valve-regulated battery
should be placed in an operating environment in which the battery
room temperature does not
exceed 90°F (33°C). The Liberty Series
1000 batteries can tolerate a temperature up to 120°F (49°C) with
significant de-rating of expected life. They must be contained in the
optional steel jacket if temperatures are expected to exceed 100°F
(38°C). Valve-regulated lead acid batteries will incur a 50 percent
reduction in expected life for each 15°F (9°C) in average temperature
above 77°F (25°C).
Note: Operation at high temperature causes VRLA batteries to draw
more current thereby increasing the internal temperature of the
cells. As the temperature increases more current is supplied to
the cells. This condition can lead to destruction of the cells by
an effect sometimes referred to as “thermal runaway.” Care
should be exercised when ambient temperatures exceed 90
Fahrenheit.
TABLE 4
ADJUSTMENT OF FLOAT VOLTAGE FOR TEMPERATURE
FOR LIBERTY SERIES 1000 ®
Given in volts per cell and accuracy of adjustment
AMBIENT TEMPERATURE RANGE
67°F-87°F 80°F-100°F 90°F-110°F 100°F-120°F
2.26 Vpc 2.24 Vpc 2.22 Vpc 2.20 Vpc
+/-0.010 Volts +/-0.010 Volts +/-0.010 Volts +/-0.010 Volts
Note:
1. If the average ambient temperature changes over time more than 20°F (11.1°C) and no correction in float
voltage is made, permanent battery degradation will occur.
2. Temperature variations within the battery string of more than 5°F (2.8°C) can cause cells at the extremes
to be either over or under-charged, depending on where the float voltage has been set.