C&D Technologies RS-990 Liberty Series 1000 - Manual (Page 19)

Higher than normal storage temperature (77°F [25°C] nominal) will
accelerate internal self-discharge of a battery by a factor of two for
each 15°F (9°C) over nominal 77°F (25°C) storage temperature. This,
in turn, will reduce the allowable time before initial and subsequent
charging.
Therefore it is very important that boost charges be given at the
appropriate time to avoid major remedial action or damage to
product.
All batteries, including Liberty Series 1000, are capable of generating
potentially explosive gases when charged at higher than normal
voltages typical of initial or equalizing charge. The Liberty Series 1000
cells are equipped with a “flame arrestor and pressure relief valve”
assembly that seals the cells during normal charge and operation but
allows it to safely vent in case of overcharge. Removing the cover
and/or valve assembly can cause the release of potentially explosive
gases and such action will void the warranty.
CAUTION
Never expose a cell or battery to sparks or an open flame.
When working on a battery, discharge static electricity on the
body, tools, etc., by touching a grounded surface in the vicinity
of the battery rack.
1.3 Constant voltage charging
The recommended method of providing an initial/equalize charge is to
first determine the maximum allowable voltage that may be applied to
the connected equipment. Divide this by the number of cells in the
battery to obtain maximum average voltage per cell allowed by the
equipment. Adjust this number down to a recommended initial value
found in Table 3 and continue charging at this voltage for the time
specified. Next put the battery at the recommended float voltage for a
17
TABLE 3
CHARGE VOLTAGES FOR LIBERTY SERIES 1000 CELLS
CHARGE VOLTAGES AT 77°F (25°C)
Cell Type Open Minimum Float Voltage Initial Charge Typical Charging
Circuit Cell (Vpc) Voltage (Vpc) Time for Initial
(Vpc) Voltage (Vpc) Charge
All Liberty 2.15 2.20 2.26 +/- 0.01 2.33 +/- 0.02 12 - 16 Hours
Series 1000 ®
Note 1:
1 - Applies to average cell voltage. Battery voltage should be set at average cell voltage multiplied by the number of cells in unit or string. Individual cell voltages may
vary by +/- 0.05 Volts from the average.
2 - Charging time will vary due to open circuit stand, temperature and charger voltage available.
3 - If cell temperature is below 60°F (16°C), double the charge time for initial or equalize charge.
Note 2:
All lead-acid batteries lose a certain amount of charge when removed from a constant voltage source charger, set at a potential that is higher than the open circuit
potential of the battery. As the charge is lost, the electrochemical process produces lead sulfate in the positive and negative plates of every cell in the battery. If left
uncharged for a significant period of time, the lead sulfate will begin to form large crystals of lead sulfate. Because of their size, these crystals may be somewhat
difficult to reduce (break down) through normal charging procedures and may inhibit the complete electro/chemical process necessary to sustain a healthy lead-acid
battery. Frequently, higher-than-normal charging potentials or even more sophisticated remedial approaches may be necessary to recover the affected battery. In
cases of severe sulfation, replacement may be the only solution.