C&D Technologies RS-1476 Standby Battery Vented Cell - Manual (Page 20)

Single Cell Equalize: Some equipment may not have the required equalizing potentials available thereby
lengthening the charging period. As an alternative, a single-cell charger with ac line isolation may be paralleled
across the affected cell while still part of the overall battery to provide an over-voltage to the subject cell. Set
points similar to system equalize should be used. Termination of the charge should occur when the cell voltage
stabilizes (three consecutive hourly readings). Again, contact your C&D representative with questions on system
issues.
4.3 Performance characteristics
Battery performance is rated at 77°F (25°C). Operation at higher temperatures increases capacity, but reduces life
approximately 50 percent for every 15°F (9°C) rise. Operation at lower temperatures reduces capacity but extends life.
It is recommended to size the battery with additional margin for operation at the minimum expected temperature.
Battery performance at a given rate is related to the internal resistance of the cells and the external resistance of the
conductors connecting the cells. Aging increases internal resistance that results in greater voltage drop, or losses. The
effects of aging have the greatest impact on high rate performance. A battery whose resistance has increased by 10%,
for example, when discharged at its 8 hour rate will experience a loss of approximately 10% of its reserve capacity
or provide only 7.2 hours of support. But the same battery discharged at its 15 minute rate will experience a loss of
approximately 20% capacity and may not provide adequate support time.
Typically during the last half of the battery service life, capacity will begin to fall slowly at first, then at an increasing
rate. Lead acid batteries have been historically considered to reach the end of their useful life when they have
reached 80% capacity. It is recommended that a battery be sized with an aging margin to compensate for loss of
capacity as the battery ages. At short duration high rates there may be little or no time left when the battery reaches
80% capacity. It is strongly recommended that in such applications, an aging factor be applied to assure that the
critical load will be supported for adequate time at end of life. For further information on this topic, refer to Annex K of
IEEE Std-450, Recommended Practice for Maintenance, Testing and Replacement of Vented Lead Acid Batteries for
Stationary Applications and IEEE Std-1184, Guide for Batteries for Uninterruptible Power Supply Systems.
NOTE: Frequent charge/discharge cycles accelerate battery aging and performance degradation.
4.4 Environmental requirements
Recommended operating temperature range for standby battery operation is: 60°F (15°C) minimum to 90°F (32°C)
maximum; 77°F (25°C) yearly average.
Operating temperature limits to prevent mechanical and/or performance degradation (or failure) is: 32°F (0°C)
minimum to 120°F (49°C) maximum at standard atmospheric pressure.
SECTION 5 - BASIC BATTERY MAINTENANCE
CAUTION
For multi-cell batteries, a battery string must be disconnected from the charging bus before working on individual
cells or batteries. In multi-cell containers, disconnecting an inter-cell (same containers) connector does not
guarantee the absence of voltage or current at the end terminals. A potential shock hazard may therefore exist. This
is very important since there is always the possibility of a small current leak path across an inter-cell partition.
Proper maintenance will prolong the life of a battery and will aid in ensuring it is capable of satisfying its
performance requirements. A good battery maintenance program will also serve as a valuable aid in determining
the need for battery replacement.
NOTE: These recommended procedures are designed to minimize specific gravity measurements and emphasize
cell voltage measurement as an indicator of acceptable operation. The reason for this choice of procedure
is that voltage measurements, particularly with digital voltmeters, tend to be more accurate in comparison to
readings taken with either a digital or an analog hydrometer. Specific gravity measurements are significantly
influenced by method of measurement, current cell conditions and recent maintenance (see Part 4 section
1.3 for the specifics related to specific gravity measurements). In addition, hydrometer measurements are a
common source of spillage of electrolyte onto cell covers and connecting hardware and cell posts. NOTE:
If spillage does occur and is not immediately removed and neutralized it will become a source of corrosion
and staining of the lead parts. This condition is sometimes mistaken as electrolyte leakage from post seals,
gravity sampling tubes and even container to cover seals.
The frequency of battery inspections should be based on the criticality of the loads that must be supplied by the
battery under emergency conditions and the availability of other power sources. As a minimum, records of 3
quarterly reports and 1 annual inspection per year must be maintained to preserve warranty. Record findings
clearly and date originals and copies.
PART 2
CHARGING AND OPERATION OF BATTERY (CONTINUED)
RS1476/0215/CD 18 www.cdtechno.com