Voltmeter Calibration; Section 3 - General Information And Maintenance; Performance Characteristics - C&D Technologies LIBERTY 1000 Series Installation And Operating Instructions Manual

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To avoid over-voltage, periodically check battery voltage with a
calibrated digital voltmeter. If an over-voltage is recorded, check and
readjust the rectifier and/or panel meter calibration as necessary. Place
the battery at the recommended float charging voltage as soon as
possible. Restoring the proper float voltage will preclude further dam-
age caused by charging at an over-voltage but it cannot reverse dam-
age that has already been sustained by the battery.
Liberty Series 1000 batteries produce virtually no gas
emissions during normal operation. However, potentially
explosive gases may be released under abnormal operating
conditions or initial/equalize charge. Provide adequate
ventilation so hydrogen gas accumulation in the battery area
does not exceed one percent. Do not smoke, use open flame
or create sparks near battery.

2.4 Voltmeter calibration

Panel voltmeters used in conjunction with float charging systems
should be kept in accurate calibration by checking with a known
standard per the manufacturer's recommendations. Always measure
battery voltage at the battery terminals and compare the reading with
the panel meter to eliminate the effect of line drop between the battery
and connected system or charger. Battery voltage should always be
measured with a digital voltmeter with at least a 3
minimum accuracy of 0.25 percent. Battery voltage must be measured
at the battery, not at the system connection. This type of instrumenta-
tion is also particularly useful in recording individual cell potentials.

SECTION 3 - GENERAL INFORMATION AND MAINTENANCE

3.1 Performance characteristics

Battery performance at a given discharge 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% capaci-
ty and provide only 12 minutes of support to its final voltage. Internal
cell resistance is provided in Table 2, Part 1 of this manual.
Typically during the last half of the battery service life, performance
will begin to fall slowly at first, then at an increasing rate. Lead-acid
batteries have reached the end of their useful life when performance
has fallen to 80 percent of published ratings.
Note: Frequent charge/discharge cycles accelerate battery aging and
performance degradation.
To insure adequate performance it is recommended that a battery be
sized with additional margin for operation at minimum expected tem-
perature and for loss of capacity as the battery ages.
CAUTION
1 ⁄ -digit display and a
2