Lucent Technologies Round Cell Batteries
Issue 3 December 1999 Operation and Maintenance 7 - 5
Check and Record Individual Cells for Crystals, continued
If Crystals Appear
on All Cells in a
String
If lead-sulfate crystals appear on all cells in a string, check the following
as possible causes for the abnormal condition:
• Rectifier voltage: The appearance of lead-sulfate crystals may
indicate a low battery plant float voltage. Check the battery plant
float voltage and make appropriate rectifier adjustments.
• Plant discharge: A battery discharge resulting from a power failure or
other reasons may produce lead-sulfate crystals on the cells. This is
normal with all lead-acid cells since lead sulfate is the material
produced when a lead-acid cell is discharged. If the cause of the
lead-sulfate crystals is a recent discharge, the crystals will disappear
when the cells have been fully recharged on float (usually within two
weeks). Check plant records to determine if a discharge has occurred.
Another method of determining if a plant discharge has occurred is to
measure cell specific gravities. Readings of .03 less than the
nameplate values on most cells would be a clear indication that a
plant discharge has occurred.
• If the presence of lead-sulfate crystals on all cells in a string is not
attributable to a plant discharge or improper rectifier voltage, report
the condition to Lucent Technologies.
If Crystals Appear
on One or a Few
Cells
If lead-sulfate crystals appear on one or a few cells in a string, the
following actions should be taken:
Crystals on One or a Few Cells
Step Action
1
Check to see if a plant discharge has occurred.
2
Measure the cell voltage. If a crystalline cell reads 2.09 volts
or less and the crystal deposit is heavy, the cell is shorted and
should be reported to Lucent Technologies.
3
Measure temperatures of cells in each tier of the string to
determine the extremes of temperature differences.
Temperature differences of 5°F (2.8°C) or more between cells
in a string can result in the appearance of lead-sulfate crystals
in the warmer cells. Provide appropriate ventilation if
temperature differences exceed 5°F (2.8°C).
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