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Rev.12/31/97
6.12 SPECIFIC GRAVITY READINGS
6.12 SPECIFIC GRAVITY READINGS
Specific gravity readings are only needed every 5 years to determine if the
electrolyte needs to be replaced (see 6.9 above). When taking a hydrometer
reading, squeeze the bulb before inserting, insert the nozzle to the top of the
plates, then release the bulb. This procedure will avoid introducing air
bubbles and prevent floating oil from being drawn into the barrel. The
sample should always be returned to the cell from which it was taken. Wash
out the hydrometer thoroughly with distilled water. Electrolyte remaining in
the hydrometer absorbs carbon dioxide from the air, forms a coating, and
causes false readings. Specific gravity changes with temperature, and if the
electrolyte temperature is different from 77 EF, add 0.001 to the reading for
electrolyte needs to be replaced (see 6.9 above). When taking a hydrometer
reading, squeeze the bulb before inserting, insert the nozzle to the top of the
plates, then release the bulb. This procedure will avoid introducing air
bubbles and prevent floating oil from being drawn into the barrel. The
sample should always be returned to the cell from which it was taken. Wash
out the hydrometer thoroughly with distilled water. Electrolyte remaining in
the hydrometer absorbs carbon dioxide from the air, forms a coating, and
causes false readings. Specific gravity changes with temperature, and if the
electrolyte temperature is different from 77 EF, add 0.001 to the reading for
every 4 EF above 77 EF. Subtract 0.001 for every 4 EF below 77 EF.
Do not take specific gravity readings when gas bubbles are visible in the
electrolyte. False readings will result unless the bubbles are allowed to
electrolyte. False readings will result unless the bubbles are allowed to
dissipate. Specific gravity readings cannot be taken on cells just after adding
water; the readings should be delayed until mixing has occurred.
Do not try to maintain a single supply of distilled water for serving both ni-
cad and lead-acid batteries. Water will become contaminated with traces of
sulfuric acid from the filler bulb by the transfer between lead-acid cells and
the water container. A separate supply of distilled or approved mineral
water, used only for nickel-cadmium batteries, is necessary. Provide a
separate hydrometer that is used exclusively for testing nickel-cadmium
cells.
sulfuric acid from the filler bulb by the transfer between lead-acid cells and
the water container. A separate supply of distilled or approved mineral
water, used only for nickel-cadmium batteries, is necessary. Provide a
separate hydrometer that is used exclusively for testing nickel-cadmium
cells.
6.13 ELECTROLYTE RENEWAL
6.13 ELECTROLYTE RENEWAL
Traces of potassium hydroxide are lost with the gas while the battery is on
charge, resulting in gradual lowering of specific gravity over the years.
Performance deteriorates as the battery ages, and cannot be restored by
normal charges. When this condition occurs, check the electrolyte color by
inserting a clear glass draw tube to the top of the plates. Place a thumb over
the top end and partially withdraw the tube; do not totally remove the tube.
This procedure avoids spills on the tops of the cells. After observing the
color, release the electrolyte back into the same cell. Clear electrolyte is in
good condition. Electrolyte that has absorbed small quantities of carbon
dioxide from the air will appear cloudy. Impurities accidentally introduced
in cells during manufacture or by addition of contaminated water may also
color the electrolyte. Electrolyte that becomes colored or cloudy is
contaminated with impurities and should be changed.
charge, resulting in gradual lowering of specific gravity over the years.
Performance deteriorates as the battery ages, and cannot be restored by
normal charges. When this condition occurs, check the electrolyte color by
inserting a clear glass draw tube to the top of the plates. Place a thumb over
the top end and partially withdraw the tube; do not totally remove the tube.
This procedure avoids spills on the tops of the cells. After observing the
color, release the electrolyte back into the same cell. Clear electrolyte is in
good condition. Electrolyte that has absorbed small quantities of carbon
dioxide from the air will appear cloudy. Impurities accidentally introduced
in cells during manufacture or by addition of contaminated water may also
color the electrolyte. Electrolyte that becomes colored or cloudy is
contaminated with impurities and should be changed.
Electrolyte renewal may also become necessary because of overcharging and
overflow of electrolyte, causing cell specific gravity to fall below
manufacturer's specified minimums. A rapid reduction in the life of the
battery will follow with continued operation. The electrolyte should be
changed when the specific gravity falls below 1.170 (see 6.8 above).
overflow of electrolyte, causing cell specific gravity to fall below
manufacturer's specified minimums. A rapid reduction in the life of the
battery will follow with continued operation. The electrolyte should be
changed when the specific gravity falls below 1.170 (see 6.8 above).