To prevent electrolyte from spraying out or foreign
STATE OF CHARGE
matter from entering the battery, always keep the vent
The specific gravity of the electrolyte gradually
plugs in place. You can remove the vent plugs when
decreases on discharge and gradually increases on
taking temperature and specific gravity readings or
charge. This decrease or increase is directly proportional
adding water. Always keep the vent hole free of
to the number of ampere-hours taken out of or put into
a battery. You can determine the state of charge of a
All batteries and battery lockers must be kept clean
vented battery, where the electrolyte is accessible, by
and free of foreign matter. Clothing, cloth, or wiping
testing the specific gravity of the electrolyte. The only
rags should not be allowed to remain in battery lockers.
way you can determine the state of charge of a sealed
When vent plugs are removed from cells, you must
battery is by measuring its open-circuit voltage.
prevent anything from falling into the battery cell. You
should avoid spilling acid or water in battery rooms.
Collections of acid or dirt around a battery will lead to
trouble and will cause corrosion. After adding water to
the batteries, wipe the tops of the cells and the sides of
Except in an emergency, do not charge batteries in
the batteries clean. If acid has collected on the case,
an enclosed space, unless the space has adequate
remove it by wiping the case with a cloth moistened in
ventilation. Stop charging if ventilation is interrupted.
a diluted ammonia solution or bicarbonate of soda
Do not resume charging until ventilation is restored. The
solution. While using ammonia or bicarbonate of soda,
UPS system on gas turbine-powered ships is interlocked
make sure the solution does not enter the battery cells.
with the ventilation system. If ventilation is interrupted,
the UPS charging system will shut down.
Before starting a charge, make sure the electrolyte
is at the proper level. The proper electrolyte level is
In this chapter, we have discussed the UPS systems
about 3/8 inch above the plates or separators. If the
used on the different classes of gas turbine-powered
electrolyte is too high, it will flood out of the filling tubes
ships. We have also discussed some of the basic
during the charge. This is caused by the expansion that
maintenance and safety procedures you should use
takes place inside the cell as the temperature rises and
when operating and maintaining the UPS system on
by gassing. If the electrolyte gets too far below the top
of the plates or separators and remains there, the
The conditions under which the UPS batteries are
exposed parts will dry and harden and will no longer
used vary from ship to ship. The frequency of inspection
function. This will cause a reduction in capacity and
and maintenance necessary to ensure that the UPS
shorten the life of the battery.
batteries are in good operating condition will also vary.
For detailed maintenance procedures associated with
the UPS batteries, refer to the appropriate technical
As a GSE, you will find that your involvement with
Since a certain amount of gas is always given off
the UPS system will vary from ship class to ship class.
from a vented battery, flames or sparks of any kind must
On some ships, the maintenance of the complete UPS
never be allowed near any storage battery. Extra care is
necessary after opening a battery compartment that has
system will be your responsibility. However, on other
ships you may be responsible for only the dc power at
been sealed. No light switches should be turned on, no
the power supplies. In any case, this chapter should have
electrical connections of any kind should be made or
provided you with a basic understanding of the UPS
broken, and no work should be performed in the
systems found on gas turbine-powered ships.
compartment until it has been ventilated.