battery is 60/1.5, or 40 ampere-hours. You can
1.060. At the end of a charge, its closed-circuit
determine the number of ampere-hours expended in any
voltmeter reading while the battery is being charged at
battery discharge by using the following items:
the finishing rate is between 2.4 and 2.6 volts per cell.
The specific gravity of the electrolyte corrected to 80F
1. The specific gravity when the battery is fully
is between 1.210 and 1.220. In climates where the
charged
temperature is 40F and below, authority may be
2. The specific gravity after the battery has been
granted to increase the specific gravity to 1.280.
dischargd
STATE OF CHARGE OF BATTERIES
3. T h e r e d u c t i o n i n s p e c i f i c g r a v i t y p e r
ampere-hour
After a battery is discharged completely from full
Voltage alone is not a reliable indication of the state
charge at the lo-hour rate, the specific gravity has
of charge of a battery, except when the voltage is near
dropped about 150 points to about 1.060. You can
the low-voltage limit on discharge. During discharge,
determine the number of points the specific gravity
the voltage falls. The higher the rate of discharge, the
drops per ampere-hour for each type of battery. For each
lower the terminal voltage. Open-circuit voltage is of
ampere-hour taken out of a battery, a definite amount of
little value because the variation between full charge and
acid is removed from the electrolyte and is combined
complete discharge is so small--only about 0.1 volt per
with the plates. For example:
cell. However, abnormally low voltage does indicate
injurious sulfation or some other serious deterioration
of the plates.
TYPES OF BATTERY CHARGES
The following types of charges maybe given to a
storage battery, depending upon the condition of the
battery:
Initial charge
Normal charge
Equalizing charge
Floating charge
Emergency charge
Battery Initial Charge
For example, if 70 ampere-hours are delivered by
the battery at the 10-hour rate or any other rate or
When anew battery is shipped dry, the plates are in
collection of rates, the drop in specific gravity is 70 x
an uncharged condition. After the electrolyte has been
1.5, or 105 points.
added, you must convert the plates into the charged
condition. You can accomplish this by giving the
batter y a long, low-rate initial charge. The charge is
given according to the manufacturer's instructions,
which are shipped with each battery. If the
manufacturer's instructions are not available, refer to
the detailed instruction in current directives.
Battery Normal Charge
For example, if the specific gravity of the previously
considered battery is 1.210 when the battery is fully
A normal charge is a routine charge that is given
charged and 1.150 when it is partly discharged, the drop
according to the nameplate data during the ordinary
in specific gravity is between 1.210 and 1.150, or 60
cycle of operation to restore the battery to its charged
points. The number of ampere-hours taken out of the
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