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BATTERY
8-5
(1)
The battery electrolyte temperature must
NEV-
ER
exceed
125
degrees Fahrenheit.
If this temperature is reached, the battery should
be cooled by reducing the charging rate or remove
the battery from the circuit.
(2)
As the batteries approach full charge the electro-
lyte in each cell will begin to gas or bubble. Excessive
gassing must not be allowed.
(3) Do not fast charge longer than one hour.
If the battery does not show
a significant change in
specific gravity after one hour of "FAST" charge, the
slow charge method should be used.
Remember to use the temperature correction when
checking specific gravity.
NOTE: T h e manufacturers o f
high
rate charging
equipment generally outline t h e precautions and
some models have thermostatic temperature limit-
ing and t i m e limiting controls.
WARNING: When batteries are being charged an
explosive gas m i x t u r e forms beneath t h e cover o f
each cell. Do not smoke near batteries o n charge
o r which have recently been charged. Do not break
live circuits at t h e terminals of the batteries o n
charge.
A spark
will occur where t h e live circuit is
broken. Keep a l l open flames away f r o m the bat-
tery.
Slow Charging Batteries
Many discharged batteries can be brought back to
good condition by slow charging, especially batteries
that are sulphated.
The battery should be tested with a hydrometer
and a record kept of the readings taken at regular
intervals throughout the charge. A voltage test should
also be made, noting the voltage uniformity between
cells. Any subnormal voltage in any cell may indicate
a shorted cell. When a cell has a specific gravity read-
ing that is
25
points
(.025)
or more below the other
cells, that cell is defective and the battery should be
replaced.
Safe slow charging rates are determined by allow-
ing one ampere per positive plate per cell. The proper
slow charging rate would be
4
amperes for
a
48
am-
pere hour battery; or
5
amperes for a
59
ampere hour
battery; and 6 amperes for a
70
ampere hour battery.
The rate of charge for a normally discharged bat-
tery is one ampere per positive plate per cell.
The average length of time necessary to charge a
battery by the slow charge method at normal rates is
from
12
to 16 hours, however, when a battery con-
tinues to show an increase in specific gravity, the bat-
tery charge should be continued even if it takes
24
hours or more.
NOTE: Watch t h e temperature o f batteries careful-
ly and if t h e temperature o f any one of t h e m
reaches
1 10°F., lower t h e charging rate.
The battery
will
be fully charged when it is gassing
freely and when there is no further rise in specific
gravity after three successive readings taken at hour-
ly intervals. Make sure hydrometer readings are cor-
rected for temperature.
The rate of charge for a sulphated battery should
be no more than
Y 2
the normal slow charge rate.
Many sulphated batteries can be brought back to a
useful condition
by
slow charging at half the normal
charging rate from
60
to
100
hours. This long charg-
ing cycle is necessary to reconvert the crystalline
lead sulphate into active materials.
Batteries that are sulphated have the following
characteristics:
(1)
Battery temperature tends to increase rapidly
while charging.
(2)
Gravity under charge increases very slowly or
not at all.
(3) Battery will gas excessively under normal
charging rate.
(4)
Excessive voltage required to obtain normal
charging rate.
NOTE: When a battery takes a full charge,
but
is
returned several times in need o f a recharge, check
f o r a cracked cell partition with a syringe to pro-
vide air pressure; bubbles will appear in a n adja-
cent cell if a crack is present.
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