of a battery: by
its
'Ampere Hour' electrical
capacity (AH) or
its
'Watt Hour' electrical capac-
ity
(WH). Generally speaking, the 'Ampere
Hour Capacity'
is
used.
Electrical capacity (AH)
=
discharge current
(A) x hours of dis-
charge
(H) required
for battery to reach
discharged terminal
voltage
The capacity of a battery will vary according to
its
discharge current rate, the ambient tempera-
ture during discharge, and the time and manner
in which the battery
is
used.
The capacity will also vary according to the
temperature of the electrolyte during discharge.
The higher the temperature, the larger the capac-
ity; and the lower the temperature, the lower the
capacity.
-
When starting the engine, the battery discharges
at a very high current flow rate. Accordingly,
it
can be readily understood that starting
is
more
difficult when the ambient temperature is very
low, because the capacity of the battery
is
lower-
ed. In addition, the viscosity of the engine oil
also increases as the temperature drops.
(3)
Inspection of the Battery
a)
Electrolyte Capacity
The water content of the electrolyte will
evaporate during use, or will be reduced in
volume because of electrolysis. If there
is
in-
sufficient electrolyte, the
battery
is
liable to
sustain damage, and
it
there
is
too much, the
electrolyte will overflow and damage the body
and other parts of the tractor.
According1y;the level of the electrolyte in the
battery should be inspected regularly, and re-
plenished with distilled water when insuffi-
cient. The level of the electrolyte should be
M
,
sufficient so that the separators of the plates
are not exposed.
If
the plates are exposed to the atmosphere,
sulfation will ensue, and
it
will no longer be
possible to recharge the battery.
Too
low
&rrm
level
OMrfilled
b) Specific Gravity
The specific gravity of the electrolyte of a bat-
tery varies according to the temperature.
The specific gravity should be adjusted to the
specific gravity at
68°F
120°C).
Use
a hydrometer to get the specific gravity
reading:
Specific
gravity
1.260
1.220
1.160
1.090
1.080'
1.050
Usable
ar
it.
Recharge
immediately.
Condition
100%
75
50
25
10
0
Charged
condition
Usable
limit
Discharged
Fully
discharged
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