Advertisement
(2
89)
ELECTRICAL
SYSTEMS
BATTERY
10-13
The state of
charge
of the battery as well as
the temperature of the
electrolyte
has an im-
portant
bearing on its capacity for supplying
energy. Battery
efficiency is
greatly
r
educed
by
decreased
elect r olyte temperature as it has a
decided numbing effect on its electrochemical
action.
Under high
discharge
such as cranking,
battery voltage drops to
lower
values in cold
temperatures
than in warm t
emp
eratures.
The following
comparison
shows how
states
of
charge
at
temperatures
of 80°, 32° , and
0°
F. affect efficiency and
cranking
pow
er,
with
efficiency
in the
f
ully charged
state
at
80°
F.
equal to 100
%.
.
.
TL
. .
. . ....
.
O
°F
.
. .
.
..
.
.
"
. .
.60°F .
.
.
~.,j
.
. .
81)"
F
.
.
0
.
.
SUI DISCHARGE
<!'
VARIOUS TIMPlRATUREl
.
-
~
Of
.
........
.
~
60
f.
1-100°F .
.
-
- - -
~
80
f.
•
100 F
•
1.170
1.160
1.290
1.210
1.300
1.270
1.2
10
1.2
60
~
;;: 1.24
0
...
~
1.2
30
~
1.
2 2
V
5;
1.210
1.200
1.190
1.110
and add water as required; also check the
spe-
cific gravity with a hydrometer (par. 10-19).
A boosting charge at a moderate rate (par. 10-
22), without excessive overcharge, must be
given
batteries
in storage whenever the spe-
cific gravity falls to 1.215,
corrected
for tem-
perature.
Batteries
used for display
purposes
or standing in cars in
storage
must
be
treated
in the
same manner
as batteries in stock.
When a
new car,
or a new replacement bat-
tery is delivered, make certain that it is fully
charged and the elect r olyte is at proper level:
This is
extremel y
important
because
the deli
v-
ery
of a partially
discharged
battery may not
only
lead to its r
eturn
for charging but may
also r
esult
in
shortened
life of battery.
10-
16 IM PO RTA N CE OF KEEPING
BAT
TERY
PROPERLY CH
A RG ED
The
battery
has
three major
functions: (1)
It
provid es
a sour ce of
energy
for cr
anking the
engine. (2)
It
acts as a
stabilizer
to the voltage
in
the
electrical
system.
(3)
It
can for a limited
time
furnish energy when
the demands
of the
elect r ical units in operation exceed t
he
output
of t
he
generator.
In order
fo
r the
battery
to continue to func-
ti
on,
it
is necessa r y t
hat current withdrawl
from the battery be ba
lanced
by cur r ent
input
from the
generator so
t
hat t
he
battery is main-
tained in a properly
charged cond iti on.
If
the
outgo
exceeds
the input
the battery
will be-
come
discharged so that it
cannot
supply suffi-
cient energy. The
proper
functioning of the
generator
and r
egulator, therefore,
has an im-
portant bearing on the proper
functioning
of
the battery.
Figure I O-I-Chart of Ba tt e ry Self-Disch
arge a
t
Vario us
Temperatures
10
20
30
40
SO
60
DAYS
STAND ING
70
10
90
State
of
Charg e
Battery
Apprax.
(Speciflc
Gra~ity)
Temperature
Efficiency
Fully
Charged
.
.
.
...
.
.
.
.
80
°
100
%
(1.2 65- 1.290
@
80
°
F
.)
.
.
.
32
°
65
%
0
°
40
%
Half
Charged .
.
. ..
. .
.. ..
80
°
46
%
(1.205-1.2 30
@
80
°
F
.)
.
. .
32°
32
%
0
°
21
%
N
early Discharged
.
. .
..
.
80
°
25
%
(1.1 40-1.1 65
@
80
° F.)
..
.
32
°
16
%
(I n d
anger
of fre
ezing)
..
.
0
°
9
%
Stiff
engine
oil r
esulting
from cold
tempera-
tures increases the
load of cranking the engine.
At 32° F., the load of cranking may be 165
%
of the load at
80°
F.
,
and at
0°
F
.
the load of
cranking
may
run as high as
250
%
of the load
at
80°
F
.
Th
e
combined effect of zero
cold-in
r
educing battery
ca pacity to
%
of it s normal
power
and in
increasing the
cranking load due
to stiff oil to
possibly 2%
t
imes the
warm
weather
load
emphasizes the
need for keeping
4
3
---..
r-.
2
r-.
I
I"'.
I
I\.
\
2
1\
3
\
/
4
1
\
\
7
6
/
7
1
\
1
/
8
\
9
r---
l/
I
1.
0 00
1.0~0
lI00
lI
~ O
12 00
1.
2 5 0
1.
3 00
1.3~
1.400
SPECIFIC
GRAVITY
Fig u re IO
-2-Freezing Points
af
Battery
Electrolyte a
t
Various
Specific
Gravities
Advertisement
