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ELECTRICAL SYSTEMS
TROUBLE DIAGNOSIS
10-7
consideration must be given to the conditions
under which
the
car is operated.
In
very low temperatures
the capacity of a
storage
ba
tter y
is considerably r
educed
and
the
energy
r
equired
for cranking the
engine
is con-
sid
erab ly
in
creased, therefore,
a higher a
verage
state of charge
is r
equired
in cold weather.
Frequent starting
,
particularly in cold
weather,
accompanied
by
short runs may take
more
ener gy from
the battery
for cranking
than the
generator
can r
eplace
in
the limited
running
time.
This condit ion is aggravated by
night driving wh
en
lights
are
turned
on.
Wh
en the
car is
operated
under these condi-
tions an
occasional
booster charge may be re-
quired to keep the battery at a
safe
state of
charge.
2.
Low Charging Rate.
In case of prema-
ture battery failure the charging rate of gen-
erator should always be checked and
adjusted
if
below
sp
ecifications.
See paragraph 10-26
and 10-29.
3.
Internal
Condition. The internal condi-
tion of
the
battery may be such that it cannot
hold a charge
satisfactorily.
Check electrolyte
level and specific gravity and give battery a
high
discharge
test,
(par. 10-18, 10-19, 10-20).
c. High Discharge Failure of Ba"ery
One of the most common causes of battery
failure is overcharging, that is, continued in-
put of excessive charging current after the
battery has reached a fully charged condition.
One evidence that battery is being over-
charged
is the need for frequent addition of
water to the battery in order to maintain the
electrolyte level above the tops of the battery
separators, since overcharging causes rapid
water loss
.
When this becomes evident the
charging rate of generator should be imme-
diately
checked and adjusted (par. 10-26 and
10-29) to avoid internal damage to battery.
Another evidence
of overcharging
when this
has continued for an
appreciable
period of
time,
is the external appearance of battery. If the
positive ends of cell
covers
are pushed up it in-
dicates that the positive plates have swelled as
a result of overcharging. A battery in such con-
dition usually require replacement to insure de-
pendable
service.
10-8 GENERATING SYSTEM-TROUBLE
DIAGNOSIS
When an
y
complai nt is regist ered rega r ding
t
he operation of
t
he
generator or
regulat or,
trouble
diagnosis
should be governed by the fol-
lowing points.
a. Charge Indica tor Reading
The
charge indicator
does not
-indicate total
charging
rate
of generator
since it
does
not
in
-
dicate current sup plied
to
electrical units ot her
than t
he battery.
To interpret t
he indicator
r
eading correctly t
he condit ion of
battery
must
be
known
; theref or e the battery
should be
t
ested (par. 10-19) before making any
other
check.
b. Fully Charged Ba"ery and Low Indicator
Reading
This is a
normal condition. Discharge battery
by cr anking engine for seve
ral
seconds, then
note
indicator r
eading
with
engine
running
abo
ve
idle sp
eed.
Charge indictor should show
a high charging rate for a short
time
until
en-
ergy
removed
from battery has been
restored,
after which indicator will r
eturn
to near zero.
c. Fully Charged Ba"ery and High Indicator
Reading
.
In
analyzing trouble
of this nature, the effect
of battery
temp erature
must be
considered.
Where the
battery
is operating at high
tem-
perature, a high charging rate may be obtained
even with a normal voltage r
egulator
setting
and with
otherwise
normal operation of the
equipment. If
battery
is not operating at high
temperature,
this condition indicates improper
operation
of the generating system which will
result in battery
overcharge
and high voltage
in the electrical
system.
Inspect and test gen-
erator (par. 10-26).
d. Low Ba"ery and Low or No Indicator
Reading
This condition may be caused
by
high resis-
tance in the charging
circuit
due t
o
loose con-
necti ons
or
def ective leads,
inoper at ive genera-
tor, or defect ive generator
regulator. Inspect
and test
generator a
nd charging circuit wiring
(par. 10-26) and if source of trouble is not
found test generator regulator (par 10-29)
.
Burned resistance units, winding, or fused reg-
ulator contacts result from open circuit opera-
tion or high resistance in charging circuit.
Check for these conditions
carefully.
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