Buick LeSabre 1965 Service Manual page 582

1 0 - 1 2 TROUBLE DIAGNOSIS
ELECTRICAL SYSTEMS
bright but no cranking action will
take place. The first named con-
dition indicates that nothing is
wrong with the battery, cables,
and cranking system. The other
conditions indicate trouble as
follows:
4. If lights go out as cranking
motor solenoid switch is closed,
it indicates a poor connection in
the circuit between battery and
cranking motor. Check battery
cables and clean and tighten loose
or corroded terminals (par.
10-11).
5. If lights dim considerably as
cranking motor solenoid switch is
closed, it indicates that the bat-
tery is run down, or there is a
condition in cranking motor or
engine which causes an excessive
current drain on the battery. A
low battery will be indicated by a
clattering noise in cranking motor
solenoid because the battery can-
not sustain the voltage required to
hold solenoid plunger "in" after
switch contacts close and the
"pull in" winding is shorted out.
Test battery with a light load test
(par. 10-9). If battery is found to
be in good condition check crank-
ing motor fear. 10-28).
6. If lights stay bright but no
cranking a c t i o n occurs when
cranking motor solenoid switch
is closed, it indicates an open
circuit in cranking motor, switch,
or control circuit. See para-
graph 10-28.
b. Undercharge Failure
of Battery
The most frequent trouble expe-
rienced with storage batteries is
failure to maintain a state of
charge sufficient to crank the en-
gine and also furnish current to
the ignition system, lights and
accessories. Failure to mainatin
a proper state of charge may be
due to one or more of the fol-
lowing conditions:
1. Operating Conditions. When
determining cause of premature
failure of a battery, consideration
must be given to the conditions
under which the car is operated.
In very low temperatures the ca-
pacity of a storage battery is con-
siderably reduced and the energy
required for cranking the engine
is considerably increased.
Frequent starting, particularly in
cold weather, accompanied by
short runs may take more energy
from the battery for cranking than
the generator can replace in the
limited running time. This con-
dition is aggravated by night driv-
ing when lights are turned on, or
by operation of an air conditioner
in heavy traffic.
When the car is operated under
these conditions, adjusting the
voltage regulator to the high limit
may allow enough increase to
keep the battery at a safe state of
charge. If the high limit setting
does not maintain a safe state of
c h a r g e an occasional booster
charge should be given to the
battery or an extra output gener-
ator obtained through dealer.
2. Low Charging Rate. In case of
premature battery failure, the
charging rate of generator should
always be checked and adjusted if
below specifications. See para-
graph 10-21.
3. Internal Condition. The inter-
nal condition of the battery may
be such that it cannot hold a
charge satisfactorily. Check elec-
trolyte level and light load test
the battery (par. 10-11).
c. Overcharge Failure
of Battery
A common cause of battery fail-
ure is overcharging, that is, con-
tinued input of excessive charging
current after the battery has
reached a fully charged condition.
One evidence that battery is being
overcharged is the need for fre-
quent 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 immediately checked
and adjusted (par. 10-21) to avoid
internal damage to battery.