Buick LeSabre 1965 Service Manual page 580

1 0 - 1 0 BATTERY CABLE TESTING
ELECTRICAL SYSTEMS
water has been added. The water
must be thoroughly mixed with the
electrolyte by charging for at
least 30 minutes before hydrom-
eter values are reliable.
3. If hydrometer has built-in
thermometer, draw liquid into it
several times to insure correct
temperature b e f o r e t a k i n g a
reading.
4. Hold hydrometer vertically
and draw in just enough liquid
from battery cell so that float is
free floating, and with bulb fully
released. Hold hydrometer at eye
level so that float is vertical and
free of outer tube, then take read-
ing at surface of liquid. Disregard
the curvation where the liquid
rises against float stem due to
surface tension.
5. Avoid dropping liquid on car
or clothing as it is extremely
corrosive. Any liquid that drops
should be washed off immediately
with soda solution.
1 0 - 1 1 TESTING AND
CLEANING
BATTERY AND
CRANKING MOTOR
CABLES
Whenever the battery is tested
(par. 10-9) the battery and crank-
ing motor cables should also be
inspected for condition and tested
for resistance. Resistance in the
cables and connections causes
voltage drop, and excessive volt-
age drop is liable to cause start-
ing difficulties.
Carefully inspect the battery to
junction block, battery to engine
(ground) and cranking motor to
junction block cables. If cable
strands are broken, corroded, or
loose in terminals the cable
should be replaced with the cor-
rect c a b l e to insure ample
capacity.
Check terminals at both ends of
each cable for tight connections.
Since l o o s e connections are
usually dirty or corroded, any
l o o s e connections should be
thoroughly cleaned before being
tightened. If terminals are tight
and cables are apparently in good
condition, it is advisable to test
them with a low-reading volt-
meter to detect any abnormal in-
ternal resistance.
a. Testing Resistance of
Cables and Terminal
Connections
Battery cables and terminal con-
nections may be tested with
equipment comprising a voltmeter
(5 volts maximum), ammeter of
300 or more amperes capacity,
and carbonpile rheostat having a
minimum capacity of 300 amperes
connected in s e r i e s with the
ammeter.
1. Adjust rheostat to p r o v i d e
maximum resistance ("OFF"
position).
2. Connect ammeter positive (+)
lead to battery terminal stud on
junction block. Connect ammeter
negative (-) lead to one side of
rheostat and connect other side of
rheostat to ground on engine,
preferably at point where battery
ground strap is attached. In the
instrument shown in Figure 10-5
the ammeter and rheostat are
connected in series inside the
case.
3. Connect voltmeter negative (-)
lead to battery terminal stud on
Figure 10-5—Battery Cable
Test Connections
junction block. Use prod with
voltmeter lead, if necessary, to
insure direct contact with the
terminal stud. Do not connect to
the ammeter lead clip. Attach a
prod to voltmeter positive (+)
lead and apply the prod to center
of battery positive (+) post (Fig-
ure 10-5). Make sure that clips
of voltmeter leads have clean
metal contact with prods.
4. Adjust rheostat until ammeter
reads 200 amperes, immediately
read voltmeter, then turn rheostat
to starting ("OFF") position to
avoid excessive drain on battery.
Voltage drop across battery pos-
itive cable and terminal connec-
tions should not exceed 2/10 volt.
5. Connect voltmeter positive (+)
lead to ground on engine. Attach
prod to voltmeter negative (-)
lead and apply prod to center of
battery negative (-) post. Voltage
drop across the battery ground
cable and terminal connections
should not exceed 2/10 volt at
200 amps.
6. A reading in excess of 2/10
volt when testing either battery
cable indicates excessive resist-
ance in cable or connections.
Clean and tighten cable or con-
nections. Clean and tighten cable
terminals (subpar. b, below) and
recheck for voltage drop. If volt-
age drop still exceeds 2/10 volt
replace cable with a genuine
Buick cable to insure ample
capacity.
7. If cranking is below normal
speed, connect the ammeter pos-
itive (+) lead to the battery ter-
minal stud on cranking motor
solenoid switch, leaving the other
lead attached to ground in engine.
8. Connect voltmeter negative (-)
lead directly to battery terminal
stud on solenoid switch. With prod
of voltmeter positive (+) lead ap-
plied directly to battery terminal
stud on junction block, repeat Step
4 above. The voltage drop across
cranking motor cable and ter-
minal connections should not ex-
ceed 2/10 volt at 200 amperes.