ELECTRICAL EQUIPMENT - Q.4
TEST 4
Check of Alternator Output
Disconnect battery earth cable, and connect test
ammeter between the alternator main terminal and
disconnected cables. Reconnect battery earth
cable, and switch on the full electrical load and leave
on for 3 or 4 minutes. Leave load on and start
engine and run at approximately 2000 rev/min. The
alternator output should balance the load, and at the
same time show a charge to the battery.
Check Warning Light Control
If warning light does not function either by remaining
"on" or "off", but the system is charging satisfactorily,
connect voltmeter between the alternator "AL"
terminal and earth. Reading should be 7.0-7.5 max
(12 volt alternator) or 14.0-15.0 (24 volt alternator).
Connect leads 'E' and 'WL' together. If warning lamp
lights the warning light control is faulty and should
be replaced.
6.
Fault Diagnosis Procedure for 11 AC
Alternator Fails to Charge
(a) Check driving belt for correct tension and wear.
(b) Apply Tests 1 and 2.
Low-Unsteady Charging Rate
(a) Check driving belt for correct tension and wear.
(b) Check for high resistance at battery terminals and in
the circuit wiring and connection. Check all
connections made to earth.
(c) Apply Test 2.
Flat Battery or Low State of Charge
(a) CHECK condition of battery with hydrometer and
high rate discharge tester.
(b) Check driving belt for correct tension and wear.
(c) Check that the field isolating relay contacts open
when master switch is off; otherwise battery will
discharge through rotor winding.
(d) Check that flat or low battery is not caused by
insufficient alternator output caused by abnormal
electrical loads by applying Test 4.
Excessive Charge Rate to a Fully Charged Battery
(a) Apply Test 3.
Noisy Alternator
(a) Alternator loose in mounting brackets.
(b) Worn, frayed or loose drive belt.
(c) Worn bearings, fully out of alignment.
(d) Rotor damaged or pulley fan loose on shaft.
(e) Open circuited, or short circuited rectified diodes, or
stator winding open-circuit.
(f)
Loose pulley.
