Piper SARATOGA PA-32-301 Maintenance Manual page 191

PIPER AIRCRAFT
PA-32-301/301T
MAINTENANCE MANUAL
BATTERY SUPPLY VOLTAGE TEST.
If aircraft ammeter shows discharge with engine running perform this test before checking alternator
voltage output. The test will verify that the battery voltage is being supplied to the regulator. Alternator cannot
provide output unless field voltage is supplied.
1. Disconnect connector at voltage regulator.
2. Connect voltmeter positive lead to pin I of disconnected plug(B lead of regulator) and negative lead
to aircraft structure.
3. Turn "Master Switch" ON. (Bat and Alt). Voltmeter should read battery voltage. If voltage is not
present. check continuity of wiring harness from regulator plug to alternator circuit breaker. Assure that
alternator regulator circuit breaker is closed and not defective.
VOLTAGE OUTPUT NO-LOAD TEST.
This test as well as the following voltage output load test. should be performed whenever an
"overcharging" or "undercharging" condition is suspected.
Visual check as previously outlined. should be made and engine should be at normal operating
temperature.
1. Connect voltmeter positive lead to positive battery terminal and negative lead to negative battery
terminal. Record Reading.
2. Assure that all switches and lights are off - no load condition.
3. Start engine and slowly increase speed to approximately 1500 RPM.
4. Check voltmeter reading. The voltage should increase, but not more than 4 volts above voltage
recorded in step 1.
5. If the voltage does not increase. or if the increase is within the 4 volt limit. proceed to VOLTAGE
OUTPUT LOAD TEST.
6. If voltage increase exceeds 4 volts. stop engine and isolate "overvoltage" problem as follous:
A. Disconnect regulator plug from regulator and repeat the test with plug disconnected.
B. Voltmeter should show no increase in voltage as excitation voltage to alternator is cut-off -
Replace regulator.
C. If voltage increases with the regulator plug disconnected. excitation voltage is being supplied to
alternator field by short circuitry. Isolate and check continuity of wiring harness. repair or replace.
VOLTAGE OUTPUT LOAD TEST.
This test is. in effect. a continuation of the preceding No-Load Test. although this portion applies more to
a condition of "undercharge" than "overcharge".
1. Reconnect regulator plug.
2. Voltmeter connected to negative and positive post of battery - record voltage reading.
3. Turn off all accessory switches - open circuit breakers where switches do not control circuits.
4. Start the engine. Apply a load by turning on the landing light.
5. Slowly increase engine speed to 1500 RPM.
6. Voltage reading step 2 should increase a minimum of 0.5 volt above previous reading.
7. Turn off landing light and shut down engine.
8. If voltage fails to increase above 0.5 volt - open alternator portion of master switch. An "under-
voltage" condition exists. Proceed as follows to isolate problem.
EFFECTIVITY: FORD
24-32-08
Page 24-26
Added: August 23, 1982
1H23