Battery Supply Voltage Test; Voltage Output No-Load Test; Voltage Output Load Test - Piper 6X Maintenance Manual

(3) Battery Supply Voltage Test

If airplane ammeter shows discharge with engine running, perform the following test before
checking alternator voltage output. The test will verify that battery voltage is being supplied to
regulator. Alternator cannot provide output unless field voltage is supplied.
(a) Disconnect connector at voltage regulator.
(b) Connect voltmeter positive lead to pin 1 of disconnected plug (B lead of regulator) and
negative lead to aircraft structure.
(c) Turn BATT MASTR and ALTR switches ON. Voltmeter should read battery voltage. If
voltage is not present:
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2

(4) Voltage Output No-Load Test

Perform this test, as well as the following voltage output load test, whenever an overcharging
or undercharging condition is suspected. Make a visual check as previously outlined. Engine
should be at normal operating temperature .
(a) Connect voltmeter positive lead to positive battery terminal and negative lead to negative
battery terminal. Record voltage reading.
(b) Assure that all switches and lights are OFF, i. e., no load condition.
(c) Start engine and slowly increase speed to approximately 1500 rpm.
(d) Voltmeter reading should increase, but not more than 4 volts more than voltage recorded
above.
(e) If the voltage does not increase, or if the increase is within the 4 volt limit, proceed to

Voltage Output Load Test.

(f) If voltage increase exceeds 4 volts, stop engine, and isolate overvoltage problem as
follows:
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2
3
(5) Voltage Output Load Test
This test will determine if there is an undercharge condition.
(a) Connect regulator plug.
(b) Connect voltmeter to negative and positive post of battery. Record voltage reading.
(c) Turn OFF all accessory switches. Open circuit breakers where switches do not control
circuits.
(d) Start the engine. Apply a load by turning on the landing light.
(e) Slowly increase engine speed to 1500 rpm.
(f) Voltage reading should increase a minimum of 0.5 volt above previous reading.
(g) Turn OFF landing light and shut down engine.
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Jun 1/03
THE NEW PIPER AIRCRAFT, INC.
PA-32-301FT / 301XTC
MAINTENANCE MANUAL
Check continuity of wiring harness from regulator plug to alternator circuit breaker.
Ensure that alternator regulator circuit breaker is closed and not defective.
Disconnect regulator plug from regulator and repeat the test with plug disconnected.
Voltmeter should show no increase in voltage because excitation voltage to
alternator is cut-off. Replace regulator.
If voltage increases, with the regulator plug disconnected, excitation voltage is being
supplied to alternator field by a short circuit. Isolate and check continuity of wiring
harness. Repair or replace.
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