Electrical System - Piper Cherokee Archer II Operating Handbook

Piper Aircraft Corporation
PA-28-181, Cherokee Archer II

7.9 ELECTRICAL SYSTEM

The electrical system includes a 14-volt, 60 amp alternator, a 12-volt battery, a voltage regulator, an
overvoltage relay and a master switch relay. The battery is mounted in a thermoplastic box immediately
aft of the baggage compartment. The regulator and overvoltage relay are located on the forward left side
of the fuselage behind the instrument panel.
Electrical switches are located on the right center instrument panel, and the circuit breakers are located on
the lower right instrument panel. A rheostat switch on the left side of the switch panel controls the
navigational lights and the radio lights. The similar switch on the right side controls and dims the panel
lights.
Standard electrical accessories include a starter, electric fuel pump, stall warning indicator, cigar lighter,
fuel gauge, ammeter, and annunciator panel.
The annunciator panel includes alternator and low oil pressure indicator lights. When the optional gyro
system is installed, the annunciator panel also includes a low vacuum indicator light. The annunciator
panel lights are provided only as a warning to the pilot that a system may not be operating properly, and
that he should check and monitor the applicable system gauge to determine when or if any necessary
action is required.
Optional electrical accessories include navigation lights, anti-collision light, landing light, instrument
lighting, and cabin dome light. Circuits will handle the addition of communications and navigational
equipment.
WARNING
Strobe light should not be operating when flying through overcast and clouds since reflected light can
produce special disorientation. Do not operate strobe lights in close proximity to ground, during takeoff
or landing.
The words "master switch" used hereafter in this manual indicate both sides of the switch; battery side
"BAT" and alternator side "ALT" are to be depressed simultaneously to OFF or ON as directed.
Unlike previous generator systems, the ammeter does not indicate battery discharge; rather it displays in
amperes the load placed on the alternator. With all electrical equipment off (except master switch) the
ammeter will be indicating the amount of charging current demanded by the battery. As each item of
electrical equipment is turned on, the current will increase to a total appearing on the ammeter. This total
includes the battery. The average continuous load for night flight, with radios on, is about 30 amperes.
This 30 ampere value, plus approximately two amperes for a full charged battery, will appear
continuously under these flight conditions. The amount of current shown on the ammeter will tell
immediately if the alternator system is operating normally, as the amount of current shown should equal
the total amperage drawn by the equipment which it is operating.
If no output is indicated on the ammeter during flight, reduce the electrical load by turning off all
unnecessary electrical equipment. Check both 5 ampere field breaker and 60 ampere output breaker and
reset if open. If neither circuit breaker is open, turn off the "ALT" switch for 1 second to reset the
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