Cessna SkyHawk SP 172S NAV III 2005 Pilot Operating Handbook page 259

CESSNA
MODEL 172S NAV III
SECTION 7
AIRPLANE AND SYSTEMS DESCRIPTION
ELECTRICAL SYSTEM
(Continued)
EXTERNAL POWER RECEPTACLE (Continued)
NOTE
Set the AVIONICS switches BUS 1 and BUS 2 to
OFF if no avionics are required. If maintenance on
the avionics equipment is required, a 28 VDC
regulated and filtered external power source must be
provided to prevent damage to the avionics
equipment from transient voltages. Set AVIONICS
switches BUS 1 and BUS 2 to OFF before starting
the engine.
The following check should be made whenever the engine has been
started using external power (after disconnecting the external power
source).
1. MASTER Switch (ALT and BAT) - OFF.
2. TAXI and LANDING Light Switches - ON.
3. Engine RPM - REDUCE to idle.
4.
MASTER Switch (ALT and BAT) - ON (with taxi and landing
lights turned on).
5. Engine RPM - INCREASE (to approximately 1500 RPM).
6. Main Battery (BAT) Ammeter - CHECK (battery to be
charging, amps positive).
7. Low Voltage Annunciator - CHECK (no LOW VOLTS
annunciation).
NOTE
If the Main Battery (M BATT) ammeter does not
show a positive rate of charge or the low voltage
warning annunciation does not go off, the battery
should be removed from the airplane and properly
serviced prior to flight.
172SPHAUS-OO
U.S. 7-53