Cessna T188C - Page 306

MODEL
188
& T188
SERIES
SERVICE
MANUAL
direct-current,
single-wire, negative ground
electri- maintaining
residual voltage. A diode is also
incor-
cal system. A
single 12 or optional 24-volt battery
porated on the switch
to prevent spiking when
the
supplies power for starting.
furnishes power for
al- switch is operated.
ternator excitation and furnishes a reserve source of
power in the
event of alternator failure.
An engine-
16-5. AMMETER.
driven alternator is the normal source of power dur-
ing
flight and
maintains
a battery
charge controlled
16-6.
DESCRIPTION.
The ammeter
is connected
by a voltage
regulator.
An external
power
source
between
the
battery and
the aircraft
bus.
The am-
receptacle
is offered as optional
equipment
to supple-
meter indicates
the amount of
current flow either
to
ment
the battery-alternator
system for
starting
and
or from
the battery.
With a
low battery
and the
en-
ground
operation.
gine operating
at cruise
speed the ammeter
will show
the full alternator output when all electrical equip-
16-3. MASTER
SWITCH.
ment
is off. When
the battery
is fully charged
and
cruise RPM is maintained with all electrical equip-
16-4. DESCRIPTION.
The operation of
the battery
ment off, the
ammeter will
show a minimum
charg-
and
alternator
is controlled
by
the master
switch.
ing rate.
Thru
aircraft
serial
188-0572,
the master
switch
is
a pull
type with
double-pole,
single-throw
contacts.
16-7.
BATTERY
POWER
SYSTEM.
The
switch,
when
operated,
connects
the
battery
con-
tactor
coil to ground and the
alternator field circuit
16-8. BATTERY.
to
the battery,
activating
the power
systems.
Begin-
ning with aircraft
serial 188-0573
a new type
master 16-9.
DESCRIPTION.
Thru 1977
Models the 14-volt
switch
is installed. This switch is
an interlocking aircraft
are equipped with a 12-volt
battery with an
split rocker
with the battery
mode on
the right side
approximate
25 ampere-hour
capacity.
A larger,
and
the alternator
mode on the left
side. This ar-
heavy
duty, 12-volt, 33
ampere-hour
battery is offer-
rangement
allows the battery
to be on the
line without
ed as optional
equipment. On
aircraft with
the 28-volt
the alternator,
however,
operation
of the
alternator
electrical
system,
a 24-volt,
17
ampere-hour
capacity
without
the battery
on the
line is not
possible.
The
battery
is utilized.
Beginning
with 1978
Models
the
switch is labeled BAT and ALT. A new master switch aircraft has a 28-volt system and the battery is 24
is installed
with the 100
amp alternator.
This switch
volts with approximately
12.75
ampere-hour
capacity
is also a interlocking
split rocker with the
exception also the optional
battery is 24-volts with approximate-
it is equipped with a set of contacts in the off position, ly 15.5 ampere-hour capacity. On the A188B the
a jumper wire to ground. This grounds the alternator battery is located just aft of the firewall on the right
field in the
off position preventing
the alternator
from
hand side of the
fuselage. On
the T188C the
battery
is located
in the tailcone
on the right
hand side.
16-10.
TROUBLE
SHOOTING.
TROUBLE PROBABLE CAUSE REMEDY
BATTERY WILL NOT SUPPLY Battery discharged. 1. Measure voltage at "BAT"
POWER TO
BUS OR IS INCAP-
terminal of battery contactor
ABLE OF CRANKING ENGINE with master switch and a suit-
able load such as a taxi light
turned on. Normal battery will
indicate 11.5 volts or more on
a 14 volt system or 23 volts or
more on a 28 volt system. If
voltage is low proceed to step
2. If voltage is normal, pro-
ceed to step 3.
Battery faulty. 2. Check fluid level in cells
and charge 12-volt battery at
14 volts or 24-volt battery at
28 volts for approximately 30
minutes or until battery voltage
rises to 14 volts on 12-volt bat-
tery
or 28 volts
on 24-volt
bat-
tery. If tester indicates a good
battery, the malfunction may be
assumed to be a discharged bat-
tery.
If
the tester
indicates
a
faulty battery, replace the
battery.
16-2