Electrics Section T
Charging system
The charging system comprises the battery,
alternator and ignition warning
light
as
shown
in
Figure
7.
It is important that the charging system is kept
in
good
working
order for the ignition, starting
and
lighting systems depend upon it. These
systems
will
be rendered inoperative
if
the
battery is in
an
extremely
low
state
of
charge.
The
electrolyte level in the battery should be
regularly checked and topped up
if
necessary.
Keep the battery
terminals clean and tight.
The correct fan
belt tension is important. A slack
belt
will
slip and prevent the alternator charging
the battery
to
its
full
capacity.
Attention
should also
be
given
to
the cleanliness
and security
of
the earth leads.
The ignition warning light serves the dual
purpose
of
reminding the driver
to
switch
off
the
ignition, and acting
as
a no-charge indicator.
With
the ignition switched on the warning
light
should
only
be
illuminated
when
the engine is
not
running, or is
idling
at a very
low
speed.
As the engine speed increases the
light
should
dim
and
go
out. Failure
to
do
so indicates a
fault in the charging system.
The
alternator is described in
full
in the
following
text
but
for
details
of
the other charging system
components refer
to
the General Electrics on
page 18.
Alternator
Description
The alternator is a
12
pole,
two
brush machine
and is driven by a belt from the crankshaft
pulley. To ventilate the interior components a
multi-bladed fan is fitted behind the alternator
pulley.
The brushgear is enclosed in a moulding
screwed
to
the slip ring end bracket thus giving
protection against the adverse affects
of
dust
and moisture.
Voltage control is achieved by a
Model
14TR
microcircuit
voltage regulator
built
into
the
slip-ring end bracket.
A
normal type
of
charge indicator
(warning)
light
system is used in conjunction
with
this
alternator. The warning
light
is connected in
series
with
the
'field'
supply diodes and is
extinguished when the generated voltage at the
diodes side
of
the light equals that at the
battery side.
7
The
only
attention the alternator is likely to
require is the
occasional changing
of
the
commutator bushgear. Remove
alternator cover,
unscrew
two
4BA
bolts and
lift
brushbox
moulding from slip ring end bracket. Check
whether brushes and
slip rings are free
of
oil or
grease.
If
necessary, the brushes and springs
can be
cleaned
with
a petrol moistened cloth.
Check brush and spring assemblies
for
freedom
of
movement in the brushbox moulding.
If
the
overall length
of
the brushes have
worn
to
7·62mm
(0·30in) the brush and spring
assemblies
will
have
to
be
removed and replaced.
Wipe away any
dirt
or oil
which
may collect
around the slip ring end cover ventilating
apertures. The bearings are packed
with
grease
during
assembly and do
not
require attention.
Note:
Serious
damage
can
occur
to
the
alternator
if
the
following
points
are
not
observed:
1 Ensure that the negative terminal
of
the
battery is earthed. Reversed cable connections
will
burn
out
the alternator diodes.
2 Never earth the
output
(B+)
terminal
of
the alternator. It should be connected directly
with
the battery positive terminal.
3
Always
disconnect the battery earth cable
at the battery before removing the alternator or
its connecting wires. Serious damage
to
the
wiring
harness and the alternator can result
from accidentally earthing the
output
terminal.
4 Never attempt
to
operate
with
the
output
lead between the battery and
output
terminal
disconnected. A very high voltage
will
develop
which
could burn out the rotor or damage the
diodes.
5 When the battery is
to
be recharged in the
car, disconnect both battery
cables before
connecting a charger.
6 When a
slave battery is used
to
start the
engine, ensure the
leads are connected correctly,
i.e. positive
to
positive, negative
to
negative.
Testing the alternator
First check the driving belt for condition and
tension. The nominal
hot
ratings are given in
the specification at the end
of
this section.
These figures may
be
exceeded slightly
when
the alternator is running cold. To avoid
misleading results, the
following
test procedure
should therefore
be
carried
out
with
the
alternator running
as
near
to
its normal operating
temperature
as
possible.
Alternator
output
test
1
Withdraw
the
two-part
connector from the
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