Owners Manual
ELECTRICAL
Ammeter Readings
When noting ammeter readings,
it
must be remem-
bered that during daytime running when the battery is in
good condition, the dynamo gives only a trickle charge
so that the charge reading will seldom be more
than
a
few
amperes.
A discharge reading may be given immediately after
switching on the headlamps. This usually happens
after a long run, when the voltage
of
the battery is
high. After a short time, the battery voltage will fall,
and the regulator will respond, causing the dynamo
output to balance the load.
When starting from cold, the charging current will
rise until
it
reaches a steady maximum
at
a speed
of
say,
20
m.p.h.
(32
k.p.h.), after which
it
will
remain
fairly high for about
10
minutes and then fall to a
steady charge which is most suitable for the particular
state
of
charge
of
the battery.
It
will be noticed from the ammeter readings, that
the dynamo does not charge
at
very low engine speeds.
This is because
it
is
not
rotating fast enough to generate
energy to charge the battery. The cut-out, which is
an automatic switch and allows the flow
of
current
from the dynamo to the battery only, is connected
between the dynamo and the battery.
It
closes when the
dynamo is running fast enough to charge the battery
and opens when the speed is low or the engine is
sta-
tionary, thus preventing current from flowing from the
battery through the dynamo windings.
CONTROL
BOX
This unit contains the cut-out and voltage regulator.
The regulator controls the dynamo output in accordance
with the load on the battery and its state
of
charge.
When the battery is discharged, the dynamo gives a high
output, so that the battery receives a quick recharge,
which brings it back to its normal state in the minimum
time.
On the other hand,
if
the battery
is
fully charged
the dynamo is arranged to give only a trickle charge,
which
is
sufficient to keep
it
in good condition without
any possibility
of
causing damage to the battery by
overcharging.
The regulator also causes the dynamo to give a
controlled boosting charge immediately after starting
up, which quickly restores to the battery, the energy
taken from
it
when starting. After about
30
minutes
running, the output
of
the dynamo has fallen to a steady
rate best suited to the particular state
of
charge of
the battery.
The cut-out is an automatic switch for connecting
EQUIPMENT
0/9
and disconnecting the battery with the dynamo. This
is necessary because the battery would otherwise
dis-
charge through the dynamo when the engine is stopped
or running
at
a low speed.
Regulator Adjustment
The regulator is carefully set before leaving the
works to suit the normal requirements
of
the standard
equipment, and in general
it
should
not
be necessary
to alter it. If, however, the battery does
not
keep in a
charged condition, or
if
the dynamo output does
not
fall when the battery
is
fully charged, it may be advisable
to check the setting and
if
necessary to readjust.
It
is important, before altering the regulator setting,
when the battery is in a low state
of
charge, to check
that its condition is not due to a battery defect or to
the dynamo belt slipping.
Fig. 12. The Control Box.
A.
Locknut. B. Regulator adjusting screw.
Checking and Adjusting the Electrical Setting
The regulator setting can be checked without
removing the cover
of
the control box.
Withdraw the cables from the terminals marked
"A"
and
"Al"
at the control box and join them to-
gether. Connect the negative lead
of
a moving coil
voltmeter
(0-20 volts full scale reading) to the
"D"
terminal on the dynamo and connect the other lead
from the meter to a convenient chassis earth.
Slowly increase the speed
of
the engine until the
voltmeter needle
"flicks" and then steadies; this should
occur
at
a voltmeter reading between the limits given
overleaf for the appropriate temperature
of
the regulator.