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THE ELECfRICAL EQUIPMENT
N
The electrolyte is
prepared
by mixing d
istilled
water
and concentrated
sulph
uric acid 1·835 S.G. The mixing
must be carried out
in
a
lead-lined
tan
k
or a suitable
glass o
r
earthenware
vesseL
Steel
o
r
iron
containers
must
not
be used. The acid
must
be
added
slowly
to
the
water
while
the
mixture
is
stirred
with
a glass rod.
Never
acid
the
wate.
r
to
the
acid, as the severity of the
resulting
chemical
reaction may
have
dangerous con-
sequences,
Heat
is produced
by the mixture
of
acid and water,
and it
~hould
therefore
be allowed
to
cool before it is
poured
into
the battery,
otherwise
the
plates, separators,
and moulded
container
may be damaged.
The
temperature of
the
filling-in acid,
battery, a nd
charging
room should be above 32• F.
(0°
C.).
To
produce
electrolyte
of the correct
specific
gravity:
Add I part by •·olume
of
To obtain
specific gravity
1·835
S
.G.
acid to distilled
(corrected to
60°
F.
[l
6•
C.D
water
by volume as below
1·340
2·0 parts
1·290
2·7
parts
1·270
2·8 parts
1·210
4
·0
parts
Carefully
break
the seals
in the
filling
holes and
half-fill each cell
in
the bartery with dilute
sulphuric
acid solution
of
the
appropriate
specific gravity (accord-
ing
to temperature). The quantity
of
electrolyte required
to
half-fill
a
two-volt cell
is
+
p int
(·28
litre). Allow to
stand
for at
least six
hours, then
complete
the filling
of
the cells by the
addition
of
more
diluted
acid
of
the same
specific
gravity as
before until
the level
reaches the bottom
of
the filling
boles,
and
allow
t
he battery to
stand for at
least another
two
hours
before commencing
the
first
charge.
C harge at a constant cu rrent of
3·5
amps.
until
the
voltage and temperature-corrected
specific
gravity
readings
show no increase
over
five successive
hourly
readings.
This period is dependent upon the
length of
time the bauery has been stored since manufacture, and
will
be from
40
to 80
hours,
b ut
usually not
more than 60.
Throughout
the
charge the acid must be kept
level
with the tops
of the
separators in each
cell
by the addition
of electrolyte
of the
same specific gravity
as
the
original
filling-in acid.
If, during
charge, the
temperature of the acid
in
any
cell of the
battery
reaches the maximum permissible
temperature o
f
100°
F.
(38•
C.) in climates
ordinarily
below 90• F
.
(3r
C.)
or
120•
F
.
{49•
C.)
in
climates
frequently above
90•
F.
(32°
C.). the charge must be
interrupted
and the battery
temperature
a
llowed to
fall
at
least
to•
F.
(5·5·
C.)
before charging is
resumed.
At
t he
end
of
the first
charge, i.e.
when specific gravity
and voltage
measurements
remain constant,
carefully
MGA (Twin
Cam).
hsue
2.
23026
check the
specific
gravity
in
each cell
to ensure
that it
lies
within
the
limits specified.
If any cell requires a
djustment
the electrolyte above
the
plates must be
siphoned
off and
replaced either with acid of
the
strength used for the
original filling
in,
or
d
istilled water,
according
to whether
the
specific
gravity
is
too low or too high respectively.
A
fter
s uch
adjustment,
t he gassing charge should be
continued
for
one or two hours to ensure adequate
mixing
of the
electrolyte. Re-check,
if
necessary,
re-
peating
the
procedure u
ntil
the desired
result
is
obtained
.
Section N.2
DYNAMO
To
test
oo
vehicle
when
dynamo
is
not
charging
(I) Make sure that
belt
slip
is
not
the
cause of the
trouble,
It
should be
possible
to
deflect
the belt
approximately
t
in.
(
13
mm.)
a
t
the centre of its
longest
run between
two
pulleys
with
moderate
hand
pressure.
If
the
belt is
too slack,
loosen the
two dynamo
suspension bolts
and
then the bolt of
the
slolled a
djustment
link. A gentle pull on the
dynamo outwards will enable the correct
tension
to
be applied to the
belt
and all three bolts
should
then
be
tightened
firmly.
(2) C heck the dynamo and control box connections.
The dynamo terminal
'
0'
should
be
connected
to
the
control
box terminal
'0'
and
the
dynamo
terminal
'F'
connected
to the
control box
terminal
~F".
(3)
After
switching off
all
lights
and accessories
dis-
connect
the
cables
from the dynamo terminals
marked
'
D' and 'F'
respectively.
(4)
Connect
the two terminals
with
a
length
of
wire.
(5)
Start
the
engine and
set
to
run
at
idling
speed.
{6)
Clip the negative
lead
o
f
a moving-coil-type
volt-
meter, calibrated 0-20
volts, to one
dynamo
terminal
and t
he
other
lead to a
good
earthing
point
on the dynamo yoke.
{7) Gradually increase the engine
speed,
when the
voltmeter
reading should rise
rapidly
and without
fluctuation.
D
o
not
allow the voltmeter
reading
to
reach 20 volts. Do not race the engine
in
an
a
ttempt
to increase the
voltage.
1t is
sufficient
to
run
the dynamo up to a speed
of
1,000
r.p.m.
If there is
no
rea
di
ng, check the brush
gear.
If the reading is low {approximately 1 volt), the
field winding may be
faulty,
If the
reading
is approximately
5
volts,
the
arma
ture wind
ing
may be
fa
ulty.
If the dynamo is in good
order,
leave the
tempora ry
link in
position
between
the terminals
a nd restore the original
connections, ta king care
N
.5
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