Raytheon Beech Baron E55 - Page 604

Raytheon
AiKraft
Company
BARON
55
AND
58
SHOP
MANUAL
h. The
foam
sometimes
seen
in cells
during
charging
does
not
indicate
a
defect.
Foaming
usually
occurs
after
water
is added
and
will
disappear
after
a
few
cycles
of
operation.
The
various
charging
procedures
for the nickel-cadmium
battery
are
outlined in the
following
paragraphs:
CONSTANT
CURRENT
CHARGING
CAUTION:
Monitor
the
battery
closely
during charging (especially during
the
latter
stages)
to
prevent
an
overcharge
that
will heat
up
and
damage
or
destroy
the
battery.
Although
slower,
the
constant
current
method is
the
recommended
way
of
charging
the
battery.
Most
shops
are
equipped
with
constant
current
chargers.
In
cases
where
the
chargers
are
limited
to
6
ampere
capability,
it
will be
necessary
to
start
the
charge
of
most
batteries
at
a
lower
rate
than
recommended
on
the
battery
nameplate,
if
a
reduced
rate
is
used,
a
longer
charging
time
is
required.
The
constant
current
method
is much
more
effective
in
correcting
cell
imbalance
and
temporary
loss of
capacity
and it
permits
easy
computation
of the
charge capacity
in
ampere-hours.
When
using
this
method,
one
must
usually
monitor and maintain the
constant current
by
manually
adjusting
the
charger.
The
following
procedures
for
constant current
charging
are
generally
applicable
to
all
airplane
nickel-cadmium
storage
batteries:
a.
The
time
required
to
charge
a
nickel-cadmium
storage
battery
varies with
respect
to
the
discharging
current,
capacity rating,
and
amount
of
charge already
in the
battery.
If
fully
discharged,
the
battery
should be
charged
to
140
percent
of
its
nominal
ampere-hour
rating.
b. When
using
the
constant
current
method of
charging,
the
battery
may
be
charged
in
two
steps
by
using
the
START rate
of current
and
the
FINISH
rate
of
current.
(Lower starting
rates
may
be
used
if
required by
such
factors
as
equipment
limitations).
These
rates
are
usually given
on
the
battery
nameplate.
The
two
step
method
is
commonly
used
by
the
military.
Single
rates,
slow
or
fast,
are
usually
preferred
by
commercial
service
shops
because
of
their
simplicity.
The
single
fast
charging
rate
is
5.0
amperes per
hour
for
7
hours.
The
slow
charging
rate
is
2.5
amperes
per
hour for
14
hours.
For
slow
(capacity/lO),
single
rate,
constant
current
charging
voltage.
A
battery
is
charged
at
the
START rate
until the
battery temperature
takes
a
sharp
rise
or
until
the terminal
I
voltage
(while
battery
is
charging)
reaches
29.5
volts
(for
a
24-volt I9-ceil
battery)
(Ref. Figure
1).
When the
29.5
volt
point
is
reached
or
the
temperature
takes
a
sharp
rise,
the
charging
current
is reduced to
the
FINISH
rate
and
continued
until
one-third of
the
initial
charge
in
ampere-hours
is
added.
When
the
voltage
rises
to
29.5
volts,
the
charge
received
by
the
battery
is
approximately
equal
to
that removed
when
it
was
previously
discharged.
The
addition
of
ampere-hours
at
the
FINISH
rate
equal
to
one-third
of
the
ampere-hour input
at
the
START rate
will
usually
ensure
that
the
battery
is
fully
charged.
Dec
31/03Page
6
SECTION
13