Raytheon Beech Baron E55 - Page 605

Raylheon
Aircraft
Company
BARON
55
AND
58
SHOP
MANUAL
c.
The
time
required
for
completing
the
charge
at
the
FINISH
rate
may
be
computed
by
the
following
formula:
TF
=(IS
X
TS)
/(3
x
(F)
TF
Time,
in
hours,
required
for
finishing
charge
Is
Starting
charge
rate
in
amperes
Ts
Time,
in
hours,
of
charge
at
the
starting
rate
until
29.5
volts
or
temperature
rise
occurs
I
F
Finish
rate
in
amperes
As
an
example,
assume
that
a
20
ampere-hour battery
is
charged
at
a
start
rate
of
8
amperes
for 2
hours,
at
which
time
the
voltage
rises
to
29.5
volts. The
ampere-hour
input
at
the
start rate
is
then
is
x
Ts
8
x
2
1S
ampere-hours.
The
ampere-hours
of
additional
charge
required
are
(Is
x
Ts)/
3
TF
IF
16/3 5.3.
If
a
finish
rate
of
2
amperes
is used the
finish
rate
charge
time
will
be:
TF
=(IS
X
Ts)/
(3
x
IF)
(8
x
2)/(3
x
2)
16
6
2.7
hours
d.
While
the
battery
is
being
charged,
the
charging
current
should
be
kept
constant
at the
rate
being
used.
If
the
battery
charger
is
not
a
self-regulating type,
this
operation
can
be
achieved
by
manually adjusting
the
charger
on
a
periodic
basis.
e.
During
the
finish
charge,
the
individual
cell
voltages
should be
measured with
a
precision
voltmeter
to
determine
if all
cells
are
rising
evenly.
Should
some
cells
indicate
a
voltage
lower than the others
by
0.05
volts
or
more,
it
is
advisable
to leave
the
battery
on
charge
a
while
longer
for
additional
equalization.
Do
not
allow
the
battery
to
overheat.
CONSTANT
POTENTIAL
CHARGING
Nickel-cadmium
batteries
can
be
charged
much
faster
by
the
constant
potential
method,
but
the
charging
time
will
depend
on
the
current-delivery
capability
(300
ampere
generators
are
good
charging
sources).
A
disadvantage
of
I
constant
potential
charging
is
that
full
capacity
cannot
normally
be restored
if
a
battery
suffers
from
temporary
loss
of
capacity.
It
should
also
be
noted
that such
a
loss
of
capacity
is
quite
common
in
batteries after
prolonged
use
in
a.
Vented,
19-cell,
24-volt,
nickel-cadmium
batteries
will
normally
be
charged
at
28.5
volts
in the
shop
when
charging
with
a
constant
potential
voltage.
Note
that
charging
a
19-cell
battery
at
28.5 volts
is
equivalent
to
charging
each
cell
at
1.50
volts.
The
initial
charging
current
may
be
as
high
as
10
times the
ampere-hour rating
of
the
battery,
depending
on
the
amount
of
charge already
in
the
battery.
The
high
initial
current
will
not
damage
the
battery,
butthe
charging
equipment
should
have
an
inherent
current-limiting
capability
or
be
provided
with
overload
protection.
b.
The
time
required
to
charge
will
depend
primarily
on
the
current-delivery capability
of
the
charging
unit.
The
lower the
charging
current,
the
longer
the time
required
to
charge.
If
the
battery
does
not
suffer
from
temporary
loss
of
capacity,
nearly
full
charge
(approximately
90
percent
of
rated
capacity)
may
be restored
within
I
hour
at
28.5
volts
charging potential,
provided
the
charging
equipment
is also
capable
of
delivering
current
equal
to
two-to-three
times the
ampere-hour
rating
of the
battery
(Ref.
Figure 2).
1
E21
SECTION
13
DecP~;bjPage
7