Heart Interface HF12-1200 - Page 10

resistance
of these
batteries
is lower
than
that
of conventional
lead-acid
batteries.
This
means
!!at
the
battery voltage
stays
higher
under
load,
which
adds
a measure
of
performance
ro
the
Heart.
leep-cycle
battery
c-apfity
is
expressed
in
amp-hours,
usually
this
number
will
refer
ta a20
hour
discharge
cycle..For
example,
a 100
amp-6our
battery
*ill
deliuer
5 amps
foi
ZO
hours.
If
the discharge
rate
is
greater
than
5 amps
the
overall
amp-hours
available
will
be
reduced.
Drawing
2!
ayns,
a
100amp-hour-batlery
will
deliver
only
about
80
amp-hours.
Drawing
100
amps
the
battery
will
deliver
about 45
amp-hours.
. !":!-"ycle
batteries
can
be discharged,
sOVo
without perrnanent
damage.
This
means
that
a 10O
amp-hour
battery
hag
S! amps
of
useful
capacity.
The
number
of
discharge
cycles
in
the life
of a battery
is
directly
dependent
on how
deepiy
they
are
discharged.
rf
lou
oniy
draw
SAVo of the batJev.cagpity
each
time
before you
iecharg-e,
your
batteiy
bank
will
lait
much
longer
than
a bank
of
batteries which
is
discharged,
g0%
eich
time.
To-size your
battery
bank
you
need-to
determine
approximately
how
many
amp-hours
you
will
consume
between
charging
cycles.-Start
by looliing
on eacir of
your
afpfiances
ioi
the number
of watts
that it
consumes.
Then
figure
out
how
miny
hours
thi
apptiairce
will
run
between-
charging
cycles.
For
example,
a small
refrigerator
consume
s
240
watts.
It
will
operate forabout
l0hoursperday.
This
meansitwill
consume
about
2400
watt-hours
perday.
A
corollary
of
Ohm's law
tells
us
that
watts
equals
volts
times
amps.
Therefore,
if
we
divide
$e
yatl;.h9urs
by
our 12
volt
battery
voltage
wE
get
200
amp-hours.
Figure
in
about lAVo
extra
for
inefficigncy,
so that this
refrigerator
will
draw
about
220
amp-tr6urr p",
day from youi
battery
bank.
A minimu*
oq
a 280
amp-hour
battery
bank will
be necessary
ro
power
the
above
refrigerator
for
oneday,
assuming
that
we
diicharge
the
battery
bank
io
gdEo.
elarger
bank
will
allow for less
deep
dischargrng
and
longer
battery life.
WATTS=VOLTSxAMPS
WATT
HoURs
=
WATTS
CONSUMED
By
APPLIANCE
x
HOURS
oF
USE
AMp.
HOURS
=
WATT
HOURS
/
VOLTS
USING BATTERIES:
YourHeart
Interface-operates
9n
a 12
volt
battery
bank.
The
actual
voltage
of this
bank
may_get
as low
as 10.5
volts
or as
lriqh
as 14.5
volts.
Within
this range
the
ouiput
voltage
of
the
Heart
will remain
constanr
at
ll9-I2l
volts
RMS.
. lattery_bank
oulput
voltage
will
drop
under
load.
The larger
the
battery
bank
the
smaller
the
voltage
drop
will
be.
For
ttiis
reason
it
is
advantageous
toiuur
ur rirgdof
u
i;;i;;fi;;;
as
practical,
especially
if
you
will
be startingiaductiie
loads
such
as
reffrgeration
motors
or
well
pumps.
In
most
cases,
inductive
loads
will
start
easier
if
the
banery
"6itug"
ir
retativeiy
high.
AsyouuseyourHeartyou
will find-ituseful
tomonitorthe
stareof
chargeo{yourbattery
bank.
This
will let
you
know
when it is
time
to recharge
without
letting
ttre
t6*
uanery
cutour
circuit
shut
the unit
down
unexpectedly.
The state of charge
of a
battery
can
be measured
by
two instruments,
a hydrometer
or
9