User Manual
BATTERY
INTERNAL RESISTANCE
BATTERY
INTERNAL RESISTANCE
The difference
is
shown graphically between
the
cell that
is
showing
the highest cell voltage
to the
cell that
is
showing
the
lowest cell voltage
(largest cell voltage difference) indicated
on the
graph. When
the
cell
voltages read equal,
the bar
extends
all the way to the
right
(O).
This
indicates that
the
cells
are all
balanced
to a
satisfactory level. When
the cells have
a
difference
in
voltage
the bar
shortens
and
indicates
towards
the
left
(X). In
order
to
maintain long lasting battery life
if the
balance gauge does
not
show
a
satisfactory cell balance then
a
cell
balancer should
be
applied
to the
pack before
use. If the
cell balance
indication
is low
after
the
battery
has
been used this
can be
normal
and
charging should occur with
a
balance charger.
BATTERY
INTERNAL RESISTANCE
The Mega Meter
has
been created
to
give
you the
ability
to
make
an informed determination
of
what
the
true cell
and
pack ratings
by providing
a
useful measure,
the
cell internal resistance.
• Connect battery
to
Mega Meter
via
Voltage Port
to
power
on the
• Mega Meter Using supplied cable (pitch 2.54mm)
to
measure
indi-
vidual internal resistance
• Press MODE'
to
select
'INT.
RESISTANCE' function
• Press 'ENTER'
to
confirm selection
Connection Diagram
for
Measurement
of
Battery
Internal Resistance
Once
we
have
an
idea
of the
internal resistance
of a
cell
we can
then
use that
to
determine
how
efficient
our
power setup
is as
well
as
knowing
how
much power
is
being turned
to
heat
in the
battery pack
and additionally know
how
much
the
voltage
can
potentially drop under
load.
BATTERY CHECKER
•mSHECBl
Int
.Resistance
WATT METER
SERUO TESTER
Res: 33 noh
TACHOMETER
RPM
TEMPERATURE
THRUST CALC...
SET
UP
Let
it be
stated that there
is no
perfect test
for
cell internal resistance.
Due
to the
nature
of
batteries, cells exhibit characteristics
of
resistance
capacitance
and
inductance
of
which
all
contribute
to the
measured
internal resistance. Internal resistance
can
vary considerably even
within
the
same
cell,
this makes
the
task
of
determining
the
internal
resistance
a lot
harder.
Factors effecting resistance readings:
Contact
corrosion
While
not
actually part
of the
cell itself, having dirty contacts
to the
cells
can make
a
noticeable difference
in the
resistance. Wiping clean
the
contacts
can
improve contact resistance
by 10 or
more milliohms.
Cell
temperature
For many cell chemistries
the
resistance
of the
pack decreases initially
from room temperature
to a
certain level (perhaps
45C)
after which
the
resistance
of the
pack will increase again. Lithium cells
in
particular
suffer poor cell resistance near
OC.
Cell
charge
Generally
the
closer
to a
full charge
a
cell
is the
lower
the
internal
resistance.
Cell
age
As cells become older their internal resistance tends
to
increase.
The Mega Meter
has
been built
to
allow cells
to be
tested under
a
known
set of
loads which will facilitate comparisons.
-
09 -