Table of Contents
Advertisement
SECTION
14.
INSTALLATION AND MAINTENANCE
TABLE 14.3-2. 21XL Battery and AC
Transf
ormer
Specif
ications
Lead
Acid Battery
Battery Type
Float
Life
@
25oC
Capacity
Shelf Life,
fullcharge
Charge
Time (AC Source)
AC
Transformer
Input:
lsolated Output:
Gates #810-0011X
8
years minimum
2.5
amp-hour
Check twice yearly
40
hr
full charge,
2O
hr
95o/"
charge
120V AC,
60
Hz
20V DC
@
350 mA
max.
There
are inherent hazards associated with the
use of sealed lead
acid batteries. Under normal
operation, lead acid batteries generate a small
amount
of hydrogen
gas.
This gaseous
by-
product
is
generally insignificant because the
hydrogen
dissipates naturally before build-up to
an explosive level
(4"/")
occurs.
However,
if
the
batteries are shorted or overcharging takes
place, hydrogen
gas may be generated at a
rate
sufficient to
create
ahazard.
Campbell
Scientific makes the following
recommendations:
1
.
A 21X equipped with standard lead acid
batteries
should NEVER be used
in
applications requiring INTRINSICALLY
SAFE equipment.
2.
A lead acid battery should not be housed
in
a gas-tight enclosure.
14.4
SOLAR PANELS
Auxiliary photovoltaic power sources, such as
Solarex Models MSXS, MSX10, and MSX18
Solar Panels may be used
to maintain charge
on lead acid batteries.
TABLE 14.4-1.
MSX5
and
MSX10
Solar Panel
Specifications
MSX5 MSX10
MSX18
Typical Peak
Power
4.2
8.9
18.6
(Watts)
Current
@
Peak
(Amps)
Amp Hrs/week
.27
.59
1.06
6.4
14.4
26.4
14-4
NOTE: Specifications assume
1
kWm2
illumination at a panel
celltemperature
of
25oC. Individual panel performance may
vary
as much as
107o.
When selecting a solar panel,
a rule-of-thumb
that on a stormy overcast day
the panel should
provide enough charge
to meet the system
current drain
(assume
1Oo/"
of average annual
global radiation,
kwm2).
Specific site
information,
if
available, could strongly
i
the solar panel
selection.
For
example,
local
etfects such
as mountain shadows, fog from
valley inversion, snow, ice, leaves, birds,
etc.
shading
the panel should
be
considered.
Guidelines are available
lrom the Solarex
Corporation
for solar panel selection called
"DESIGN
AIDS FOR SMALL PV POWER
SYSTEMS". lt provides a method for
calculating solar panel size based on general
site location and system power requirements. lf
you need help
in
determining your system
power requirements
contact Campbell
Scientif
ic's Marketing Department.
14.5
DIRECT BATTERY CONNECTION
TO THE 21X
Any
10
to 13V DC supply may
be
connected to
the 12V and ground terminals
on
the
21X.
Be
careful
not
to short the leads together when
connecting them to
the datalogger.
A blocking diode prevents the external battery
from charging
the internal alkaline batteries.
14.6
VEHICLE POWER SUPPLY
CONNECTIONS
When
a
vehicle's starting motor
is
engaged, the
supply voltage drops considerably below
the
nominal
12
volts.
lf
the
21X
is
connected
directly to the vehicle's power supply, the 21X's
batteries are also pulled down causing
an E08
error each time the
vehicle
is
started.
Avoid
problem by placing a
diode (1N4001) and a
3
ohm,
5
watt resistor
in
series with
the positive
lead going to the +12V
terminal (Figure 14.6-1).
The diode allows the vehicle
to power the 21X
without
the datalogger attempting to charge the
vehicle.
The
ground lead should be
16
AWG or
larger
to reduce the potential for ground
reference
errors
in
the measurements.
Advertisement
Table of Contents
