Campbell CR23X, Operator'S Manual, Page: 232 / 374

SECTION 14. INSTALLATION AND MAINTENANCE
14-6
the solar panel selection. For example, local
effects such as mountain shadows, fog from
valley inversion, snow, ice, leaves, birds, etc.
shading the panel should be considered.
Guidelines are available from the Solarex
Corporation for solar panel selection called
"DESIGN AIDS FOR SMALL PV POWER
SYSTEMS". It provides a method for
calculating solar panel size based on general
site location and system power requirements.
If you need help in determining your system
power requirements contact Campbell
Scientific's Marketing Department.
Connect solar panel leads to the green
connector at the side of the CR23X next to the
power switch (rechargeable base only). Polarity
does not matter.
14.5 DIRECT BATTERY CONNECTION
TO THE CR23X WIRING PANEL
For some applications, size restrictions or other
operational considerations may preclude the
use of Campbell Scientific power supply
options. In these cases the power supply may
be connected directly to the CR23X. Any clean,
battery backed 11 to 18 VDC supply may be
connected to the 12 V and G connector
terminals on the front panel. When connecting
external power to the CR23X, first, remove the
green power connector from the CR23X front
panel. Insert the positive 12 V lead into the
right-most terminal of the green connector.
Insert the ground lead in the left terminal.
Double check polarity before plugging the green
connector into the panel.
Diode protection exists so that an external
battery can be connected to the green G and
12 V power input connector, without loading or
charging the internal batteries. The CR23X will
draw current from the source with the largest
voltage. When power is connected through the
front panel, switch control on the standard
CR23X power supplies is by-passed.
14.6 VEHICLE POWER SUPPLY
CONNECTIONS
14.6.1 CR23X WITH BATTERY BASE
Some vehicle testing applications use the
vehicle's 12 Volt power system as the primary
supply for a CR23X with a battery base.
However, when a vehicle’s starting motor is
engaged, the system voltage drops
considerably below the nominal 12 volts needed
for uninterrupted datalogger function. To
counter this problem, diodes have been placed
in the CR23X in series with the 12 V Power In
connector. This allows the battery base to
supply the needed voltage during motor start.
The diodes also prevent the separate power
systems of the CR23X and vehicle from
attempting to charge each other.
CR23X
Panel
+12V
G
FIGURE 14.6-1. Connecting Vehicle Power
Supply
If a CR23X without batteries is to be powered
from the 12 Volts of a motor vehicle, a second
12 V supply is also required at the time of
vehicle start-up. When the starting motor of a
vehicle with a 12 V electrical system is
engaged, the voltage drops considerably below
the nominal 12 V, which would cause the
CR23X to stop measurement every time the
vehicle is started. The second 12 V supply
prevents this malfunction. Figure 14.6-2 shows
the general case for connecting the two
supplies to the CR23X. The diode allows the
vehicle to power the CR23X without the second
supply attempting to power the vehicle. To
reduce the potential for ground reference errors
in measurements, the ground lead should be 16
AWG or larger.