SECTION 14. INSTALLATION AND MAINTENANCE

14.4 SOLAR PANELS

Auxiliary photovoltaic power sources may be used to maintain charge on lead acid batteries.

When selecting a solar panel, a rule-of-thumb is that on a stormy overcast day the panel should provide enough charge to meet the system current drain (assume 10% of average annual global radiation, kW/m2). Specific site information, if available, could strongly influence 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.

14.5DIRECT BATTERY CONNECTION TO THE CR10 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 wiring panel. Any 9.6 to 18 VDC supply may be connected to the 12 V and G terminals on the wiring panel. The metal surfaces of the wiring panel and mounting bracket are at power ground. Make connections to the wiring panel first and then to the power supply. If the power supply must be connected first, connect the positive to the wiring panel before the ground to avoid shorting to the wiring panel or mounting bracket.

14.6VEHICLE POWER SUPPLY CONNECTIONS

If a CR10 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 CR10 to malfunction every time the vehicle is started. The second 12 V supply prevents this malfunction. Figure 14.6-1 shows the general case for connecting the two supplies to the Wiring Panel. The diode allows the vehicle to power the CR10 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.

FIGURE 14.6-1. Connecting to Vehicle Power Supply

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