SECTION 14. INSTALLATION AND MAINTENANCE

FIGURE 14.3-1. PS12 12 Volt Power Supply and Charging Regulator
TABLE 14.3-1. Typical Alkaline BatteryService and Temperature
Temperature (°C)% of 20°C Service

20 - 50

100

15

98

10

94

5

90

0

86

-10

70

-20

50

-30

30

NOTE: This data is based on one "D" cell under conditions of 50 mA current drain with a 30 ohm load. As the current drain decreases, the percent service improves for a given temperature.

The five foot external battery cable can be connected to a large capacity (amp-hour) battery to power the system for an extended period of time. The red and black leads connect to the positive and negative battery posts, respectively. The alkaline cells act as a power backup in this case. A diode in the PS12ALK isolates the lead acid supply from the alkaline batteries.

14.3.2 PS12LA LEAD ACID POWER SUPPLY

The PS12LA power supply includes a 12 V, 7.0 amp-hour lead acid battery, a AC transformer (18 V), and a temperature compensated charging circuit with a charge indicating diode. An AC transformer or solar panel should be connected to the PS12 at all times. The charging source powers the CR10 while float charging the lead acid batteries. The internal lead acid battery powers the datalogger if the

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