SECTION 14. INSTALLATION AND MAINTENANCE

charging source is interrupted. The PS12LA specifications are given in Table 14.3-2.

The two leads from the charging source can be inserted into either of the CHG ports, polarity doesn't matter. A transzorb provides transient protection to the charging circuit. A sustained input voltage in excess of 40 V will cause the transzorb to limit voltage.

Some solar panels are supplied with a connector, this connector must clipped off so the two wires can be inserted into the two terminal ports. It is recommended that these two leads be stripped and tinned.

The red light (LED) on the PS12LA is on when a charging source is connected to the PS12LA CHG ports. The switch turns power on and off to the 12 V ports, battery charging still occurs when the switch is off.

CAUTION: Switch the power to "off" before disconnecting or connecting the power leads to the Wiring Panel. The Wiring Panel and PS12LA are at power ground. If 12 V is shorted to either of these, excessive current will be drawn until the thermal fuse opens.

The external port, labeled EXT, is not meant to be used with the PS12LA. The primary power source is the charging source, and the secondary power source is the internal lead acid battery. Connecting a lead acid battery to the external source is the same as connecting two lead acid batteries in parallel, causing one battery to drop voltage and the other to raise voltage. Alkaline batteries connected to the external port must have a diode in series to block charging which would cause an explosion. (The PS12ALK battery pack has this diode.)

Monitor the power supply using datalogger Instruction 10. Users are strongly advised to incorporate this instruction into their data acquisition programs to keep track of the state of the power supply. If the system voltage level consistently decreases through time, some element(s) of the charging system has failed. Instruction 10 measures the voltage at the 12 V port, not the voltage of the lead acid battery. External power sources must be disconnected

from the CR10 and charging circuit in order to measure the actual lead acid battery voltage.

14-5