Campbell Scientific CR3000 CR3000 Micrologger - Page 86

Section 7. Installation 86 The charging source powers the CR3000 while float charging the batteries. The batteries power the CR3000 if the charging source is interrupted. The table Sealed Rechargeable Battery and AC Transformer Specifications (p. 87) lists the recommended operational temperature range and other specifications. Leads from the charging source connect to the CHARGING INPUT by way of two, screw-secured terminals on the connector. Polarities of the leads on these terminals do not 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. A red LED (light) is on the base near the connector. It is illuminated when a voltage is present at the charge terminals. The charge terminals must be between 17 and 24 Vdc or at 18-V RMS ac for charging to occur; however, the LED will also illuminate when the connected voltage is not adequate for charging. The POWER switch controls CR3000 power. Battery charging continues when the switch is in the OFF position. Monitor the power supply using CRBasic instruction Battery(). Incorporating this instruction into the CRBasic program will enable continuous tracking of power-supply performance. If the system-voltage level consistently decreases through time, an element of the charging system is degraded or has failed. The Battery() instruction measures the voltage internal to the CR3000, not the voltage of the battery. The measured voltage will be about 0.3 Vdc less than the voltage at the internal or external 12-Vdc input due to a Schottkey diode. External-power sources must be disconnected from the CR3000 to measure the battery voltage. Replacing Sealed Rechargeable Batteries Replacement of rechargeable batteries may be indicated if the supplied power shows signs of degrading. See Power Supplies (p. 438). To replace the batteries, perform the following procedure while consulting figure Sealed Rechargeable Battery Wiring (p. 88). Install new batteries with the following procedure: 1. Position the power switch on the side of the base to OFF. 2. Loosen the two knurled thumbscrews at the lateral edges of the datalogging module face. 3. Disconnect the green terminal strips from the wiring panel, if necessary. 4. Carefully separate the datalogging module from the base, unplugging the white connector that connects the module to the base. The connector is located just under the lower-left lip of the datalogging module, near the ground lug. A small lever on the side of the connector must be depressed before pulling it out. 5. Remove the two batteries and replace with batteries specified in table Sealed Rechargeable Battery and AC Transformer Specifications (p. 87). 6. Reconnect the white power connector to the datalogging module. Re-seat the module and tighten down the knurled thumbscrews. Re-seat the terminal strips if necessary. 7. Switch the power switch to ON. 8. Check for normal datalogging function before leaving the site.