Campbell Scientific CR3000 Micrologger - Manual (Page 421)

421
Section 9. Maintenance
Temperature and humidity can affect the performance of the CR3000. The
internal lithium battery must be replaced periodically.
9.1 Moisture Protection
When humidity tolerances are exceeded and condensation occurs, damage to
CR3000 electronics can result. Effective humidity control is the responsibility of
the user.
Internal CR3000 module moisture is controlled at the factory by sealing the
module with a packet of silica gel inside. The desiccant is replaced whenever the
CR3000 is repaired at Campbell Scientific. The module should not be opened by
the user except to replace the lithium coin cell providing back up power to the
clock and SRAM. Repeated disassembly of the CR3000 will degrade the seal,
leading to potential moisture problems.
Adequate desiccant should be placed in the instrumentation enclosure to prevent
corrosion on the CR3000 wiring panel.
9.2 Replacing the Internal Battery
Caution Fire, explosion, and severe-burn hazard! Misuse or improper
installation of the lithium battery can cause severe injury. Do not recharge,
disassemble, heat above 100°C (212°F), solder directly to the cell, incinerate, or
expose contents to water. Dispose of spent lithium batteries properly.
The CR3000 contains a lithium battery that operates the clock and SRAM when
the CR3000 is not powered. The CR3000 does not draw power from the lithium
battery while it is powered by a 12-Vdc supply. In a CR3000 stored at room
temperature, the lithium battery should last approximately 3 years (less at
temperature extremes). In installations where the CR3000 remains powered, the
lithium cell should last much longer.
While powered from an external source, the CR3000 measures the voltage of the
lithium battery daily. This voltage is displayed in the Status table (see the
appendix Status Table and Settings
(p. 529)
). A new battery supplies approximately
3.6 Vdc. The CR3000 Status table has a Lithium Battery field. This field
shows lithium-battery voltage. Replace the battery when voltage is approximately
2.7 Vdc. If the lithium cell is removed or allowed to discharge below the safe
level, the CR3000 will still operate correctly while powered. Without the lithium
battery, the clock will reset and data are lost when power is removed.
• The CR3000 is partially disassembled to replace the lithium cell. See figure
Loosening Thumbscrews
(p. 422)
through figure Remove and Replace Battery
(p.
424).
When the lithium battery is removed, the user program and most settings
are maintained. Items not retained include
o Run-now and run-on power-up settings.
o Routing and communications logs (relearned without user intervention).