Internal battery

The lithium battery powers the internal clock and SRAM when the data logger is not powered. This voltage is displayed in the LithiumBattery (see Information tables and settings (advanced)) field in the Status table. Replace the battery when voltage is approximately 2.7 VDC. The internal lithium battery life is extended when the data logger is installed with an external power source. If the data logger is used in a high-temperature application, the battery life is shortened.

To prevent clock and memory issues, it is recommended you proactively replace the battery every 2-3 years, or more frequently when operating continuously in high temperatures.


The battery is replaced during regular factory recalibration, which is recommended every 3 years. For more information, see Data logger calibration.

When the lithium battery is removed (or is depleted and primary power to the data logger is removed), the ClosedCRBasicCampbell Scientific's BASIC-like programming language that supports analog and digital measurements, data processing and analysis routines, hardware control, and many communications protocols. program and most settings are maintained, but the following are lost:

  • Run-now and run-on power-up settings.
  • Routing and communication logs (relearned without user intervention).
  • Time. Clock will need resetting when the battery is replaced.
  • Final-memory data tables.

A replacement lithium battery can be purchased from Campbell Scientific or another supplier.

  • AA, 2.4 Ah, 3.6 VDC (Tadiran TL 5903/S) for battery-backed SRAM and clock. 3-year life with no external power source.

See Power requirements for more information.


Misuse or improper installation of the internal lithium battery can cause severe injury. Fire, explosion, and severe burns can result. 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 Status field Battery value and the destination variable from the Battery() instruction (often called batt_volt) in the Public table reference the external battery voltage.

Replacing the internal battery

It is recommended that you send the data logger in for scheduled calibration, which includes internal battery replacement (see Data logger calibration).


Any damage made to the data logger during user replacement of the internal battery is not covered under warranty.

  1. Remove the two screws from the back of the panel.

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  2. Pull one edge of the canister away from the wiring panel to loosen it from the internal connectors.

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  3. Lift the canister edge out of the enclosure tabs.

  4. Remove the nuts, then open the clam shell.

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  5. Remove the lithium battery by gently prying it out with a small flat-bladed screwdriver. Replace it with a new battery.

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  6. Reassemble the data logger. Take particular care to ensure the canister is reseated tightly into the connectors by firmly pressing them together by hand.