The internal battery is not rechargeable. In the case of low internal battery voltage, data will only be maintained as long as a power supply is connected. Collect all data from the data logger before disconnecting the power.
The battery, a 15598, is not user replaceable. The data logger should be returned to Campbell Scientific to have the battery replaced. To request a returned material authorization (RMA) number, follow the steps listed on our Repair and Calibration page.