What type of batteries does the logger use and how long do they last?

The logger uses four AA 1.5V lithium batteries, which are user-replaceable in the field. With W-CT or W-CTD sensors at a 1-minute logging interval, battery life is typically 2 years. With the W-DO sensor at a 5-minute logging interval, battery life is typically 1 year. Faster logging intervals, burst mode, excessive Bluetooth connections, and statistics sampling will reduce battery life.