It is always recommended that you readout the data logger before replacing the batteries. If you replace the batteries while the Micro Station is logging, it will stop recording data. The data will be overwritten the next time you launch it. If the batteries are dead, be sure to readout the data prior to re-launching the data logger after you have replaced the batteries. To replace the batteries, unscrew the top cover. Remove the battery strap and the old batteries. Insert the new batteries and replace the battery strap.
From the Device menu in HOBOware Pro, select Launch. In the Logger information section of the Launch Screen, select the appropriate battery type (lithium or alkaline). Double-check the battery gauge to make sure that you have not installed old or defective batteries. Replace the battery strap and cover.