Newly purchased and installed an Expansion Jacket w/ 2nd battery fitted inside. The 2nd battery, when docked or plugged, is viewed and manged by the OS. When I detach them and switch to battery, the OS doesn't recognize the second battery, thus I work with only one. The device BIOS is the most recent (01.45 Rev. A) and the OS is MS Windows 10 Pro 1803 Build 17134.81.