Hi, Thank you for writing to us! Type"Device" into Cortana's search field, found device manager, clicked the drop down for "batteries", then disabled/ re-enabled AC Adapter and ACPI Compliant Control Method Battery. The battery icon appeared almost immediately after doing so and it is still there after restarting my computer. It is also no longer greyed out like it was before doing so. Kindly private message the service tag and email address. Thanks Robin
I did not even know I had gotten an update but I noticed my battery icon was missing from the taskbar.  I replaced it at Settings-Personalization-Taskbar and then noticed I had gotten a new update... KB3211320, so I assume that is what removed the icon.
Today's Windows Update removed battery icon from Taskbar