Hello,
I am on KDE. When I connect a Bluetooth headphone, everything works fine but there is no indication of the device's battery level in Battery and Brightness widget or anywhere in the top panel.
I need to use upower -d to check the battery level. Is there any way for the battery percentage to be shown somewhere at the top. I couldn't find any widget too.
Thanks
Try conky, not in the bar, but on the desktop, where you like.
Thank you for suggesting it.
I found that it is a very useful software.
Does it answer the OP?
If not, Plasma allows you to add Battery applets/widgets and some or all can display battery %. I don’t understand why you say you didn’t find any, where did you look for?
If they are not already on the list of applets you can downlaod it using the Get Widgets button in the widgets list.
Or maybe you mean none use upower -d… 
I didn't find any battery widget which shows the battery status of my bluetooth devices.
I just realized, that upower -d doesn't show the battery of my bluetooth devices. I was wrong.