While clicking on the battery widget on the lock screen, nothing happens. I hope it is supposed to take us to the battery settings page when clicking that widget(because all other widgets do).
Also, when any Bluetooth devices (headset, watch,..) are connected , then this widget (on lock screen) only shows the battery percentage of that Bluetooth device (evethough the widget is supposed to show the phone's battery level) and not the phone.
If you click on the widget while in the lock screen edit mode then you can select which device to show. 
