The technical indicator of a fully charged battery is
240KW/400KW industrial rooftop - commercial rooftop - home rooftop, solar power generation system.
I''ve only been using this for 2 weeks since purchase and just discovered this function recently. This keyboard has been plugged for more than 24 hours and the red light where the USB C is plugged in disappeared, that''s why I know it''s fully charged. It should display a green light if you press fn+B if the KB is fully charged, so they say.