It takes up to six hours to fully charge your Logitech Ultrathin Keyboard Mini. Low-power USB ports and low-power USB chargers may take longer to charge than other sources.
We recommend charging your keyboard until the charging light turns solid green.
To charge the keyboard:
Locate the USB Micro cable that came with your keyboard.
Insert the micro connector into the port on the keyboard.
Plug the larger USB plug into either a PC or your iPad Mini charging adapter.
The status light will:
Blink while the keyboard is charging
Turn solid green when your keyboard is fully charged
Please see answer 360023415953 for battery information.