Asus BU401LG - Manual (Page 26)

 Notebook PC E-Manual
Getting started
NOTE: If your Notebook PC does not have its battery pack installed, use
the following procedures for installation.
Charge the Notebook PC for 3 hours before using it in
battery mode for the first time.
NOTE: The power adapter may vary in appearance, depending on models
and your region.
Charge your Notebook PC.
A. Connect the AC power cord to the AC/DC adapter.
B. Plug the AC power adapter into a 100V~0V power source.
C. Connect the DC power connector into your Notebook PC’s power
(DC) input.