Samsung Galaxy S9 Manual page 6

Steps to phone setup
Charge up
To charge your phone, first connect the
Adaptive Fast Charger to the USB cable, and
connect the USB to your phone. Then plug the
Adaptive Fast Charger into an outlet. Keep your
phone plugged in until it reaches 100% battery.
WARNING: Use only Samsung-approved charging devices.
Samsung accessories are designed to maximize battery life.
Using other accessories may invalidate your warranty and may
cause damage.