Charging in Galaxy S9|S9+?

For fastest charging times, use the Adaptive Fast Charger that came with your phone.

Steps:

1. Navigate to Apps > Settings.

2. Swipe to and touch Device maintenance (or Device Care), and then touch Battery. 

3. Touch More Options > Advanced settings. 

4. To turn on Fast cable charging, touch the slider.

While charging, the phone and the charger may become hot. This does not affect the phone's lifespan or performance and is in the phone's normal range of operation. If the phone or charger goes out of normal range, charging automatically stop so they can cool down. 

To charge your phone wirelessly, place the phone on top of the wireless charging station (not included). Though it may seem like a basic step, make sure the wireless charger is plugged in.