Question

benefits of 18w on a battery​

Answer 1

Answer:

All phones “take” only what they want/can handle.

having a charger that can handle less, is bad. It might tell the phone to charge slowly, or overheat.

having a charge that is larger than you need is a waste.

say your phone charges at 2.1A. Power (W) is volts (5V) times amps, or 10.5W watts. Any of those chargers will work. And none is any better for battery life.

since the phone charging circuit always tries to draw 10.5W, 18W sounds good.