Delete comment from: Ken Shirriff's blog
Unindoctrinated: the current rating for a power supply is the maximum it can provide. It's up to the device how much it actually uses, but it needs to stay below the maximum. Manufacturers use a variety of proprietary signals between the charger and the device to indicate how much current the charger can provide. Most likely, the wall plate is incompatible with Samsung, so the tablet doesn't know how much power the wall plate can provide so the tablet charges slowly. With the Samsung charger, probably the tablet only "wants" 1.23A even though the charger could provide up to 2A. For an experiment you could try cranking up the screen brightness to max and watching a video over WiFi and see if the tablet draws more current.
Jan 18, 2017, 2:46:43 PM
Posted to A dozen USB chargers in the lab: Apple is very good, but not quite the best