Why is my smartphone charging very slow on USB ?
Better read: Data Consistency in Distributed System - CAP, PACELC Morality series - a heptalogy This blog is mainly focused on my Philosophical and theoretical ideas. From time to time I have practical posts that are too few to deserve a blog by themselves. I still hope my other work (like above) is even more valuable than such practical article as below. * * * Sometimes the phone is connected to a charger, it reports "charging", however the battery level increases painfully slow, or it could even actually decrease. What is the solution? On short: Update 2020 : prefer original chargers. Even using QC 3.0 charger, some Samsung phones (like A51) will charge faster with original charger - when the display is ON. With display OFF, QC 2.0/3.0 chargers might still be as fast as original chargers. For phones, prefer the 1A ("phone") charger port to the 2A ("tablet") charging port. The 2A port is likely to charge slower than the 1A port (see below why)...