Why does my phone charge more quickly at some outlets than at others (with the same charger) My cell phone seems to charge slowly, especially at my home (I've tried different outlets).  But recently I was in a coffee bar, and it seemed to charge a lot - a lot! - faster.  I was using the same charger. (My phone is an inexpensive Samsung Galaxy phone, I paid like $50 for it.)
Could be because 


Coffee bar may  be using charging stations which may look like regular charging wall outlets but seem to be designed to charge faster (have not been able to get technical view to back that yet and am searching) 
Outlet at home is not providing sufficient wattage either in terms of voltage or amperage, may be because of poor electrical earthing