[Q] understanding fast charge topic

hi all, I try to understand fast charge algorithm of stock jb sony xperia ion. I have a bench type, volts and amps adjustable power supply. when I test charging with data wires shorted usb cable (fast charge mode), its about 1.35 amps at 5 volts. But however original sony ac wall charger is faster than this constant voltage method.
So, I guess there is something beyond shorting data wires for fast charge...
How can we push more than 1.35 amps without ori ac wall charger? Any ideas are welcome. thanx! :)


P.S: if I use a regular usb cable (data wires not shorted), phone draws only 0.46 amps at 5 volts.