Originally Posted by schm1dt
I charged my A700 with my HTC USB charger (HTC TC E250) in standby mode this night. It charged from 23% to 64% in about 10 hours. There was nothing at the A700 that showed it is charging.
To be honest, 4% per hour is "nearly not charging".
This is known as trickle charge. The device might charge if the micro USB provides enought mili amps AND the device does not need much power when connected (i.e. screen off).
I really doubt that the device will charge on USB when the screen is on, but on the other hand the device will definitly discharge slower when connected to USB.
I have a small calculation to explain things:
The original charger operates with 12V at 1.5 Amps = 18 Watts (which is not USB compatible so they hat to change the jack to ensure it will not be pluged in to a normal USB device and damage it)
If you would like to have the same Power over USB with its 5V max voltage you would need at least 3,6 Amps. Now that is far to much for those little pins on the micro USB jack and the currency would damage the pins when pluggin in and out.
USB standard specification normally is 500mA = 0,5 Amps ( -> 2,5 Watts in comparison with 3,6 Amps 18Watts)
So I think Acer has done a quite nice compromise.
Hope that clarifies matters a bit.
MBM525 [CM10] 28-07-2012, powered by Quarx
Acer A510 Stock ICS 4.0.3 - rooted