Samsung Galaxy Tab, charging technique through USB Cable From Galaxy Tab is not being charged through USB Cable

@Chris Stratton


  Tablets have larger batteries than phones and may be unable to
  sufficiently charge from the half amp limit of a USB port, especially
  while they are fully on (screen on and full speed processor clock).
  
  Some will barely charge if the screen is off but come with high
  current 5v "usb-like" wall chargers, others use a higher voltage
  charger on a custom connector - typically something round. Sometimes
  the "usb-like" ones are actually special cables with extra pins that
  tell the tablet that a special high-current charger is being used.


@NobbZ


  The Samsung Galaxy Tab has a loading current of 2 A, but the
  USB-Specificication only allows 500 mA for the whole bus.


From http://en.wikipedia.org/wiki/Universal_Serial_Bus

@USB 3.0


  Battery Charging Specification 1.2 released in December 2010. Several
  changes and increasing limits including allowing 1.5 A on charging
  ports for unconfigured devices, allowing High Speed communication
  while supplying a current up to 1.5 A, and allowing a maximum current
  of 5 A


So, What kind of USB Cable should be used to Charge Samsung Galaxy Tablets, for example Samsung Galaxy Tablet 2 (GT - P5100)
I don't think the cable is particularly important.  Its the jack that the cable plugs into that makes a difference.  



Basically, if the tablet can tell that its plugged into a special (high amp) jack, then the tablet will charge more quickly (at 2A), otherwise the tablet will assume its plugged into a standard USB port and charge at the specification limit (500 mA).  The best way to get an adapter that the tablet can identify is to use the official wall adapter.  I believe there is no "standard" way of doing this, so different manufacturers may do different things (e.g., using an Apple USB charger may not work).

You should be able to see what your tablet is doing based on the battery icon in the system tray (assuming its similar to the older Galaxy Tab that I have).  On my tablet the icon will have a small red "X" if its being charged through a "normal" connection, and should have no such "X" if its being charged through a high-amp connection.

See How much power does a Galaxy Tab 10.1 charger need to supply?

And Do Samsung tablets have the same USB connector as Apple&#39;s iPad?

And Why is charging from computer using USB slower than using an outlet?