There are at least two charger protocols for USB charge only chargers and you can't tell which one you have just by the Amp and Volt information on the charger.
From about 2007/2009 the non-iPhone chargers short the two data pins.
iPhone Chargers do not and read the data pins to control or limit the Amps.
A 2.0 Amp iPhone charger may only put out .5 Amps (and may over heat your phone).
Many of the Generics went after the iPhone/iPod market and don't tell you.
If its a USB charger and says universal and iPhone "it is not".
There are some dual USB car chargers with the iPhone protocol on one side and non-iPhone on the other.
Originally Posted by Rolo42
Aside from voltage(s), power supplies have a limit on how much current they can provide (Amperes/milliamperes). The Samsung travel charger is rated at 1A, or 1000mA, which is what the phone will draw if it senses it is not attached to a PC; if senses it is attached to a PC, it will only draw 500mA.
Always check the device's power requirements and check the power supply's capabilities. The voltages must match but the power supply can have a higher current rating; a lower one will cause problems and risks damaging the device, the power supply, and causing a fire.
There are several "do it yourself" site showing how cut open an iPhone protocol charger and solder up the data pins. A little too much for me.
If you care it was while trying to find out why the generics I had did not work for my S3 I found
iPhone doesn't follow the:
September 2007 Open Mobile Terminal Platform,
the 17 February 2009 the GSM Association (GSMA) agreed standard charger for mobile phones,
the 22 April 2009 CTIA endorsed protocol, or
the Universal Charging Solution embraced by the International Telecommunication Union (ITU) On 22 October 2009.
And the generic don't tell you.
I know too much time on my hands.