I have a few problems with my USB car charger. All that I bought so far recarregavam the tablet or the phone very well. Usually the source loads the device much better.
So I decided to do a test. I bought an expensive USB charger, FoneMax brand (about of 9 U.S. dollars) and a cheap no-brand ($ 1.99). This below is the FoneMax.
The finish of this charger FoneMax is much better than average.
The specification says the 3.1: works well for charging iPads or cellphones.
There's the charger with your two USB outputs.
Next to the FoneMax we have the cheap USB charger (still in packaging).
The cheap charger has a LED on the side while the FoneMax lights around outer circle. In there's a cheapie increased power output, for iPads and tablets, and a lower power for cell phones.
But it's pretty obvious that the charger has cheap construction more fragile.
I tested both and it worked perfectly. The cheapie heats up a little more and the more expensive FoneMax is the best I've ever seen. The difference in quality is the same price difference, What is typical in Chinese websites. I leave the link to the products, purchased in DealExtreme: