This charger is total junk. It does not work the way it should. As soon as my phone. Gets a little warm it stops charging (but still shows that its charging), and battery start to drain. This happens in both modes, 1a and 2.1a with different cables. My old griffin PowerJolt doesnt give me such problems. Avoid this low quality piece of junk!
The issue I had is probably related to the cable I was using. I did not use the included USB Cable and it did not work well.