I doubt you will see 2.1amp charge. I have not tested the mentioned chargers. I ran a direct wired 12volt outlet to the backseat for my daughter. I pulled the fuse at the battery and placed a multimeter inline measure amperage. I used cheap and expensive chargers and usb data cords withe various Androids phones/tablets. None of the devices was a gs4. There were two gs3's. I saw a momentary spike to . 94amps. Most devices/chargers were below this level. I did not use a dedicated Android charge cable (data +/- shorted).