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99 of 108 people found the following review helpful
Does not charge at full power unless modified; Included cable limited to 500mA
on January 14, 2013
The product I received was not able to supply the advertised current with the supplied USB cable or any other USB cable. The supplied USB cable would never be able to supply >500mA regardless of the charger, AC or USB. I needed to modify the 2.1A port in able to draw the advertised current. I needed to modify a USB cable to draw the advertised current from the non-modified 1A port.
Out of the box, this charger will not provide the advertised 2.1A or 1A to your USB device. I used my HTC Rezound android phone and the Battery Monitor app to see two things: 1) The charge mode when plugged into each USB port, and 2) The amount of current being sourced to the phone.
1) The phone only recognized the "USB" charge mode, and not "AC" charge mode. In the "USB" charge mode, the phone will limit itself to 500mA only. In "AC" charge mode, the phone will remove the 500mA restriction and take as much power as it can handle. I used both the supplied USB cable and ones that came with AC adapters that when plugged in, indicate "AC" charging. There was no USB cable that I tried that allowed AC charging from this product.
After some research, I found that the 2 inner pins (data +, data -) on the physical USB connector need to be shorted together in order for the phone to recognize AC charging. I opened this charger and soldered the 2 data pins together on the 2.1A port, but left the 1A port alone. Using a USB cable known to source >500mA from an AC adapter, I connected my phone to the charger's 2.1A port in the car. The charge mode indicated "AC" and no longer "USB". I then removed the cable from the 2.1A port and plugged into the unmodified 1A port, and the phone indicated "USB" charging.
I then used the supplied USB cable in both ports, but the phone only indicated "USB" charging for each one. I tried the cable on an AC adapter and the phone still indicated "USB" charging. I disconnected the cable and sliced it open to find that there were no wires for data + or data - (the 2 inner pins). This means that regardless of the charger, this cable would not allow full-rate charging at 2.1A or 1A since the USB device would see data + and data - as an open circuit, instead of a short circuit, and limit itself to 500mA.
2) After the soldering modification, I witnessed current rates on the phone via the Battery Monitor app exceeding 900mA from the 2.1A port, which is the net amount of current going to the battery after supplying power for existing phone functions (CPU, screen, radios, etc).
Further, I took another USB cable that has data lines, cut open the outer insulation and spliced together the 2 data lines (green & white insulation). After re-insulating the cable, plugged it into my phone and the 1A port (the not modified port). The phone indicated "AC" charging and >500mA net current to the battery.