Have you noticed how your Samsung smartphone charges faster if you are using the wall-charger that came with the phone than though other chargers? It's sometimes twice as fast! What's up with that?
Most Samsung Galaxy phones (from the originals up through the Galaxy S II, and even the Galaxy Nexus and presumably the Galaxy S III) can charge at 750 to 800mA, but when charging over "generic" chargers, you'll likely only charge at 350mA. That's less than half as fast as the "official" chargers.
One XDA-Developer wanted to know why, and found out the secret lies inside the "official" Samsung wall-chargers. Specifically, between its middle two pins! If the middle pins are connected ("shorted" in electrician-speak), a software switch is triggered inside the phone which allows full-speed charging.
Not long ago we told you about a custom kernel that would allow you to force fast-charging on your Galaxy Nexus. That hack works by telling the Nexus to ignore the two center pins, and just allow full-power charging, regardless of whether or not they're connected.
It should be noted that this hack is for Samsung phones only, and other phones might not know what to do with shorted center pins, so you'll want to label your hacked charger accordingly.
For more information and high-resolution pictures so you can hack your own cheap charger, head over to the source!