So I just had a problem with my iPhone 4 charging. When I plugged it in, it would make the charge jingle but the plug would show up in the battery like it was fully charged (I think it may also show up when charging with unsupported charger) instead of the charging spark (or lightning bolt thing) that usually shows up when charging. Lucky for me I had a spare iPhone battery lying around and swapped it out. This was after I tried turning my phone off multiple times and doing a hard reset, which didn't fix the problem. Anyway, the new battery fixed the problem, and now it charges just fine. Im not sure what was wrong with my old battery, it is a few years old, but it seemed to hold a charge just fine before it just stopped charging. If anyone else has this problem I would recommend trying a hard reset first and then if that doesn't work try swapping the battery before you go messing with the dock connector since it is a lot easier.