charging... weird...
 

i found a cable in my house which fits my mp4 player and charged it using the AC adapter, it charged half my battery in 10minutes. Is tha a good thing?

A cable is a cable I suppose. As long as the contacts are the same it should go right. The output voltage of the adapter is a fixed value. Is it charging faster now than before? It may look half charged, but is it playing half the time of a full loaded player? Charging the second half usually takes longest.