draining

A friend of mine recently purchased a Samsung galaxy music S6012-its an android device and ships with ICS by default.However,it has come to his notice that the battery on his phone has been draining too fast since the day it was purchased.It just seems to be depleting one percent every 3 minutes...

Should you discharge a Li-ion battery all the way before plugging it in? Is it especially pertinent when you get a new battery / laptop? Should you keep draining it all the time, or leave it plugged in whenever you can? All battery tips are welcome.

Hi guys..today morning I kept my mb for charging n still after 2hrs battery show was 2o% n refuses to go beyond that. what could be the reason? is it dead? pls reply. its draining now ... regards Mandar