For those that keep going back to the technical charging capabilities of a Lithium Ion battery they are missing the key point with these phones...
The PHONE is wrong on how much charge is in the battery. It the phone thinks the battery is at 100%, it stops charging even it the battery has only 50% charge - and also if the phone thinks the battery has 1% it shuts off even if the battery has 60% charge.
When you load different ROMS and make lots of system changes, the phone tries to determine how much battery power is left, and it just isn't the best at doing that.
My phone shut off last night after running it down to 0% battery (not on purpose, just couldn't get to a charger).... when I plugged it into the charger it immediately said that it had 55% battery left.
The method described in this thread works, not because it defies the laws of science, but because it resets the phones tracking of battery % to allow it to be more accurate.