This wasn't my idea so I'm linking to the originator of this to give credit where credit is due:
Calibrating your battery and Android - Android Central Forums
IMO this is great for anyone who didn't fully charge their battery with their phone off when they received theirs. If you purchased a 1500mah or Seido "1750mah" battery, I think this will benefit you immensely! I did this in conjunction with Hydra's undervolt kernel and I'm at 1 day 2hrs with 25% battery life left on my HTC 1500mah battery
Calibrating your battery and Android - Android Central Forums
IMO this is great for anyone who didn't fully charge their battery with their phone off when they received theirs. If you purchased a 1500mah or Seido "1750mah" battery, I think this will benefit you immensely! I did this in conjunction with Hydra's undervolt kernel and I'm at 1 day 2hrs with 25% battery life left on my HTC 1500mah battery