After a year using my phone, I noticed the battery drains too fast, but after shutting down I manage to make it work again for a couple of minutes before it shuts down automatically.
The thing is...
"When you follow the steps to recalibrate your battery and delete the batterystats.bin file from your phone, you are getting rid of more than what you think… Stored inside that batterystats.bin file, your phone keeps detailed logs of the capacity of your battery and uses it on how it can be utilized more efficiently." Read Full
or oppositely, quoting Dianne Hackborn
"It (refering batterystats.bin) has no impact on your battery life."
I know it's not possible to make it as good as new, but at least reset it in a way it would read that last bit of energy accurately?