I recently purchased an extended battery for my ailing Galaxy S4. It's supposedly rated at 4000 mAh over the previous 2600 mAh OEM battery.
First time I threw it in, I turned on the phone, chucked in the battery, and sat it on the charger for an hour or so.
It actually lasted a pretty long time. About 2 days and 5/6 hrs. SoT (not fantastic for 4000 mAh, but it's new so what the heck).
So, listening to the advice of others, I threw it on the charger until completely topped off while the phone was shut down. Again, I discharged it from 100%. However, this time, the battery drained much faster than usual. There weren't any particular apps draining the battery, it just drained faster.
Seeing as this was strange, I drained it to 0%, and charged it back up. Still, the same terrible battery drain. It may be I have to cycle it a couple more times.
Advice? How should I correctly calibrate an extended battery?