I've used almost every single rom since gb.
The way I'm measuring the battery life is,
1. Calibrate battery whenever I flash the new rom.
2. I take a walk almost everyday about 4 miles (spent 1.5 hours). During the walk, I turn on the music player with speaker phone + 3g for lyrics download.
3. Measure the battery consumption just after returned to home
4. The result was very vary based on the roms (+modems)
5. So far, the best result I 've got is thru fd05 (agat's tFD05 + fd05modem/kernel)
6. Based on this calculation I would get about 20- 24 hours with my daily normal usage.
Sent from my SPH-D710 using xda premium