[Droid Incredible Android Development] chad0989:
Sorry I've been MIA for the last week or so. Final exams will do that with 30 credit hour semesters. Off for two weeks now so expect something in that time period.

Also regarding battery life:

Its nearly impossible to judge battery life based on a few hours or single days use. I see this not only in my thread but also invisblek's and Lou's. One will flash a kernel and comment on battery life within hours and flash back to an earlier release that they had been using. Please don't do this, stick with a release for at least two or three days before you judge it.

Battery life is highly variable depending on dozens of factors -- kernel, software, usage, location just to name a few. Probably the biggest factor some may not realize is signal strength/3g use. For example, last week on wednesday I was in the basement at school in the lab for ~6 hours or so--where -102dB is considered good, if there is signal at all (minute on minute off intermittent reception). I got in at 6a.m. with a full non-bumped charge. With moderate usage during the time I was in the lab and the rest of the day, I was already down to 23% on my way home at 5:00 or so. In contrast the following day, with a very similar routine with the exception that I wasn't in the lab at all, at 11p.m. when I went to bed, I still had 66%. 43% higher after 6 more hours by changing only my location throughout the day.

Also just for general information there are only a couple of things one can change in the kernel that affect battery life.

1) Voltages - in short, lower voltage = better battery life. However voltages can only be lowered to an extent before you introduce instabilities. This is the purpose of the addition of HAVS/SVS to kernels, you can maintain stability at a lower voltage at a lower frequency, therefore the ideal is to find the minimum voltage/load that everyone is stable at at a given frequency.

2) Frequency - again lower frequency = better battery life. But again you can only lower frequency so much before you start really degrading performance. Hence trying to tweak the cpu frequency governors to scale down when possible but scale up when needed, however its difficult to get the gov to scale up rapidly enough precisely when needed. This is why if you pause for lets say 15-30 seconds and then go to do something you may get a hiccup. Now to remedy this there are a couple of options. First you can make it scale up more aggressively, but now you're sacrificing battery life since if you're hopping to max frequency when not necessarily needed. You can also increase the minimum frequency, which smooths it out a lot (which is why I had it at 384 for awhile) but sacrifices the battery life. Its extremely difficult to find the perfect balance.

In addition, when the screen is on and you're actively doing something (playing angry birds for example), your always going to be at whatever your max frequency is, so essentially all kernels are going to have pretty similar battery drain with any cpu intensive task -- as everyone is trying to use the minimum voltages they can at any given frequency (since that's the only thing you can really do and still maintain the performance needed for such a task).

So the best place to really stretch battery life is screen off, if you can absolutely minimize battery usage when the screen is off then you have more for when the screen is on. This is why most of us have been using 245/245. Now that I have some time I WILL be trying to see what I can do with 128/384.

These last two things I mentioned, the real stretching of battery life when the screen is off, combined with the fact that there isn't much you can really do when the screen is on and you are really actively using the phone, is what seems to give the illusion to some that battery life is absolutely amazing when the screen is off but horrendous when using it. The reality is that the battery life is amazing when the screen is off but really just slightly improved or typical when the screen is on because of how you happened to be using the phone (and the fact that most aren't willing to sacrifice interactivity too much in order to stretch life out/3g is also a killer). It really is not unusual to go through 1%/1.5-2minutes if you are doing a CPU intensive task. Where you might be able to stretch 1% much longer if you are just reading something or doing something over wifi as opposed to 3g.

Hopefully that clears some things up.