I understand what you are saying but if one person tries the exact same ROM/kernel combination as another person, why do they get different results. Sometimes major results?
I mean there are only a few variables that could change from one persons use to another. I've just tried many different combos that people say they are getting 20+ hours of batter with 40-50% battery left and i'm barely getting 12 hrs with light to medium usage. I am getting 3g signal all day and I leave it on WiFi when i'm home.
Here is my best understanding of it:
The kernel essentially determines how your phone's resources are going to be utilized. What gets the highest priority, how quickly it operates, etc. The widgets, data sync patterns, apps, up/awake time, settings, coverage, WiFi availability, and everything else that are unique to you will utilize what a kernel does differently than every other user. For some people, a particular kernel "just works". For others, it does not.
Frankly, the 20+ hours with 40-50% battery life people are nothing I strive for in the least. I guarantee that I use my phone more than most people that post on here, so my 14 or so hours until fully discharged is perfectly acceptable to me. I want GPS always at the ready, I want my e-mail syncing as much as possible, I fire up my internet browser frequently, and I take my phone in to the shitter and play power hungry games.
Use a ROM/kernel combo for a few days and get an idea of how long it lasts. Then try to change one or both of them out and see how long that lasts after a few days. The baseline is what results you get with "normal" use, not what someone else posts on a message board. When people post battery results from a ROM/kernel, really, the only relevant info is how much more (or less) battery life they got compared to what they normally receive. The actual number of hours is moot, since I will never use my phone in exactly the same fashion that they do.
