Originally Posted by x-geo
the question is simple..... i have a E790 and i want a Rom, kernel, mod or configuration for best battery life... any suggestions?
Best configuration for extended battery life = power off when not in active use.
Not trying to be a jerk here, but while stating that question is simple, the answer most certainly isn't. There are a huge number of factors that play into battery life, and you haven't provided any info at all to us to provide good answer.
The answer depends on how you use the device. Do you need extended idle time but not high performance? underclock, undervolt, freeze all your background apps. Do you have lots of stuff running in the background? Try greenify paid with xposed features. Do you want the most possible screen on time? drop your brightness as low as you can stand it. Run in Airplane mode. Are you in a crappy service area? Turn off cell radio and use Wifi only.
We don't know what you need for connectivity, or how you use the device, or what apps you run, or anything else. We need tons more info to try to chase battery life. We don't know what will constitute "acceptable" performance, to you, when down-tuning processor speeds and brightness and things. These are all things you need to experiment with to find what works best for you.
In general, I've found that for my use-case, the new 4.3 ROMs are marginally better on battery life than prior versions. I typically get about 4 hours screen on time, with around 20 hours up-time, and minimal phone calls (15min per day or so) and end up having 15-20% battery left when I put the phone on the charger. In moderate use, I look for wakelocks to be roughly twice my screen on time. I don't run much processor intensive stuff, the majority of my awake time is spent at minimum clock speed.