[Verizon LG G2] jonstrong:
I have to agree with the second sentence above -- my battery life on the G2 was great with JB, and is even better with KitKat. What I've noticed, though, is that usage patterns make a tremendous difference. That shouldn't be a major revelation - but the differences aren't what you necessarily expect them to be. Think of it this way: each type of process that consumes battery power may have been modified in different ways in the transition from JB to KK. Some may be improved and some may be less efficient than their earlier counterpart. Some of this may just be a byproduct of the changes Google felt necessary for each individual module. Some may be due to interprocess activities, and reflect some kind of synergistic effect. Net, however, is that we may all have a somewhat different experience re battery life moving from JB to KK, and can reasonably attribute the differences to installed apps, apps that we may have frozen or uninstalled, our differing use cases and usage patterns, lengthy phone calls with the screen dark vs. hours of online gaming vs. hours of streaming video, etc. We all most likely have different settings, as well, for screen brightness and auto settings. Finally - we also have unique RF (radio frequency) environments, being in stronger or weaker signal areas for 3G and 4G, and may use different apps when we're in our out of range. In short - there are a TON of variables suggesting that we will all have somewhat different experiences.

In general - I average something like 24 to 36 hours of overall battery life per charge, and this typically includes 4.5 to 6 hours of OST (on screen time). I rarely stream video. If I stream music, it's generally when I'm in my car (streaming to the head unit via BT), and I frequently plug the charging cable in when I'm doing that, just to be sure I have a full charge when I get to my destination.

One thing I noticed with 24A / KitKat - there are various apps that need the screen open full time that do NOT seem to stress the battery much at all. This was a surprise for me, as I had always considered use of the display to be a pretty dependable impact on battery life. One use case in particular blew me away: Having not played in a while, I downloaded and installed Reversi from the Play Store. It has 10 levels of difficulty, and to get back into it, I started at level 1, moved quickly up to 3 and 4, and as I started to get back into the game play, I was beating the game more and more often, and kept pushing my way up to higher levels. It's a simple game - but strategy becomes more important as each higher level of difficulty allows the game "opponent" (your phone/computer) to simulate more scenarios and more move sequences (plies) before it makes its move -- and these additional plies are where it becomes harder and harder for typical humans to keep up. In the end, I find the game addictive. I got to level 10 (out of 10) a little while ago, and can beat the game about 25% to 30% of the time -- but as long as I continue to improve and raise that win rate, I'm hooked. Net of all this: if I'm restless at night, I can lay in bed and battle the game for 3 hours at a clip.

The significance of this, however, is that when playing this game at Auto brightness with a 50% base level, the battery charge drops from 100% only a few percent down in 3 or 4 hours of play - with the screen on the entire time, maybe 10% or 11% at the most. This suggests that it might be possible for me to play Reversi continuously for 8 or 9 hours, and still have 50% or better charge. I consider this pretty amazing for this slender phone with the stock battery -- and I do NOT use any particular battery saving tools (like Greenify), and in these tests I have Wi-Fi and Bluetooth on full time (never turn them off), as about 2 bars each for 3G and 4G.

In the end, with my installed apps (over 100), usage patterns, and RF / signal situation, battery life is *definitely* better with KitKat on my vs980 than it was with Jelly Bean.