My battery has gone absolutely berserk after the 4.2 update.
I've always had decent to short battery life with my one, getting to 17 at an absolute stretch. Shortly after updating I went on vacation for two weeks to somewhere with no cell reception and a poor WiFi connection. My battery tanked. Like big time. I went through 40% on standby overnight, and the battery just wasn't lasting anything like normal, with Google services accounting for almost all of the drain.
Then, I return hope, and my battery shot up to being outstanding. For most of the last week I've experienced easy 20 hr plus usage, with battery to spare. It has been insanely good - so much better than ever before. Google services still high though.
Today, it's back to normal - 14hrs use, 21% left. Google services still high (55% of my battery use today).
So I'm not sure what to think really. 4.2 has given me both the worst battery life I've had, and even better than could have ever imagined. It seems like there must be a bug somewhere, Google services use is just crazy high regardless.
Nb, this isn't a third party app issue - my wife also has a One and experienced broadly the same changes, without the same incredible high (but with better life previously on 4.1 than me anyway). Google Services usage also crazy high.
Sent from my HTC One using AC Forums mobile app