Google's Trevor Johns wrote in an update on November 6 that the battery-draining issue in Android Lollipop on Nexus 5 phones has been resolved.
Hopefully now Android 5.0 will roll out to more users on the Nexus 5 and other older Google flagships, and when it does it should actually improve your battery life, not make it worse.
Original story follows…
Google said last month that Android 5.0 Lollipop would arrive on the Nexus 5 and other devices "in the coming weeks," but so far three have come and gone without the update arriving.
Now Phandroid speculates that the Lollipop delay on those handsets might be thanks to a battery-draining bug that's been reported on Google's issue tracker.
The glitch is causing the Nexus 5's battery to drain more quickly than it should when wi-fi is activated in the OS's developer preview version.
There's no specific evidence that the issue is causing a delay in Lollipop's rollout, but Google employees have at least acknowledged it.

Well that's something

"Android Engineering is aware of an issue affecting Nexus 5 users running Android 5.0 which causes significant 'Miscellaneous' battery usage while WiFi is enabled," Google Android Open Source Project Senior Developer Programs Engineer Trevor Johns wrote in a thread about the bug.
"This appears to be caused by an abnormally high number of IRQ wakeup events," he added. "We are continuing to investigate this issue."
Users who haven't yet received the Lollipop upgrade they're waiting for may be frustrated with the delay, but in the end it's better for Google to make sure they're not making Android phones and tablets worse with new updates.