Android is a great operating system, but like any other OS or software it isn't without its bugs. There are more than a few to note and if you're running a device that's on Lollipop chances are you may have come into contact with a bug that drains your battery pretty heavily. This is present for some users but not all, and it seems to be hitting some users more heavily than others. Whatever the case, it's a bug that many users would like to see dealt with so the issue is put to rest, thus gaining them back their battery longevity throughout the day.
The good news is that Google will reportedly be taking care of the bug with Android 6.0 Marshmallow. For those who are unaware the bug which drained the battery of some Lollipop users (and is still draining the battery for those users most likely) was caused by the mobile radio staying in an active state. This was particularly problematic because many people weren't aware of what was causing the issue for quite some time, and chances are there are still some users who may not have an idea as to what's causing their battery to deplete like they've been on it consistently throughout the day without pause. Virtually any app that was using the mobile radio could cause the bug to enable too, which made it that much harder to narrow down since loads of apps will use the mobile radio at some point.
Since the fix is expected within Android 6.0 Marshmallow that unfortunately means there likely won't be a fix coming any time soon to an unknown number of users. There's no telling how long it might take for some who have reported the bug on the issue tracker to get their update to Marshmallow, and with that being the case the bug will be sticking around for some time for those who individuals. For the Nexus 6 and Nexus 9 users who are experiencing this bug, the problem should be taken care of rather quickly as those two devices will probably be getting Marshmallow soon after Google launches it.