In case anyone was vexed with lack of a battery percentage indicator in Android L, that has continued since Kitkat, I have provided a very useful link below. It is basically telling you to download a certain battery app from the Play store, which was added by the XDA developers.
I had a battery life app installed on my Nexus 5, but it didn't work with the lockscreen notifications properly when I upgraded to lollipop, so it kept giving a vastly out of date reading.
If you install this particular app you will see the actual battery percentage within the battery icon at the top of the screen, which is also visable whilst the screen is still locked. Iwill try to add a screenshot to illustrate...
http://nexus7.wonderhowto.com/how-to/unlock-android-ls-hidden-battery-percentage-icon-status-bar-015...
