You don't need a custom kernel now heh. However I do recommend rooting the device so you can use super user to control stuff better.
The 2 main issues are...
1: High amp charging. Make sure your nexus is charging at the full current.
2: Reducing battery drain when off. This is the fun part! Using tasker and a rooted nexus I have a "on" and "off" profile. When power is applied via not wireless it wakes up, bypasses key guard, turns on wifi, turns on blue tooth, and launches waze. When I turn off the ignition tasker kills waze fully, turns off all the radios, then goes to sleep.