Best for battery?

About Batteries in Modern Apple Laptops

Apple - Batteries - Notebooks

Extending the Life of Your Laptop Battery

Apple - Batteries

MacBook and MacBook Pro- Mac reduces processor speed when battery is removed while operating from an A-C adaptor

Battery University

Apple - Batteries - iPod

Apple - Batteries - iPhone

Apple - Batteries - iPad

Apple Portables- Calibrating your computer's battery for best performance

Mac notebooks- Determining battery cycle count

How to Calibrate Your Mac, iPhone, or iPad Battery | MacBlend

Welcome to the Apple Support Communities

To keep the battery life, I recommend you to make full cycles (charge your Mac when the battery is under 20% and charge it until 100%). This is the best way to keep your battery life. If you want more information about your battery, see > http://www.apple.com/batteries/notebooks.html

Do not routinely allow the battery to discharge below 20%, never let it drop to 0% unless unavoidable. Plug it in as often as possible.