Apple’s battery website is an excellent resource to help understand how batteries work, the best way to charge batteries, optimal storage conditions, and much more.
A few years ago, in a blackout, I wrote an article about maximizing battery runtime and while those tips hold true, the article as a whole is a bit dated. After all, it was written before the iPhone existed!
Among the best nuggets of knowledge from Apple:
Use your battery-powered device regularly. If you infrequently use your iPod or laptop, or have backup devices, remember to charge and discharge the battery every month or so. Here’s an iCal reminder (link will open iCal).
Assess just how you use your iPod. Do you really need Wi-Fi on all the time? If not, disabling it will help battery life. If your iPod or iPhone has 6 pages of rarely used apps, get rid of the ones you don’t use. Most of us don’t really need the push mail functionality—if you fall into that category, go to Settings/Fetch New Data and turn it off.
When you get your laptop, plug it in, charge it fully, and run software update. There are energy saving updates now and again that you should take advantage of.
If you’re not going to use your device for a long time, storage is best at 70 degrees (F) or so and with a 50% charge.
Apple’s battery website makes for good reading for anyone who’s had premature battery consumption or failure, and I encourage everyone to read it thoroughly.