How long is the maximum battery life of the iPad?

As also noted elsewhere, Apple reports that all iPad models -- regardless of generation -- provide "up to 10 hours of surfing the web on Wi-Fi, watching video, or listening to music" and the 3G-equipped models provide"up to 9 hours of surfing the web using [a] 3G data network."

Also see:

• What is the battery life of the original iPad in "real-world" tests?
• What is the battery life of the iPad 2 in "real-world" tests?

Why won't my iPad battery charge completely? Why does my iPad run out of power so quickly?

If the battery in your iPad isn't charging completely or the battery life suddenly seems like it is running out of power more quickly than it used to, Apple recommends that one try restarting and resetting the device and if that doesn't work, as a manner of last resort, try restoring it. Please note that restoring the iPad will erase all data. Be sure that you have recently backed up your iPad before restoring it.

How can I conserve my iPad's battery life?

Apple's own support site has a useful document of tips to help conserve and extend the runtime of the iPad as well as prolong the life of the battery. Such tips include updating to the latest software (as Apple routinely tweaks battery performance), optimizing your settings in ways to reduce power consumption, locking your iPad when not in use (so the screen isn't drawing power when it isn't being used), and using the device regularly, along with other helpful advice.

BatteryUniversity.com additionally provides additional tips on how to prolong the life of lithium-based batteries, like those used in the iPad models.

How do I replace the battery in the original iPad and the iPad 2?

When the battery no longer holds a sufficient charge, you are required officially to send any iPad to Apple for replacement. Apple charges US$99 for servicing plus US$6.95 for shipping (US$105.95 plus tax).

Interestingly, in addition to providing pricing information, Apple formally states that the company "will replace your iPad for a service fee" and "you will receive a replacement iPad that will not contain any of your personal data." This indicates that Apple reserves the right to send a different iPad rather than actually replacing the battery in the one sent in. This replacement of the entire device certainly does not appear to be the most environmentally friendly solution.

Although it is not the easiest procedure -- and involves carefully prying off the display, disconnecting tiny cables, and removing numerous interior parts in addition to the battery itself (which is glued down tight) -- iFixit provides instructions for both the original iPad and iPad 2 models that an extremely technically savvy user could use to replace the battery on his or her own.

Based on hands-on experience, if you have successfully replaced the battery in an iPod -- particularly a model that involves slogging through copious quantities of adhesive and/or soldering -- you are unlikely to find it too much more difficult to replace the battery in an iPad. Replacing the battery in an iPad does not involve soldering, but it is extremely challenging nevertheless and professional installation is strongly recommended.

Naturally, self-replacement of the battery in any iPad violates the warranty as well, should your iPad still be covered by its original warranty or an extended one.