Make sure it's fully 100% charged (see link below).
The quickest way (and really the only way) to charge your iPad is with the included 10W USB Power Adapter. iPad will also charge, although more slowly, when attached to a computer with a high-power USB port (many recent Mac computers) or with an iPhone Power Adapter (5W). When attached to a computer via a standard USB port (most PCs or older Mac computers) iPad will charge very slowly (but iPad indicates not charging). Make sure your computer is on while charging iPad via USB. If iPad is connected to a computer that’s turned off or is in sleep or standby mode, the iPad battery will continue to drain.
Apple recommends that once a month you let the iPad fully discharge & then recharge to 100%.
How to Calibrate Your Mac, iPhone, or iPad Battery
At this link http://www.tomshardware.com/reviews/galaxy-tab-android-tablet,3014-11.html , tests show that the iPad 2 battery (25 watt-hours) will charge to 90% in 3 hours 1 minute. It will charge to 100% in 4 hours 2 minutes. The new iPad has a larger capacity battery (42 watt-hours), so using the 10W charger will obviously take longer. If you are using your iPad while charging, it will take even longer. It's best to turn your new iPad OFF and charge over night. Also look at The iPad's charging challenge explained http://www.macworld.com/article/1150356/ipadcharging.html
Also, if you have a 3rd generation iPad, look at
Apple: iPad Battery Nothing to Get Charged Up About
Apple Explains New iPad's Continued Charging Beyond 100% Battery Level
New iPad Takes Much Longer to Charge Than iPad 2
Prolong battery lifespan for iPad / iPad 2 / iPad 3: charging tips
The other day I had a chance to try and trouble shoot a friends pad with battery woes. It was worth the time.
I fired up the app System staus and turned everything of, then started putting it back on, one at a time.
Screen brightness and radio use do make a difference, but not much in idle state. And even the 4 g, if you are not doing much, made very little difference.
What did make a huge difference, at least in this case, was a subscription app to a newspaper, set for auto update.
Took me a while to chase it down, but the thing was trying to update itself on almost constant basis. Even while sleeping. The person was losing almost 10 pct per hour while sleeping, and at least that much while awake. Killing off that single app brought idle usage down to near zero, where it belongs.
So after you have done all the stuff recommended above, which are all spot on, start looking at apps, and find the one that has a constant need to communicate with the mother ship.
Thanks, pjl. My new iPad was draining after just five or six days in standby. I had a trial period for a few newspapers that ran out weeks ago but I still had them in news stand, so they were updating unbeknownst to me. I went into settings>store and turned off the switch that allows them to download new content. Hopefully that will fix my problem. The iPad is supposed to last 30 days in standby. I would be happy with 15, but five is unacceptable.
BTW, it turns out that my short battery life was caused by drain from the cellular radio. I didn't realize that I had the cellular access turned on in the settings even though I hadn't activated a cellular data plan with any carrier. I guess the cellular radio is turned on by default on all iPads that have the hardware for it. I turned off the radio and now the battery level never goes low.
Optimise Your Settings
There are a number of iPad settings you can adjust to minimise power consumption and extend battery life, including screen brightness. These tips may help extend your battery life.
Adjust brightness: Managing the screen brightness is the best way to extend iPad battery life. By default, your iPad has Auto-Brightness turned on. Auto-Brightness adjusts iPad screen brightness based on ambient lighting conditions; lowering brightness in low light conditions helps to extend battery life. You can adjust brightness yourself: go to Settings > Brightness & Wallpaper and drag the slider to the left to lower the default screen brightness.
Lock your iPad: It may seem obvious, but you should lock your iPad when you aren’t using it. To lock iPad, press the Sleep/Wake button. You can also set the Auto-Lock interval so your iPad will turn off more quickly after a period of inactivity. To set Auto-Lock, go to Settings > General > Auto-Lock and set the interval to a short time, such as one minute.
Turn off Wi-Fi: If you know you’re not going to be using Wi-Fi, you can turn it off to save power. Go to Settings > Wi-Fi and set Wi-Fi to off. Note that if you have an iPad with cellular capability and use it to browse the web, battery life may be improved by using Wi-Fi instead of cellular data networks.
Turn off cellular data: Using cellular networks when you’re out of range of Wi-Fi connectivity allows you to stay in touch but may also decrease battery life, especially in areas with limited coverage. To disable cellular data networks, from the Home screen choose Settings > Cellular, and set Cellular Data to off. Note: You will no longer be able to send or receive data via a cellular data network.
Use Airplane Mode (Cellular models) in low- or no-coverage areas: Because your iPad always tries to maintain a connection with a Wi-Fi network or cellular data network (Cellular models), it may use more power in low- or no-coverage areas. Turning on Airplane Mode can increase battery life in these situations. To turn on Airplane Mode, go to Settings and set Airplane Mode to On.
Minimize use of location services: Applications that actively use location services, such as Maps, may reduce battery life. To disable location services, go to Settings > General > Location Services, or use location services only when needed.
Turn off push notifications: Some applications from the App Store use the Apple Push Notification service to alert you to new data. Applications that rely extensively on push notifications (such as instant messaging applications) may decrease battery life. To disable push notifications, go to Settings > Notifications, and set Notifications to off. Note that this does not prevent new data from being received when the application is opened. Also, the Notifications setting will not be visible if you do not have any applications installed that support push notifications.
Fetch new data less frequently: Applications such as Mail can be set to fetch data wirelessly at specific intervals. The more frequently email or other data is fetched, the quicker your battery may drain. To fetch new data manually, from the Home screen choose Settings > Mail, Contacts, Calendars > Fetch New Data, and tap Manually. To increase the fetch interval, go to Settings > Mail, Contacts, Calendars > Fetch New Data and tap Hourly. Note that this is a global setting and applies to all applications that do not support push services.
Turn off push mail: If you have a push mail account such as Yahoo! or Microsoft Exchange, turn off push when you don’t need it. Go to Settings > Mail, Contacts, Calendars > Fetch New Data and set Push to Off. Messages sent to your push email accounts will now be received on your phone based on the global Fetch setting rather than as they arrive. If the global Fetch setting is set to Manually, you will not be able to locate your iPad using the Find My iPad feature.
Auto-check fewer email accounts: You can save power by checking fewer email accounts. This can be accomplished by turning off an email account or by deleting it. To turn off an account, go to Settings > Mail, Contacts, Calendars, choose an email account, and set Account to Off. To remove an account, go to Settings > Mail, Contacts, Calendars, choose an email account, and tap Delete Account.
Manage the use of downloaded applications: Use of certain applications — such as games that prevent the screen from dimming or shutting off, or applications that use location services — can reduce battery life.
Use Your iPad Regularly
For proper reporting of the battery’s state of charge, be sure to go through at least one charge cycle per month (charging the battery to 100 per cent and then completely running it down).
The cellular radio uses energy to look for a signal, even if you haven't activated it. When the signal is weak, it uses a lot more energy. In my case, this turned 30 days of standby battery life into 5 days. It can be even worse. Coverage isn't too bad here in Miami. I bet it's worse in many other places, especially the suburbs and exburbs and smaller cities.