The quickest way (and really the only way) to charge your iPad is with the included 10W or 12W (5W on Mini) 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 (2.5W, 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
http://www.macblend.com/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
http://allthingsd.com/20120327/apple-ipad-battery-nothing-to-get-charged-up-abou t/
Apple Explains New iPad's Continued Charging Beyond 100% Battery Level
http://www.macrumors.com/2012/03/27/apple-explains-new-ipads-continued-charging- beyond-100-battery-level/
New iPad Takes Much Longer to Charge Than iPad 2
http://www.iphonehacks.com/2012/03/new-ipad-takes-much-longer-to-charge-than-ipa d-2.html
Apple Batteries - iPad http://www.apple.com/batteries/ipad.html
Extend iPad Battery Life (Look at pjl123 comment)
https://discussions.apple.com/thread/3921324?tstart=30
New iPad Slow to Recharge, Barely Charges During Use
http://www.pcworld.com/article/252326/new_ipad_slow_to_recharge_barely_charges_d uring_use.html
Best Practices for iPad Battery Charging
http://www.ilounge.com/index.php/articles/comments/best-practices-for-ipad-batte ry-charging/
Tips About Charging for New iPad 3
http://goodscool-electronics.blogspot.com/2012/04/tips-about-charging-for-new-ip ad-3.html
How to Save and Prolong the battery life of your new ipad
https://discussions.apple.com/thread/4480944?tstart=0
Prolong battery lifespan for iPad / iPad 2 / iPad 3: charging tips
http://thehowto.wikidot.com/prolong-battery-lifespan-for-ipad
iPhone, iPod, Using the iPad Charger
http://support.apple.com/kb/HT4327
Install and use Battery Doctor HD
http://itunes.apple.com/tw/app/battery-doctor-hd/id459702901?mt=8
To Extend a Device’s Battery Life, Get to Know It Better
http://tinyurl.com/b67c7xz
iPad Battery Replacement
http://www.apple.com/batteries/replacements.html
In rare instances when using the Camera Connection Kit, you may notice that iPad does not charge after using the Camera Connection Kit. Disconnecting and reconnecting the iPad from the charger will resolve this issue.
? Cheers, Tom 
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