There’s been a lot of talk about iPad batteries with the introduction of the third generation iPad. Some people are reporting decreased battery life, others are reporting longer charging times or possibly that their iPad is no longer charging fully overnight when previous models would. The fact is, the battery in the new iPad is significantly larger than the battery in the first and second generation iPads although it continues to use the same 10w charger. A larger battery with the same power charger is going to require longer charging time. When I first received my new iPad I noticed problems with battery life including my battery draining faster than normal. However this problem was solved by a simple battery calibration and since then I have noticed my third generation iPad battery life has been about on par with my first generation and I can still charge my iPad from 0 to 100% overnight if I use the proper charger. Seems all the hype about problems with iPad batteries is overblown.
Calibrating the iPad's battery is simple. When your first receive your new iPad, and every month or so thereafter, run your iPad’s battery all the way down to the point when the device turns itself off due to lack of power and simply will no longer function. Then, plug the iPad in to the Apple 10w charger and allow it to fully charge uninterrupted. Don't unplug it and plug it back in, don't play with it, just let it charge. For convenience, it’s best to allow this process to happen overnight or when you’ll be away for the day. For good measure, you may want to let the iPad stay on the charger for a bit after the indicator reads 100%. This process allows the iPad to give you more accurate battery readings. Note that this same process works with iPhones, iPods and Macs too and is good practice for exercising your batteries. I have an OmniFocus task set to remind me to calibrate my batteries once a month.
Also, make sure you’re using the included 10w charger. With my first generation iPad I would regularly use my old iPhone charger to charge it overnight without problems since I had a few spare iPhone chargers laying around. Although you can charge the iPad battery off of a computer’s USB port or off the lower power 5w charger that is included with the iPhone and other USB chargers it is not as efficient. This wasn’t a problem for me when charging the first generation iPad overnight, but with the larger battery on the new iPad it no longer gets the job done. Note that the iPad charger and older iPhone chargers look very similar. Pull out a magnifying glass and look at the fine print on the bottom of the adapter to confirm you’re using the proper 10w adapter.
You can find more information from Apple directly at http://www.apple.com/batteries