Is your iPad wifi only or with cellular ? SOmetimes it happens because of the poor 3G signal at your area and your ipad is constanly searching for the signal, that's why it consumes your battery even though with all your apps closed.
The best way to test it is to put on Airplane mode when u go to bed and see if it makes any diff.

P/s Personal experience.

Sometimes, the battery indicator might not be that accurate especially when your ipad is with lower battery level.

For example, you leave your ipad with wifi on with 98% at the night and found out that your ipad with 97% when you wake up. If you leave your ipad with wifi on with 50% of battery in the night, u may actually found that your ipad left with 47% of battery when u wake up.

This has to do with the battery indicator and it is software related. We cant exactly predict the amount of battery life left, but we DO ABLE to approximate it accurately with minimum error

This post has been edited by christcwl9: Jul 18 2012, 02:06 PM

Bro, this is because Apple implement something on it which will make the charging process faster in the early ( Before it reaches 80% ) to provide user a faster time to charge and take their idevices out.

For the battery draining part, i am not very sure it is a fact or not, but i strongly agree that no battery monitor software is 100% accurate. Have you tried to turn off your ipad when it is 95% and when turn on back it shows 100% ? I experienced this until boring dy and my 100 to 99% after 8 hours charge seems drop so fast, like the same rate as 80 to 79%, which opposed to some who claim that the 1% can actually last for around 1 hour of wifi browsing after a full charge ( 8 hours + charge ).

This is most commonly experienced by me after updated to latest firmware IOS 5.1.1. So i think Apple had to do something with the code of it about their battery level detection.

SO at the end of the day, if you can get 10 Hours of straight usage, thats more than enough already No need to care about those tiny changes in battery level as it might be probably due to the error in battery level detection.

LOL! Ur ipad already 1 year + bro ? Yea, i can get 10 hours aproximately for constant use. My usage is all the time surfing via 3G I seldom play game on it, and i dont think it can last 10 hours straight for gaming But i do read some reviews on it claiming that they can run up to 9 hours + of gaming, but i am not sure about wat is the condition when they test the new iPad, perhaps with quite low brightness and as well as the weather there is not that hot as in Malaysia. Many possibilities take into account here.

After some time , your battery will degrade, and no worries, as long as it can hold up for you for the day, it is totally fine And for you information, the battery is to be undergone Full charge and recharge cycle for 1000 times

Yea i am using around 40% brightness as well, but due to i am constanly using 3G and wifi is always off, so my ipad will consume more energy compared to those who use wifi only.

If u have extra $, try to sell ur ipad 2 and get the new ipad

Good to hear that ya sometime apple things is such mysterious