One of the iPad 3 quirks that has come to light recently is that the device apparently shows itself as 100% charged when in fact it is not or more accurately...'before it really is'.   Upon perusing the tech blogosphere and reading up on the issue there seem to be two theories as to why this is taking place.   Apple itself has chimed in to say that iOS constantly charges and recharges to maintain a full charge but this clearly does not answer all the questions.   On ZDNET, tech maven Ina Fried discusses how if she uses the iPad 3 when the device first says it is fully charged she gets 10.4 hours of use but if charged all night long...way past to when the iPad 3 says it is fully charged...then the device actually lasts for 11.6 hours, a full 1.2 hours longer.   

Some techies have postulated that this 'false 100%' reading might be a way for Apple to prolong the battery life of the iPad.   Since Lithium batteries such as are in the iPad 3 tend to last longer when they are not repeated charged to 100%, some have thought this might be a way of prolonging battery life.   If this is the case one would think Apple would come out and list it as a 'feature'.  Alas...they have not.  Another possibility is that that perhaps there is some inconsistency between batteries in different iPad 3s depending on the vendor of the battery.   By giving a 10 hour operating time officially it gives them some room to maneuver in case some find their batteries last longer or shorter than others but still above the advertised 10 hour mark.  Alas...we may never have a definitive answer but just keep in mind that if you charge your iPad 3 for longer than the battery meter says 100% you can get a possible hour or more of operating time from your battery pack.  Good to know...if still a bit confusing.