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
Apple Batteries - iPad http://www.apple.com/batteries/ipad.html
Extend iPad Battery Life (Look at pjl123 comment)
New iPad Slow to Recharge, Barely Charges During Use
Tips About Charging for New iPad 3
Prolong battery lifespan for iPad / iPad 2 / iPad 3: charging tips
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.
The reason for this MUST be one of the following:
- your brightness is close to max. The iPad 3 is known to consume more power with maxed out brightness than prev. models.
"The worst thing Apple ever did was to offer a percentage charge readout on the screen. So much paranoia. Has anybody ever challenged a car's fuel guage at an accuracy of one percent?"
Well, it's still very important in finding out how, say, a specific app taxes the CPU if you don't have, say, Xcode (with its Instruments: see http://www.iphonelife.com/blog/87/reliable-cpu-usage-measurements-idevices ) around or it doesn't report the CPU usage at all.
Then, by, say, running the given app for an hour (at minimum brightness and over Wi-Fi so that it's mostly the CPU usage that contributes to the power usage and not the backlight / 3G) and comparing, you can already get a somewhat reliable measurement of an app's CPU usage. These figures can also be directly compared to those of other apps.
For goodness sake, why? I have never felt compelled to test anything about the iPhone. It works within its given parameters, I charge it whenever convenient, without the aid of a stopwatch, and do not care at all about CPU usage of specific apps. I just use it and enjoy it. I'll fret about battery usage if and when affects my normal use of the phone, not when x percent is seen to last y minutes.
There can be VAST differences in the battery usage of some kinds of mostly multimedia apps (radio players, video players, voice recorders etc.) - typically ones that you use for sometimes even hours (as I do by playing back MPEG2 TS files on my iPad). Then, it's very good to know which of the available apps have the least CPU usage, particularly if noone has ever measured them.
... and when you can't charge it because you're in an aeroplane / train / gym, far away from any kind of wall socket? Then the CPU usage and the consequent power consumption does matter. And, as I've pointed out above, if you don't have access to Instruments or other means of CPU usage measurement utilities, using the battery percentage still gives you a usable tool to measure the CPU usage.
Well, using an external battery itself is a complication that could easily be avoided by knowing which apps to prefer to, say, play back MPEG-2 or WMV content - or even H.264 if one, for some reason, wants to prefer software playback (for example, for audio / video DSP functionality not available while using the hardware decoder: reverb, audio boosting, saturation / contrast / brightness change etc.).
There are vast differences in the CPU usage of software video (or, for that matter, audio) decoders. Just an example: ProPlayer and AVPlayerHD have the least CPU usage when playing low- or standard-res WMV1/2 content. All other players (including the, otherwise, great GoodPlayer) have at least twice the CPU usage.
Unless one finds reliable, already-made measurements of CPU usage on the Net and/or gains access to a developer Mac with Xcode + Instruments to quickly (1-2 minutes at most) measure the CPU usage, long-time (1+ hour) tests using the battery percentage meter is the easiest way to measure the CPU usage of an app.
Thanks for the replies especially Carolyn Samit, Texas Mac Man, Menneisyys – a very thoughtful reply and last but not least the one which made me laugh James Ward4.
I think I posted in hast. I was just browsing on a couple of travel agent websites, which one in particular was unresponsive at times, also tried with a different browser and it was pretty much the same results.