Can I connect my friend's iPad to my MacBook and keep it from syncing or deleting any files?

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

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 - iPadhttp://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

Tips About Charging for New iPad 3

http://goodscool-electronics.blogspot.com/2012/04/tips-about-charging-for-new-ip ad-3.html

Prolong battery lifespan for iPad / iPad 2 / iPad 3: charging tips

http://thehowto.wikidot.com/prolong-battery-lifespan-for-ipad

 Cheers, Tom 😉

As TMM has pretty much stated, this is not a very efficient way to charge the iPad. It may not charge at all in fact, depending on how old the Mac is, if it has the high powered USB hub required for the iPad to charge. If you want to give it a shot - that is up to you.

In order to prevent the iPad from syncing when you plug it in to the Mac .... Launch iTunes and go to iTunes>Preferences>Devices>Prevent iPod, iPhones and iPads from syncing automatically. Click OK. Quit iTunes.

Now you can connect the iPad to the Mac, launch iTunes, click on the iPad name on the left side, and browse iTunes to see what is on the iPad.