Best way to charge an Iphone?

Would it make a difference if i charge my iphone 3gs on a laptop or direct source like a plug to the socket? I also want to know if there's a way o determine if your battery needs replacement like a software perhaps other than the most common symptoms like the phone acting a little weird.

Every hour my phone seems to deplete 1% and most of the features are turned off or mybe i should turn off the battery percentage?

Charge mine on laptop all the time but i think ac is faster. Try a battery saver app

You may need a external battery for you iphone 3gs, here are many kinds of external battery for cell phone and tablet pc

http://www.laptopbatteryinc.com/external-batteries.htm

The best way is to charge it to the socket.