I don't understand why this happens to some people, Dishfan is experiencing this on two iphones in a row. Yet millions of owners do not have any problem. My wife has an iphone5 and uses it daily with an Apple charger and cable that came with the phone. She is not a tech genius, nor a tech buffoon. In otherwords, she can be responsible for charging her iphone when needed. And, she knows not to use the ipad power pack on the iphone 5 or vice versa. She never has a problem.
This is not just with iphones, but remember the few people who had exploding laptop batteries? I'd think if the issue was with the device, all of them would be trouble. It's possible a low level of quality control can produce some lemons but to get two in a row? What are the odds? I think it must be something besides the phone, charger and cable.
My SIL received my old MacBook Pro and immediately, he started having trouble keeping it charged, He wanted to buy a new battery since that is what the genius at the Apple store told him. I said Hell no! Not until I check it out. I went to his house and discovered the outlet he was using to plug in the Macbook charger was split. The top was live and the bottom was switched with the wall switch. He plugged it in the bottom, checked to see that it was charging and then left the room turning off the ceiling light, never knowing that the wall outlet also got switched off. When he returned the next morning he entered the room turning the switch on and noticed the Mac was still charging but not "taking" the charge. So he thought. Sometimes these problems can be elusive and you have to dig a little deeper to find the real root cause. Don't assume the wall outlet you are using is perfect. It's just one example of any number of reasons some people have trouble with a gadget that millions of people have no problem with.