I recently started having trouble charging my iPhone. Hours after plugging it in to charge, I’d return to find the phone’s battery at the same level I left it. Turns out the iPhone 5 and 6 are prone to having dust, lint and debris build up in the lightening port–the hole at the bottom of the iPhone where the cable plugs in.
Fixing the problem is pretty simple. Get a can of compressed air and blow out the debris. I was shocked to see how much lint and dust blew out of my lightening port! Do not try to blow out the debris using your mouth because the moist air will make the dust and lint stick to the inside of the phone. (Same goes with blowing out dust from your computer or any other electronics.)
Keeping my phone in my pocket was probably the source of the problem. My phone will still stay in my pocket, but I now I know to use a little compressed air to clean out the lightening port every few weeks.