Scott got an Anker backup battery and sometimes he gets a warning that the accessory may not be supported, and it stops charging the phone. It even does it with the Apple charging block. Rich says that Apple has a program called Apple MFI (made for iPhone). If his accessory is MFI, then the culprit could be a failing cable. It could also be that his phone's connector could have some lint in it preventing his cable from connecting completely. Rich suggests taking a toothpick and sweeping it out. A gentle burst of canned air is a good idea too, but he should be sure to be gentle.