Why does iPhone 5 charge to 100% then not work when disconnected?
I suspect the battery, but not sure. It will charge to 100%, but then when disconnected it almost immediately stops working. Erratic. When left overnight without charging, it may or may not have charge remaining. Or, when left unplugged would not work until plugged in, at which point it might show 100% or 40% or whatever.
Also, could signal strength be part of the problem? Severe problem occurs in relatively remote locations or in airplane.